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Network of Excellence in Training © COPYRIGHT 2002, NExT. All Rights Reserved Casing Cementing

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Page 1: 5 - Casing Cementing

Network of Excellence in Training

© COPYRIGHT 2002, NExT. All Rights Reserved

Casing Cementing

Page 2: 5 - Casing Cementing

2© COPYRIGHT 2002, All Rights Reserved

• Lecture Contents:

– Lecture Objectives,

– Primary Cementing,

– Cement Classifications,

– Cement Additives,

– Casing Hardware,

Casing Cementing

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3© COPYRIGHT 2002, All Rights Reserved

• Lecture Objectives:

– At the end of this lecture, YOU will be able to:

• Understand the difference between primary and secondary cementing jobs,

• Identify classes of cements appropriate for different depth range,

• Explain how the properties of cement may be altered by the use of additives,

• Identify basic casing hardware and describe ways to assist in the preparation of a cement job.

Casing Cementing

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Casing Cementing– Primary cementing is the introduction of

cementacious material into the annulus between casing and openhole to:

• Provide zonal isolation,

• Support axial load of casing string and other strings to be run later,

• Provide casing protection against corrosion,

• Support the borehole,

– Secondary cementing or Remedial jobs:

• Squeeze cementing,

• Cement plug.

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Casing CementingPrimary Cementing;

• Conductor Pipe:

– Large excess required,

– Thru-drill pipe cementing common,

– BOP’s not unusually connected,

– Common Cements; Accelerated

– Top-Fill if necessary.

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Casing CementingPrimary Cementing;

• Thru-Drill Pipe Cementing (Stinger Cementation);– Key Points:

• Cement Contamination,

• Channeling,

• Displacement,

• Pump until Cement is at surface.

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Primary Cementing;

• Outside Cementing (Top-Fill);

– Purpose:• Bring Cement to Surface.

– Macaroni TBG used:• Max depth 250 - 300 ft,

• High friction Pressures,

• Only access via casing spool side outlet

Casing Cementing

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Primary Cementing;

• Surface Casing;

– Excess of 100%,

– Recommended thru-drillpipe method to save:

• Cement and Rig time.

– Common Cements:

• Lead light slurry with high yields,

• Neat tail slurries with good compressive strength,

• Reduce WOC to a minimum with accelerators.

Casing Cementing

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Casing CementingPrimary Cementing;

• Intermediate/Production Casing:

– Cemented to surface or into previous casing shoe,

– Two stage cement jobs may be required,

– Plugs, casing equipment and casing accessories are used,

– Require large cement volumes, excess of up to 50%.

• Common Cements:

– Typically filler slurries followed by high compressive tail,

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Casing CementingCasing String Components;

• Float Shoe or Guide Shoe:

– It is attached to the bottom casing joint,

– It serves as a guide for the casing as it is being run into the wellbore and acts as a one way valve.

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Casing String Components;• Float Collar:

– This is set about two-three joints above the casing shoe, and act as a one way valve,

– When it is used, the cement plugs land on top of it.

Casing Cementing

Ball Type

Flapper Type

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Casing CementingCementing Accessories:• Cementing Basket, to minimize losses in weak zones.• Centralizer, to centre casing in bore hole to promote

even distribution of cement around casing.

Centralizer Cementing Basket

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Casing CementingCementing Accessories;;

• Scratchers, to scratch offthe mud cake to improvecement bond

Reciprocating Scratcher

Rotating Scratcher

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Casing CementingCementing Hardware;

• Wiper Plugs:

– To Separate Fluids, (cement/chemical wash/mud)

– Wiping the casing clean,

– Surface indication of placement.

Bottom Plug (pump through) Top Plug (Solid)

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Casing Cementing

• Surface Equipment: Cement Head.

Double Plug Cement HeadSingle Plug Cement Head

Cementing Hardware;

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Formation Integrity Test (FIT)• Purpose:

– To investigate cement strength around the shoe (Cement Integrity Test),

– To approximate fracture gradient, (Leak Off Test),

– To investigate wellbore capability to withstand pressure below the shoe,

– To collect regional information on the formation strength for optimization of well design on future wells.

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Formation Integrity Test (FIT)• Test Procedure:

– Drill 5 to 10 ft below the last casing shoe,

– Circulate to condition mud (MW in = MW out),

– POOH to last casing shoe,

– Connect cement unit to test surface line,

– Close Pipe Rams,Start pumping at slow rate(i.e. 1/4 BPM) (A),

– While pumping, observe the pressure build-up until it deviates (B),

– Record pressure. (C),

– Bleed-off and record return.

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Formation Integrity Test (FIT)Leak-off or Cement Integrity Test procedure:

Pre

ssu

re

BBLSA

C

B

A-B: Linear Increase

B: Start of Leak-off

B -C: Mud Penetrating the formation

C: Leak-off pressure is reached

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Casing CementingPrimary Cementing;

Two Stage Cementing;

• Reasons to do: – Separation and isolation of zones,

– Reduces hydrostatic,

– Can leave zone in the annulus uncemented (cement at TD and surface),

– Loss zone.

STAGE COLLAR

FIR

ST

ST

AG

ES

EC

ON

D S

TA

GE

FLOAT COLLAR

FLOAT SHOE

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Casing CementingCasing String Components;

• Multiple Stage Cementer:

Running in Position Cementing Position Closed Position

OPENING

PLUG

CLOSING PLUG

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Casing String Components from bottom up;• Float shoe

– guide and check valve to prevent cement back flow• 3 Casing joints

– to capture any contaminated cement

• Float collar– second check valve– landing of bottom and top wiper plugs

• DV collar or Stage Collar (optional)• Centrilizers• Scratchers

– to remove mudcake and improve cement bond– to prevent / reduce cement channelling

Casing Cementing

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Primary Cementing

Primary Cementing;

• Liner cementation;– Run on liner hangers with Drill pipe

– Cemented to Top Of Liner (TOL)

– Drill pipe and liner wiper plug combination used

– Generally small volumes

Drill pipeWiper Plug

LinerHanger

Liner WiperPlug

Running Tool

Shear Pin

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Primary Cementing

Primary Cementing;

• Notes on Liner cementation;

– Liner-lap integrity is critical wrt isolation/sealing(200-400 ft)

– Small clearance between borehole and liner OD

– Incomplete removal of mud

– Liner riding on low side of borehole

Drill pipeWiper Plug

LinerHanger

Liner WiperPlug

Running Tool

Shear Pin

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Casing CementingSecondary Cementing; (Remedial job):

• Squeeze cementing– to squeeze off water layers

– to repair primary cementing jobs

NOTE: generally not effective:– risk of creating vertical fracs

– fluid losses and early setting of cement, (flash set)

• Cement plug– to abandon depleted zones

– to abandon well

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Casing CementingCement Classifications;

• API identifies classes and properties for cement:

A, B, C, D, E, F, G, H, J.

• The criteria used for the selection:

– downhole temperatures influence setting time

– slurry density in relation to drilled formations

– compatibility with formation (sulfate) waters

– rheological properties to displace mud

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Casing Cementing• Cement Properties:

– Be impermeable to gas, if present while setting.

– Develop strength quickly once it has been placed,

– Develop sufficient strength in the long term,

– Develop casing and formation bond strength,

– Have low permeability to prevent gas and fluid migration

– Maintain quality under severe temperature and pressure.

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Casing CementingCement Compressive Strength is required for:

– Securing and supporting the casing,

– Withstanding the shock loading of drilling and perforating,

– Supporting hydraulic pressures without fracturing,

– Withstanding the load of tectonic forces such as salt zone.

Overburden Pressure

Mobile Formation

Cement

Hydrostatic Pressure

Casing

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Casing Cementing• Cement Compressive Strength:

– Lab test proves that CS required to support casing is

normally less than 100 psi,

– 500 psi are required before drill-out cement,

– High CS are required to withstand hydraulic

pressure during injection and production operation,

– CS, typically increases with time as cement hardens,

but under temperatures over 230 0F, the CS may

decrease over a period of time, this is called

STRENGTH RETROGRESSION.

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Casing CementingCement Additives;

• Accelerators:

– Accelerators generally work to decrease the thickening time and build early compressive strength, reduce WOC. (e.g. CaCl2).

• Retarders:

– These are chemicals used to delay cement setting time, in order to allow enough time for proper slurry placement, (e.g. Lignosulfonates).

• Dispersants:

– These help maintain a uniform distribution of components in a slurry and result in maintaining flow properties.

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Casing CementingCement Additives;

• Extenders:

– They are used to decrease the density and increase the volume, to prevent fractures. (e.g. Bentonite)

• Weighting Agents:

– These are chemicals used to increase the cement slurry density, to prevent kicks. (e.g. Barite)

• Lost Circulation Materials (LCM):

– They help to combat fluid loss, formation damage and to prevent losing water to prevent unwanted setting or no setting at all.

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• Demos:

Casing Cementing

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• Now YOU should be able to:

– Understand the difference between primary and secondary cementing jobs,

– Identify classes of cement appropriate for different applications,

– Explain how the properties of cement may be altered by the use of additives,

– Identify basic casing hardware.

– Describe the cementing process

Casing Cementing

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Network of Excellence in Training

© COPYRIGHT 2002, NExT. All Rights Reserved

Casing Cementing

End of Lecture End of Lecture