cementing services

Cementing Servicesand Products Catalog

Cementing Services and Products Catalog

© Schlumberger 2003

Schlumberger225 Schlumberger DriveSugar Land, Texas 77478

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transcribed in any form or by any means, electronic or mechanical, including photo-copying and recording, without prior written permission of the publisher.

TSL-4274

An asterisk (*) is used throughout this document to denote a mark of Schlumberger.† Mark of NExT‡ Mark of Den norske stats oljeselskap a.s. (Statoil)

Cementing Services and Products ■ Contents iii

Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Reservoir solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Research and development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Quality, Health, Safety and Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Key cementing technology highlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Deepwater cementing products and services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Deepwater slurries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

DeepCRETE deepwater cementing solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8FlexSTONE Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DeepCEM additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Well stress analysis software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9CemCADE software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Advanced plug placement module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Offshore cementing skids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9DeepSea EXPRES offshore plug launching system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Surface dart launcher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Subsea tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

A gas migration control service—GASBLOK service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Gas flow risk analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Routes for gas migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14CemCADE software—placement and postplacement risk analysis . . . . . . . . . 14

Cement slurry design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15High risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Low risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Slurry properties for gas migration control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Cement placement design and execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

iv

Lost circulation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Lost Circulation Advisor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

InstanSeal system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

InstanSeal Cement system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20ShearSEAL lost circulation fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20


PERMABLOK system for plugging zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21CemNET advanced fiber cement to control losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21


ZONELOCK S sealing system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22ZONELOCK SC permanent system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Mud removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23WELLCLEAN II engineering solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23


Pipe centralization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Displacement regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Fluids design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

WELLCLEAN II simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

WELLCLEAN II advisor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Chemical washes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

MUDPUSH spacers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Cementing Services and Products ■ Contents v

Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29CemCADE cementing design and evaluation software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29


Stress analysis model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

SoniCalc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35CemCRETE concrete-based oilwell cementing technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36LiteCRETE low-density slurry system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37


DeepCRETE deepwater cementing solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

DensCRETE Advanced Cement Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

SqueezeCRETE remedial cementing solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

CemSTONE Advanced Cement Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43FlexSTONE Advanced Cement Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44


ThermaSTONE extreme temperature cement technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

DuraSTONE Advanced Cement Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Cementing Slurry Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Lightweight Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

LiteCRETE cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50D049 lightweight cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Foamed cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Improved Bonding Cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51FlexSTONE Cement—advanced flexible cement technology . . . . . . . . . . . . . . . 51WELBOND cement—improved bonding cement system . . . . . . . . . . . . . . . . . . . . 51SALTBOND cement—cement system for cementing across salt zones . . . . . 51RFC regulated fill-up cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52SELFSTRESS expanding cement system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Fast Strength Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52DeepCEM Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52ARCTICSET cement—cement system for use through permafrost . . . . . . . . . 53Right-angle set cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Cements for harsh environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Acid-resistant cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Carbon dioxide-resistant cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Synthetic cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

UniSLURRY cement systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

UNIFLAC unified fluid-loss additive for cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

UNISET set control additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Cementing additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Accelerators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Antifoam and defoam agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Antigelation agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59DeepCEM additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Dispersants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Expanding Additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Extenders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Fluid-loss control additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Gas migration control additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Lost circulation control materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Retarders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Surfactants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Special additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Suspending and antisettling agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Thixotropic additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61UniSLURRY additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Weighting agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Spacers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Chemical washes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

vi

Cementing Services and Products ■ Contents vii

Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75CemSTREAK land cementing unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75


CPF-376 double-pump cement trailer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

CPT-372 double-pump cement truck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Offshore cementing skids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79Standard equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Optional equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

LAS liquid additive system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

CemCAT cementing computer-aided treatment software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

SFM-C process control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Nonradioactive densitometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87Execution analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87Post-cementing analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87Cement evaluation services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Sonic services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88SlimAccess tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

SCMT Slim Cement Mapping Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Ultrasonic services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90USI UltraSonic Imager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90Cement integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90Pipe integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91Nonstandard environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Marks of Schlumberger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

viii

Reservoir solutionsSchlumberger has been supplying products and services to the oil and gas industry for more than75 years. Our trained, highly qualified professionals team with operating companies to maximizeasset values with reservoir solutions that combine best practices and advanced oilfield tech-nologies with service quality and environmentally sound operations.

As exploration and production activities have expanded, our relationships with operatingcompanies have evolved. Today, we provide many services which help in finding hydrocarbons,constructing and completing wells to produce them and stimulating the wells to maximize theirproduction. We do this from service locations in all oil and gas well producing areas of the world.We are committed to innovations to provide real-time solutions to make the finding and produc-tion of oil and gas more cost effective and to maximize recoverable reserves.

With the movement toward a more holistic approach to oil and gas development, geoscientistsand engineers gain a thorough understanding of the reservoir by using exploration & productionproduct technology, field services and project management skills from oilfield technology alongwith software and information management services integrated with information technology(IT). Using this approach, the value of the reservoir is increased and the capital expendituresand negative cash flow are minimized.

Cementing Services and Products ■ Preface 1

Preface

Cash

flow

Reservoir Optimization Traditional Development

Time

Development MaturityDelineation

AccelerateProduction

MinimizeCapex

MinimizeOpex

DeferAbandonment

MaximizeProduction

MaximizeRecovery

Exploration

+

–

Cementing plays a role in this process by providing zonal isolation in the wellbore. High-quality zonal isolation allows more accurate well testing to define the reservoir, maximizes recov-ery at the least cost (reduced costs for produced water and its disposal), provides more effectivestimulation through placement focused on the reservoir, more effective enhanced recovery andreduced abandonment costs.

Research and developmentResearch has been a fundamental commitment since Schlumberger was founded in 1927. Despitefluctuations in business activity, our long-term commitment to research and development (R&D)is unwavering. During the market turndown in the late 1980s, we continued to spend heavily inR&D and we now invest nearly $1 million a day in research for oil and gas applications.

Schlumberger employs top-level scientists, engineers and support personnel, recruited fromthe best technical universities worldwide. Our research teams are multidisciplinary, embracingphysics, chemistry, materials science, mathematics, statistics, computer science, signal process-ing, instrumentation, earth science, and solid and fluid mechanics.

Our global R&D network provides a stimulating environment for the development of advancedtechnologies. This network includes■ Schlumberger-Doll Research, Ridgefield, Connecticut, a center of excellence for oilfield

research since the 1940s■ Schlumberger Cambridge Research, Cambridge, England, which has been developing new

concepts and techniques to help oil and gas companies find and produce hydrocarbons since 1981

■ Schlumberger Austin Research, Austin, Texas, at the leading edge of information technologydevelopment since 1989

■ Schlumberger Stavanger Research, Stavanger, Norway, established in 1999 as our firstresearch satellite to conduct research activities at strategic locations around the world

■ Moscow Research, established in Moscow, Russia, in 2002 ■ Dhahran Research, established in Dhahran in 2001 ■ Schlumberger Reservoir Completions Center, near Houston, Texas, launched in 1999 to

develop products and services for intelligent completions.

2 Cementing Services and Products

Quality, Health, Safety and EnvironmentAt Schlumberger, we strive to continually improve the quality of our products and services; to pro-tect the health, safety and property of our employees, our customers, our contractors and thirdparties; and to safeguard the environment in communities where we live and work. This proac-tive approach results in greater efficiency; reduced accidents, pollution and waste; and a morehealthful workplace.

Quality, health, safety and environment (QHSE) training, provided through state-of-the-artlearning techniques, is mandatory for all Schlumberger personnel. All new employees receiveboth general and job-specific QHSE orientation prior to their first work assignments, andemployees transferring to new positions or locations receive formal orientation about specificQHSE issues related to their new work environment. Our suppliers and contractors are evaluated,qualified and selected based on their ability to deliver a quality product or service in a safe,healthy and environmentally acceptable manner.

Schlumberger practices go beyond environmental compliance. As stewards of the environ-ment, we take proactive steps toward recognizing and eliminating detrimental practices.

QHSE requirements are incorporated into all stages of product design, development anddelivery. Prior to initiating a project or delivering a service, a formal assessment is conducted toensure that all QHSE aspects have been addressed.

TrainingSchlumberger training is continuous—employees receive both formal and on-the-job trainingthroughout their careers. We periodically assess all our training programs for content, quality andeffectiveness and we employ the latest technology to ensure that our training remains “best inclass.”

Our training emphasizes the use of IT. We have developed on-line and CD-ROM training modulesand achieve full use of IT by providing worldwide connectivity to the internal Schlumbergercommunications network and to the Internet. Both new employees and those studying foradvancement can use the Internet for their training courses.

Schlumberger technical training programs sponsor on-line, in-house and field training in allphases of equipment selection, application and operation, as well as effective design, executionand evaluation. Structured training programs and seminars provide the latest information andtechnical knowledge, and we conduct directed learning programs and seminars around theworld.

Within Schlumberger, no education is ever really complete. Methods and techniques change,as do market conditions and regulatory guidelines. Following formal university and in-housetraining, employees continue to gain knowledge through experience and pre- and postjob ses-sions in which principles and practices are continually improved.

The NExT† Network of Excellence in Training, an alliance of Heriot-Watt University inScotland, Texas A&M University, the University of Oklahoma and Schlumberger, provides trainingthat fills a learning gap for working professionals, both within and outside the company, to helpthem diversify their skill sets and learn about emerging technologies. Delivery methods includetraditional classrooms, mentor-supported on-line distance learning, CD-ROM self-study programsand custom on-site courses.

Our policy is to attract the very best graduates, then train and develop them. The majority ofSchlumberger managers started in the field directly after graduating.

Preface 3

Key cementing technology highlightsOur high-quality cementing solutions are based on application of best practices, environmentallysound wellsite operations, and innovative technology with safety as a highest priority. That tech-nology includes Advanced Cement Technology, CemSTREAK* rapid deployment cementers, deep-water cementing with DeepCRETE* cement and DeepCEM* additives, and UniSLURRY* cementsystems

Advanced Cement Technology increases the solids content of slurries by optimizing blends ofseveral particles with different sizes in which the smallest particles fill the spaces between largerparticles. Because of the higher solids content, the cement has greater strength, reduced per-meability and greater resistance to corrosive fluids.

The CemSTREAK unit is a lightweight, low-maintenance truck with four-wheel drive. It canhandle almost any cementing application, even in hard-to-reach well locations. Equipmentdesign makes rig-up, rig-down, cleanup and movement to next location fast and efficient. Thisdesign allows a single unit and crew to cement as many as six wells in one day.

In deepwater cementing, DeepCRETE slurries, with their excellent slurry and set-cementproperties, are combined with DeepCEM additives, providing improved rheology, rapid strengthdevelopment, and high strength. Compared with conventional cement technology, these tech-nologies reduce the risk of shallow flow and shorten the waiting-on-cement time and its associ-ated high cost.

UniSLURRY systems can be used for all types of cementing operations, including casing, liner,squeeze and plug cementing. Similarly, the additives are functional throughout the range of appli-cation conditions. This versatility simplifies the logistics of offshore cementing by reducing thenumber and quantity of additives that have to be transported and stored.


Schlumberger provides high-quality services for well construction and remedial applications.These services are based on best practices, environmentally sound wellsite operations, andinnovative technology, and always have safety as a first priority.

Cementing is a process used to support and protect the casings in a well and to achieve orrenew zonal isolation. Zonal isolation is required to prevent liquids or gases from flowing fromone zone to another within the wellbore. This isolation allows the completion and productionand subsequent abandonment of the well at the lowest possible cost. Isolation allows moreaccurate well testing to define the reservoir, maximum recovery at the least cost (reduced costsfor produced water and disposal), more effective stimulation through placement focused on thereservoir, more effective enhanced recovery and reduced abandonment costs. Without isolation,the cost of each of these processes is increased and its effectiveness is reduced.

When isolation is not achieved by the primary cement job (cementation of the casing string)a squeeze job is required to correct the deficiency. Squeeze jobs are also used during the well’slife to meet changing objectives as the well and field age.

Occasionally, cement plugs are set in the well to allow changes in drilling. Plugs are also usedto isolate intervals within the well when it is depleted and abandoned.

All these cementing treatments require careful design of the cement systems to provide therequired properties of the slurry before setting and of the cement once it is in place and set.Designs must consider the conditions in the well at the time of cement placement as well asconditions that may occur at any time during the life of the well. In addition to the design of theslurry and set-cement properties, the mechanics of the placement process must be designed toaccomplish optimal mud removal and cement placement. On location, the cement must beproperly mixed to achieve the required properties and pumped into place, maintaining theintegrity of the well.

To achieve the cementing objectives, various additives can be used to modify the slurry andset-cement properties. Specific cement slurry systems are employed to meet especially demand-ing applications. A new, innovative approach to cementing is Advanced Cement Technology. Thistechnology utilizes principles from the concrete industry, specially adapted for oilfield use, to for-mulate slurries with lower water content. These advanced principles eliminate the problems ofconventional slurries, which require high water content for optimal pumpability that ultimatelyreduces the compressive strength of the set cement.

This Advanced Cement Technology has two families; CemCRETE* concrete-based oilwellcementing technology and CemSTONE* technology. CemCRETE technology increases the solidscontent of the slurry using a custom-designed particle-size distribution. More solids in thecement mean greater compressive strength, reduced permeability and greater resistance tocorrosive fluids. CemSTONE technology uses this high solids content together with particleshaving specific properties to modify the set-cement performance (such as durability, flexibilityand expansion) to the needs of the well. When coupled with stress analysis model software,cements are designed with properties to provide isolation for the life of the well.

Cementing Services and Products ■ Introduction 5

Introduction

Our cementing software is used worldwide by Schlumberger engineers. CemCADE* cement-ing design and evaluation software, which allow simulation based on well data and formationconditions, is used to plan the proper placement of the slurries and ensure the integrity of thewell is not compromised. DESC* design and evaluation services for clients improves communi-cations and solutions development by placing a dedicated Schlumberger engineer in the client'soffice with access to information hubs, technology centers and the most complete family ofapplication software in the industry.

Purpose-built and highly specialized mixing and pumping equipment is employed to properlyexecute the treatment, while the CemCAT* monitoring and recording system provides a recordof the treatment. Use of the CemCAT record, along with design parameters and placement andisolation evaluations such as those provided by USI* UltraSonic Imager logs, allows the designengineer and service team to make performance enhancements and use principles of continuousimprovement to enhance the value of the cementing process.


Deepwater cementing products and servicesDeepwater drilling poses unique challenges for cementing. Large-diameter casings are set inpoorly consolidated formations, frequently with a narrow pore-fracture pressure window andhigh potential for shallow-flow hazards (water or gas). Compounding the problems is the lowtemperature found at the sea bottom and the first few thousand feet below mudline. With sub-sea wellheads, launching cement wiper plugs is also more complicated. Logistically, the distancefrom shore makes versatility in cement slurry design an important consideration. Add to this thedifficulty of remedial work in the deepwater environment and annular sealing throughout the lifeof the well becomes more critical.

Abnormally pressured sands, with a high probability of shallow-water or gas flow, character-ize many deepwater geological environments. Such flows present problems in cementing opera-tions, affecting the integrity of the well. Consequences of uncontrolled shallow flows includesubsidence, compromised seafloor stability, loss of well support and buckling of structural cas-ing, and compromised wellbore integrity, resulting in well control problems and potentially lossof the well and supporting structures.

Schlumberger provides innovative products and services for solutions to deepwater cement-ing challenges. DeepCRETE slurries, DeepCEM additives and GASBLOK* gas migration controlslurries (when gas-flow potential exists) deliver the properties necessary to provide rapid set-ting, control of potential flows and the long-term isolation needed to ensure the integrity of thewell and protect the environment. The DeepSea EXPRES* offshore plug launching system allowsthe efficient release of bottom and top wiper plugs in subsea cementing heads to prevent cementcontamination and control displacement. Engineers use CemCADE software, proven over twodecades, for placement design and to assure well security and control. Offshore cementing skids,built for performance and reliability, provide the means to efficiently mix and pump the high-quality slurries required in this tough cementing environment.

Cementing Services and Products ■ Services 7

Services

Innovative deepwater cementing solutions provide effective and efficient cementationof wells drilled in deepwater.


Deepwater slurriesDeepCRETE cement slurry systems are based on CemCRETE Advanced Cement Technology com-bined with DeepCEM additives to minimize risk of shallow flow, enhance strength development,reduce waiting-on-cement (WOC) time and to provide low permeability of the set cement.

When needed, FlexSTONE* Advanced Cement Technology slurries can be employed to provideset-cement durability, with annular cement sheaths able to withstand changing downholestresses without failing.

DeepCRETE deepwater cementing solutionThe DeepCRETE deepwater cementing solution is a combination of efficient technologies pro-ducing slurries that let you cement weak, deepwater zones where low temperature and potentialshallow flow exist, yet quickly return to drilling. This DeepCRETE technology, which provideslow-density slurries with excellent strength and low permeability, is ideal in the environmentencountered in deepwater well construction. Without requiring special equipment or personnel,DeepCRETE slurries isolate the formation with a light cement that develops strength rapidly.This is done using the CemCRETE concept combined with DeepCEM liquid additives, to delivershort transition time and rapid setting at low temperatures. With CemCRETE technology, per-meability and strength are independent of slurry density and superior to those of conventionalcements.

See page 36 for additional information on CemCRETE Advanced Cement Technology.

FlexSTONE CementFlexSTONE systems offer mechanical properties that can be engineered to meet the changingstresses in the wellbore; excellent flexibility and chemical resistance while maintaining lowerpermeability and good compressive strength. FlexSTONE systems, with these properties cus-tomized to the well, will resist stresses and maintain isolation. These slurries also expand to sealany microannulus. As FlexSTONE cements are engineered to be more flexible than the formationthey seal, this expansion of the cement sheath occurs both outwards (toward the formation) andinwards, (toward the casing), thus assuring complete hydraulic isolation.

See page 44 for additional information on FlexSTONE Advanced Cement Technology.

DeepCEM additivesDeepCEM liquid cementing additives were created for short transition time and early compres-sive strength development. Such properties are necessary for isolation and early casing releaseto ensure successful cementation in the unconsolidated, low-temperature environment of thesurface and conductor casings in deepwater wells. When combined with Schlumberger GASBLOKgas migration control technology, DeepCEM slurries provide the solution to shallow gas or waterflow control. These additives can be used in foamed cement slurries.

Use of these systems allows elimination of the special blends often needed to overcome chal-lenges related to low temperature in deep ocean drilling.

DeepCEM additives include the nonretarding dispersant (D185) and cement set enhancer(D186). The non-retarding dispersant provides the dispersion required for good slurry designwithout retardation at low temperatures. Even at the low temperatures encountered in deep-water wells, D186 set enhancer is more effective for early strength development than standardcement accelerators such as calcium chloride.

Services 9

Well stress analysis softwareStress analysis model software is used to identify potential well stresses and their magnitudethroughout the life of the well. Engineers then design the appropriate set-cement properties towithstand these stresses. Where required, FlexSTONE technology is designed with the propertiesidentified using this software. FlexSTONE systems are purpose-built to offer control over proper-ties not possible with conventional oilwell cement. These include such set properties as flexi-bility and expansion using proprietary flexibility and expanding additives for continuous wellintegrity and zonal isolation for the life of the well.

CemCADE softwareCemCADE software can be used to design all primary cementing operations, from large-diameterconductor casing to the deepest liners. Use of CemCADE software helps the engineer ensure thatwell security is respected at all times and points in the well during the cementing treatment. Bycoupling centralization calculations with a numerical fluid placement simulator, CemCADE soft-ware allows easy flow regime and annular flow rate selection. It also aids in design of wash,spacer and slurry for optimum displacement of mud and cement placement. Displacement opti-mization helps to prevent channeling, ensuring zonal isolation.

The program utilities and underlying physics are enhanced continually to reflect the latestdevelopments in cementing technology. Of particular interest for deepwater operations are thetemperature simulator, gas migration predictor, and swab and surge pressures calculator. Thetemperature simulator allows a calculation of fluid and wellbore temperatures that considerswellbore environment parameters such as seawater temperature and current. Better knowledgeof the temperature makes selection of retarder or accelerator concentration more accurate aswell as allows WOC time determination based on modeled wellbore temperatures.

Advanced plug placement module Due to the high operating cost in deepwater, time for any operation must be minimized. This isespecially true when setting cement plugs. A module assists engineers in designing plugs tominimize contamination during placement, resulting in much higher plug-setting success. Thissuccess minimizes the need for repeat plugging operations, thus saving valuable rig time.

See page 29 for additional information on CemCADE software.

Offshore cementing skidsThe performance and versatility of Schlumberger skid-mounted cementing units make them thebest option for offshore, high-pressure pumping services. These state-of-the-art units, capable ofdelivering up to 1490 kW [2000 hhp] of power, can be used as backup or supplemental mud pumpsas well as efficient cementing units. Power to drive the pumps comes from high-performancediesel engines or air-cooled electric motors.

These units are fitted with state-of-the-art sensors for data acquisition and monitoring, and anoptional remote control system permits operation of the unit from an adjacent control room.When a Schlumberger SLURRY CHIEF* cement mixer is used in combination with the skid,cement-mixing rates of more than 1.9 m3/min [12 bbl/min] can be achieved for optimal job exe-cution.

See page 79 for additional information on offshore cementing skids.

Liquid additive metering systems provide versatility in the ability to adjust cement slurry prop-erties right up to the time of the cementing treatment. This is especially beneficial in deepwateroperations, as the requirements may not be known until the hole section is drilled. If dry-blendedcements were used, not knowing the requirements until the section is drilled would require con-siderable time waiting for testing, blending and delivery of the cement.

DeepSea EXPRES offshore plug launching systemThe Schlumberger DeepSea EXPRES offshore plug launching system is a remotely operated sys-tem for releasing cementing wiper plugs from a subsea tool. It combines a design for safety withhighly functional, high-quality plugs to provide a reliable system for launching plugs in a subseasystem. This system uses solid plugs, which are more reliable than the flow-through type. Plugsare released with minimum or no shutdown of the cementing operation.

Applications■ Casings hung from subsea hangers■ Top and bottom plug operation in casing sizes from 244 to 508 mm [95⁄8 to 20 in.]

Benefits■ Dart release takes only seconds, reducing rig time.■ Uninterrupted pumping improves mud removal. ■ High pumping rates allow improved mud removal. ■ Casing pressure test can be combined with bump.■ Casing running tool can be activated without removing treating lines. ■ Remote operation improves safety.

Features■ Wiper plugs are efficiently designed. ■ Fluids are not pumped through the plugs.■ Plugs do not contact casing wall during rig-up.■ Surface pressure provides positive indication of each plug release.■ Plug launch qualified at flow rates up to 1.9 m3/min [12 bbl/min].■ Optional three plugs separate up to four fluids.


Cement mixing and pumping units are specially designed for use on offshore drilling rigs.

Surface dart launcher A surface dart launcher (SDL) holds the darts, which are launched during the cementing opera-tion. When they reach the subsea tool, these darts release the casing wiper plugs. The standardconfiguration can hold two darts up to 610-mm [24-in.] long. The SDL is modular, so additionalhardware can be added to launch more darts.

Fluids are pumped around the outside of the dart holder. To launch a dart, the EXPRES*system power pack, operated from the rig floor, rotates the valve a quarter turn. This rotationaligns a hole in the valve body with the dart and launches the dart.

The SDL offers full top-drive compatibility. The fluid inlet swivel provides two 50.8-mm [2-in.]WECO connections and permits pipe rotation with the treating lines attached. The 114.3-mmNC50 [41⁄2-in. IF] connections at top and bottom allow the entire string to be supported androtated. Both circulating mud and displacement fluid can be pumped through the topdrive.

Darts offer several advantages over “free fall” balls. The darts wipe the inside of the drillpipeand separate the fluids to prevent contamination. They also provide positive fluid displacement.The time and uncertainty spent waiting for a ball to reach the downhole assembly are eliminated.

Services 11

DeepSea EXPRESS offshore plug launching system is a reliable tool for releasing cement wiperplugs when subsea hangers are used.

Subsea toolThe subsea tool (SST) retains the casing wiper plugs until they are released by the arrival of thedarts. Hydraulic pressure acting through the dart and a rod releases the plugs. The SST acceptsup to three plugs for 219 to 340-mm [85⁄8 to 133⁄8-in.] casing or two plugs for 406 to 508-mm[16 to 20-in.] casing.

The deepwater cementing products and services portfolio of Schlumberger provides all thecomponents required to provide zonal isolation for the life of the well.

A gas migration control service—GASBLOK serviceGas migration, or annular gas flow, is a problem that has plagued the industry for many years.There is no one cause of gas migration, nor is there any one solution to it. To effectively controlgas migration, the nature of the problem must be understood so that the proper techniques canbe applied. This implies a careful analysis of the potential for flow as well as an integratedapproach to its control. During this analysis, one must consider not only the potentially produc-tive intervals, but also the intervals that may not be economically productive, including gasstringers, which can exist behind any casing string.

Among the reasons for gas migration are an uncemented channel, failure to maintain over-balance pressure before and during cementing, loss of overbalance pressure after cement place-ment, development of flow paths after cement setting and insufficiently low permeability toprevent gas from flowing through the set-cement matrix. Obviously, each of these arises from dif-ferent mechanisms. Therefore, control of gas migration must address the totality of the sourcesfor flow.

Controlling gas migration takes much more than just complex cement slurry design. Slurrydesign addresses only one facet of the complex problem, albeit a very key one. An element of theoverall process of controlling gas flow is achieving zonal isolation through the intervals contain-ing the gas. An additional element is maintaining overbalance pressure during the critical tran-sition period. The final element is preventing gas from migrating along the annulus. TheGASBLOK service considers these elements as three phases of the process: remove the drillingfluid to provide the proper environment for zonal isolation, delay gas entry, impede propagationof the gas.


Each of these phases requires careful analysis and design to achieve the desired overallresult—a well that is free of gas migration. The first step, that of achieving zonal isolation, isaccomplished by the cement, but only after the drilling fluid has been removed from the wellboreto allow cement to fully occupy the annulus between the borehole and the casing. Mud removalis accomplished by techniques that have been developed by Schlumberger through the years, cul-minating in the WELLCLEAN II* engineering solution for mud removal. This solution considersthe factors that impact mud removal and provides a systematic approach to removal of mud.

The second step is to design the placement process so that an overbalanced condition is main-tained until late in the transition of the cement from a liquid to a solid. The nature of the settingprocess makes it difficult to maintain overbalanced pressure; after placement, cement undergoesa gradual gelation, resulting in loss of hydrostatic pressure. Ideally, the pressure is maintainedabove formation pressure until the cement is set. In practical terms, this is extremely difficult todo. Another option is to minimize the time between development of gel strength and setting whilemaximizing the overbalanced pressure (without risking breaking the well down). This is done byanalyzing the pressures in the well and employing options that maximize the overbalanced pres-sure. Several tools in CemCADE cementing design and evaluation software assist in this step.Obviously, a component of this step is the design of the slurry.

The third step, impeding propagation of the gas, depends on the use of slurries with specialproperties so that gas cannot invade and migrate along the cemented annulus. Special proper-ties, such as those provided by GASBLOK slurries, are required during the critical transitionperiod as well as after setting. Additionally, to maintain isolation for the life of the well,CemSTONE Advanced Cement Technology may be required.

Applications■ Zonal isolation in gas wells■ Prevention of annular gas migration from nuisance gas stringers

Benefits■ Minimized risk of gas migration ■ Long-term solution■ Reduced exposure to hazardous gas flow■ More trouble-free operations

Features■ Tailored to specific well conditions■ Effective at any density ■ Effective at any temperature■ Compatible with CemCRETE and CemSTONE technologies■ Integrated solution employing materials and techniques■ Materials with low environmental impact■ Engineering tools to assess risk and tailor treatment to severity

Services 13

Gas flow risk analysisA risk analysis is an important element in the design for gas migration control. Such an analysisincorporates knowledge of all the gas sources (from openhole logs and drilling logs), the poten-tial for gas flow from each source and the potential routes through which gas can migrate.

Routes for gas migrationGas migrates in a well when the pressure becomes underbalanced. If the cement is in place andset when this occurs, the potential for flow depends on the integrity of the cement, both its com-plete filling of the annulus and its mechanical durability. Paths for gas flow develop as a result ofincomplete mud removal (a mud channel), free fluid development in the cement slurry, or aninterfacial gap (microannulus) at the cement-pipe or cement-formation interface. An additionalpath can be created if the cement fails mechanically, producing a crack along its length. Thesepaths can also be created by changing mechanical stresses in the well.

A path can be created if the well becomes underbalanced before the cement has developedsufficient strength to prevent its propagation through the column, that is, while the cement isunset. In this case, gas can migrate through the unset cement, forming a channel.

CemCADE software—placement and postplacement risk analysis CemCADE cementing design and evaluation software has two tools that aid in preventing gasinvasion of the cement before it has developed adequate strength to control gas flow. The first isa tool common to most cementing simulators, an analysis of the fluids and pressures in the wellduring and after the cementing process to determine well security and control. If an underbal-anced condition develops during cement placement, a warning is given and the fluids and/orplacement process are redesigned.

A second tool, called postplacement analysis module, provides the design engineer with anindication of the relative risk of gas migration based on the degree of overbalance and the wellgeometry. The engineer can then assess variations in slurry placement and treatment executionvariables to propose the lowest-risk method of cementing the well. In cases where the risk isjudged to be small, less-aggressive solutions can be proposed; conversely, if the risk is judged tobe high, more aggressive solutions should be considered.


Very critical Critical Moderate Low Very low

25 pa50 lbf/100 ft2

75 pa150 lbf/100 ft2

150 pa300 lbf/100 ft2

250 pa500 lbf/100 ft2

Postplacement analysis provides the design engineer with a relative degree of risk for use in selection ofmethods of controlling gas migration.

Cement slurry designSlurry design for controlling gas migration requires attention to the entire realm of slurry and set-cement properties. These include free fluid, fluid loss, rheology, thickening time, gel strengthdevelopment, setting profile and set mechanical properties including permeability. In wells witha high risk of flow, slurries with special properties to stop gas invasion and flow may be required.Their use is normally based on the perceived risk of gas flow.

After assessment of risk, the design engineer develops the slurry design and placementaccordingly. For scenarios with low risk, control of free fluid, rheology, gel strength developmentand fluid loss may be adequate to control gas flow. Where the risk is higher (or uncertain), theuse of more complex slurries with special properties to contain the gas are required.

High riskSchlumberger slurries for high-risk gas migration scenarios have very special properties. Theseslurries are called GASBLOK slurries, proven for over two decades. GASBLOK slurries are part ofthe overall GASBLOK technology, a systematic approach to solving the gas migration problem.These slurries use either a specially designed and patented latex additive or a customized micro-gel polymer.

The latex provides unique properties to cement slurries and the set cement. Being a suspen-sion of solids, the latex provides excellent rheological properties and control of gelation withoutaffecting the hydration process. Free fluid is easily controlled and setting is rapid. The finelydivided latex particles provide efficient pore-blocking in the developing cement matrix during thetransition from liquid to solid and in the set cement. This pore-blocking minimizes the invasionof the cement by gas and prevents its movement. Microgels provide similar effects, but with spe-cially designed hydrated polymer particles.

The GASBLOK family of additives includes D500 GASBLOK LT additive, D600G GASBLOK MTadditive, and D700 GASBLOK HT additive for low, moderate and high temperatures, respectively.A surfactant, D701 GASBLOK stabilizer, is used to control transition time and setting in certaincases. These additives, used so successfully in controlling gas migration for the past two decades,have been modified to make them acceptable in more environmentally sensitive areas, such asthe North Sea.

Low riskWhen the risk of gas migration is judged to be low, less-aggressive designs are required. Slurriescan be designed with more conventional fluid loss additives in place of the GASBLOK latices ormicrogel. Besides fluid loss control, excellent slurry and set properties must still be maintained.

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Slurry properties for gas migration controlLaboratory and field evaluations have demonstrated that several properties of cement slurriesare critical in controlling gas migration.

Fluid loss control is important, because maintaining the proper ratio of water to solids is crit-ical to maintaining the rheological properties for effective placement of the slurry as well as pre-venting premature gelation. Premature gelation will lead to long transitions to a set matrix andresult in unacceptably early hydrostatic pressure decay. Such hydrostatic pressure decay wouldin turn lead to an underbalanced condition. If occurring before the cement develops a solidmatrix, this situation can easily lead to gas invasion of the cement and migration along the annu-lus to points of lower pressure.

Simultaneously, the proper water/cement ratio must be designed and maintained to controlslurry stability. An unstable slurry can allow the development of free fluid and/or solid sedimen-tation. Free fluid can create a water channel in the column of cement, leading to gas flow.Sedimentation can lead to changes in density of the slurry and result in inadequate fluid pres-sure to control the formation pressure. An additional impact of the water/cement ratio is that ofthe slurry and set-cement permeability. As the water/cement ratio increases, so does the perme-ability of the cement matrix. A permeable cement matrix makes control of gas more difficult; ifpermeability is sufficiently high, there may be migration through the matrix after setting.


Result■ Interzonal communication■ Pressure charged formations■ Gas to surface■ Blow out

Poor mudremoval

(rheology)

Freefluid

Highfluidloss

Cementhydration

Gelstrength

development

Bulkshrinkage

Chemicalcontraction

Gaschanneling

withincementmatrix

Gaschanneling

alonginterfaces

Unplanned costs■ Remedial work■ Lost production■ Damage to equipment and facilities

Many slurry properties must be correctly designed for success when cementingacross gas-bearing formations.

The setting behavior of the cement is important for several reasons. Initially, early settingdetermines the relationship of strength development to hydrostatic pressure decay (and under-balance and gas flow initiation). Subsequently, permeability, shrinkage, expansion and long-termdurability are controlled by the setting behavior. As discussed previously, permeability must bekept low to minimize or prevent gas flow through the set-cement matrix. Shrinkage can resultin the development of microannuli between the cement and pipe or wellbore wall. Shrinkagecan also result in radial cracking of the cement, which provides another path for gas to flow.Long-term durability can be enhanced with CemCRETE and CemSTONE Advanced CementTechnology.

CemCRETE and CemSTONE slurries are highly effective in achieving the properties necessaryfor gas migration control. CemCRETE slurries provide low-permeability cement, even at very lowdensities. They also have excellent slurry properties (stability, rheology, etc.). CemSTONE slur-ries have very high durability and, if required, can be designed to expand. When coupled withGASBLOK technology, both slurry systems provide excellent properties to meet the demandingrequirements for gas migration control.

Cement placement design and executionThe control of gas migration requires more than special slurries. Successful control involvesmany elements.

Mud removal design—Mud removal is critical to achieving zonal isolation. Schlumbergerengineers use the advanced WELLCLEAN II technology for designing the flow regime, fluids andpumping schedule to achieve mud removal.

Coverage of zone of interest—There must be adequate slurry covering all the gas-bearing for-mations, not just the pay zone.

Maximize overbalanced pressure—Pressure decay, an unavoidable consequence of thechange from slurry to set cement, results in loss of overbalance. By maximizing the overbalancepressure, the age and therefore the strength of the cement is greater at the time an underbal-anced condition is reached. The Schlumberger engineer uses the postplacement tool inCemCADE cementing design software to optimize the overbalanced pressure.

Gas migration risk—The Schlumberger engineer uses the postplacement module of CemCADEsoftware to evaluate design and operational effects to lower risk of gas flow. Application ofpressure on the annulus following placement, as well as other operational procedure changes,can reduce the risk.

Well security and control—Throughout the cementing process, the pressures in the well mustbe sufficient to control the gas yet not be so high as to cause lost circulation. The U-tube simu-lator in CemCADE cementing design software provides a plot showing the pressures at all timesduring the cementing treatment and aids the engineer in maintaining security and control inthe well.

Hydrostatic-pressure-relieving devices—At times, openhole casing packers are used to isolatesections of the wellbore. Care must be taken with these devices, as they have the effect of pre-venting full hydrostatic pressure transmission and can aggravate the problem. Any loss of volumebelow the packer (such as by fluid loss) can result in very rapid hydrostatic pressure loss and sub-sequent rapid gas migration through the entire section isolated by the packer. Gas pressure canbuild up beneath the packer and cause failure of the packer.

Well design—Although not a common approach to solving gas migration, changes can be madeto the well design to change the level of risk. Using the postplacement module of CemCADE soft-ware, the Schlumberger engineer can work with the well design team to evaluate parameters andredesign the well for the lowest risk for gas flow. An example of a well parameter that plays a partin gas migration risk is the annular gap size. Increasing the annular gap will lower the risk of gasmigration.

Schlumberger engineers integrate all the elements of gas migration control. The risk analysis,the complete placement design and the optimum design of the cement slurries minimize the riskof gas migration, providing zonal isolation and well integrity.

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Lost circulation systemsLost circulation is a frustrating, costly and time-consuming problem. Some of the major conse-quences of lost circulation include increased cost resulting from

■ poor or no removal of cuttings, requiring additional wiper trips ■ stuck drill pipe■ excessive mud lost■ remedial work to cure losses■ rig time required to cure losses.

Reservoir damage and loss of well are also possible as a result of

■ lack of zonal isolation caused by poor cement coverage■ formation damage resulting from mud losses■ blowout after a drop in hydrostatic pressure.

To select the correct technique to effectively solve lost circulation, it is necessary to know thereasons for the losses; i.e., the type of loss and the drilling history.

Very often lost circulation treatments fail due to the lack of information such as the types oflosses and their relative depths. A lack of knowledge can lead to selection of the wrong treatment,which usually results in poor success, excessive costs and time, and the frustration caused byrepetitive failures.

Lost circulation can occur at any time in the life of the well. During construction, lost circu-lation can be encountered while drilling and while cementing. These problems are solved by dif-ferent methods. A tool for identifying the best solution is the Lost Circulation Advisor.

Lost Circulation AdvisorThe Lost Circulation Advisor is software developed jointly by Schlumberger and M-I, LLC. It is acase-based reasoning tool, used to analyze lost circulation problems and recommend the besttreatment to control the losses. The advisor is a knowledge-management software based on thefield experience and the lost circulation expertise of field engineers. Regardless of the loss type(partial or complete) and the operation (drilling or cementing), the advisor guides field person-nel toward the best lost circulation treatment. Based on the input data that include well data,previous lost circulation treatments, operation (drilling or cementing), estimated loss rate andopenhole stratigraphy, the advisor identifies the type of loss and its depth. Finally, the LostCirculation Advisor recommends the best lost circulation treatment from a list of generic andspecialized systems available from M-I, LLC and Schlumberger. Once the best lost circulationtreatment is identified, complete technical data are provided for the design of the treatment.

Applications■ All types of lost circulation

Benefits■ A simple software based on knowledge management, not complicated mathematical models■ A systematic and analytical approach to lost circulation■ A guide to the best lost circulation treatment and the relative depths■ Validated cases provide more precise solutions■ A low cost solution to complex problem


Features■ Case-based reasoning■ Identifies whether the losses are to permeable formations, natural or induced fractures, vugs,

or cavernous formations■ Estimates the depth of losses ■ Identifies the best lost circulation treatment based on the operation (drilling or cementing)■ Provides technical information for use in designing the recommended treatments

InstanSeal systemThe InstanSeal‡ system is a unique technology for combating high mud losses. It is often moretime and cost effective than other lost circulation control methods. The InstanSeal system usesshear activation to trigger formation of a rigid gel. This unique activation method saves crucialdrilling time and money over other lost circulation methods.

The base fluid for InstanSeal lost circulation control is an emulsion. The emulsion containsgelling polymer and crosslinker in separate phases. The emulsion is converted when the slurry ispumped through the nozzles in the bit, crosslinking the polymer. This results in rapid action andexcellent control of polymer placement into the loss zone.

Applications■ Severe lost circulation

Benefits■ Internally activated■ Valuable rig time savings■ Downhole mixing of fluids not required

Features■ Use to 95°C [200°F]■ Set time is independent of bottomhole temperature (BHT)■ Can be weighted to 1440 kg/m3 [12 lbm/gal] ■ Requires no tripping ■ Set time is short and is adjustable ■ Is acid-soluble when set ■ Can be mixed up to 3 weeks before use

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500 psi

Emulsion Set gel

Water phase containing high concentration of polymer

Crosslinker particle

Oil phase

Cement

Activation of the InstanSeal system is by shearing force rather than chemical action.This makes placement across the loss zone more certain.

InstanSeal Cement systemThe InstanSeal Cement system is similar to the InstanSeal system, but has powdered cementadded to the oil phase. Once the emulsion is broken and the system forced into the loss zone, thecement will become wet with water and will set. This provides a more permanent solution whenrequired. InstanSeal Cement is stable to 110°C [230°F].

ShearSEAL lost circulation fluidShearSEAL* shear-activated, high-temperature lost circulation fluid is a highly innovative, lost circulation solution. The system can be used at temperatures to 163°C [325°F] versus 95°C [200°F] for InstanSeal system. If necessary, it can be weighted to 2040 kg/m3 [17 lbm/gal] (vs. 1440 kg/m3 [12 lbm/gal]). It can be mixed using batch-mixing techniques or continuouslywith a static, in-line mixer. The crosslinked gel is not shear sensitive, has improved elasticity,exhibits no syneresis and is removable with light acid.

The base fluid for ShearSEAL lost circulation control is an emulsion. The emulsion containsgelling polymer and crosslinker in the oil phase. The emulsion is converted and the polymercrosslinked when the slurry is sheared through the nozzles in the bit. For activation, only a1725-kPa [250-psi] pressure drop at the bit is required. Activation as the bit results in rapidactivation and excellent control of placement of the gelling polymer into the loss zone.

In addition to use for lost circulation control, ShearSEAL system can be used to create supportbeneath a cement plug and to fill the rathole during cementing of the casing.

Applications■ Severe lost circulation■ Support for cement plugs

Benefits■ Internally activated■ Saves rig time ■ Requires no downhole mixing of fluids

Features■ Use to 163°C [325°F]■ Set time independent of BHT ■ Can be weighted to 2040 kg/m3 [17 lbm/gal]■ Requires no tripping ■ Set time is short and adjustable ■ Is acid-soluble when set ■ Can be mixed up to 3 weeks before use


PERMABLOK system for plugging zonesThe PERMABLOK* fluid system to permanently plug a zone is used to solve lost circulation prob-lems (either during drilling or before cementing), plug high-permeability zones and provide con-solidation of weak formations. Such high permeability can appear as interconnected porositywithin the matrix, or micro- or macrofissures including vugs.

PERMABLOK systems are internally activated solutions with very low initial viscosities. Thesolutions have controlled gelling (pumping) times and set to form a rigid, drillable gel. With atemperature limit of 79°C [175°F], these solids-free liquids have many applications, includingpumping through the bit. PERMABLOK systems can also be used to permanently plug formationsand to consolidate loose formations that threaten, slow or halt drilling.

CemNET advanced fiber cement to control lossesWhen cement is pumped downhole, some of the cement can be lost into natural fractures, fis-sures, vugs or highly porous zones even when the fracture pressure is not exceeded. CemNET*advanced fiber cement is composed of an inert, fibrous material capable of forming a networkacross the loss zone, allowing circulation to be regained. The CemNET fibers are engineered toan optimal size for sealing such loss zones.

CemNET fiber (D095 or D096) is compatible with most cementing systems and additives with-out affecting the cement properties. CemNET fiber is added to the slurry in the mixing tub or abatch mixer. This feature allows the CemNET fibers to be used only in the portion of the slurry tobe pumped downhole where losses are expected to occur. Once dispersed in the slurry, theCemNET fibers create a physical network that forms a bridge when flowing past loss zones,resulting in control of losses and improved fill of the cement during treatment.

CemNET fibers seal formations having potential for losses during treatment, reducing both theamount of cement used and disposal during cleanup. In operations where CemNET fibers are notused, operators often pump excess cement in anticipation of losses to fractures, fissures, vugs orhighly porous zones. By adding CemNET fibers to the existing cementing program, well costs arelowered. These cost reductions are a result of smaller excesses of cement needed to achievereturns, reduced disposal of large excesses returned to surface, and more significantly, reducedremedial cementing in the event that cement is not returned to surface.

In some cases, the use of CemNET fiber in the cement has resulted in regained returns.

Services 21

CemNET fibers are inert and require no special handling. They can be readily dispersed in water-base fluids such as cement. An interlocking network is formed,allowing the cement to bridge and resume circulation.

Applications■ Regain circulation while cementing■ Most cement slurry formulations ■ All temperatures■ Any slurry density

Benefits■ Minimizes losses during cementing ■ Raises cement tops ■ Helps prevent cement fallback■ Reduces the need for costly remedial operations■ Reduces excess cement requirement■ Makes cement returns more predictable, thus decreasing disposal costs■ Provides coverage of loss zones during cementing operations

Features■ Fibers added directly to the slurry during mixing, without dry blending ■ Does not affect cement properties■ Compatible with most cementing systems and additives■ Forms bridging network in the slurry

ZONELOCK S sealing systemThe ZONELOCK* S permanent zone sealing system is a solution of silicate that forms a rigid,semipermanent gel when in contact with a heavy calcium or sodium brine. The system is com-posed of two solutions: one silicate and one calcium chloride. This system is very effective andworks independently of temperature. It can be used to effectively seal problem zones of brine pro-duction or lost circulation. The solutions can be pumped in multiple stages to cover the zonemore effectively.

ZONELOCK SC permanent system The ZONELOCK SC system includes the ZONELOCK S system followed by a spacer and thencement. When the cement contacts the gel resulting from the silicate-calcium brine solution, thecement sets very rapidly. This ZONELOCK SC system forms a permanent seal that can only beremoved by drilling.


Mud removalWELLCLEAN II engineering solutionEffective mud removal is considered the most basic requirement for cementing success. Failureto achieve removal of mud can result in failure to isolate productive intervals, allowing produc-tion of unwanted fluids, misapplication of stimulation treatments, and chronic issues of sustainedcasing pressure and gas migration. When such conditions exist, additional costs and efforts areincurred.

Applications■ Mud removal in oil and gas wells, including deviated, extended-reach, horizontal and injection

wellbores■ Oil-base mud (OBM) or water-base mud (WBM)

Benefits■ Enhances zonal isolation■ Eliminates production of unwanted downhole fluids ■ Reduces occurrence of sustained casing pressure■ Minimizes casing corrosion through improved cement bonding■ Reduces remedial operations and their associated costs

Features■ An engineered approach using specialized tools and products■ Ability to assess the effect of all relevant parameters on the mud removal process■ A wide range of flexible preflush systems for all application conditions■ Proven results in the field■ Environmentally friendly spacers

Recognizing that effective mud removal cannot be achieved without considering the effect ofall relevant parameters, the WELLCLEAN II engineering solution utilizes innovative productsand tools to design cement placement for effective zonal isolation. These products and toolsinclude■ optimized chemical wash systems

■ a wide range of custom spacers for all applications

■ WELLCLEAN II simulator, CemCADE software and WELLCLEAN II advisor engineering tools

■ a testing methodology focused on evaluating the effectiveness of preflushes in removal ofdrilling fluids.

Pipe centralizationBecause fluids in the annulus tend to flow more freely on the wide side, casing centralization iscritical to ensure continuous flow all around the annulus. Schlumberger engineers use the cen-tralization module of CemCADE software to design the optimum degree of standoff to meet therequirements for mud removal.

Services 23

Displacement regimesComplete mud removal can be achieved using either laminar or turbulent flow regimes. Thechoice between the two regimes depends on several parameters and conditions, including wellgeometry and fluid properties. The design engineer must analyze all the relevant parameters tomake the right selection. The WELLCLEAN II simulator is a powerful tool for showing criticalresults with the chosen fluids and flow regimes. These include such parameters as the percent-age of cement coverage, the risk of leaving a mud film or channel at the end of the cement job,and for turbulent flow, the contact time—all as a function of depth and time.

Fluids designKnowledge of cement and spacer fluid properties is essential to ensure proper zonal isolation.The effectiveness of each fluid to displace the fluid ahead of it can be checked using theWELLCLEAN II simulator. Output will clearly predict channeling that exists between the fluids.Based on WELLCLEAN II simulator output, the design engineer is guided to improve mud dis-placement through modification of spacer and cement properties and flow parameters.

WELLCLEAN II simulatorEnsuring complete zonal isolation is the ultimate goal of cementing operations. However, fre-quently this goal is not achieved. Because incomplete mud removal is a repeated source of unex-pected costs for operators, every effort should be made to ensure critical zonal isolation on theprimary cement job.

A two-dimensional numerical simulator, the WELLCLEAN II simulator uses computationalfluid dynamics to predict the process of cement placement. Based on well geometry and trajec-tory, downhole fluid properties, volumes, pump rates, and casing centralization, Schlumbergerengineers predict the efficiency of mud removal and identify whether a mud channel will be left.

Using the WELLCLEAN II simulator, engineers can make the necessary design changes to opti-mize the operation and achieve zonal isolation.

The design engineer uses visually displayed displacement patterns produced by theWELLCLEAN II simulator as a guide to the most efficient and complete form of mud removal.

Applications■ Mud removal and cement placement to achieve zonal isolation in vertical, extended-reach or

horizontal wells

Benefits■ Enhanced zonal isolation■ Reduced costs associated with mud removal by optimizing job design■ Predictable results validated by physical experiments and field performance

Features■ Accurate rheological description of fluids (Herschel-Bulkley model)■ Simulation of fluid placement in turbulent and laminar flow■ Maps fluid position and concentration in annulus■ Maps fluid velocity and flow regime■ Provides animated view of fluid displacement process as a function of job time■ Detects potential detrimental contact between mud and cement during displacement


WELLCLEAN II advisorThe WELLCLEAN II advisor design tool greatly facilitates the selection and adjustment of addi-tive concentrations in spacer fluid for the optimal rheological properties to achieve in the ulti-mate goal of mud displacement and zonal isolation. Engineering and laboratory time are reducedby this software, because of its recommendation of additive concentrations to meet the require-ments of the specific mud removal scenario (flow regime, required fluid properties) at the tem-perature of the well.

Chemical washesChemical washes are used in cases where increased density is not needed for well control andwhere turbulent flow is required. These fluids have a density and viscosity close to those of wateror oil. When pumped ahead of the cement slurry, they assist in mud removal by diluting, thinning,and dispersing mud and by water-wetting the casing surface, improving the quality of the bondbetween the cement and the casing and formation.

When oil-base fluid is used for drilling, base oil is often the first preflush fluid and is followedby chemical washes containing surfactants and/or solvents.

Schlumberger offers a comprehensive line of MUDCLEAN* chemical washes for all applications.

Services 25

Depth(ft)

Wide Narrow

Fluidsconcentration

map

Mud riskon the

wall

Wide Wide Narrow Wide

4600

5000

5400

5800

6200

Mud Spacer Cement

HighMediumLowNone

Depth(ft)

Wide Narrow Wide Wide Narrow Wide

4600

5000

5400

5800

6200

Fluidsconcentration

map

Mud riskon the

wall

Modeling allows the engineer to analyze various mud removal scenarios andselect the best one to achieve zonal isolation.

Table 3-1. Schlumberger Chemical Washes

Name Function Type Mud Removed

MUDCLEAN WBM Disperse and thin drilling fluids WBM

MUDCLEAN OBM Disperse, thin and invert the emulsion OBM of OBM drilling fluids; water-wet the casing for better bonding

Applications■ Cementing jobs where a light preflush is pumped in turbulent flow

Benefits■ Improved bonding and hydraulic isolation

Features■ Displace mud by thinning, turbulence and erosion■ Preflushes for any type mud ■ Compatible with cement slurries■ Compatible with WBM and OBM■ Leave surfaces water-wet■ Easy to mix in the field

MUDPUSH spacersSpacers are weighted fluids that provide a compatible buffer between the drilling fluid and thecement slurry and offer control of rheological and flow properties. They can be designed for tur-bulent or laminar flow regimes. Performance of the spacer is optimized using engineering toolssuch as the WELLCLEAN II simulator. Their effective use results in displacement of drilling fluidaround and along the annulus for effective zonal isolation.


Chemical washes are lightweight, thin fluids that remove mud by turbulent flow.

To provide effective mud removal, Schlumberger offers a wide range of MUDPUSH* spacer fluidsto suit zonal isolation criteria under all well conditions.

Schlumberger offers a comprehensive line of MUDCLEAN* chemical washes for all applications.

Depending on well conditions and on the fluid properties, the spacer is designed to be pumpedin either turbulent or laminar flow. Performance of the spacer is optimized using engineeringtools such as the WELLCLEAN II simulator.

The MUDPUSH II spacer properties are specially formulated to address environmental con-cerns. Properties include lower toxicity, better biodegradation and lower bioaccumulation to pro-duce a minimal impact on the environment.

MUDPUSH II spacers have less retarding effect on the cement than earlier versions of spac-ers. Any contaminated cement slurry is subject to less delay in strength development. This provescritical, especially at tops of liners when relatively fast strength development is required.

In wells drilled with an oil-base drilling fluid, the proper surfactant and, in some instances, asolvent, are tailored to the base oil. These surfactants and solvents are added to basic MUDPUSHspacer to disperse the oil phase into water and provide a water-wet surface for better bonding tothe cement.

Services 27

MUDPUSH II spacer properties are engineered in the laboratory to optimizemud removal in the field.

Table 3-2. Schlumberger Spacers

Name Base Fluid Density Flow Regime Temperature Type Mud Removed(kg/m3 [lbm/gal]) Limit (°C [°F])

MUDPUSH II Water (up to 20% salt) 1200–2400 [10–20] Turbulent or laminar 149 [300] Water- or oil-base

MUDPUSH WHT Water (any salinity) 1560–2400 [13–20] Laminar 232 [450] Water- or oil-base

Applications■ All cementing operations to 232°C [450°F]

Benefits■ Turbulent or laminar flow displacement■ Predictable displacement along the entire cemented interval■ Good fluid loss control over a wide density and temperature range

Features■ Density range from 1200 to 2400 kg/m3 [10 to 20 lbm/gal] or 1560 to 2400 kg/m3 [13 to 20 lbm/gal]

for MUDPUSH WHT spacer■ Compatible with cement ■ Excellent suspension properties■ Compatible with fresh, sea or salt water■ Compatible with all drilling fluids (water- and oil-base)■ Stable rheological profile with increasing temperature■ Excellent reproducibility between laboratory and field performance■ Extremely stable■ Easy to mix in the field


In the upper log, a conventional spacer resulted in poor isolation in the permeable section(140-mm [51⁄2-in.] liner at inclination of 55° with 1800-kg/m3 [15-lbm/gal] cement. The lowerlog shows a 178-mm [7-in.] liner in a horizontal well cemented with lightweight cement andusing MUDPUSH II spacer for mud removal.

CemCADE cementing design and evaluation software Cementing in today’s challenging wells is a complex task. Wells may have depleted intervals,resulting in narrow windows between pore and fracturing pressures. Deviations can make casingstandoff by centralizers hard to determine. Mud removal may be difficult as a result of the stand-off and exotic drilling fluids.

CemCADE software provides tools to assist the engineer in evaluating all the parameters andin designing cementing slurries and procedures to cement the well and achieve the requiredzonal isolation. The software is used for all types of wells and casings, from land to offshore indeepwater and from large-diameter conductor casing to the deepest production liner. Toolsassist in calculation of centralizer placement, pump rates and spacer properties to achieve mudremoval and cement placement; calculation of densities and pumping parameters help maintainwell control. Additional tools evaluate the risk of gas migration and allow the engineer to selectappropriate solutions to minimize this risk. A module assists engineers in designing plugs to min-imize contamination during placement, resulting in much higher plug-setting success. A simula-tor aids in determining the temperatures to expect during cementing, providing better data forcement slurry design and better schedules for thickening-time tests and compressive-strengthtests to determine optimum WOC.

A key use of CemCADE software is the optimization of the mud removal process for effectivemud displacement and zonal isolation using WELLCLEAN* mud removal technology. Thisoptimization requires knowledge of the stresses placed on the mud by displacing fluids. Thesestresses, which contribute to displacement of the mud, depend on fluid densities, viscosities,flow regimes and fluid velocities. An additional factor is the degree of casing standoff in the openhole, which has a large effect on localized fluid velocity and flow regime. CemCADE softwareprovides tools that integrate the standoff calculation, the fluid properties, the pump rate andthe U-tube phenomenon to assess the ability of a combination of fluid properties and flow ratesto achieve the mud removal required for zonal isolation. A proprietary placement simulator,WELLCLEAN II software, assists the engineer in evaluating the potential effectiveness of mudremoval by the chosen fluids.

Applications■ Primary cementing on land and offshore wells■ Centralizer selection and centralization optimization ■ Mud removal optimization■ Gas migration risk assessment and optimization■ Temperature simulations■ Preparation of cement slurry testing schedules■ Foamed cement design■ Postjob analysis ■ Plug cementing

Cementing Services and Products ■ Software 29

Software


Benefits■ Optimized design for effective zonal isolation■ Well security and control■ Minimized risk of annular gas migration■ Optimized plug design■ Postjob analysis for continuous improvement■ Real-time comparison of treatment parameter plots with design plots

FeaturesThe fluid placement simulator evaluates well control and pipe integrity by computing and com-paring hydrostatic and dynamic pressures with the formation fracture and pore pressures, andtubular burst and collapse ratings. This is done for all points in the well during the cementingprocess.

■ Fluid test data (e.g., rheology and thickening time) managed in a database.■ Standoff is optimized using caliper and directional survey data and properties of the central-

izers. ■ Forces to run the casing in the hole are calculated. ■ WELLCLEAN technology and fluid-fluid displacement theory is used to predict mud removal

and help ensure zonal isolation. ■ Temperatures in the well during conditioning and cementing are determined, enabling slurry

design for specific conditions. ■ Schedules for thickening-time tests are constructed using temperature simulator.■ Temperature schedules for retarder optimization to avoid premature setting or excessive WOC

time resulting from over-retardation.■ Postplacement analysis aids in analysis and minimization of the risk of gas migration after

cement placement.■ Postplacement analysis aids in selection of operational procedures and slurry properties for

minimization of risk of gas migration.■ Surge and swab calculations check well security during running and moving casing. ■ Tables to be used to schedule and monitor foamed cement job.■ Foamed cement job optimization.■ Export well data and cementing parameters to external software, such as SoniCalc acoustic

log calculator. ■ Postjob evaluation using quality assurance and quality control plots from data recorded dur-

ing the treatment. ■ Pressure signature evaluation of unanticipated events.■ Design balanced plug with minimized chance of contamination during placement. ■ Volumes for balanced fluids.■ Well control and pipe integrity are checked during forward or reverse circulation following

plug cementing.

Software 31

CemCADE simulator computes well security and control pressures experienced forall depths during the cementing process.

Temperature plots show a profile of the temperature in the casing and in theannulus at selected times during the cementing process.

Stress analysis model Wells are exposed to many changing conditions that create mechanical stresses on the casing andthe cement sheath behind it. These stresses can come from pressure changes; fluid weightchanges during drilling and completion; pressure testing and pressure treating such as squeezecementing or high-pressure stimulation treatments; changes in well pressures caused by reser-voir pressure depletion. Temperature changes, especially in upper portions of a well producinghigh-temperature fluids, can also generate mechanical stresses.

FlexSTONE cement is designed to prevent cement failure caused by these mechanicalstresses. This flexible and expansive cement can survive the mechanical stresses and maintainisolation in the wellbore, when properly designed. A proper design requires knowledge of the cur-rent stress conditions in the well as well as the future conditions that will occur over its life.

Stress analysis model software was developed by Schlumberger to predict the stresses to beexperienced by the cement sheath throughout the life of the well. By analyzing the changing con-ditions of the well, the mechanical stresses are determined. The software also assesses themechanical properties of the cement to determine if the cement will survive these stresses. Ifnot, the mechanical properties of the cement can be modified so that the cement will survive toprovide isolation for the life of the well.


Using SAMsoftware,set-cementpropertiesare matchedto formationproperties andfuture well conditions.

Mechanical propertiesof FlexSTONE cementare adjusted throughstatic testing.

FlexSTONE design process.

Applications■ Any primary cementing application

Benefits■ Isolation for the life of the well■ Cement designed for the conditions of the well

Features■ Evaluates well stresses based on anticipated well operations■ Evaluates cement behavior under anticipated stresses■ Allows selection of minimum cement mechanical properties to maintain isolation

SoniCalcSoniCalc software is a tool which allows the logging engineer to import well and cementing datafor use in set up and interpretation of CBL and USI cement evaluation logs. Importing the dataavoids redundant data entry and entry errors. The software provides anticipated acoustic prop-erties and evaluation parameters for the cements and other fluids used in the well. Tool setupparameters are provided so tool setup and computed output is correct for the well being logged,improving logging service quality. These data assist in interpretation of evaluation logs and indetermining if remedial treatments may be required.

Applications■ Cement evaluation logging

Benefits■ High reliability cement evaluation logs■ High service quality■ CBL and USIT cement evaluation logs with parameter setup precisely for fluids and cement in

the well to be logged■ USI interpretive plots set up for exact fluids and cement used in the well

Features■ Imports data from cement design/execution files for minimum data entry and high reliability■ Calculation of anticipated acoustic impedance and amplitude results for cements used in well,

especially lightweight cements■ Tool setup parameters for CBL tools■ Tool setup parameters for ultrasonic tools

Software 33

IntroductionIn today’s remote areas and extreme environments, exploration puts increasing demands on thetechnology required for developing new reserves. No new technology is better tailored to thesedemands than Advanced Cement Technology from Schlumberger. Incorporating 10 years ofresearch and development, Advanced Cement Technology provides a range of cement alterna-tives, tailored to the well, to achieve zonal isolation for the life of the well.

CemCRETE Advanced Cement Technology decouples set-cement properties from slurry den-sity. With CemCRETE systems, properties such as permeability and strength are superior tothose of conventional cements. Slurries can be lighter (or heavier) than ever, without compro-mising properties of the set cement.

CemSTONE systems, the newest generation of Schlumberger Advanced Cement Technology,offer set-cement properties that can be adjusted to meet the requirements of the well. They arepurpose-built to withstand mechanical stresses and changes in temperature and pressure thatdamage conventional cements. CemSTONE systems offer control over properties never possiblewith conventional oilwell cement, allowing you to meet your requirements for such set proper-ties as flexibility, expansion and impact resistance.

Cementing Services and Products ■ Materials 35

Materials

Standard cement slurries require water to fill the void between particles. CemCRETE slurries fill the interparticle void with more solids, giving superior cement properties.


CemCRETE concrete-based oilwell cementing technologyCemCRETE slurries are systems that allow deeper casing points, better high-pressure, high-temperature (HPHT) wells or reduced time WOC in deepwater. Special formulations enablerepair in wells where microcements are ineffective. There are several varieties of CemCRETEslurries, depending on the application.

LiteCRETE* slurry systems provide high strength and low permeability, even at densities aslow as 900 kg/m3 [7.5 lbm/gal] necessary to cement across weak formations.

DeepCRETE slurries let you cement shallow, weak zones in wells drilled in deepwater, mini-mize the risk of shallow water flow and return to drilling in a short time.

DensCRETE* technology gives you very high-density cements when needed for well control, to2880 kg/m3 [24 lbm/gal], with low viscosity.

SqueezeCRETE* remedial cementing slurries are specifically designed to solve problems bypenetrating narrow gaps more efficiently, without bridging or dehydrating during placement.

CemCRETE Advanced Cement Technology is a high-performance alternative to conventionaloilwell cement slurries that changes the fundamental rules for cementing. Casing strings can beset deeper without worrying about lost returns. Cements in HPHT wells can be placed at lowercirculating pressures and higher rates. Channels and failures in primary cement, which are toosmall for repair using microcement slurries, can be repaired. CemCRETE slurries produce newanswers for today’s tough problems, providing zonal isolation for the life of the well.

Unfortunately, in conventional cementing slurries, the amount of water needed for mixing andpumping is much more than is optimum for set cement. CemCRETE technology disconnectsthese two phases of cement performance to give both optimum slurry properties and excellentset-cement performance.

CemCRETE technology increases the solids content of the slurry by using engineered particle-size distribution. Smaller particles fill the void space between larger ones, resulting in a slurryrequiring less water, yet retaining good fluid properties. Putting more solids into your cement pro-vides greater compressive strength, reduces cement permeability and increases resistance to cor-rosive fluids. Choosing solids with different properties allows designs of slurries to meet therequirements of the application.

CemCRETE designs mean cements for production casing can be lower density while main-taining optimum properties for isolation. You can set lighter, longer cement columns. Casingpoints can be deeper. Once the liquid slurry is in place, the resulting set cement performs betterthan standard cement for the life of the well. In remedial operations, increasing solids contentimproves the penetrating ability of the slurry and decreases placement pressures.

Over 3200 cementing treatments have been done in less than 4 years using CemCRETEAdvanced Cement Technology.

0.10

0.05

Permeability(mD)

0.15

0.20

0.25

0.0012.0 lb/gal

Conventional12.0 lb/galLiteCRETE

15.8 lb/galConventional

17.5 lb/galDensCRETE

Properties of CemCRETE cements are superior to those of cement made usingconventional technology.

Materials 37

LiteCRETE low-density slurry systemWhen cementing across weak formations, it can be difficult to place sufficient cement behind thecasing without using extended, low-density cement slurries or multiple-stage cementing opera-tions. A simple, low-density slurry that performs like conventional-density cements can eliminatethese restrictions and allow you to set casing deeper or perhaps eliminate a casing string.

LiteCRETE technology is the new high-performance system that could allow you to redesignyour casing program. LiteCRETE technology, one of the CemCRETE Advanced CementTechnology family of innovative systems, provides production-quality cement properties atextended-slurry densities. LiteCRETE slurries can be mixed from 900 to 1560 kg/m3 [7.5 to 13 lbm/gal] for effective placement across weak zones. Once set, these cements provide compressive strength and permeability superior to any other lightweight system and even comparable to those of 1900-kg/m3 [15.8-lbm/gal] cement.

3500

3000

2500

2000

1500

1000

500

08 9 10 11 12 13

Compressivestrength

(psi)

Density (lbm/gal)

Foamed cement

LiteCRETE cement

Permeability(log mD)

Density (lbm/gal)

3

2

1

0

–1

–2

–3

–48 9 10 11 12 13

Strength and permeability of LiteCRETE slurries are superior to foamed cement.

With low-density LiteCRETE slurry, you can frequently eliminate stage cementing in longintervals. With performance similar to higher-density slurries, you can get exceptional perfora-tion quality without reducing cement integrity. LiteCRETE systems are even strong enough forhydraulic fracturing treatments or setting kickoff plugs.

Applications■ Across weak formations where high performance cement is required■ Low density slurries as low as 900 kg/m3 [7.5 lbm/gal]■ Alternative to stage cementing or topping out■ Alternative to foamed cement■ Across completion intervals■ Kickoff plugs

Benefits■ Production quality zonal isolation across easily fractured formations ■ Longer cement columns without losses due to hydrostatic pressure ■ Elimination of two-stage cementing ■ Reduced damage to completion intervals due to slurry or filtrate invasion■ Whipstock plugs at lower densities with less tendency for contamination or falling downhole

Features■ Cement with low density but that has completion quality properties■ Slurry preparation without special equipment or additional personnel ■ Set-cement properties vastly superior to other lightweight systems at equivalent densities

In some cases, special properties may be built into CemCRETE slurry systems to meet specificperformance criteria. For instance, casing strings through permafrost zones must be cementedwith slurries having protection from freezing. For this application, Schlumberger developedArctic LiteCRETE cement.


DeepCRETE deepwater cementing solutionDeepCRETE slurries let you cement weak zones in deepwater wells, minimize risk of shallow-water flow and return to drilling in a short time.

Drilling in deepwater environments means higher costs. Weak formations can fail under thehydrostatic load of the cement column causing incomplete zonal coverage, additional delay andmore expense. Slow-setting cement can allow flow of shallow water or gas, risking the integrityof the well and potentially the surface location. Low bottomhole temperatures can delay com-pressive strength development, increasing WOC time. When cementing operations are com-pleted, every minute spent WOC costs money.

DeepCRETE technology is a combination of efficient technologies for cementing in the diffi-cult deepwater scenario where low temperature and potential shallow flows exist and is a part ofthe Schlumberger deepwater drilling solution. This is all done without complicating deepwateroperations. DeepCRETE technology isolates the formation with a lightweight cement slurry(1200–1650 kg/m3, 10–14 lbm/gal) that develops strength faster than conventional cement sys-tems without requiring special equipment or personnel. New DeepCEM additives, which facili-tate rapid strength development in the low temperatures, are combined with CemCRETEtechnology to form a highly effective system that provides the short transition time, early strengthdevelopment and good fluid-loss control necessary to cement the surface and conductor casingin deepwater wells with risk of shallow flow. The lighter weight allows placement across weak for-mations.

DeepCRETE systems, with a lower heat of hydration, are the right choice in areas where gashydrates are a concern. Once set, DeepCRETE cement is less permeable than conventionalcements, which protects the casing from corrosive brines.

DeepCRETE systems mixed at 1500 kg/m3 [12.5 lbm/gal] develop sufficient compressivestrength to return to drilling in less than 24 hr even at 4°C [40°F]. When combined withSchlumberger gas migration technology, DeepCRETE systems provide the right solution forshallow water or gas-flow problems.

Applications■ Placement of full columns of cement for complete coverage across weak, shallow formations

in deepwater■ Potential shallow water or gas flows

Benefits■ Cement circulation to surface across weak shallow formations ■ WOC time minimized in low-temperature environments ■ Control and isolation of shallow water or gas formations ■ Low-density, low-temperature cementing without complicated equipment setup or additional

personnel on the rig

Features■ Rapid compressive strength development even at 4°C [40°F] ■ Low density with compressive strengths comparable to those of higher-density cement ■ Low density with low permeability■ Slurry preparation without special equipment or additional personnel ■ Compatible with Schlumberger gas migration technology

Materials 39

DensCRETE Advanced Cement TechnologyWhen working on HPHT wells, the fewer unplanned concerns there are, the smoother the opera-tion runs. An ideal cement system offers simple robust design, lower viscosity and the versatilityof slurry density that can be easily increased on location.

Using unique, engineered-particle size technology, DensCRETE systems give you very high-density cements, up to 2880 kg/m3 [24 lbm/gal], with low viscosity. Because of higher com-pressive strength and lower permeability, DensCRETE slurries outperform conventionalhigh-density slurries to provide high-pressure zonal isolation for the life of your well.

The primary applications for DensCRETE technology include high-pressure primary cement-ing, well control plugging, whipstock or kickoff plugging, and grouting operations.


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1500

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00 5 10 15

hours

20 25 30

psi

DeepCRETE @ 12.5 lbm/galClass G @ 15.8 lbm/gal

At 65°F

At low temperatures, 1500-kg/m3 [12.5-lbm/gal] DeepCRETE slurry develops strength faster than conventionalClass G cement at 1895 kg/m3 [15.8 lbm/gal]. WOC time is reduced, saving rig time and money.

100

50

Frictionpressure

(lbf/1000 ft)

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250

01 3 5 7 9

Pump rate (BPM)

ConventionalDensCRETE

CemCRETE technology results in slurry formulations that have excellent flow properties. Friction pressures aremuch reduced, resulting in the ability to place slurries at greater flow rates, which reduces placement timeand increases the range of flow rates for better mud removal.

High-pressure drilling can require sudden changes in mud weight. With DensCRETE tech-nology, you can increase the slurry density by 120 kg/m3 [1 lbm/gal] on location, just asquickly. You don’t risk losing time or money reblending cement. With reduced risks, shorterplacement times and lower costs, DensCRETE systems offer the high-density cementingalternative with higher performance.

Applications■ High-pressure primary cementing■ High density slurries to 2880 kg/m3 [24 lbm/gal]■ Well control plugs■ Sidetrack and whipstock plugs■ Grouting

Benefits■ Easier slurry placement in narrow fracture-pressure/pore-pressure windows■ Reduced costs and risks associated with long WOC ■ High-density cements that can be continuously mixed

Features■ High-density cement slurry with lower viscosities ■ Greater density differentials with high-density drilling fluids ■ Shorter placement times allow slurries with shorter pumping time and consequently shorter

WOC time■ Stability at high temperatures without special additives ■ Easy design of high-density systems■ Reduced additive requirements■ Ability to increase the density at the wellsite using special additives

SqueezeCRETE remedial cementing solutionsOil and gas wells, old or new, can develop isolation problems that normal cements or even micro-cement cannot repair. Microannuli, leaking liners and old perforations are just some of the prob-lems that may yield unsatisfactory results even after multiple cement squeeze attempts.SqueezeCRETE technology is specifically designed to solve these problems by enabling moreefficient slurry penetration into narrow gaps without bridging or dehydrating during placement.It even penetrates farther and more efficiently than microcement.

In laboratory testing, SqueezeCRETE slurry has been injected into gaps as small as 120 micrometers [0.005-in.]. Once placed, SqueezeCRETE slurry develops more than 13.8-MPa [2000-psi] compressive strength and extremely low permeability. This system canseal liner tops, microannuli or other situations where primary isolation has failed.SqueezeCRETE systems are resistant to acid and corrosive brine, allowing the cement to sealold perforations even when future acid stimulations are planned. SqueezeCRETE systemscan be prepared using conventional cementing equipment.

Materials 41

Applications■ Microannulus repair■ Repair of leaking liner tops■ Repair of leaking perforations■ Squeeze of small channels■ Plugging and sealing of old gravel packs

Benefits■ Improved penetration into difficult-to-repair and difficult primary isolation problems ■ Superior channel-filling properties result in complete isolation repair ■ Low placement pressures improve fluid placement ■ Restoration of zonal isolation or well integrity

Features■ Superior injectivity compared to other remedial systems including microcements ■ Superior slurry properties, including low viscosity, low fluid loss■ Superior set-cement properties, including high compressive strength and low permeability


Syringe containing the slurry to be injected

Transparentplate

Porous plate

Spacer medium,delimiting a “channel”

Filter paper

Injection point Injection point

Well-dispersed microcement slurry SqueezeCRETE slurry

In this 120-micrometer [0.005-in.] slot test, well-dispersed microcement (A) bridged immediately afterentering the slot, while SqueezeCRETE slurry (B) penetrated and filled the entire length of the slot,providing a complete, effective seal.

CemSTONE Advanced Cement Technology CemSTONE systems provide reliable, long-term zonal isolation, despite changing downhole con-ditions. These systems control set-cement properties, such as flexibility, expansion and impactresistance, so the cement can withstand stresses that destroy conventional oilwell cements. Thefollowing systems are included in the CemSTONE family.

FlexSTONE systems provide mechanical properties that can be adjusted to match the wellborestresses and provide permanent zonal isolation to seal wellbore fluids behind casing.

ThermaSTONE* chemically stabilized cement for ultrahigh-temperature applications com-bine the patented engineered particle-size technology with new cement blend chemistry to pro-duce cement having excellent strength, long-term durability and corrosion resistance ingeothermal and steamflood wells.

DuraSTONE* Advanced Cement Technology systems are tougher and have better impact resis-tance than conventional cements, so they are more durable and provide better isolation underrugged drilling and completion conditions.

Even when conventional cement is properly placed and initially provides zonal isolation,changes in downhole conditions can induce stresses that cause the cement sheath to lose itsintegrity. Large increases in wellbore pressure, temperature or tectonic stresses can crack thesheath and can even reduce it to rubble.

Radial movement of casing caused by temperature changes, pressure changes or cement bulkexpansion can cause the cement to lose its bond to the casing, and bulk shrinkage can cause thecement to lose its bond to the formation; in either case, a microannulus is created. Changes inmud weight during drilling and completion can contribute to these pressure changes.Temperature or pressure changes can also generate tensile stresses that can cause cracking ofthe cement sheath and loss of zonal isolation.

Proprietary additives, combined in proven engineered-particle blends, enable CemSTONE sys-tems to meet specific mechanical property requirements, such as elasticity, expandability, com-pressive and tensile strength, durability, and impact resistance. As a result, these systems canwithstand downhole stresses for the life of the well, providing long-term wellbore integrity thatconventional cement cannot.

This long-term integrity reduces remedial cementing costs, ensures isolation for stimulationtreatments, reduces the possibility of annular pressure during a gas well’s producing life, and canextend the productive life of steam injection wells and wells in tectonically active areas. Durable,impact resistant systems substantially improve success when setting problematic kickoff plugs,leading to rig time savings and ultimately lower drilling cost. These systems also improve the sta-bility of the cement sheath across other areas subjected to subsequent high drilling impacts, suchas multilateral junctions.

Combined with stress analysis model software, these CemSTONE slurries provide powerfulengineered solutions. Engineers can model changes that will occur in the cement sheath over thelife of the well and optimize the mechanical properties of the set cement to compensate for thesechanges. The result is zonal isolation for the life of the well.

Materials 43

FlexSTONE Advanced Cement TechnologyFor years, cements were designed based on the optimal properties necessary for slurry place-ment. Once placed, the set-cement properties—high compressive strength and low permeabil-ity—were assumed to be sufficient for all well conditions. Today, the importance of an isolationmaterial that will last under complicated well stresses is better understood.

The set cement must withstand stresses caused by changes in temperature and pressure in thewellbore throughout the well life. This reliability is especially relevant considering the expenseand difficulty of repairing wells.

Changes in pressure caused by production, injection or high-pressure treatments can imposestresses on the cement through the casing. Of course isolation is needed across the productiveintervals, but it is also needed in other intervals that may protect valuable surface waters or pre-vent movement of corrosive or hazardous liquid or gas behind the casing. Changes in tempera-tures resulting from production of high-temperature fluids or injection of hot fluids, such assteam, can expand the casing and create great stresses in the cement sheath. These changes cancause tensile stresses that can crack the cement.


Microannuli are createdby changing the fluid weight. CemSTONE systems can expand to reseal the well.

Complicated completions techniques such as multilaterals shatter conventional cement. CemSTONE systems provide better durability.

Temperature shock that occurs when hot produced fluids pass through lower temperature surface casings causes stress cracks in conventionalcement. CemSTONE systems are very resistant to thermal and mechanical stresses.

Any changes in wellborestresses can cause loss of isolation. Stress Analysis Model software can help optimize design parameters to improve well life.

Modern well construction techniques can destroy conventional cements.CemSTONE systems have superior mechanical properties.

FlexSTONE Advanced Cement Technology systems offer mechanical properties that can beengineered to meet the changing stresses in the wellbore; lower permeability than conventionalcements, along with good compressive strength, better flexibility and better chemical resistance.FlexSTONE systems, with these properties customized to the well, will resist stresses and main-tain isolation. FlexSTONE systems also expand to seal any microannulus. Because FlexSTONEcements are engineered to be more flexible than the formation they seal, this expansion of thecement sheath occurs both outward (i.e., toward the formation) and inward, (i.e., toward the cas-ing), thus assuring complete hydraulic isolation.

With FlexSTONE systems, you will have a seal in your well that provides long-term protectionfrom microannuli formation, stress cracking, corrosive fluid invasion, annular gas pressure andfluid migration. As part of the new Advanced Cement Technology solution, FlexSTONE systemsoffer zonal isolation for the life of the well.

Applications■ HPHT gas wells■ Casings subjected to changing stress loading■ Casings isolating gas, either productive or nuisance■ Steam injection wells ■ Areas with high tectonic stresses

Benefits■ Maintains zonal isolation during and after stimulation treatments ■ Extends productive life of steam injection wells ■ Long-term isolation and casing protection in dynamic stress environments ■ Long-term isolation and casing protection in corrosive environments ■ Protection from annular gas and fluid migration■ Prevention of sustained casing pressure ■ Prevention and healing of microannuli resulting from decreases in pressure or temperature

while drilling and completing

Features■ Mixed and pumped with conventional equipment ■ Flexibility adjusted to the requirements for the life of the well■ Linear expansion two to three times greater than possible with conventional cement systems ■ Lower permeability than conventional cement—independent of slurry density ■ Resistance to corrosive fluids

Materials 45

ThermaSTONE extreme temperature cement technologyGeothermal wells have a combination of properties that make cementing especially difficult.Coupled with the geothermal temperatures, which require special slurries, geothermal wells alsoare generally in reservoirs with low strength and are subject to high tectonic stresses as well ascorrosive brines and carbon dioxide. Conventional cements, even when designed for the hightemperatures, are usually unable to provide long-term well stability and protection from the cor-rosive fluids. ThermaSTONE stabilized cement systems are made possible by combining patentedblend chemistry with proven CemCRETE particle-size technology. The unique combination ofchemistry and particle-size technology produces set cement having excellent strength and cor-rosion resistance not available with conventional high-temperature cements.

Conventional cements, even when modified for use at high temperatures, have low strengthand high permeability because they have to be mixed at low densities to avoid fracturing the frag-ile formations found in most geothermal reservoirs. Their chemistry is also subject to rapid attackby corrosive fluids. ThermaSTONE geothermal cement systems employ an innovative chemistryto produce a mineral phase, which is stable at geothermal temperatures. When combined withCemCRETE technology, very low density cements can be prepared, allowing full placement acrossthe entire annulus (without fracturing the formations) and providing high strength and low per-meability necessary for long-term durability and resistance to corrosive fluid attack.

Compressive strength development by ThermaSTONE cement systems is far less sensitive tostatic temperatures in the well than conventional cements. Systems that are retarded for veryhigh bottomhole temperatures still develop compressive strength at surface temperatures in areasonable length of time. This property allows long casing strings to be cemented in high-tem-perature wellbores without the need for two-stage cementing. This property, combined with theability of the ThermaSTONE system to provide superior mechanical properties at low densities,provides a cement system that is custom made for the geothermal environment.

As part of the new Advanced Cement Technology solution, ThermaSTONE systems offer zonalisolation for the life of geothermal wells.


T/E ratio Permeability(µD)

0

2

4

6

8

10

12

Bond strength(MPa after 4 weeks set time)

Well isolationproperties

Conventional cementFlexSTONE system

Properties of conventional cements are not adequate for difficult well isolation.FlexSTONE systems have higher strength-to-Young’s modulus ratios (T/E) andhigher bond strength while maintaining low permeability.

Applications■ Geothermal wells with production temperatures above 250°C [482°F]■ Steam injection or production wells■ Any high-temperature well (>250°C [482°F]) requiring low permeability and brine or carbon

dioxice resistance

Benefits■ Zonal isolation in geothermal wells■ Long-term durability for improved well life■ Elimination of two-stage cementing

Features■ Engineered cement mechanical properties ■ Mixed and pumped with conventional equipment ■ Lower permeability than conventional cement—independent of slurry density ■ Density range from 1320 to 920 kg/m3 [11.0 to 16 lbm/gal] ■ Rapid strength development at shallow depth, even when retarded for high temperature at TD ■ Excellent durability at high temperature in presence of aggressive brine■ Excellent durability at high temperature in presence of carbon dioxide

DuraSTONE Advanced Cement Technology Previously, oilwell cements were designed to be pumped, to develop strength and then to remainrelatively undisturbed behind casing, thereby providing isolation and pipe support throughoutthe production cycle of the well. Mechanical shocks during further drilling or other well opera-tions that can destroy the integrity of the cement sheath were not considered, although theycould impair zonal isolation.

Modern reservoirs require more complicated technology. Complex drilling programs call forbicentered bits, multilaterals or milled windows, and difficult sidetracks. Completions use largerperforations or higher perforation densities in ever thinner producing intervals. Isolation in thesesituations is critical; it requires a tougher material with better tolerance to vibration and impact.

DuraSTONE Advanced Cement Technology systems are more durable or tougher than con-ventional systems. DuraSTONE systems have all the desirable properties of production qualitycement, but they survive flexural stress, vibration and impact. With DuraSTONE designs, you canmaintain zonal isolation across sections of the well that will be subjected to extreme mechanicalimpact stresses.

Drilling tests have shown DuraSTONE systems to be two to three times tougher than conven-tional cements; this allows faster kickoff in less distance, even in hard formations.

As part of the new Advanced Cement Technology solution, DuraSTONE systems offer zonalisolation for the life of the well.

Materials 47

Applications■ Multilateral completions ■ Reentry wells ■ Sidetrack plugs, especially in hard formations■ Across shoes where impacts are high during subsequent drilling

Benefits■ Zonal isolation integrity across multilateral junctions ■ Improved security against failure of the cement sheath in high-impact areas ■ Better isolation in high-density, precision perforating ■ Improved success in setting sidetrack plugs

Features■ Engineered mechanical properties ■ Mixed and pumped with conventional equipment ■ Increased durability■ High resistance to impact ■ Lower permeability than conventional set cement—independent of slurry density ■ Broad density range (1200–3360 kg/m3 [10–28 lbm/gal]) ■ Greater drilling resistance for faster sidetracks


DuraSTONE Advanced Cement Technology systems are more durable and have betterimpact resistance than conventional cements, so they provide better isolation underrugged drilling and completion conditions.

Cementing Slurry SystemsPortland Cements—API/ISO Classes A, B, C, G and H Portland cements are supplied, whereavailable. Where not locally available, they can be supplied on request. These cements conformto the specifications published in API Specification 10A (ISO 10426-1:2000). API/ISO cements,depending on class, are supplied as Ordinary (O) grade (Classes A and C), Moderate SulfateResistant (MSR) grade (Classes B, C, G and H) or High Sulfate Resistant (HSR) grade (ClassesB, C, G and H). Sulfate resistance is necessary to protect against attack of the hydrated (set)cement by soluble sulfates. Where several grades exist, local requirements determine the gradethat is available.

Lightweight CementsLightweight cements are used to control losses to weak or high-permeability formations. In mostcases, cement extended by the addition of water and additives to prevent water separation areadequate to control the losses. These cements generally have low strength and high permeabil-ity. However, when low density with either high strength or low permeability is required, specialformulations are necessary to meet those requirements.

Applications for lightweight cements include very weak, fractured and highly permeable orvuggy formations. Such cements can be used in primary, squeeze or plug cementing.

Materials 49

Drillingresistance

Energy forflexural failure

0

2

4

6

8

10

12

14

16

Impactresistance

DuraSTONEsystem

performance

Conventional cementperformance

3X

15X

3.5X

DuraSTONE systems are tougher than conventional cement. They have betterdrilling resistance and impact resistance, and significantly more energy isrequired to cause flexural failure.

LiteCRETE cementLiteCRETE cement is a special formulation using patented technology to produce very lowpermeability and high strength. LiteCRETE cement is discussed in detail in the section onCemCRETE cements.

D049 lightweight cementD049, TXI lightweight oilwell cement is a special cement with lightweight components inter-ground to provide an economical, low-density, high-yield slurry. Because of the composition, thelow specific gravity and the particle size of the grind, slurries can be mixed over a wide densityrange without extenders. This feature gives high versatility and flexibility to D049 lightweightcement. By varying the mix water-to-cement ratio, slurries can be mixed over a density range of1440 to 1700 kg/m3 [12.0 to 14.2 lbm/gal] without excessive free fluid or high rheology.

Because of the chemical composition and particle size, D049 lightweight cement providesexcellent strength. Strengths at low densities are superior to conventionally extended cements.In most cases, the strength of D049 lightweight cement is adequate for completion, making a tailslurry unnecessary. Elimination of a separate tail slurry can simplify the cementing operation andimprove the quality of the isolation.

D049 lightweight cement requires no blending and no special additives. Properties of D049lightweight cement can be adjusted to meet almost any performance criteria needed to cementa well.

Foamed cementFoamed cement is prepared by adding a gas (generally nitrogen) and producing stabilized foamby the use of surfactants. Foamed cement has been very effective in controlling losses when veryweak formations are cemented or where formations are highly permeable. The thixotropicnature, in addition to the low density of the cement, makes it highly effective in these scenarios.In addition to their low density, foamed cement slurries provide excellent strength and relativelylow permeability compared to low-density cements prepared by conventional means. Foamedcement has greater durability than conventional cements.

This cement can be made at virtually any density, depending on the density of the base slurryfrom which it is prepared and the amount of gas which is added. Virtually any cement used in theoil field can by used as the base slurry.

A further advantage of foamed cement is that the density at which it is mixed can be selectedimmediately prior to the job, unlike the case of preblended cements. Additionally, by merelyadjusting the gas ratio, the density can be changed during the job to provide slurries with differ-ent properties in different parts of the well.


Low-density LiteCRETE cement or foamed cement can float on water. After a short period,the high-porosity foamed cement sinks as a result of water absorption. LiteCRETE cementcontinues to float as a result of its low porosity and permeability, which is beneficial for preventing gas flow and damage to the cement or casing by corrosive fluids.

Improved Bonding CementsFlexSTONE Cement—advanced flexible cement technologyFlexSTONE cement systems provide mechanical properties that can be adjusted to match thewellbore stresses. When designed with the assistance of stress analysis model software, flexibil-ity and expansion properties provide permanent zonal isolation to seal wellbore fluids behindcasing. FlexSTONE cement was discussed in detail previously.

WELBOND cement—improved bonding cement systemWELBOND* improved bonding cement systems were developed to improve zonal isolationthrough better bonding. They improve the cement-to-pipe and cement-to-formation bonds by con-trolling fluid loss and by adhesion properties provided by latex additives. Furthermore, their lowpermeability when set prevents fluid movement behind the casing.

For optimal bonding properties, the latex concentration is adjusted to control fluid loss below70 mL/30 min. When bonding is not an issue but fluid-loss control is a necessity, the latex isadjusted to control fluid loss to less than 100 mL/30 min. This formulation provides a cost-effective alternative to polymeric fluid-loss agents, particularly at high temperatures.

WELBOND slurries can be used over the entire range of temperatures, densities and depthsthat normally occur in oil and gas wells.

SALTBOND cement—cement system for cementing across salt zonesThe cementing of wells penetrating massive salt formations poses a number of problems.Frequently, cementing across salt formations makes it necessary to use slurries containing highconcentrations of salt. Historically, salt-saturated cement slurries have had technical limitations.Many additives cannot tolerate saline environments or are degraded in the presence of salt.Other additives, which can tolerate the salt, often result in undesirable performance.

Effects of the salt and additives used with it have led to poor early strength development, espe-cially when conventional fluid-loss additives were used. The unusually high plasticity of saltcauses it to deform, or flow, when it is subjected to stress. Thus, under normal overburden pres-sures salt zones will typically encroach upon a well drilled through them. The nonuniform natureof this flow results in point-loading on casing strings, often causing their failure and collapse. Toreduce this risk it is essential that the cement slurry develops good, early compressive strength,thereby preventing the movement of the salt formation into the wellbore.

One of the key performance problems in high-salinity cements is obtaining sufficient controlof fluid loss. Many polymers do not perform well in high–salinity systems. Thus, standard fluid-loss additives could not provide the level of fluid-loss control needed and drastically increasedslurry rheology. Additionally, formulations for cementing through salt greatly delayed strengthdevelopment, leading to operational delays and exposure to hazards while waiting for the cementto set.

SALTBOND* slurries are specially designed for use across salt zones. They use a special addi-tive that provides fluid-loss control and dispersion in salt-rich slurries. API fluid-loss values as lowas 40 mL/30 min are obtained while good rheological characteristics; short, controllable thick-ening times; and good early strength is obtained. The normal temperature range over which theseslurries can be applied is 49 to 121°C [120 to 250°F] BHCT.

SALTBOND slurries contain 18 to 37% (based on the weight of water) salt and exhibit thefollowing properties:■ Fluid loss as low as 40 mL/30 min

■ Very low rheological characteristics

■ Short, controllable thickening times

■ Good early strength development

Materials 51

With a low rate of fluid loss and low rheology values at high salinities, the SALTBOND servicealso provides controllable thickening times and high early compressive strengths. The result isvaluable protection against casing collapse.

SALTBOND slurry advantages■ Good fluid-loss control (less than 100 mL/30 min)

■ Low placement (friction) pressures help prevent loss of circulation

■ High early compressive strength helps prevent casing collapse

■ Predictable slurry properties attained with only one additive (and one retarder, if required)

■ Good bonding against salt formations

■ No potential dissolution of the salt formation while cementing

RFC regulated fill-up cementRFC* regulated fill-up cement slurries are highly thixotropic, forming a rigid gel structure shortlyafter slurry movement has stopped. They also expand. RFC slurries provide a number of distinctadvantages over conventional cement slurries because of their thixotropic and expansive prop-erties. Thixotropy minimizes losses and provides better bonding and zonal isolation throughexpansion. RFC cement is a mixture of Portland cement and plaster.

With minimized losses, RFC slurries provide more predictable fill-up in the well. RFC slurriesare advantageous in any application where it is desirable for the slurry to quickly become immo-bile after placement. In addition to primary cementing where losses are minimized, these sys-tems can also be used to provide a gelled barrier to prevent further penetration during squeezecementing, thus improving success of squeeze cementing.

An important property of RFC cement is the expansion of the set cement. The plaster reactswith the tricalcium aluminate in Portland cement to provide expansion during the early strengthdevelopment. This expansion acts to compensate for slight dimensional changes in the piperesulting from thermal or pressure changes following cement placement. Thus, the expansionhelps prevent microannulus development, resulting in improved zonal isolation.

SELFSTRESS expanding cement systemSELFSTRESS* expanding cement provides improved bonding. Their maximum application tem-perature is 85°C [185°F] BHST. SELFSTRESS cements can be used where thixotropic propertiesare undesirable. SELFSTRESS cement is composed of Portland cement, plaster and salt or dis-persant, depending on the application. Other additives, such as retarders, fluid-loss agents, dis-persants, and extenders, may be used as required.

Fast Strength DevelopmentDeepCEM CementWhen cementing at shallow depths below the mudline in deepwater wells, rapid strength devel-opment is critical to prevent water flow and to provide adequate strength to continue operations,avoiding costly waiting time.

DeepCEM cement additives provide the dispersion needed to minimize adverse gelationeffects, minimize friction pressure and to enhance compressive strength development. DeepCEMdispersant, D185, unlike most dispersants, does not retard at the very low temperatures encoun-tered at shallow depths below the mudline. This property, coupled with the rapid set-enhance-ment offered by D186, the DeepCEM set enhancer, provides the rapid strength developmentneeded in this tough cementing environment. DeepCEM set enhancer provides much more rapidstrength development than standard accelerators.


Slurries formulated with DeepCEM additives are simpler and easier to design than other slurryformulations for deepwater cementing. When used with DeepCRETE Advanced CementTechnology slurries, these benefits are provided in a system that has low density, avoids lossesand sets rapidly.

This same technology is used in land operations where fast strength development at lowtemperatures is required.

ARCTICSET cement—cement system for use through permafrostARCTICSET* cements are designed for low-temperature applications across permafrost zones.They will not freeze but will set and develop adequate strength in wells having temperatures aslow as–9°C [15°F]. ARCTICSET cements have low free-water separation, low permeability, excel-lent durability to temperature cycling, and controllable pumping times and gel strength properties.To ensure that the mix water does not freeze before the cement hydrates, a freeze depressant isused. Heat of hydration is low to prevent thawing of the permafrost.

ARCTICSET formulations are available for a variety of wellbore conditions including normaldensity, lightweight and with lost circulation materials (LCM).

Right-angle set cement At low temperatures, conventional accelerators like calcium chloride often do not provide eitherearly setting or rapid strength development. This is especially true below 20°C [68°F].

Right-angle set cement systems are designed for use at low temperature, between 0°C [32°F]and 30°C [86°F], where short WOC time and/or short transition time are required. Applicationat temperatures to 122°F (50°C) is possible. Regardless of the temperature, a compressivestrength of 500 psi can be obtained 1 to 2 hr after the setting begins, while the slurry transitiontime from 30 to 100 Bc consistency is only a few minutes. The thickening time of an RAS systemcan be adjusted easily between half an hour and several hours, without impairing this right-anglesetting property.

Right-angle set cement is known by several names, depending on the application, includingsurface-set cement and quick-setting cement.

Cements for harsh environmentsIn some situations, cement with special resistance properties is required. This is true in wellswith soluble sulfates that can attack the cement (generally controlled by the chemistry of thePortland cement during manufacture) or when other chemical compounds may contact thecement. Sulfate resistance is imparted to the cement in moderate and high sulfate resistantcements during manufacture. Resistance to attack by other chemicals is controlled by selectionof the components added to the cement or by using special cements, such as synthetic cement.

Acid-resistant cementIn some situations, cement is exposed to acid. Portland cement is acid soluble, although in mostcases acid treatment does not cause failure to the cement sheath. When large volumes of acid arepumped at high rates and expose old perforations that have been sealed with cement, the plugsin the perforations sometimes fail. Acid-resistant cement can prevent such failures.

Acid-resistant cement is made from conventional API cement with a special formulation oflatex that reduces the permeability of the cement and imparts acid resistance. When used forplugging perforations, this formulation has been effective in wells where acid treatments havecaused failure of the plugged perforations in other cement formulations.

When complete resistance to attack by acid or other chemicals is required, synthetic cementcan be used.

Materials 53

Carbon dioxide-resistant cementCarbon dioxide-resistant cement was developed for completions in wet, carbon-dioxide corrosiveenvironments. Applications include source, injection and production wells in carbon dioxideenhanced oil recovery projects or production from oil or gas wells with high levels of carbon diox-ide. Under these conditions, wet carbon dioxide chemically attacks cement. The end result is aloss of strength and structural integrity in the casing sheath.

This cement is 45% more resistant to carbon dioxide leaching than either conventional cementor typical fly ash-cement blends of equivalent density. Although the carbon dioxide corrosion rateis dependent on the amount of water present and is difficult to predict, the use of carbon diox-ide-resistant cement translates into improved performance with respect to completion life atapproximately the same cost per sack as conventional cement. These systems are applicable inthe temperature range of 16 to 93°C [60 to 200°F].

Some cements which perform well in harsh environments have been discussed previously.Because of their low permeability, the cements of Advanced Cement Technology, CemCRETE andCemSTONE cements are well-suited for such use, either on their own, or supplemented with thespecial treatments used to prepare the acid-resistant cement or carbon dioxide-resistant cement.

Synthetic cementSynthetic cement is designed for completing waste (such as acid) disposal wells. It is character-ized by high corrosion resistance, and high compressive and shear-bond strength. Syntheticcement is resistant to attack by strong acids and bases, such as 37% hydrochloric and 60% sulfu-ric acids, as well as 50% sodium hydroxide, at elevated temperatures. However, it is not resistantto organic solvents such as acetone or chlorinated solvents. The system density can be adjustedfrom 1140 to 1560 kg/m3 [9.5 to 13.0 lbm/gal]. The upper temperature limit of synthetic cementis between 93 and 104°C [200 and 220°F], depending on the required pumping time.

Remedial cementing is another application for synthetic cement. Computer modeling showsthat it can enter microleaks and microannuli at low differential pressures.

UniSLURRY cement systemsThe UniSLURRY cement system concept is a new methodology for designing cement slurries inwhich the additives use chemistry designed to perform specific functions. Because they are built-for-purpose, they are highly effective and have minimal effects on properties other than those forwhich they are intended. Only a few universal additives are required to work in the entire rangeof well conditions, from conductor casing to production liner. Additionally, UniSLURRY additiveswork together synergistically.

These features improve the entire cementing process, from prejob laboratory testing to executionin the field. The innovative, superior chemistry common to all UniSLURRY additives provides tech-nical and economical advantages, such as reduced additive consumption and shorter WOC times.Prejob laboratory testing is shorter and more efficient because a few reliable and predictableUniSLURRY additives have taken the place of many, less-efficient additives. Stocking of materials atthe warehouse and on location is more efficient because fewer additives are needed to complete allcement jobs. Mixing on location is improved because smaller quantities of additives are required.

UniSLURRY systems can be used for all cementing operations, including casings, liners, plugs andsqueeze jobs. The UniSLURRY concept can be used over a wide temperature and density range,addressing most oilfield cementing requirements.

The UniSLURRY family consists of four members: UNIFLAC* S solid and UNIFLAC L liquid uni-fied fluid-loss additives and UNISET* LT and UNISET HT liquid unified retarders. These versatile,unified additives cover all cementing conditions and bring to everyday cementing operations aquality previously found only in highly technical areas such as deepwater or HPHT wells. Theirversatility simplifies the logistics of cementing operations by reducing the number and quantity ofadditives that have to be transported and stored at the wellsite. The environmentally friendlyUniSLURRY products are used for both land and offshore operations. They are the first choice whenlogistics are an issue; e.g., on offshore or remote locations.


Conventional cementing additives have addressed a particular range of temperature and set ofconditions, such as maximum water salinity or cement type, making them highly specialized. Thisspecialization has made the design of cement slurries both time-consuming and complicated.

The UniSLURRY products perform over a broader range of temperatures and salt concentrationsand work in any application; cementing casing or liner, squeeze or plug. Their performance is con-sistent and practically independent of the cement type or brand. UNIFLAC additives and UNISETadditives work synergistically, allowing reduction of additive concentration while maintaining slurryquality.

All UniSLURRY additives share some common benefits and features:

Benefits■ Simplified slurry design ■ Cost-effective ■ Minimized rig time ■ Fewer additives for simplified wellsite logistics ■ Low sensitivity to cement variations for reduced slurry-design time

Features■ Universal fluid-loss and retarder additives for any condition ■ Low sensitivity to cement brands ■ Low sensitivity to temperature and concentration variations ■ Lower concentrations needed■ Highly predictable concentration and thickening time■ Minimized WOC time ■ Environmentally friendly chemistry

The benefits of the UniSLURRY additives extend to every aspect of the cementing operation:■ Laboratory testing—UniSLURRY additives make the laboratory-testing process more efficient.

Consistent and predictable, the UniSLURRY additives work with simpler and more reliabledesigns (both UNIFLAC additives and UNISET additives exhibit nearly linear dependence on tem-perature and other parameters).

■ Logistics—When cementing with traditional additives, the temperature limitations often make itnecessary to use different sets of additives on different strings of pipe. This makes it necessary tostock numerous additives, both at the warehouse and at the wellsite. Because UniSLURRY addi-tives can be used on all casings from conductor to liner, surplus additives from one job can be usedon the next cementing job. Unnecessary handling between jobs is avoided, precious space on therig is conserved, and waste is reduced, thus reducing the overall cost and enhancing operationalsafety and efficiency.

■ Job execution—UniSLURRY technology simplifies cement job execution at the wellsite. Feweradditives are required to obtain the needed slurry properties. This benefit simplifies the mixingoperation, especially in remote locations using liquid additives.

UNIFLAC unified fluid-loss additive for cementInadequate fluid-loss control can lead to serious problems during cementing operations. Loss offluid from the cement slurry can result in friction pressure increases, shorten thickening timeand increase the risk of microannulus and loss of zonal isolation.

Materials 55

UNIFLAC universal fluid-loss additive for cement is a universal and cost-effective solution forfluid-loss control in all cementing applications. The additive is a custom-made, third-generation poly-mer that is available in liquid (D168) or solid (D167) form. The solid additive can be dry-blendedwith the cement or predissolved in the mix water. Its robust properties make slurry design very sim-ple and produce predictable results in the field, from the conductor casing to the liners. Test resultsdemonstrate the very low sensitivity of UNIFLAC additive to variations in temperature or concen-tration. It also has a low sensitivity to cement brands.

The same additive is used at all temperatures, from 10 to 260°C [50 to 500°F]. Synergy betweenUNIFLAC additive and Schlumberger UNISET retarders provides additional operational benefits.When used with UNIFLAC additive, the concentration of UNISET retarder required to achieve adesired thickening time is reduced and early compressive strength development reduces WOC time.

Applications■ All cementing applications ■ Wells with temperatures from 10 to 260°C [50 to 500°F]

Benefits■ Economical■ Savings from less WOC time■ Simplified slurry design ■ Simplified logistics—few additives required

Features■ Low sensitivity to cement brands ■ Low sensitivity to temperature■ All densities■ Fresh to salt-saturated mix water■ Compatible with all additives, including calcium chloride accelerator and silicate extenders ■ Synergy with Schlumberger UNISET retarders ■ Low concentration requirements ■ Excellent slurry rheology


0.6

0.5UNIFLAC-L

(gal/sk)

0.7

0.8

0.9

0.4

0.2

0.1

0.3

0.050 150 250 350 450

Temperature (°F)

13.0 lb/gal16.2 lb/gal18.5 lb/gal

UNIFLAC L additive concentration to achieve API fluid loss of 50 mL/30 minis easily predictable at different temperatures and slurry densities.

UNISET set control additivesSchlumberger UNISET set control additives provide a unique set of properties that are not avail-able with conventional retarders. Cement retarded using UNISET additives exhibit a rapid set-ting behavior, even with longer thickening times for increased safety factors. Their synergisticbehavior with UNIFLAC additives allows lower concentrations (as much as two-thirds reduction),thus improving economics.

Excessive retardation by conventional retarders impairs strength development, extending WOCtime and making the cement vulnerable to invasion by well fluids or mechanical damage fromchanging stresses in the well. In extreme cases, some cementing treatments must be done inseveral stages to avoid excessively long setting times. This complicates and increases the overall costof the operation.

UNISET HT additive retards to provide sufficient time to place the cement, yet promotes early andrapid strength development to minimize WOC time. UNISET HT additive is also much less sensitiveto temperature variations than other cement retarders. It is the preferred retarder for the mostchallenging situations when temperature is not well defined or if there is a large difference betweentemperature at the top of the liner and the bottom of the cement.

Materials 57

6

4

Thickeningtime (gal/sk)

8

10

12

20.00 0.05 0.10 0.15 0.20 0.25

Concentration (gal/sk)

D177 and D168

D177

Use of UNISET retarder with UNIFLAC additive results in synergy thatallows much reduced concentrations.

Applications■ All cementing operations

Benefits■ Simplified slurry design■ Much reduced risk of problems from inherent temperature errors■ Cost benefits from simplified logistics, reduced additive usage and shorter WOC time■ Lower concentrations are required due to synergy with UNIFLAC additives

Features■ Full range of temperature■ All densities■ Fresh and sea water■ Highly reliable and predictable concentration and thickening time response■ Only two additives cover the entire temperature range■ Synergistic with UNIFLAC fluid-loss additives■ Rapid setting and compressive-strength development

UNISET additives are available for low- to moderate-temperature (UNISET LT) and high-temper-ature (UNISET HT) applications. UNISET LT additive covers applications to about 120°C [250°F],and UNISET HT additive can be used from about 80 to 260°C [180 to 500°F].

UNISET retarders are compatible with most other Schlumberger cementing additives.


4

3

Time to reach50 psi at 320°F (hr)

5

6

7

2

12 4 6 8 10 12

Thickening time at 350°F (hr)

D121/D28

D121/D28

16-lbm/gal slurry

When UNISET HT additive is used, extended thickening times do not result inthe excessive WOC times found with conventional retarders.

Cementing additivesThe following paragraphs and tables describe the performance of cementing additives by func-tional group. Some materials are discussed in more detail in sections on specific functional systems. The Cementing Additive Quick Guide and Cementing Additive List provide descriptionsof additives listed by functional group and by code, respectively. The list gives general applicationconditions for each additive. These application conditions reflect those tested during productdevelopment. In many cases, the products can be used outside the quoted conditions with testingappropriate to specific applications.

AcceleratorsAccelerators are materials that cause cement to hydrate and develop strength earlier and faster.They are commonly used to provide improved strength at low temperatures and to counteract theretarding effects of other additives. Accelerators also shorten the thickening time.

Antifoam and defoam agentsAntifoam agents prevent or reduce the foaming tendencies of cement when it is mixed. This isnecessary because the properties of cement slurries and the set cement depend on thewater/cement ratio. Since most field mixers determine the ratio by measuring the density of theslurry, entrained air causes the slurry to be mixed at improper ratios. Some materials act betteras antifoam agents, but not well as defoamers. Other materials act as either defoamers or foampreventers.

Antigelation agentsIn some cases, gelation is caused by the chemical makeup of the cement. Many times this gela-tion can be controlled by dispersants (see below), but some require special materials to controlthe gelation, depending on its cause.

Materials 59

0.4

0.2

Concentration (gal/sk)

0.6

0.8

1.0

0.0180 200 220 240 260 280 300 320

Pump rate (BPM)

The relationship between concentration and temperature is linear, makingconcentration selection simple when using UNISET HT retarder. The graphshows the concentration required for a thickening time of 4 to 5 hr.

DeepCEM additivesDeepCEM liquid cementing additives were created for short transition time and early compres-sive-strength development. Such properties are necessary for isolation and early casing releaseto ensure successful cementation in the unconsolidated, low-temperature environment of thesurface and conductor casings in deepwater wells. They are also useful in other low-temperaturesituations. DeepCEM additives are discussed in detail on p. nn.

DispersantsDispersants act to reduce the viscosity of cement by breaking up aggregates of the fine cementparticles. This reduction in viscosity allows mixing at lower water/cement ratios for higherdensity, improved fluid-loss control and pumping at reduced pressures.

Expanding Additives Expanding additives react chemically after hydration (setting) to produce an increase in the bulkvolume of the cement. This provides benefits in zonal isolation and protection of the casing. Whenused across soft formations, flexible systems may be required to prevent microannulus formation.

ExtendersExtenders allow the production of a greater volume of slurry from the powdered cement. This fea-ture can result in reduced cost and, where the extenders are lightweight (or they allow additionalwater to be used), lower density. The advantage of reduced cost is obvious. Reduced density isimportant where weak formations are to be cemented. Such weak formations could part andallow loss of the slurry during the cementing operation. A variety of materials are available to pro-vide for different requirements of lower density, lower cost and other performance parameters.

Fluid-loss control additivesFluid-loss control additives minimize the loss of water from the slurry into permeable formations.This helps to maintain the properties of the cement slurry during placement and until the cementsets.

Gas migration control additives Gas migration control additives are used to reduce the risk of gas invading the cement andmigrating in the wellbore. Gas migration in discussed in detail in the section on gas migrationcontrol.

Lost circulation control materialsMaterials used to prevent or halt losses of slurry from the wellbore, are called LCM. In additionto LCM added to the cement, special lost circulation control products are available for combat-ing lost circulation during operations other than cementing. They are discussed in the section onlost circulation.


RetardersRetarders are used to lengthen the time that a cement slurry can be pumped or remains fluid toperform other operations (such as pulling pipe after spotting a cement plug). They are requiredat elevated temperatures or when large volumes of slurry require a long time to pump at lowertemperatures.

SurfactantsSurfactants are used in chemical washes and spacers with OBM (discussed in the section on mudremoval) and to create stable foam when adding a gas to make foamed cement.

Special additivesThere are a number of additives that do not fit neatly into functional groupings.

Fibers are used for controlling lost circulation (see section on CemNET advanced fibercement). Special types of fibers also improve the impact resistance and tensile strength ofcement (see section on DuraSTONE cement).

The flexibility of cement can be improved by the use of special additives. This increase in flex-ibility provides increased resistance to failure by mechanical stresses imposed on the cementduring well operation. (See section on FlexSTONE cement.)

Granular salt (sodium chloride) and potassium chloride are used primarily to change the ionicnature of the water in the slurry. This helps to minimize adverse formation interactions. In caseswhere the formation is salt, high concentrations of salt, up to saturation, are commonly used toprevent leaching salt from the borehole wall.

Silica is used to combat strength retrogression. Strength retrogression is a change in thehydration products that are formed when cement is exposed to high temperatures (>110°C[230°F]). Silica is available in coarse or fine grades for cementing.

Suspending and antisettling agentsOccasionally, segregation can occur in a cement slurry. This segregation may be in the form ofwater separation (known as free fluid) or in solid particle sedimentation. In either case, amaterial to suspend the solids is used to maintain slurry integrity.

Thixotropic additivesThixotropic additives produce an intentional gelation of the cement to aid in placement of thecement. Thixotropic cement is discussed previously under RFC cement.

UniSLURRY additivesA special set of additives has unique and synergistic properties. These UniSLURRY additiveshave been purpose built to perform their function and have properties that distinguish themfrom other fluid-loss or set-control (retarder) additives listed below. UniSLURRY additives,UNIFLAC fluid-loss additive, UNISET LT retarder and UNISET HT retarder, were discussed indetail previously.

Materials 61

Weighting agentsWeighting agents are used to increase the density of the cement when needed for well control.

SpacersSpacers are generally thickened, weighted fluids used to aid in mud removal and to separate themud from the cement to prevent any compatibility problems.

Chemical washesChemical washes are generally thin fluids with surfactants to aid in mud removal and to separatethe mud from the cement to prevent any compatibility problems.

The following tables list additives by functional category (Cementing Additive Quick Guide)and by additive code (Cementing Additive List).


Materials 63

Table 5-1. Cementing Additive Quick-Guide

Code Form, Liquid (L) Material and/or Application Temperature Rangeor Solid (S) Application (BHCT except where noted)

AcceleratorsD044 S Sodium chloride No limitD077 L Calcium chloride Below 55°C [130°F]D186 L Set enhancer 7–55°C [45–130°F]S001 S Calcium chloride Below 55°C [130°F]S002 S Calcium chloride Below 55°C [130°F]

Antifoam AgentsD046 S Foam preventer No limitD047 L Foam preventer No limitD144 L Defoamer No limitD175 L Defoamer No limitM045 L Defoamer No limit

Chemical WashesD122A L Chemical wash concentrate No LimitD191 L Surfactant for washes and spacers Maximum 250°C [482°F]D192 L Chemical wash concentrate No Limit

DeepCEM AdditivesD185 L Low temperatures; nonretarding Maximum 57°C [135°F]D186 L Set enhancer 7–55°C [45–130°F]

DispersantsD065 S Freshwater systems Maximum 121°C [250°F] D065A S SALTBOND additive for high salinity systems Maximum 121°C [250°F]D080 L Liquid equivalent to D065 Maximum 121°C [250°F]D080A L SALTBOND additive for high salinity systems Maximum 121°C [250°F] D121 S Dispersant, retarder, fluid loss additive 121–274°C [250–525°F]D145A L Low temperature Maximum 85°C [185°F] D185 L Low temperature; nonretarding Maximum 57°C [135°F]D604AM L SALTBOND additive for high salinity systems Maximum 121°C [250°F] D604M L Easy-to-disperse cement Maximum 121°C [250°F]

Expanding AdditivesD053 S Additive for RFC and SELFSTRESS systems Maximum 85°C [185°F]D174 S Low to moderate temperatures Maximum 110°C [230°F] BHSTD176 S High temperatures 80–204°C [176–400°F] BHST

ExtendersD020 S Bentonite Maximum 232°C [450°F] BHSTD035 S Class F fly ash Maximum 232°C [450°F] BHSTD048 S Class F fly ash Maximum 232°C [450°F] BHSTD056 S Diatomaceous earth No limitD072 S Expanded perlite Maximum 232°C [450°F] BHSTD075 L Sodium silicate Limited by ability to retardD079 S Sodium meta-silicate Limited by ability to retardD124 S LITEFIL* ceramic microspheres Maximum 232°C [450°F] BHSTD125 S Expanded perlite Maximum 232°C [450°F] BHSTD128 S Attapulgite Maximum 232°C [450°F] BHSTD132 S Class C fly ash Maximum 232°C [450°F] BHST


Table 5-1. Cementing Additive Quick-Guide (continued)


ExtendersD152 S Premium bentonite Maximum 232°C [450°F] BHSTD154 S Microsilica Limited by ability to retardD155 L Microsilica Limited by ability to retardD602 S Diatomaceous earth No limit

Fluid-Loss AdditivesD008 S Fluid loss control 85–232°C [185–450°F]D059 S High-salinity systems 38–93°C [100–200°F]D065A S SALTBOND additive for high-salinity systems About 121°C [250°F]D080A L SALTBOND additive for high salinity systems About 121°C [250°F]D112 S Low-density systems 4–93°C [ 40–200°F]D167 S UNIFLAC additive 0–204°C [32–400°F]D168 L UNIFLAC additive 0–204°C [32–400°F]D300 L Low to moderate temperatures, nonretarding Maximum 121°C [250°F]D604AM L SALTBOND additive for high-salinity systems About 121°C [250°F]

Gas-Control AgentsD500 L GASBLOK LT additive for low temperatures Maximum 71°C [160°F]D600G L Latex GASBLOK MT additive for 66–121°C [150–250°F]

moderate temperatures 149°C [300°F]D700 L Latex GASBLOK HT additive for high temperatures 121–191°C [250–375°F]D701 L GASBLOK stabilizer for high temperatures Maximum 191°C [375°F]

Lost Circulation Materials (LCM)D024 S Gilsonite granules Maximum 149°C [300°F] BHSTD029 S Cellophane flakes Maximum 132°C [270°F]D042 S KOLITE* LCM 538°C [1000°F] BHSTD095 S CemNET fiber Maximum 150°C [302°F]D096 S CemNET fiber Maximum 232°C [450°F]D130 S Polyester flakes Maximum 70°C [158°F]

RetardersD008 S Moderate temperature; also controls fluid loss; 54–104°C [130–220°F]

used mostly with high-salinity systemsD013 S Low temperatures Maximum 85°C [185°F]D028 S High temperatures 104–149°C [220–300°F]

204°C [400°F] (with aid D121)D081 L Low temperatures Maximum 85°C [185°F]D093 S Retarder aid; high temperatures 149–204°C [300–400°F]D110 L High temperatures 79–149°C [175–300°F]

191°C [375°F] (with aid D121)D121 S Retarder aid; high temperatures 110–177°C [230–350°F]D150 L High temperatures 104–149°C [220–300°F]

204°C [400°F] (with aid D121)D161 L UNISET additive for high temperatures 85–232°C [185–450°F]D177 L UNISET additive for moderate temperatures 60–121°C [140–250°F]D800 S Moderate temperatures 52–121°C [125–250°F]

154°C [310°F] (with aid D121)D801 L Moderate temperatures 52–121°C [125–250°F]

154°C [310°F] (with aid D121)

Materials 65

Table 5-1. Cementing Additive Quick-Guide (continued)


SpacersD182 S Additive for MUDPUSH II spacer Maximum 149°C [300°F]D190 S MUDPUSH WHT additive Maximum 232°C (450°F)

Special AdditivesD030 S Coarse silica; strength retrogression control No limitD044 S Salt No limitD053 S Additive for RFC and SELFSTRESS cements Maximum 85°C [185°F]D066 S Silica flour; strength retrogression control No limitD111 L Additive for RFC cement Maximum 85°C [185°F]D140 S Activator for PERMABLOK plug Maximum 80°C [176°F]

107°C [225°F]D606 S Gelation suppressant No limitJ120 S Polymer for polymer plug 200°FM117 S Potassium chloride No limit

SurfactantsD139 L Stabilizer for foamed cement Maximum 232°C [450°F]D607 L Wash or spacer for OBM removal Maximum 232°C [450°F]F040 L Aid in OBM removal Maximum 232°C [450°F]F057 L Aid in OBM removal Maximum 232°C [450°F]F078 L Foaming agent for foamed cement Maximum 232°C [450°F]F103 L Aid in OBM removal Maximum 232°C [450°F]F104 L Foaming agent for foamed cement Maximum 232°C [450°F]U066 L Solvent for OBM removal Maximum 232°C [450°F]U100 L Solvent for OBM removal Maximum 232°C [450°F]

Suspending AgentsD153 S Antisettling agent Maximum 149°C [300°F]D162 L Antisettling agent Maximum 149°C [300°F]

Thixotropic AgentsD053 S Additive for RFC and SELFSTRESS cements Maximum 85°C [185°F]D111 L Additive for RFC cement Maximum 85°C [185°F]

Weighting AgentsD018 S Ilmenite No limitD031 S Barite No limitD076 S Hematite No limitD151 S Calcium carbonate No limitD157 S Micromax Maximum 232°C [450°F]D165 S Additive for DensCRETE slurries No limitD166 S Additive for DensCRETE slurries No limit

Materials 66

Table 5-2. Cementing Additive List

Code Name Application Description SG Primary Purpose

D008 Retarder/ Moderate White powder Used primarily with high-salinity slurries. fluid-loss temperatures Strong viscosifier; provides some fluid-loss additive control. Concentration: 0.05–1.0% BWOC.

Temperature: 54–104°C [130–220°F] as retarder; to 232°C [450°F] as fluid-loss additive.

D013 Retarder Low to moderate Brown powder 1.23 Temperature: to 60°C [140°F] when used temperatures alone and 85°C [185°F] with a dispersant.

Concentration: 0.1–0.5% BWOC. Can be used in fresh water and seawater.

D018 Ilmenite High-density slurries Black granules 3.50–4.50 High-density slurries and spacers to2300 kg/m3 [19 Ibm/gal]

D020 Bentonite Cement extender Light tan to 2.65 API untreated bentonite. To 25% BWOC whengray powder dry blended. About one-fourth as much is

required when prehydrated. Minimum density:1380 kg/m3 [11.5 Ibm/gal]. Attapulgite (D128)is used in salt water.

D024 Gilsonite Lost-circulation Black granules 1.07 LCM. Concentration: 10.6–106 kg/t [1–10 lbm/sk].control Temperature to 149°C [300°F].

D028 Retarder High temperatures Dark brownish 1.25 Temperature: 104–149°C [220-300°F];Can be used to 204°C [400°F] with a retarder aid.

Concentration: 0.05–1.0% BWOC. Can be used in freshwater and in high-salinity systems.

D029 Cellophane Lost-circulation Clear thin flakes 1.45 LCM. Concentration: 1.3–5.3 kg/t flake control [0.125–0.5 Ibm/sk].

D030 Silica Strength White to tan granules 2.65 100-mesh silica sand. Prevents strength retrogression retrogression at temperatures above control 110°C [230°F]. Concentration: 35-50%

BWOC. D030 is preferred to D066 (silica flour) in dense, low-water ratio slurries.

D031 Barite Weighting agent Grey or tan powder 4.33 High-density slurries and spacers (to 2300 kg/m3 [19 Ibm/gal]).

D035 LITEPOZ 3 Cement extender Tan to gray powder 2.48 Class F fly ash. Normally substituted for a extender portion of the cement on an absolute volume

basis (e.g. in USA, 35:65) or blended on a bulk volume basis (e.g. in Canada, 1:1).

D042 KOLITE lost- Lost-circulation Black angular 1.30 LCM. Granular material of controlled circulation control granules particle size distribution. additive Concentration: 10.6–106 kg/t [1–10 lbm/sk].

D044 Granulated Accelerator; White granules 2.16 Sodium chloride. Used where formations aresalt inhibit clay swelling; sensitive to fresh water. Accelerates cement

facilitate bonding in set when used at concentrations to 15%salt formations BWOW (by weight of water). At 18% BWOW,

its effect is essentially neutral and thickeningtimes are similar to those obtained with freshwater. Above 18% BWOW, D044 retards settingof cement. Used above 18% to minimize leaching of salt formations.

D046 Antifoam Control foaming of Tan solid 1.50 General purpose solid foam preventer. cement slurries Typical concentration: 2 kg/t [0.2 Ibm/sk].


Table 5-2. Cementing Additive List (continued)


D047 Antifoam Control foaming of Colorless liquid 1.00 General purpose liquid foam preventer. cement slurries Typical concentration: 4.5 L/t [0.05 gal/sk]

for cement slurries and 6 L/m3 [0.25 gal/bbl] for spacers.

D048 LITEPOZ 6 Cement extender Gray to tan powder 2.01 Class F fly ash. Normally substituted for a extender portion of the cement on an absolute volume

basis (e.g. in USA; 35:65) or blended on a bulkvolume basis (e.g. in Canada, 1:1).

D053 Cement agent Thixotropy and White powder 2.70 Additive for RFC cement and SELFSTRESSexpansion cement. Thixotropic slurries (RFC cement)

are used for lost-circulation control and theirexpansive properties. SELFSTRESS cement is used for its expansion. Effective up to 85°C [185°F].

D056 Extender Cement extender Light gray granules 2.10 Diatomaceous earth.

D059 FLAC* fluid- Salt cement slurries White powder 1.36 Fluid-loss control additive for salt slurries. loss additive Can be used in fresh slurries with dispersant.

Temperature range: 38–93°C [100–200°F]. Typical concentration: 0.5 to 1% BWOC. Retards at low temperatures.

D065 TIC* Freshwater or low Light brown powder 1.43 Powerful cement dispersant. Concentration: dispersant salinity slurries 0.1–1.5% BWOC. Can be used with seawater.

Temperature to 121°C [250°F].

D065A SALTBOND Fluid-loss control for Light brown powder 1.43 Dispersant and fluid-loss additive for high-additive high salinity slurries salinity slurries when “difficult-to-disperse

in salt” cement is used. Temperature to 121°C [250°F].

D066 Silica flour Strength White to tan granules 2.65 Fine silica flour (finer than 200 mesh). Preventsretrogression strength retrogression at temperatures abovecontrol 110°C [230°F]. Concentration: 35–50% BWOC.

Preferred over D030 in lightweight slurries andat very high temperatures.

D072 Perlite Cement extender White, fluffy powder 2.40 Expanded volcanic glass. Used in shallow wells;collapses at high pressure (significant at 20.7 MPa [3000 psi]).

D075 Sodium silicate Cement extender Colorless liquid 1.38 Silicate-based liquid extender. Preferred forseawater applications. When used with freshwater, requires calcium chloride addition to the mix water. Typical concentration: 18–54 L/t [0.2–0.6 gal/sk]. Minimum density: 1380 kg/m3 [11.5 Ibm/gal]. Accelerates set.

D076 Hematite Weighting agent Reddish brown powder 4.95 High-density slurries and spacers to 2300 kg/m3 [19 Ibm/gal].

D077 Liquid calcium Cement slurry Clear to straw 1.38 Liquid form of calcium chloride. Used in freshchloride accelerator colored liquid water or seawater. Maximum concentration

of 35.5 L/t (0.4 gal/sk).

D079 Sodium Cement extender White solid 2.40 Sodium metasilicate extender. Most applicablemeta-silicate for low bulk-storage requirements, such

as remote locations and offshore. Typical concentration: 0.25–3% BWOC. Minimum density: 1380 kg/m3 [11.5 Ibm/gal]. Accelerates set.

Materials 68



D080 TIC dispersant Dispersant Dark brown liquid 1.24 Liquid equivalent of D065. Concentration: 2–36 L/t [0.02–0.4 gal/sk]. Temperature to 121°C [250°F].

D080A SALTBOND Fluid-loss control Dark brown liquid 1.24 Dispersant and fluid-loss additive for high-salinityadditive for salt slurries slurries when “difficult-to-disperse in salt”

cement is used. Temperature to 121°C [250°F].Concentration: 27–81 L/t [0.3–0.9 gal/sk].

D081 Liquid retarder Low to moderate Brown liquid 1.26 Liquid equivalent to D013. Temperature range: temperatures to about 60°C [140°F] when used alone and

about 85°C [185°F] with a dispersant. Concentration: 2–9 L/t [0.02–0.1 gal/sk]. Can be used in fresh water and seawater.

D093 Retarder aid Increase White powder 1.73 Synergistic effect with all retarders, increasingperformance range their effective range. Most useful above of retarders 149°C [300°F]. Detrimental effect on most

fluid-loss control additives.

D095 CemNET fiber Lost-circulation Fibers 2.55 Controlling and preventing lost circulation. control Maximum temperature 150°C [302°F].

Concentration to 7 kg/m3 [2.5 lb/bbl].

D096 CemNET fiber Lost-circulation Fibers 1.27 Controlling and preventing lost circulation.control Maximum temperature 232°C [450°F].

Concentration to 6 kg/m3 [2.1 lb/bbl].

D110 Retarder High temperatures Brown liquid 1.13 Temperature: 79-149°C [175–300°F];to 190°C [375°F] with D093. Concentration: 2–45 L/t [0.05-0.5 gal/sk].

D111 RFC additive Liquid additive for Light green liquid 1.26 Concentration: to 72 L/t [0.8 gal/sk].thixotropic cement slurries

D112 FLAC fluid-loss Low-density slurries Tan powder 1.15 Control fluid loss, primarily in lightweight additive slurries. Temperature: to 93°C [200°F].

Concentration: 0.5–3.0% BWOC. Can be used in fresh water and seawater. Strong viscosifier.

D121 TIC III Dispersant, retarder Dark brown powder 1.38 Temperature: to 177°C [350°F]. Concentration: tri-functional and aid for fluid-loss 0.5–2.0% BWOC. Effective in freshwater andadditive control high-salinity systems.

D122A Chemical Mud thinning, Brown liquid 1.03 Typical concentration: 12 L/m3 [0.5 gal in 41.5 gal]wash dispersing and in water.concentrate removal

D124 LITEFIL Ultralightweight Gray powder 0.65- 0.85 Hollow ceramic microspheres allowing slurry extender cementing additive density as low as 1080 kg/m3 [9 Ibm/gal].

Temperature: to 232°C [450°F]. Pressure limit dueto crushing of spheres: about 35 MPa [5000 psi].Application ranges may be extended with testing.

D125 Perlite Extender Off-white, fluffy powder 2.40 Expanded volcanic glass used in shallow wells;collapses at high pressure (significant at 20.7 MPa [3000 psi]).

D128 Attapulgite Extender for salt Light tan to 2.65 Clay extender for saline waters cement slurries gray powder (including seawater).

D130 Polyester flake LCM Clear thin flakes 1.06 Concentration: 1.3–5.3 kg/t [0.125–0.5 Ibm/sk].




D132 Cement Carbon dioxide- Tan to gray powder 2.67 Class C fly ash; component of carbon agent resistant cement dioxide-resistant cement.

D139 Foamed Foamed cement Clear to hazy 1.07 Used to maintain downhole stability ofcement yellow liquid foamed cement. stabilizer Usual concentration: 9 L/t [0.1 gal/sk].

D140 Hardener Hardener for Yellow liquid 1.24 Hardener for PERMABLOK rigid gel system.PERMABLOK lost- Applications to 80°C [176°F]. May be extendedcirculation plug through laboratory testing to 107°C [225°F].

Concentration: 5–20% by volume of solution,depending on temperature, required gel timeand rigidity.

D144 Antifoaming High salinity slurries White liquid 1.00 General purpose liquid foam preventer additive and spacers and defoamer. Added to the mix water. Typical

(efficient in any fluid) concentration: 1–5 L/t [0.01–0.05 gal/sk] forcement slurries and 2.4 L/m3 [0.1 gal/bbl] for spacers.

D145A Liquid Low temperatures Viscous liquid 1.24 Dispersant, much less retarding than D080.dispersant Temperature: to 85°C [185°F] in freshwater

systems. Usual concentration: 4 to 27 L/t [0.05 to 0.3 gal/sk].

D150 Retarder High temperatures Dark brown liquid 1.11 Liquid equivalent to D028. Temperature: 104–149°C [220–300°F]; to 204°C [400°F] with a retarder aid. Concentration: 2–36 L/t [0.02–0.4 gal/sk].

D151 Calcium Weighting agent White powder 2.70 Graded calcium carbonate. Weighting material carbonate for spacers for spacers, especially where acid solubility

is required.

D152 Premium Extender Light tan to 2.65 Premium grade of bentonite having betterbentonite gray powder fluid-loss control properties when used at

high concentrations (>12%).

D153 Antisettling Suspending additive White to gray powder 2.53 Maintains slurry stability at downhole additive temperature conditions. For all densities.

Temperature: to 149°C [300°F]. Concentration: 0.1–1.5% BWOC.

D154 Extender Low temperatures Gray powder 2.20 Microsilica. Improves performance of most set cement formulations; better strength and lowerpermeability. Useful for lightweight systems to1320 kg/m3 [11 Ibm/gal], especially at low temperatures (to 85°C [185°F]). Concentration: 5–20% BWOC.

D155 Extender Low temperatures Gray liquid 1.40 Suspension of microsilica in water. Improvesperformance of set cement; usually gives betterstrength and lower permeability. Useful for light-weight systems to 1320 kg/m3 [11 Ibm/gal].Concentration: 90–360 L/t [1–4 gal/sk].

D157 Weighting High-density slurries Red brown powder 4.80 Compatible with freshwater and high-agent salinity slurries to 232°C [450°F]. Applicable

1920–2640 kg/m3 [16–22 lbm/gal]. Very small particle size (5 micrometers) enables additiondirectly to mix water, allowing last-minute density increases.

Materials 70



D161 UNISET HT High temperatures Clear liquid 1.08 Compatible with freshwater slurries and retarder salinities to 25% salt BWOW and any density.

Works synergistically with UNIFLAC fluid-lossadditives. Concentration: 9–225 L/t [0.1–2.5 gal/sk].Effective 85–232°C [185–450°F].

D162 Liquid Sedimentation control Off-white liquid 0.84 Compatible with freshwater and high antisettling salinity slurries. For all densities. additive Temperature: to 149°C [300°F].

Concentration: 0.45–2.3 L/t [0.005–0.025 gal/sk].

D165 CemHD DensCRETE slurries Reddish powder 4.95 Special grade of hematite for DensCRETE slurries.

D166 CemD DensCRETE slurries White powder 2.65 Special grade of silica for DensCRETE slurries.

D167 UNIFLAC S Fluid-loss control White powder 1.32 Compatible with freshwater and high salinityadditive slurries. Temperature: to 204°C [400°F].

All densities. Typical concentration: 0.1 to 0.8% BWOC.

D168 UNIFLAC L Fluid-loss control Colorless to yellow 1.08 Liquid version of D167. Compatible with additive liquid freshwater and high salinity slurries.

Temperature: to 204°C [400°F]. All densities.Typical concentration: 9–81 L/t [0.1–0.9 gal/sk].

D174 Expanding Low to moderate Tan powder 3.22 Temperature: 27–110°C [80–230°F]. cement temperatures Typical concentration range: 3–5% BWOC.additive

D175 Antifoaming High-salinity slurries White liquid 0.99 General purpose, liquid foam preventer and additive and spacers (efficient defoamer. Added to the mix water. Typical

in any fluid) concentration: 1–5 L/t [0.01–0.05 gal/sk] forcement slurries and 2.5 L/ m3 [0.1 gal/bbl] for spacers.

D176 Expanding High temperatures Tan powder 3.54 Temperature: 80–204°C [176–400°F]. cement Typical concentration: 1–5% BWOC.additive

D177 UNISET LT Low to moderate Light green liquid 1.10 Can be used with fresh water or seawater. additive temperatures Concentration: to 26 L/t [0.3 gal/sk].

Low sensitivity of thickening-time to changes in temperature or concentration. Maximum temperature: 121°C [250°F] if used in combination with UNIFLAC additive (D167 or D168).

D182 MUDPUSH II Low to moderate Red brown powder 1.32 Concentrate for preparing MUDPUSH II spacer; spacer temperatures used with freshwater, seawater, or high-salinityadditive spacers. MUDPUSH II spacer density can be

designed to 2400 kg/m3 [20 lb/gal].Temperature: to 149°C [300°F].

D185 Dispersant Low temperatures Colorless liquid 1.04 DeepCEM additive for cold environment ofdeep water. Nonretarding. Temperature: to 57°C [135°F]. Rheology is not affected by salt (D044) or calcium chloride (S001).




D186 Set enhancer Low temperatures Green liquid 1.35 DeepCEM additive for cold environment ofdeep water. Enhances the set profile ofcement; accelerates cement hydration resulting in early compressive strength development. It is especially effective withGASBLOK LT additive (D500) and D185 dispersant. D186 can be used withDeepCRETE systems. Preferred temperature: 7–55°C [45–130°F]. Compatible with freshwater or seawater. Concentration: to17.8 L/t [0.2 gal/sk].

D190 MUDPUSH High temperatures Colorless powder 1.23 Viscosifies to suspend weighting agents WHT additive and control fluid loss in MUDPUSH WHT

high-temperature spacer, which has a temperature limit of 232°C (450°F). Density: to 2400 kg/m3 [20 lb/gal].

D191 Surfactant For spacers and Clear opalescent liquid 0.98 Environmentally friendly surfactant used inwashes for removal washes and MUDPUSH spacers for removal of OBM of OBM, low-toxicity OBM or synthetic OBM.

Temperature: to 250°C [482°F].Typical concentration: 48 L/m3 [2 gal/bbl].

D192 Chemical Mud thinning, Dark brown liquid 1.18 Environmentally friendly surfactant used wash dispersing and in washes. No limit on temperature.concentrate removal

D300 Fluid-loss Low to moderate Green liquid 1.00 Nonretarding. Compatible with calcium chloride. additive temperatures Compatible with salinity to 10% BWOW.

Temperature: 27–120°C [80–250°F].Concentration: 32–117 L/t [0.35–1.3 gal/sk]. Only dispersants D145A and D185 can be used with D300 fluid-loss additive.

D500 GASBLOK LT Gas migration Yellow liquid 1.01 Nonretarding liquid additive. additive control at low Temperature: to 71°C [160°F].

temperatures Density: 1260–1970 kg/m3 [10.5–16.4 lbm/gal].Compatible with fresh water and seawater. Typical concentration: 45–180 L/t [0.5–2.0 gal/sk].

D600G GASBLOK MT Gas migration White liquid 1.02 Latex additive. Temperature: 66–149°C [150–300°F].additive control additive Concentration: 130–260 L/t [1.5–3.5 gal/sk] in

GASBLOK slurries; 90–180 L/t [1–2 gal/sk] as WELBOND cement. Lower concentration is required when used for fluid-loss control only.

D602 Diatomaceous Cement extender White to gray powder 2.10 Naturally occurring material used as extender.earth

D604AM SALTBOND Fluid-loss control for Dark brown liquid 1.21 Salt system dispersant and fluid-loss additive. additive high salinity slurries Temperature: to 121°C [250°F].

Concentration: 27–81 L/t [0.3-0.9 gal/sk].

D604M Dispersant “Easy-to-disperse” Dark brown liquid 1.21 Formulated to minimize overdispersion. cements Temperature: 121°C [250°F].

Concentration: 0.9–9 L/t [0.01–0.1 gal/sk].

D606 Gel- Antigelling additive White crystals 2.68 Eliminates primary gelling tendency of cement suppressing with improperly balanced sulfate. Typical additive concentration: 0.5–1.0% BWOC.

Materials 72



D607 Surfactant For spacers and Yellow liquid 0.99 Typical concentration: 2–10% by volume.washes for removalof OBM

D700 GASBLOK HT Gas-migration-control White liquid 1.02 Latex additive. Typical temperature: additive additive for high 121–191°C (250–375°F). Concentration:

temperatures 177–310 L/t [2–3.5 gal/sk]. The addition of D701 (high temperature latex stabilizer) may be required.

D701 GASBLOK Stabilizer for Clear yellow 1.05 Used to stabilize D700 GASBLOK slurry, stabilizer GASBLOK slurries viscous liquid necessary. Typical concentration: 5% by

volume of D700.

D800 Retarder Low to moderate Dark brown powder 1.26 Lignosulfonate retarder with reduced tendency temperatures for gelation. Temperature: 52–121°C [125–250°F]

BHCT; can be extended to 154°C [310°F] whenused with a retarder aid. Compatible with fresh water or salt water (to saturation). Concentration: 0.25–2%BWOC.

D801 Retarder Low to moderate Dark brown liquid 1.18 Liquid version of D800. Temperature: temperatures 52–121°C [125–250°F] BHCT; can be extended

to 154°C [310°F] when used with a retarderaid. Compatible with fresh water or salt water (to saturation). Concentration: 4.5-36 L/t [0.05-0.4 gal/sk].

F040 EZEFLO* For spacers and Clear liquid 1.04 Typical concentration: 2–10% by volume.surfactant washes for removal

of OBM

F057 Surfactant For spacers and Yellow liquid 1.07 Typical concentration: 2–10% by volume.washes for removal of OBM

F078 EZEFLO For spacers and Clear amber liquid 0.89 Typical concentration: 2–10% by volume.surfactant washes for removal Also used for foaming cement slurries

of OBM with nitrogen or air. Typical concentration: 19–18 L/t [0.1–0.2 gal/sk]

F103 EZEFLO For spacers and Clear colorless liquid 0.94 Typical concentration: 2–10% by volume.surfactant washes for removal

of OBM

F104 Foaming Foamed cement Clear amber liquid 1.01 For foaming cement slurries with nitrogen or air.additive Also used in washes and in MUDPUSH spacers

for removal of OBM. Typical concentration: 2–10% by volume.Typical concentration: 9–18 L/t [0.1–0.2 gal/sk].

J120 Polymer Polymer Plug White powder 1.00 Polymer for use in Polymer Plug lost circulationcontrol system.

J237A Fluid-loss Fluid-loss control in Creamy liquid 1.06 Typical concentration: 6 L/ m3 [0.25 gal/bbl].additive chemical washes

M045 Antifoaming Washes and spacers White liquid 1.00 General purpose, liquid foam preventer andadditive defoamer. Added to the mix water. Typical

concentration: 5 L/t [0.05 gal/sk] for cement slurries and 2.5 L/m3 [0.1 gal/bbl] for spacers.




M117 Potassium Clay stabilizer White to gray 1.98 Used in washes and spacers as a clay chloride crystals stabilizer. Typical concentration: 3% BWOW.

Sometimes used in cement slurry to controlswelling shales.

S001 Calcium Accelerator White solid 1.75 Calcium chloride 77%. Typical concentration: chloride 1 to 2% BWOC. Increases temperature of slurry

when dissolved.

S002 Calcium Accelerator White solid 1.75 Calcium chloride 95%. Typical concentration: chloride 1 to 2% BWOC. Increases temperature of slurry

when dissolved.

U066 Mutual For spacers and Colorless to 0.90 Used in washes and in MUDPUSH spacers forsolvent washes for removal white liquid removal of OBM and particularly environmen-

of environmentally tally safe OBM. Typical concentration: 2–10%safe OBM by volume.

U100 Mutual For spacers and Colorless to 0.90 Used in washes and in MUDPUSH spacers forsolvent washes for removal white liquid removal of OBM and particularly environmen

of environmentally tally safe OBM. Typical concentration: 2–10% safe OBM by volume.

Note: Temperatures, concentrations and other conditions of application are typical. Testing may allow extension of ranges.

IntroductionCementing requires specially designed equipment. Equipment may be high-powered like theCPF-376 double pump cement trailer or CPT-372 double pump cement truck or highly versatileto accomplish numerous cementing operations each day, like the CemSTREAK cementing unit.Even more specialized equipment is required for use offshore, with the skids designed to deliverhigh power with high reliability. In many cases, offshore cementing is done using liquid additivesand LAS* liquid additive systems are used for precise delivery of the additives to the mixing sys-tem. When subsea heads are used, the DeepSea EXPRESS plug launching system is used for reli-able wiper plug launching. Monitoring and recording of the cementing operation is done usingthe CemCAT computer-aided treatment software and a portable computer. Innovative mixingcontrol is accomplished using the SFM* Solids Fraction Monitor.

CemSTREAK land cementing unitThe CemSTREAK land cementing unit is a lightweight, low-maintenance truck with four-wheeldrive that can be used for almost any cementing application. Its rugged, compact designenables operation even in hard-to-reach locations. The simplicity of design and extensive testprogram provide a high level of reliability over rough terrain and in bad weather and allowquick rig-up, rig-down and cleanup. This unit enables as many as six jobs to be performed inone day.

Cementing Services and Products ■ Equipment 75

Equipment

The compact CemSTREAK unit can service wells in difficult-to-reach locations.Designed for fast rig-up and rig-down, the unit can perform multiple jobs in one day.


The CemSTREAK unit is equipped with one triplex pump and two 1.1-m3 [6.9-bbl] displace-ment tanks, one of which doubles as the mix tank. The hydraulically driven triplex pump allowscontrol of flow rates and pressures and delivers 127 kW [170 hhp] of power. Two centrifugalpumps enable high-energy mixing, pressurizing the triplex pump as well as bringing water ontothe unit.

The unit carries 38 m [125 ft] of treating hose, rated to 20.7-MPa [3000-psi] working pressure,to serve as the high-pressure conduit to the well. The hose is stored on an automated reel for fastdeployment and retrieval.

A nonradioactive mass-flow meter provides accurate measurements of slurry density, flow rateand fluid volume even during U-tubing of fluids in the well.

Cleaning of the unit starts with the displacement tanks, which minimizes wastewater andhence environmental impact.

Applications■ Cementing services ■ Low- and intermediate-range pumping services ■ Remedial cementing operations requiring very low pump rates■ Low-range pressure testing

Benefits■ Ability to reach difficult locations ■ Savings in rig time through rapid rig-up and rig-down ■ Minimal environmental impact ■ Weight compliant with various road ban rules ■ Crew of only two operators for improved logistics, reduced risks and costs ■ Downtime probability reduced or eliminated by reliability of equipment ■ Ability to mix all slurry types

Features■ Four-wheel drive ■ 127-kW [170-hhp] triplex pump ■ Rating of 20.7-MPa [3000-psi] working pressure ■ 38 m [125 ft] of 50.8-mm [2-in.] hose rated to 20.7-MPa [3000-psi] working pressure ■ Powered reel for hose storage, deployment and retrieval ■ 1.11-m3/min [7-bbl/min] pump rate ■ Nonradioactive densitometer ■ SLURRY CHIEF Mark III cement mixer ■ Oilfield or metric gauges ■ Integrated data-acquisition system■ Two 1.1-m3 [6.9-bbl] displacement tanks ■ CemCAT real-time monitoring ■ Four separate systems for pressure relief ■ Self-sufficient unit, including cement head and extra treating iron

Equipment 77

CPF-376 double-pump cement trailerThis cement trailer is a state-of-the-art mixing and pumping unit for land operations. The high-power unit allows mixing and pumping cement at rates to 2.7 m3 [17 bbl/min] and at pressuresto 68.95 MPa [10,000 psi]. Pumps are available with rating to 137.9 MPa [20,000 psi]. The unitis fully redundant, allowing operations to continue in the event of failure of one of its components.

A SLURRY CHIEF mixer with automated density control is used in conjunction with a 0.95-m3 [6-bbl] mixing tub and a 2.2-m3 [14-bbl] averaging tank. This arrangement producessuperior density control and separates the critical mixing stage from downhole pumping. It alsoprovides the ability to mix 3.2 m3 [20 bbl] of cement in batch mode for squeeze and plug operations.

The CemCAT system is used to monitor and record treatment parameters and to provide a jobreport.

Applications■ Cementing services ■ High-power pumping services ■ Remedial cementing operations

Benefits■ Full redundancy ensures ability to complete job■ Downtime reduced or eliminated by reliability of equipment ■ Ability to mix all slurry types

The CPF-376 double-pump cement truck delivers high reliability in high-pressure pumping operations.

Features■ 194-kW [260-hhp] power per triplex pump, for a total of 388 kW [520 hhp]■ 2.7-m3/min [17-bbl/min] pump rate ■ Working pressure rating to 137.9 MPa [20,000 psi]■ Fully redundant for high reliability■ SLURRY CHIEF Mark III cement mixer ■ Automatic density control system■ Two nonradioactive densitometers ■ Oilfield or metric gauges ■ Underdrive for pumping at low rates■ Direct drive centrifugal pumps for reliability■ Integrated data-acquisition system■ CemCAT real-time monitoring ■ Self-sufficient unit, including treating iron

CPT-372 double-pump cement truckThe CPT-372 truck is a high-power cement mixing and pumping unit that allows mixing andpumping at rates to 2.7 m3 [17 bbl/min] and at pressures to 68.95 MPa [10,000 psi]. The unit isfully redundant, allowing operations to continue even if one component fails.

A SLURRY CHIEF mixer is used in conjunction with a 0.95-m3 [6-bbl] mixing tub. This arrange-ment produces superior density control and separates the critical mixing stage from downholepumping. It also provides ability to mix a maximum of 3.2 m3 [20 bbl] of cement in batch modefor squeeze and plug operations.

The CemCAT system is used to monitor and record treatment parameters and to provide ajob report.


The CPT-372 double-pump cement truck delivers high reliability inhigh-pressure pumping operations.

Applications■ Cementing services ■ High-power pumping services ■ Remedial cementing operations

Benefits■ Full redundancy ensures ability to complete job■ Downtime reduced or eliminated by reliability of equipment ■ Ability to mix all slurry types

Features■ Power to 388 kW [520 hhp]■ Pump rate to 2.7 m3/min [14 bbl/min] ■ Working pressure rating of 68.95 MPa [10,000 psi]■ Fully redundant for high reliability■ SLURRY CHIEF Mark III cement mixer ■ Nonradioactive densitometer ■ Oilfield or metric gauges ■ Integrated data-acquisition system■ CemCAT real-time monitoring ■ Self-sufficient unit, including treating iron

Offshore cementing skids Schlumberger provides a versatile line of CPS* cement pumping skids specially designed to meetall offshore cement mixing and pumping requirements. These skids can produce up to 1490 kW[2000 hhp] for high-pressure pumping.

Equipment 79

CPS cement pumping skids are available in a number of configurations to fit any requirement.

Two triplex pumps equip the unit for simultaneous high-energy mixing and downhole pump-ing or for parallel downhole pumping. Two engines (diesel or electric) power the unit. Thedesign focuses on reliability, redundancy and noise reduction. The units are typically controlledfrom a local console but optional remote control packages are available. Optional marine cool-ing kits and a helicopter lift unit are available.

Cement slurries are mixed using the SLURRY CHIEF recirculating mixer fitted with an SFMquality control monitor or an SFM-C* process control unit for automatic density control. TheSLURRY CHIEF unit mixes consistent slurries at rates to 1.75 m3/min [11 bbl/min]. Equalizingtubs provide excellent slurry uniformity (3 m3 [19 bbl]).

Offshore cementing skids are fitted with all sensors necessary for direct connection to theCemCAT data-acquisition and monitoring system. The CemCAT system monitors and recordsthe critical job parameters including rate, pressure and slurry density.

Batch mixers, such as the CBS-961 twin 50-bbl mixer, are available for mixing of cementslurries or other fluids. The CBS-961 unit features two centrifugal pumps for picking up fluidsfrom remote tanks, recirculating for mixing and for delivering fluid to high-pressure pumps.

Standard equipment ■ SLURRY CHIEF cement mixer ■ Nonradioactive densitometer ■ Two triplex pumps ■ Stainless-steel displacement tanks■ Slurry pump ■ Recirculation pump ■ Two mixing water pumps ■ Full selection of fluid ends

Optional equipment ■ SFM package ■ Automatic density control■ Zone II-certified engine package ■ Remote control package ■ Split skid with bulkhead ■ Optional loose equipment skid■ Marine cool kit■ Liquid additive metering system■ Soundproof enclosure (for CPS-601 and CPS-665 units)

Applications■ All cementing jobs■ High-pressure pumping services ■ Fluid pickup from remote sources ■ Metering of mixing fluids ■ Metering and pumping of displacement fluids ■ Downhole pumping using one or both triplex pumps


Equipment 81

LAS liquid additive systemModular systems, such as the CMP-351 unit, deliver metered amounts of liquid additives to thecement slurry as it is mixed. Metering of liquid additives adds versatility to the mixing process,enabling the mixing of various slurry systems from bulk storage of neat cement. Metering can bemanual, or automatic when the CMP-751 LAS metering unit is used. With the CMP-751 unit, elec-tromagnetic flow meters control the additive metered into the displacement tanks.

Applications■ Offshore cementing operations■ Operations in remote areas

Benefits■ Allows use of neat (unblended) cement for all operations■ Provides high versatility in slurry designs■ Simplifies logistics■ Enables last-minute design without regard to time of transport from base■ Eliminates waste of unused blended cement■ Enables decisions on treatment volumes at time of job

Features■ Meters up to four different additives into mixer■ Stainless–steel construction for durability■ Remote control of additive addition■ Certified for Zone II operations■ Electromagnetic flow meters

Table 6-2. Performance of Offshore Cementing Units

CPS 361 CPS 601 CPS 665 CPS 763AC CPS 763DC CPS 2000

Power (kW [hhp]) 410 [550] 626 [840] 1044 [1400] 1194 [1600] 1194 [1600] 1490 [2000]

Max. rate at 1.6 [10] 3.1 [19.7] 2.9 [18.3] 2.9 [18.3] 2.9 [18.3] 3.8 [24.0]41.4 MPa [6000 psi] at 46.9 MPa(m3/min [bbl/min]) [6800 psi]

Table 6-1. Dimensions of Offshore Cementing Units

CPS 361 CPS 601 CPS 665 CPS 763AC CPS 763DC CPS 2000

Length (mm [in.]) 6,511 [256] 7,710 [304] 7,863 [310] 8,180 [322] 7,823 [308] 7,164 [282]

Width (mm [in.]) 2,578 [102] 3,011 [119] 2,898 [114] 3,007 [118] 3,150 [124] 3,841 [151]

Height (mm [in.]) 3,043 [120] 3,467 [136] 3,333 [131] 3,339 [132] 3,323 [131] 3,267 [129]

Operating weight (kg [lbm] 20,658 [45,550] 32,180 [70,960] 33,840 [74,600] 37,360 [82,380] 38,010 [83,810] 46,795 [103,180]

CemCAT cementing computer-aided treatment softwareThe CemCAT system is a quality control (QC) and data-acquisition software for acquiring, record-ing, displaying, and reporting cementing and related pumping treatment data in real time.CemCAT system real-time displays and plots present detailed job information to decision-makers.User friendly and quickly accessible, the CemCAT system provides enough defaults for the systemto be used quickly with a minimum of user input, or it can be completely customized.

By acquiring data from existing hardware on cementing units, the CemCAT system providesefficient data transfer between the Wellsite Reporting System and Schlumberger CemCADEcementing design software. Integration of up-to-the-minute data with design and evaluation soft-ware results in precise treatment design and execution. During the job, the CemCAT systemtracks the design and displays actual job parameters compared with planned values.

With the CemCAT system, quality assurance (QA)/QC plots can be generated at the end ofeach treatment to determine if a job was pumped within the designed density range. Internetconnectivity allows the transmission of data from a remote wellsite to anywhere in the world forreal-time analysis. The CemCAT system also provides the means to easily archive job data forfuture use.

Applications■ Primary and remedial cementing operations■ Miscellaneous high-pressure pumping services for testing blowout preventers or for leakoff or

formation integrity tests■ Matrix acidizing and coiled tubing services

Benefits■ Superior QC during all treatment phases■ Precise treatments that follow job design■ Immediate data for job-critical decisions, thus reducing risk■ Exceptional flexibility, performance and reliability

Features■ Complete integration with CemCADE design and evaluation software■ Clear, customizable digital displays and plots of job data■ Real-time data transmission from wellsite to any location worldwide■ Detailed postjob plots including QA and QC plots and reports■ Archive of job data for future use

SFM-C process controlAn important element of successful low-density slurry placement and ideal set-cement propertiesis QC. A key measure of quality in cement slurries is the solids fraction, which is the percent ofdry components in the slurry. In a conventional cementing operation, densitometers measureslurry density, and the solids fraction can be calculated from the density measurements.Variation in the solids fraction of the slurry affects all the cement properties. Too many solidsand the slurry will be too viscous and set early. Too few solids and free fluid will be high and thecompressive strength will be low and develop late. For certain slurries, such as very low densityslurries, slurry quality cannot be determined using density measurements.


In ultralightweight slurries, the densities of the dry blend and the mix water can be nearly thesame, so density measurements cannot discriminate between water and solids. The density wouldbe the same, even if the slurry consisted entirely of water. For example, a slurry designed at1020 kg/m3 [8.5 lbm/gal] with 57% solids content and monitored using only a densitometer witha variation of ± 12 kg/m3 [0.1 lbm/gal] in density will have a solids content ranging from 24%to 84%.

The SFM-C process control system provides a new method for real-time slurry QC that accu-rately determines and controls solid/liquid ratios without making density measurements. The sys-tem measures the rate of mix water and slurry flows and calculates the solids fraction from thosemeasurements. From this determination, the fluid density is easily computed. The solids fractionis automatically maintained by process control of the water and cement flow into the mixer.

The SFM-C system is a complementary technology, designed to provide QC for very low densityLiteCRETE slurry systems. Although SFM-C technology was developed specifically for light-weight-cement operations, it is effective for slurries of any density.

This new SFM-C technology allows cementing crews to maintain slurry properties while con-tinuously mixing and pumping large slurry volumes. The system requires a slurry flow meter, suchas the nonradioactive densitometer already available on cementing units, a residence tank sen-sor, a water flow meter and process-controlled valves. These retrofits can be added easily to landor offshore mixing equipment.

User friendly software helps cementing crews monitor and easily switch between automaticand manual control.

Equipment 83

SFM-C system instantly displays critical data in convenient, readable formats.

Applications■ All cementing operations■ Slurries with very low densities (less than 1320 kg/m3 [11 lbm/gal])

Benefits■ Excellent QC

Features■ Continuous-mixing control of all slurries, even at densities equal to or lower than that of water■ More sensitive method for controlling cement mixing than by density measurement■ Independent of specific gravity of components■ Automatic control of slurry quality■ Real-time monitoring■ Complete compatibility with all data acquisition systems■ Easy installation on conventional mixing equipment


100

90

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60

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00 5 10 15 20 25 30 35 40 45

Time, min

Solid

frac

tion,

%

Slur

ry d

ensi

ty, l

bm/g

al

Slur

ry ra

te, b

bl/m

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9

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00 10 20 30 40 50 60 70 80 90 100

Solid fraction, %

Volu

me,

%

88% of volume +/–2% of the solid-fraction target99% of volume +/–0.2 lbm/gal

The SFM-C system controls the solids fraction, which in turn controls the density.

Nonradioactive densitometer Density measurement and control in the oil industry have traditionally been accomplished byusing radioactive densitometers, mainly because they are nonintrusive, durable and easy to use.Unfortunately, the radioactive technique has several major drawbacks; the radioactive sourcepresents safety and environmental concerns, and the required accuracy (12 kg/m3 [0.1 lbm/gal])is difficult to attain.

Because of the deficiencies of radioactive densitometers, Schlumberger uses a nonradioactivedensitometer that employs a proven method, poses no health, safety, or environmental hazard,and provides direct density measurements with an accuracy of better than 12 kg/m3 [0.1 lbm/gal].

The nonradioactive densitometer is extremely reliable, easy to use and requires no on-site cal-ibration. Additionally, it measures flow rate with an accuracy of ±0.5% of reading and can be usedas a flow-measurement instrument for acidizing service. The vibrating tube principle governs thedensity measurement in the nonradioactive densitometer.

Equipment 85

The nonradioactive densitometer is a rugged, field-proven instrument with excellent reliability.

Applications■ Cementing operations with slurry density over 1200 kg/m3 [10 lbm/gal] ■ Land and offshore (including Zone II) ■ Process controlled operations■ Can be used for acidizing service

Benefits■ Accurate density measurement■ Reliability, requires no on-site calibration■ Minimal environmental and safety concerns

Features■ No radioactive source■ Superior accuracy and field-proven reliability for measuring density and flow rate■ Accuracy greater than 12.0 kg/m3 [0.1 lbm/gal]■ Virtually maintenance-free■ Easy configuration; easily drained and cleaned in place■ Output (density, rate) independent of changes in temperature, pressure, flow profile

or viscosity■ Fast response time


IntroductionCement evaluation plays an important role in the cementing process. By cement evaluation, thequality of zonal isolation is confirmed. In cases where zonal isolation is not achieved, the evalu-ation helps diagnose the problems that led to the poor zonal isolation. Consequently, methodsand slurry design used for the primary cementing are reviewed and improved for the next well.Results also help in deciding whether remedial work is required. Cement evaluation and QC areprocesses completed during and after every step of primary cementing.

During the design, using Schlumberger CemCADE design software, the design engineer useswell data and cementing parameters to predict the results with selected cement systems, select-ing the one providing the desired zonal isolation. During execution, the operation is monitoredand analyzed. Finally, in the evaluation, cement evaluation logs are acquired for final confirmationof hydraulic zonal isolation.

Thus, cement evaluation is a continuous process beginning with the design and continuingwith execution analysis, post-treatment analysis and analysis of cement evaluation logs to deter-mine zonal isolation.

DesignIn the design the well data are entered into CemCADE software to ensure optimum WELLCLEANmud removal, pipe centralization, cement slurry for downhole conditions, flow rate, etc. Theexecution, as designed, is simulated and theoretical mud removal and zonal isolation areassessed. If results are not satisfactory, the design is revised and the simulation is rerun.

See page 29 for more information on CemCADE software and WELLCLEAN mud removal.

Execution analysisThe purpose of primary cementing is to achieve zonal isolation. The slurry composition and theexecution procedure are designed to provide complete zonal isolation. The properties of thecement sheath are optimized to isolate all productive zones, as well as those containing waterand nuisance gas.

The first QC step and evaluation during the execution determines if the materials were mixedaccording to the design and if the displacement process followed the prescribed procedure. Thisevaluation is made using plots of the slurry density, solids fraction, flow rate and pumpingpressure during the execution.

See page 82 for more information on CemCAT monitoring software.

Post-cementing analysisIf the execution analysis indicated abnormal values of any monitored parameters, a thoroughanalysis is performed after the operation. The data acquired during the cementing operation areloaded into CemCADE cementing design and evaluation software and the execution data can beoverlaid and compared with the simulation run during the design. The simulation can also bererun using density and volumes of fluid mixed and pumped to determine if mud removal para-meters were met.

Cementing Services and Products ■ Evaluation 87

Evaluation


Cement evaluation logs are acquired for final confirmation of hydraulic zonal isolation andtops of cement.

Using the analysis from both steps, any problem areas can be highlighted with special attentionto the depths on the evaluation logs where isolation is a concern.

Cement evaluation servicesCement evaluation services are used in the final evaluation of cement integrity and zonal isolation.Used in conjunction with the execution and the post-cementing analyses, evaluation logs canhelp identify poor isolation and the reasons for that poor isolation. If remedial work is necessary,evaluation logs assist in its design to achieve the required isolation for well completion andproduction of desired fluids. Any problem identified in these analyses is targeted for improve-ment in the design or execution phases for future wells.

Cement evaluation services also play an important role in confirming the pipe’s integrity,support and isolation from formation fluids, because exposing pipe to formation fluid can even-tually lead to corrosion if the lack of isolation is not corrected.

Cement evaluation services are divided into two major groups:■ Acoustic logging can be either sonic services, with tools that provide a log of amplitude

measurements and Variable Density* sonic waveforms, or ultrasonic services, with tools thatprovide a map of the cement distribution around the pipe.

■ Other logging tools provide indirect evaluation through measurements of pressure, temperature,nuclear activity and noise.SoniCalc software is a tool that allows the logging engineer to import well and cementing data

for use in tool setup and interpretation of cement bond logs (CBLs) and USI UltraSonic Imagercement evaluation logs. Tool setup parameters are provided so that tool setup and computedoutput are correct for the well being logged, improving logging service quality. These data alsoassist in interpreting evaluation logs and in determining if remedial treatments may be required.

Only acoustic tools are discussed in this catalog.

Sonic servicesCBLs, with amplitude and/or attenuation and Variable Density waveform data, have been the pri-mary method for cement quality evaluation for many years. The principle of the cement bondmeasurement is to record the transit time and amplitude (or attenuation) of a 20-kHz acousticwave after propagation through the well fluid and the pipe wall.

The measurement is the amplitude in millivolts of the tubular first arrival (E1) at a receiverwith 0.91-m [3-ft] or shorter spacing. The amplitude of the signal is a function of the attenuationby the shear coupling of the cement sheath to the pipe. The attenuation rate depends on thecement compressive strength, cement thickness, pipe diameter, pipe thickness and percentageof bonded circumference.

A receiver with 1.52-m [5-ft] spacing is used to record the Variable Density waveform for bet-ter discrimination between sonic waves traveling through pipe and those through formation. Thismeasurement is generally used to qualitatively assess the cement-to-formation bond.

SlimAccess toolThe SlimAccess* wireline logging tool is designed for slim, complex-geometry boreholes. It gen-erates, records and digitizes acoustic waves and provides CBL amplitude, Variable Density mea-surement and attenuation measurement for cement bond evaluation. It is also used for openholeapplications such as seismic correlation, porosity measurement and evaluation of lithology. It hasa short-spacing 0.30-m [1-ft] transmitter–receiver for cement evaluation in fast formations.Besides the primary transmitter–receivers used for CBL and Variable Density measurement, theSlimAccess tool also uses a second set of transmitter–receivers for backup. It is a monopole sonictool with a diameter of 6.35 cm [21⁄2 in.], which enables it to be run in 14-cm [51⁄2-in.] casing.

Evaluation 89

The SlimXtreme* tool is the version of the SlimAccess tool for use in slim, complex-geometryboreholes under HPHT conditions.

Applications■ Determine quality of pipe to cement bond■ Determine quality of formation-to-cement bond ■ Identify cement top■ HPHT wells (SlimXtreme tool)

Benefits■ Logging in pipe as small as 14 cm [51⁄2 in.]■ Log quality minimally affected by environmental conditions

Features■ 0.30-m [1-ft] receiver for cement evaluation in fast formation■ 6.35-cm [21⁄2-in.] diameter■ Low sensitivity to environmental conditions■ Combinable with ultrasonic imaging tool for enhanced interpretation

SCMT Slim Cement Mapping Tool The SCMT* Slim Cement Mapping Tool is a sonic tool that provides a radial cement attenuationvariation map from a 0.61-m [2-ft] eight-segment receiver, as well as conventional 0.91-m [3-ft]amplitude (attenuation) and 1.52-m [5-ft] Variable Density data. In addition, the 0.61-m [2-ft]mapping receivers are effective for cement evaluation in fast formations where the 0.91-m [3-ft]receiver might give ambiguous results. Because of its slim size (4.29-cm [111⁄16-in.] diameter), thetool can be run through tubing. The SCMT tool can be run in combination with the PS Platform*new-generation production services platform or the RST* Reservoir Saturation Tool for completewell and reservoir evaluation in one trip.

The principal application of the SCMT log is cement quality and integrity evaluation aroundthe entire circumference of the pipe.

Applications■ Determination of quality of pipe-to-cement bond■ Qualitative evaluation of cement-to-formation bond ■ Identification of cement top

Benefits■ Tubing does not have to be removed from well (no rig required).■ Interpretation is valid, even in fast formations.■ Time is saved when the tool is run in combination with other tools.

Features■ Combinable with PS Platform suite or RST tool for well, reservoir and cement integrity

evaluation in the same run■ Combinable with PipeView* multifinger caliper tool for PS Platform tool string, for cement

and pipe integrity evaluation in the same run giving complete well integrity diagnosis■ 4.29-cm [111⁄16-in.] diameter■ 8-segment receiver for bond variation mapping■ 0.61-m [2-ft] receiver

Ultrasonic servicesUSI UltraSonic ImagerThe USI UltraSonic Imager provides an accurate and reliable high-resolution, comprehensive,real-time answer product revealing pipe-to-cement bond quality and downhole pipe condition.Using ultrasonic technology, the USI tool sends ultrasonic pulses between 200 kHz and 700 kHzthat travel through the well fluid and strike the casing, providing 360º azimuthal coverage usinga single rotating transducer. The transducer receives reflected signals that have undergone mul-tiple reflections between the casing internal and external interfaces. The signal decays at a ratedependent on the acoustic impedance of the material in the annulus.

USI log maps of the acoustic impedance of the material in the annulus are generated usingvery advanced processing techniques. From the acoustic impedance values, the material in theannulus is identified and maps are prepared showing the nature (gas, liquid, solid) of the mate-rial in the annulus. High-resolution maps of pipe wall thickness, internal radius and inner wallrugosity are provided for accurate evaluation of the pipe condition. The results are displayed inreal time as quantitative, self-explanatory interpreted cement and pipe integrity maps.

The combination of the USI tool with CBL and Variable Density tools provides enhancedassessment of cement-to-pipe and cement-to-formation bond quality.

Applications

Cement integrity■ Hydraulic zonal isolation evaluation ■ Remedial work decision-making and assessment of effectiveness■ Primary cementing process improvement■ Identification of gas invasion■ Determination of casing support before sidetrack■ Cement top identification and free pipe identification for pipe retrieval

Pipe integrity■ Quantification of internal and external corrosion, wear, metal loss and/or scale buildup■ Identification and quantification of pipe distortion■ Selection of optimal packer setting depth


A SCMT log showing possible channel and its position aids in decision to squeeze andin design of the squeeze cementing treatment.

Benefits■ Detailed channel identification and location■ Remedial cementing optimization■ Microannulus identification■ Accurate, effective real-time answers■ Rig time saving by acquiring cement and pipe integrity data in one run■ Continuous improvement of cementing process

Features■ Cement map showing cement quality and presence of channels■ Pipe integrity data■ Wellsite product for enhanced three-dimensional (3D) visualization■ 100% azimuthal coverage by a single, rotating transducer■ 5º radial and 3.81-cm [11⁄2-in.] vertical resolution in high-resolution mode■ Combinable with inclinometry tools to aid image orientation in deviated wells■ Combinable with CBL tools for enhanced evaluation

The USI log provides several presentations reflecting different applications. The easily read-able, color-coded images make cement coverage in the annulus easy to interpret. Problems suchas channels in cement and tubular damage can be seen directly on the images, thus revealingthe status of zonal isolation for decisions about remedial work. Enhanced field products allowvisualization of the cement distribution and quality, as well as a 3D view of pipe condition to furtherfacilitate remedial work decisions. QC log presentations are used for data validation.

Evaluation 91

A USI log with optional Variable Density data provides the best identification of uncementedchannels and aids in decisions to squeeze and in design of the squeeze cementing treatment.

Cement integrity evaluation is essential, not only for zonal isolation confirmation and help inthe remedial work decision and design, but also for the determination of the causes of poorcementing procedures. All acoustic logs are sensitive to cement-to-pipe bond. Some measure-ment methods are affected by downhole conditions more than others and in different ways. Forthis reason, a USI log and CBL combination is advisable to help diagnose zonal isolation problemsat the cement/pipe interface and the cement/formation interface. A full analysis of the cementevaluation logs will assist in diagnosing the problem and provide information to improve thecementing.

Thus, USI logs and CBLs with Variable Density data should be run together because theirresponses area complementary, especially in the presence of■ microannulus (liquid or gas)■ thin cement sheath■ fast formation■ double strings of casing■ heavily corroded casing■ inside deposits (cement, rust)■ high-attenuation mud■ lightweight cement.

Table 7-1 shows the USI log and the CBL response under the different conditions mentionedabove.


Table 7-1. Effects on Evaluation Logs

USI Log CBL

Resolution 5° radial and 3.81 cm [11⁄2 in.] vertical 360° by .91 m [3 ft]

Well-bonded cement Cement (high acoustic impedance) Low amplitude or high attenuation; characteristic Variable Density log

Lightweight cement Acoustic impedance based on properties Complicates interpretationof the cement; special processing may be required for very low density cement

Dry microannulus and/or Affected: Resolved by special processing Complicates interpretationDebonded cement

Mud layer Slightly affected Complicates interpretation

Wet microannulus Slightly affected Complicates interpretation

Contaminated cement Shown as solid with low acoustic impedance if set Complicates interpretation

Mud channel Displayed as channel filled with liquid Complicates interpretation

Gas channel Shown as channel filled with gas Complicates interpretation

Formation bond Not discriminated Qualitatively indicated on Variable Density plot

Outer casing/ Slightly affected Strongly affected if cement sheath is thinhard formation

Casing condition Very sensitive: Corrosion, wear and deformed casing Slightly affected: No indication on log of qualitycan be quantified in alternate acquisition mode

Evaluation 93

The USI log measures the bonding between the pipe and the cement, and the Variable Densitydisplay indicates the bonding between the cement and the formation. The advantage of the USIlog over the traditional CBL is at the cement-pipe interface. The USI log■ identifies liquid-filled microannulus■ identifies microdebonding■ identifies channels as small as 3.05 cm [1.2 in.]■ evaluates thin cement sheath.

The processed USI log and CBL with Variable Density data can be displayed side by side forcomplete visual cement evaluation in real time at the wellsite. This feature helps the completionengineer make sound decisions on remedial actions. The combination also helps cementingcompanies in the continuous improvement and enhancement of their cementing systems andmethods for best hydraulic isolation and cement integrity results.

Nonstandard environmentThe evaluation of ultralightweight cement systems or logging in heavy mud or nonstandard casingsizes may require advanced interpretation.

For further information about cement evaluation services, please refer to www.slb.com/oilfield.

Cementing Services and Products ■ Glossary 95

Glossary

Absolute Volume. Volume a solid occupies or displaceswhen added to water divided by its weight: the volumeper unit mass. Units are gallons per pound or cubicmeters per kilogram.

American Petroleum Institute (API). Organizationwhich standardizes materials and procedures for use inoilfield.

API Cement. One of several classes of cement manufac-tured to the specifications of API Specification 10A.Classes of API cement are A, B, C, D, E, F, G and H.

API Recommended Practice 10B. RecommendedPractice for Testing Well Cements. The standard whichgives guidelines for testing methods for cements andcement formulations for use in well cementing.Procedures are intended to be modified to conditions ofthe well.

API Specification 10A. Specification for Cements andMaterials for Well Cementing. The standard which spec-ifies requirements for API well cements and specifica-tion testing methods.

API Water. The amount of mixing water specified in APISpecification 10A for specification testing of cement tomeet API requirements. This amount in not intended tobe a guide for mix water requirements in field applica-tions.

Base Slurry. Conventional cement slurry used as thecementitious component of a foamed cement slurry.

Bc. see Bearden Units of Consistency

Bearden Units of Consistency (Bc). The pumpability orconsistency of a slurry is measured in Bearden units ofconsistency (Bc), a dimensionless quantity with nodirect conversion factor to more common units of vis-cosity.

BHCT. see Bottomhole Circulating Temperature

BHST. see Bottomhole Static Temperature

Blaine Fineness. The particle size or fineness of acement in cm2/g or m2/kg as determined from air per-meability tests using a Blaine permeameter.

Bond Log. see Cement Bond Log

Bottomhole Circulating Temperature (BHCT). Thetemperature that occurs at the bottom of a well whilefluid is being circulated. The temperature used for mosttests of cement slurry in a liquid state (such as thicken-ing time, fluid loss, etc.). In most cases, is lower than theBHST, but in some cases, such as in deepwater or in thearctic, may be higher than BHST.

Bottomhole Static Temperature (BHST). The undis-turbed temperature at the bottom of a well. After circu-lation and the well is shut in, this temperature will beapproached after about 24–36 hours, depending on con-ditions. The temperature used in most tests in which thecement slurry is required to set or is set.

Bulk Volume. The volume per unit mass of a dry mater-ial plus the volume of the air between its particles.

BWOB. see By Weight of Blend

BWOC. see By Weight of Cement

BWOW. see By Weight of Water

By Weight of Blend (BWOB). Used to define theamount (in percent) of a material added to cementwhen the material is added based on the total amount ofa specific blend.

By Weight of Cement (BWOC). Used to define theamount (in percent) of a material added to cement. Themethod used for most additives in the dry form.

By Weight of Water (BWOW). Used to define theamount (in percent) of a material added to a cementslurry based on the weight of water used to mix theslurry. Normally used only for salt.

Cement Bond Log (CBL). An acoustic log used to mea-sure the attenuation rate of a sound wave propagatingalong the casing. Can be used as an indication of thequality of cement in the annulus.

Consistometer. Laboratory apparatus used to determinethe thickening time of a cement slurry as described inAPI Specification 10A and API Recommended Practice10B.

Consistency. A rheological property of matter which isrelated to the cohesion of the individual particles of agiven material, its ability to deform and its resistance toflow. The consistency of cement slurries is determinedby thickening time tests in accordance with APIRecommended Practice 10B and is expressed inBearden units of consistency (Bc).

Contact Time. The elapsed time required for a specificfluid to pass a designated depth in the annulus duringpumping operations.

Critical Rate. The minimum rate required to achieveturbulent flow.

Curing. The ageing of cement under specified conditionsof temperature and pressure.

Dehydration. Loss of water from cement slurries ordrilling fluid by the process of filtration. Results in thedeposition of a filter cake and loss of the slurry’s internalfluid into a porous matrix. The cement is not completelydehydrated (sufficient water remains to allow setting ofthe cement).

Difficult-to-Disperse (DTD). Cement which is noteasily dispersed by a material known as a dispersant.

Difficult-to-Disperse in Salt (DTDS). Cement which isnot easily dispersed by a material known as a dispersantwhen the slurry is mixed with water containing a highconcentration of salt.

DTD. see Difficult-to-Disperse

DTDS. see Difficult-to-Disperse in Salt

Easy-to-Disperse (ETD). Cement which is highly sensi-tive to the concentration of dispersant, often leading toslurry stability problems.

Easy-to-Disperse in Salt (ETDS). Cement which ishighly sensitive to the concentration of dispersant whenthe slurry is mixed with water containing a high concen-tration of salt. Over dispersion often leads to slurry sta-bility problems.

Effective Laminar Flow. A technique for effectively dis-placing drilling mud from the annulus using a laminarflow regime.

Equivalent Sack. The weight of any cementitious mate-rial or blend based on the absolute volume of thecement. Normally used to define a “sack” of cementblend in which part of the cement has been replaced, onan absolute volume basis, by a pozzolanic material suchas fly ash.

ETD. see Easy-to-Disperse

ETDS. see Easy-to-Disperse in Salt

Expanding Cement. Cement system exhibiting a bulkvolumetric increase after setting.

Fill Cement. A cement system used to provide zonal iso-lation across generally non-productive zones locatedabove the zones of interest. May also be called leadcement.

Fly Ash. The noncombustible residue from the burningof pulverized coal. Fly ash is pozzolanic and is frequentlyused to replace a portion of the cement and reduce itsdensity.

Foamed Cement. A homogeneous, ultralightweightcement system consisting of base cement slurry, gas(usually nitrogen) and surfactants.

Free Fluid. The volume of fluid (expressed in percent)separating from a cement slurry when left static.Measured as specified in API Recommended Practice10B. Once called free water.

Gas Migration. A generic term which covers all possibleroutes for annular gas entry and propagation throughand around the cement sheath. Also known as annulargas flow.

Gel Strength. The degree to which a fluid behaves as asolid when left static.

Gilsonite. An asphaltinic material frequently used asLCM for drilling fluid and cement.

Grind. The fineness to which cement is ground. Also mayrefer to a specific production of cement (e.g. lotnumber).

Hydraulic Cement. A substance which, when mixedwith water, becomes hard like stone because of a chem-ical reaction with the water. Hydraulic cement will setunder water.

Lead Cement. see fill cement

Liquid Additive. A material used in a liquid form tomodify the properties of cement for use in oil- or gaswellcementing.

LITEPOZ. A term used by Schlumberger for certainmaterials added to cement that are lightweight and havepozzolanic properties.

Microannulus. Small gap between the casing andcement sheath resulting from downhole stresses (pres-sure or temperature).

Neat Cement. Cement containing no additives.

POD. see Point of departure

96

Point of departure (POD). A term used to describe thebeginning of thickening of a cement slurry during thethickening time test. For some slurries, the POD is usedas the thickening time.

Portland Cement. The product obtained by pulverizingclinker consisting essentially of hydraulic calcium sili-cates.

Portland Cement Clinker. Hard granular nodules com-posed essentially of hydraulic calcium silicates, withsmaller quantities of calcium aluminates and ferrites. Itis produced by the heat treatment of cement raw mate-rials in a kiln. Clinker is pulverized with gypsum in themanufacture of Portland cement.

Pozzolan. A siliceous or siliceous and aluminous mater-ial which in itself possesses little or no cementitiousvalue but will, in finely divided form and in the presenceof moisture, chemically react with calcium hydroxide atordinary temperatures to form compounds possessingcementitious properties. (ASTM C340)

Pozzolanic. Possessing little or no cementitious valuebut capable of chemically reacting with calcium hydrox-ide at ordinary temperatures to form compounds pos-sessing cementitious properties. (ASTM C340)

Prehydrate. To mix with water and allow to react oryield in the water before use. Common technique forbentonite. May also be done for convenience in cement-ing operation to allow mixing of water containing theadditives with powdered neat cement.

Primary Cementing. The first cementing operation per-formed to place a cement sheath around a casing orliner. The main objectives include zonal isolation to pre-vent fluids migration in the annulus, support for thecasing or liner and protection of the casing from corro-sive fluids.

Pumpability. The ability of the slurry to be pumped.Measured by the API thickening time test.

Pumping Time. Loosely, the total time required forpumping the cement slurry into the well, plus a safetyfactor. Pumping time can also be the time to reach a con-sistency deemed to be unpumpable (generally 70 Bc)during an API thickening time test.

Reduced Water Slurries. A cement slurry having awater content less than would normally be used withoutmodifying additives.

Right Angle Set. The characteristic of a cement slurrywhere its consistency changes from the point of depar-ture or 30 Bc to 100 Bc in a very short time.

Sack. A unit of measure of Portland cement. In theUnited States the amount which occupies a bulk volumeof 1.0 ft3. For most Portland cement, including APIclasses of cement, a sack is 94 pounds. The sack is thebasis for slurry design calculations.

Sedimentation. Separation of the components of acement slurry in which the solids settle. One of charac-terizations used to define “slurry stability”.

Slurry Density. The weight per unit volume of a cementslurry (usually kg/m3 or lbm/gal).

Slurry Yield. The volume of slurry obtained when onesack of cement is mixed with the desired amount ofwater and other additives (usually m3/kg or ft3/sk[sack]).

Slurry Stability. The ability of a cement slurry to main-tain homogeneity. Two tests are used as a measure ofslurry stability; the free fluid and sedimentation.

Squeeze Cementing. The forcing, by pressure, of cementslurry into a specified location in a well, such as chan-nels or perforations, for the purpose of achieving isola-tion.

Strength Retrogression. A decline of cement strengthat elevated temperatures. This decline is pronounced attemperatures above 110°C [230°F]. It is controlled bythe addition of silica to the cement.

Sulfate Resistance. The ability of set cement to resistdeterioration in the presence of sulfate ions.

Sulfate Resistant Cement. Cement in which theamount of tricalcium aluminate is controlled as speci-fied by API Specification 10A.

Tail Cement. The last cement system pumped duringprimary cementing. It is the cement which covers thelower sections of the well, especially planned comple-tion intervals.

Tensile Strength. The force per unit cross-sectional arearequired to pull a substance apart.

Thickening time. A measurement of the time duringwhich a cement slurry remains in a fluid state and iscapable of being pumped. Thickening time is assessedunder simulated downhole conditions using a consis-tometer that plots the consistency of a slurry over timeat the anticipated temperature and pressure conditions.The end of the thickening time is considered to be 50 or70 Bc for most applications (API RP10B).

Cementing Services and Products ■ Glossary 97

Thixotropy. The characteristic of a fluid, such ascement or drilling mud, to develop gel strength over timewhen not subject to shearing and then to liquefy whenagitated.

Turbulent Flow. Flow of a fluid characterized byswirling or chaotic motion as the fluid moves along theflow path. This is a preferred flow regime for mudremoval during primary cementing.

Water-to-cement Ratio. In a cement slurry, the ratio ofwater to cement expressed as percent; the parts of waterused to mix with 100 parts of cement.

Wait on Cement (WOC) (waiting-on-cement time). thetime necessary to wait for cement to develop requiredstrength for the next operation.

WOC. see wait on cement.

98

Cementing Services and Products ■ Marks of Schlumberger 99

Marks of Schlumberger

Mark Description

ARCTICSET cement system for use through permafrost

CemCADE cementing design and evaluation software

CemCAT cementing computer-aided treatment

CemCRETE concrete-based oilwell cementing technology

CemNET advanced fiber cement to control losses

CemSTONE advanced cement technology

CemSTREAK rapid deployment cementer

CPS cement pumping skid

DeepCEM deepwater cementing solutions

DeepCRETE deepwater cementing solution

DeepSea EXPRES offshore plug launching system

DensCRETE slurry system

DESC design and evaluation services for clients

DuraSTONE advanced durable cement technology

EXPRES extrusion plug release system (cementing head)

EZEFLO surfactants

FLAC fluid-loss additives for cement

FlexSTONE advanced flexible cement technology

GASBLOK gas migration control cement system

KOLITE cement additive for low-density slurries

LAS liquid additive system

LiteCRETE slurry system

LITEFIL cement additive for low-density slurries

MudCLEAN chemical wash for removal of drilling mud

MUDPUSH spacer family for cementing

PERMABLOK fluid system to permanently plug a zone

PipeView multifinger caliper tool for PS Platform tool string

PS Platform new-generation production services platform

RFC regulated fill-up cement


Mark Description

RST Reservoir Saturation Tool

SALTBOND cement system for cementing across salt zones

SCMT Slim Cement Mapping Tool

SELFSTRESS expanding cement system

SFM Solids Fraction Monitor

SFM-C Process control for cement slurry mixing

ShearSEAL shear-activated, high-temperature lost circulation fluid

SlimAccess wireline logging tool for slim and complex geometry boreholes

SlimXtreme slimhole, high-pressure, high-temperature well logging platform

SLURRY CHIEF cement mixing equipment

SOS slurry/oil squeeze

SqueezeCRETE remedial cementing solutions

ThermaSTONE chemically stabilized cement for ultrahigh-temperature applications

THIXOLITE thixotropic low-density cement

TIC turbulence inducer for cement

TORNADO cement mixing equipment

UNIFLAC unified fluid-loss additive

UniMIX cement slurry system

UNISET unified retarder

UniSLURRY cement systems

USI UltraSonic Imager

Variable Density cement bond quality

WELBOND improved bonding cement system

WELLCLEAN optimal mud removal service

WELLCLEAN II Engineering Solution

ZONELOCK permanent zone sealing fluid system

TSL-4274

cementing services

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