01_ml for dummies(geolog)

8/9/2019 01_ML for Dummies(Geolog)

1/167

TEP/DEG/CEF/SUB. . . Natters Around Field . . .

October 1998

MUDLOGGINGMUDLOGGING ... for dummiesCONTENTS

TOOLBOX

module 6.1

s

GENERALITIES: PAST & FUTURE PRESENTATIONs SUMMARY

s Introduction: AIMS & PURPOSES

s SENSORS, DATUM & DATA

s GAS: DEFINITION, ORIGIN,MEASUREMENTS, INTERPRETATION

s PRESSURE: GENERALITIES: Hydrost., Overburden, Pore Pressure

FORMATION: SOBG, ’d’exp, ...

WELL MEASUREMENTS: LOT, FIT, SBT,Csg Test

s SAMPLING: PROCESSING and DESCRIPTION

s LABORATORY: PREPARATION and ANALYSIS

s CORING: EQUIPMENTS and OPERATIVE TECHNICS

s REPORTING: DGR, GWR and DDR

s ANNEXESs CONCLUSION


2/167


GENERAL PRESENTATION

S U M M A R Y

MUDLOGGING: «on the road again ...»

from ... STONE AGE BIBLES

to ... 21st century BIBLES => TOOLBOX module 6.1)THEMATIC RESEARCH

ALPHABETIC RESEARCH

TECHNICAL DATA SHEETS: examples (Toolbox module 5.2)

GEOLOGICAL WELL REPORT (Toolbox module 7.0)

MUDLOGGING AUDIT (Toolbox module 2.1)


3/167


TESTING

CIRCULATINGF

I S H I N G

C

O R I N G LOGGING

DRILLING

D R I L

L I N G

R E G U L A T I O

N S

DATA

ENGINEER

MUD

LOGGER

SAMPLE

CATCHER

WELLSITE

GEOLOGIST

DATA ACQUISITION

EVALUATING

DRILLING EVENTS

MUD PARAMETERS

LITHOLOGICAL & GAS DATA

HT

DATA MANAGEMENT

WELL FOLLOW-UP

REPORT ING PREPARINGRECORDING

WELL MONITORING

DATA DISPATCHING

INTERPRETATION

DATA

DISPATCHING

D R I L

L I N

G

P R O

P O S A L

LOTFITHP

GWR

S A F E T Y

R E G U L A T I O

N S

M U D L O G G I N G


4/167


’STONE AGE’ BIBLES ...

USEFUL, BUT:- DIFFICULT TO MANAGE (heavy, huge, ...)

- BORING RESEARCH & READING M

d i u L n

go g g


5/167


... 21st century BIBLES

FILES:

- STRICKLY A4 SIZE

- MAINLY VISUAL

- ESSENTIAL TEXT

- FAST CONSULTATION

- EASY TO UPDATE

THEMATIC RESEARCH

ALPHABETIC RESEARCH

LINKAGE between FILES

WEB site

INTRANET

M U

D L O

G

I N

G

G

SENSORS

G A S

P R E S

S U R E

L A B O R A T O R Y

S AM P LI N G C O R I N G

R E P O R T I N G

A N N E X E S

CD

W S G AI M S ...

THE TRICKS OF THE TRADE

TOOLBOXmodule 6.1

… JOB PURPOSES


6/167


THEMATIC RESEARCH

INTRODUCTION: AIMS

CORING

DATUM, SENSORS & DATA

SAMPLING

ANNEXES

GAS

PRESSURE

LABORATORY

REPORTING

KEYW ORDS INDEX RESEARCH

CONVERSIONS & EQUIVALENTS

UNIT CONVERTER

BASIC WELLSITE GLOSSARY

International SPELLING CODE

. . .

TOOLBOX - module 6.1


7/167


Mudlogging KEYWORDS index research


8/167


EASY RESEARCH … Press to

BASICGLOSSARY

(GB - F - E)

KEYWORDGENERAL INDEX

OIL FIELD

ABBREVIATIONS

TECHNICAL

DATA SHEETS

UNIT

CONVERTER

More … ?

OPEN

CUTTINGDESCRIPTION

SHEET

MUDLOGGING

AUDIT

GEOLOGICAL

WELL REPORT


9/167


10/167


Geological Well Report

TOOLBOX - module 7.0

TEXT.doc

PRESSURE MEASUREMENTS

SAMPLING SEQUENCE

MUDLOG

PORE PRESSURE

DATA TRANSFER(ASCII)


11/167


MUDLOGGING AUDIT

MUDLOGGING AUDIT

C O N T E N TS

AUDIT SUMMARY Sum-1

CONCLUSIONS and RECOMMENDATIONS Rec-1

EQUIPMENT and SAFETY AUDIT Eq&S

Environment§ RIG CHARACTERISTICS Eq&S-1/5

§ S ENSORS REVIEW Eq&S-2/5

Mudlogging§ UNIT Eq&S-3/5

§ LABORATORY 1/2 Eq&S-4/5

§ LABORATORY 2/2 Eq&S-5/5

TECHNICAL and CREW AUDIT Tech

§ SENSORS accuracy Tech-1/8

§ GAS • combustible - Degaser Tech-2/8

- Detector Tech-3/8

- Analyser Tech-4/8

• n on comb ustible - Detector &An alyser T ech -5/8

§ COMPUTER 1/2: Data acqu isition and processin g T ech -6/8

§ COMPUTER 2/2: Networking and softwares Tech-7/8

§ CREW (Awareness and performance) Tech-8/8

ANNEXES: Gas flow-charts: - Degaser Ann-1- Detector Ann-2

- Analyser Ann-3

ANNEXES: Nominal gas values for Detectors & Analysers§ BAKER HUGHES INTEQ (BHI Ann-4 a-b

§ GEOSERVICES Ann-5 a-b

§ HALLIBURTON Ann-6 a-b

§ SPERRY-SUN (SSDS) Ann-7 a-b

TOOLBOX

SUBTOTAL

DIRECTION EXPLORATION GISEMENTDépartment Subsurface

SUB TOOLBOX

MODULE 2.1

MUDLOGGING AUDIT

D. GARDETTE

REF : DG/970606-1

PREDEFINED CHECKLISTS

TAG SUGGESTED ANSWERS

and ADD YOUR COMMENTS...

June 1997

TOOLBOX

module 2.1


12/167


I N T R O D U C T I O N

S U M M A R Y

- Rigsite CONTRACTORS

- Rigsite RESPONSIBILITIES

- MUDLOGGING CREW: Householder

- MUDLOGGING AIMS (1): scope of work, data ... what for?

- MUDLOGGING AIMS (2): how?, and Conclusions

- MUDLOGGING JOB PURPOSES

- ML & well behavior: WASH OUT examples

- ML & well behavior: FLOW-CHECK & CIRCULATION

- WELLSITE GEOLOGIST JOB PURPOSES

- WELLSITE GEOLOGIST AIMS

- WELLSITE GEOLOGIST: JOB SPIRIT


13/167


TOOLPUSHERGEOLOGIST

CO- MANMUDLOGGING

LOGGING(WL & LWD)

DIRECTIONALDEVIATION

POSITIONING

CORINGMWD

DRILLINGMUD

CEMENT

CASINGROV, ...

DRILLING

&

RIGMAINTENANCE

RIGSITE CONTRACTORS


14/167


RIGSITE RESPONSIBILITIES

Rigsite

role

TOOLPUSHERCO-MAN

GEOLOGISTMUDLOGGING

Rigsite

position

ACQUISITION

EVALUATION

DECISION

EXECUTION


15/167


MUDLOGGING «Householder»

DATAENGINEER

MUDLOGGER

SAMPLE-

CATCHER

OUR TEAM

YOURBOSS?

MY BOSS

YEAH!

WELLSITE

GEOLOGIST

MUDLOGGING

CREW


16/167


MUDLOGGING: AIMS (1)

MONITOR & EVALUATEOIL & GAS SHOWS

CONFIRM or ADJUST FORMATION PRESSURE ESTIMATION

ESTABLISH ACCURATE & COMPREHENSIVE DOCUMENTS, REPORTS, ...

INFORM ( IN REAL TIME) PEOPLE INVOLVED IN WELL MONITORING

OF ALL PLANNED EVENTS .... or .... IN CASE OF UNFORECASTED EVENTS => ALERT

Provide Oil Companies with validated measurements /samples related togeological, drilling and mud parameters, as per Client specifications.

DATA ... WHAT FOR?

STOREPARAMETERS

DISPATCHDATA ON REQUEST

MANAGE DATA

COLLECT WELL INFORMATION

GAS

DRLG MUD

SCOPE OF WORK


17/167


MUDLOGGING: AIMS (2)

HOW?

INSTALL ALL REQUIRED SENSORS

CONTROL SENSORS RELIABILITY and ACCURACY

RECORD CONTINUOUSLYALL MEASURED PARAMETERS

NOTIFY ANY EVENTS OBSERVED

PREPARE SAMPLES FOR DESCRIPTION & ANALYSIS

ASSIST, when needed, FOR CORE RECOVERY, TESTING OPERATIONS, ...

MUDLOGGING is a HIGHLY VALUABLE SERVICEat LOW PRICE (only 2-3% of well cost: 1500-2000 USD/d)

... M ONITOR SECURE O BSERVE but should ASSISTANT for N EVER VISUALIZING & for E NSURE EVALUATING Y OURSELF RESERVOIR

but it is a ...

CONCLUSION: the MUDLOGGING ...


18/167


MUDLOGGING : JOB PURPOSES

MONITORING

&DETECTION

QUICK

UNDERSTANDING

& FASTREACTING

RECORDING REPORTING

PARAMETERS EVENTS

DATAACQUISITION DOCUMENTS

WELL FOLLOW UP ...

?

... ON A ROUTINE BASIS

BS


19/167


ML & well behavior examples: WASH OUT

DRILLING GEOLOGY

• Possible ORIGIN:. very abrasive formations (hd SLST, Pyrite, ...). and/or deviated wells (Drillpipe along casing)

• PHENOMENA:Abnormal friction/wear along Drill-pipe / BHAupto create a hole along pipe => Wash pipe

• Surface DETECTIONin Mudlogging unit:Injection Pressure (SPP)slowly reducing to fastdropping (=> Flow-Rate may increases)

• Final Consequence => FISHING! (if not detected)

• How to solve the situation?POOH with ‘heavy slug’ inside pipesand check every stand prior breakingthe strings: then locate the WASH-OUT

• Other: TWIST-OFF, but no forewarning signs! Lost nozzles on bit (check hydraulic report)

Mudlogging crew => INFORM

Drlg Supervisor => DECIDE & ACT: WOO

. formations poorly cemented, indurated, .... and/or inappropriate drilling fluid (mud)

Mudlogging crew

=> DECIDE & ACT

then ... INFORM

=> Drlg Supervisor

Possible origin:

Refer to chapter SAMPLING


20/167


ML & well behavior : FLOW-CHECK& CIRCULATION

• WHEN? . after a fast DRILLING BREAK ( unexpected event)

. after breaking a core, prior POH (no slug pumped)

. to check possible swabbing, ( while pulling out at shoe depth), ...

• WHY? to check if well is still in equilibriumin static conditions; observed if any

Gain or Losses... and report rate (vol/ time)• HOW? Stop circulating (Pumps OFF)

Stop adding mud into Active sum ( transferring, mixing, diluting, ...)

• Duration : at least 15 min ... fct(depth, OH length)

Requested by . . . DRILLING SUPERVISOR

Water Oil Gas

time - +ACTIVEPITS - + - +ACTIVE

PITSACTIVE

PITS

15 min

5

0 EVENT

AIM OBSERVATION of WELL ANNULAR LEVEL AIM WELL CONTROL

• WHEN? . prior performing SBT, LOT, FIT, ... (=> drilling circulation: code F) . to check lithology at TD (=> geological circulation: code G) . for mud and/or well conditioning ( prior possible rising MW) . After a positive ‘Flow-Check’: gain ...

( circulate through Choke Manifold)

• WHY? to clean out annular volume ( gas cut mud, cuttings)

to homogenize mud properties (U tube)to determine coring point depth (code G)

to set casing shoe depth, ...

(to wait on weather, orders , contractors, ...)

• HOW? Stop drilling ... ‘ Flow-Check’; then

... Resume circulating (Pumps ON)

• Duration : at least ONE ‘Bottom-up’ depending on

... LAG TIME / LAG STROKE

Requested by . . . DRILLING SUPERVISOR WELLSITE GEOLOGIST


21/167


WELLSITE GEOLOGIST: JOB PURPOSES

LOGGING: wireline , LWD MUDLOGGING

MWD & MUD CORING & TESTING

LITHOLOGICAL

IDENTIFICATION

& CORRELATIONS(FACIES)

SAFETY: HP/HT

RISK EVALUATION

RESERVOIR & FLUIDS

CHARACTERIZATIONGAS & SHOWS

INTERPRETATION

DRILLING

REPORTING:

MUDLOG, GWR, ...

GEOLOGICAL INTERFACE

INPUT

OUTPUT

WELL FOLLOW UP ...

... ON A ROUTINE BASIS


22/167


SAFETY FIRST(people, equipments & RIG)

WELLSITE GEOLOGIST AIMS

SAVE MONEY

ANTICIPATE

Casing depth

Coring depth

Pressure regime

RISKS, . ..

REACH TARGETS

OIL

GAS

WATER

FIND RESERVOIRS

&

IDENTIFY FLUIDS(CONTACTS

QUANTIFY Hcb)

EVALUATE

Phi K

SwPp

Pf

FOLLOWDRILLING

PROPOSAL

(Casing,

(Mud,...)

REACTto hazardous &

unexpected events

...


23/167


24/167


DATUM, SENSORS & D A T A

S U M M A R Y

- REFERENCE DEPTHS: Onshore & Offshore

- Well PROFILES

- Well PROJECTION: horizontal & vertical views

- HORIZONTAL DRAIN NOMENCLATURE

- RIGSITE SENSORS LOCATION (simplified)

- DATA: real time & delayed

- LAG TIME: definition & control

- LAG TIME: interpretation & consequences

- DRILLING SENSORS

- MUD SENSORS

- Technical Data Sheets: TOOLBOX module 5.2

http://../TechDataSheet-GEOS.pdfhttp://../TechDataSheet-GEOS.pdf


25/167


REFERENCE DEPTHS

MSL

(Annual)Mean

Sea Level

Sea Bedor

(Sea Floor)

GroundLevel

RTE / (KB)

TMDBRT(Below Rotary Table)

ZERO reference

«SUB-SEA depth» riser

RTE / KB

(+)

(-)

0

T V D B R T o r i g i n

e 0

T V D M S L o r i g i n e

TD(Terminal Depth)

Water

Depth

PILOTHOLE(+)

ONSHORE OFFSHORE

Rotary Table Elevation(Kelly Bushing)

PERMANENT DATUM


26/167


27/167


WELL PROJECTIONS

WELLHEAD

N

S

W E

-

+

delta X

HORIZONTAL VIEW

w e l l p r o f i l e CURRENT

DEPTH

d e l t a Y

Departure2

= +(deltaX) (deltaY)2

DEPARTURE atCURRENT DEPTH

Azimuth

N140°

VERTICAL VIEW

TVDDEPTH

DISTANCE

PROJECTION PLANE:

AZIMUTH N140° w

e l l p r o f i l e

WELLHEAD

VERTICAL SECTION at CURRENT DEPTH

ANGLE

(inclinaison)

CURRENTDEPTH


28/167


HORIZONTAL DRAIN NOMENCLATURE

TMDBRT(Below Rotary Table)PILOT HOLE

VERTICALwell

WELL TRAJECTORY

TST

Layer follow-upalong azimuth drain

TST: True Stratigraphic Thickness(Reference Thickness inside drain)

Layer identification

TVD: True Vertical Depth

TVD

DrilledThickness

betweenTOP-BTM

ApparentVertical

Thickness

TOP

BTM

AIM dip calculation depends on TST, Drilled Thickn. and on Apparent Vert. Thickn.


29/167


SENSORS: SIMPLIFIED RIGSITE VIEW

Pit level

Temp° IN

Resist.IN

Dens.IN SUCTION PIT Mixing pit

(hoopers)

mud Pumpand SPM

desanders & desilters

(to sand trap)

RETURN PITDegaser, Dens.OUT

Resist.OUT, H2S

Pit level

Temp° OUTWell head

WHP, CP

BOP’sCAVE

H2S

WOH on

dead line

(=>WOB)

DRILL FLOOR(DRUM miss ing)

Kelly Bushing

Rotary TableRPM, TRQ

ROP => DepthHKPos, H2S

SPP

swivel

Stand Pipe

Flowmeter

on Flowline

hoose

Choke

Manifold

TRIP TANK

to RIG DEGASER

Notezoological nomenclature missing:

DOG HOUSE MONKEY DECK

GOOSE NECK MOUSE HOLE

CAT WALK WIDOW MAKER!

… POOR BOY !!

SAND TRAP

POSSUM BELLY

&

SHALE SHAKER

Crown Block

Travelling Block

& Hook (old)

=> TOP DRIVE

RESERVE PIT

H2S


30/167


DATA : REAL TIME or DELAYED?

GEOLOGICALMUDDRILLING

REAL TIMEDATA

downhole eventsvisible on surface

=> instantaneous data

DELAYED DATA

downhole events , carriedby mud, after LAG TIME

=> immediate data

Depth ROP

TRQ WOB

RPM SPP

SPM WHP

PITS & FLOW

(gain & losses)

GAS &

CUTTINGS (analysis &

observation)

MW data:

Temp° OUT Density OUT

Resistivity OUT

DATA TYPE

ACQUISITION

MODE


31/167


32/167


LT Interpretation & Consequences

LTobserved > LTtheoritical LTobserved CAVINGS

reducing hole cleaning efficiency

Shale shape & size (poping, propeller,. ..)

Cuttings arrive «early» regarding to ROP

Tight Hole

=> STICKY HOLE

Shale hydration (Monmorillonite)

in both cases

DRILLING PROBLEMS

IN

VIEW ... as delta P

=> Carefully check lithology

on all sieves

BUT, IT MAY ALSO BE DUE TO:

- Wrong Pump efficiency (Toolpusher data) and/or false adjustment (Data Engineer)

- Incomplete or erroneous pipes dimensions (OD & ID) and volumes, ...


33/167


DRILLING SENSORS

SENSORS

WOH Weight On Hook ............ ............. ..........Dead line orHook Load=> WOB Weight On Bit computed from Archimees law

(or buoyancy effect)

SPP Stand Pipe Pressure ..... .... ..... ..... .... Stand pipe Manifold

CP Casing Pressure .....................................Diverter Manifold andWHP Well Head Pressure

ROP Rate Of Penetration & Depth...Drawwork ax le

HKPos Hook Position / Travelling Block

RPM Revolution or ............ .............. .............. ... Rotary Table Rotation Per Minute or Top Drive

SPM Strokes Per Minute ............. .............. .........Pump piston

PRESSURE TRANSDUCERS

measuring strainon force triangle

(klbs or tons)

measuring variations

of steel diaphragm(psi or bars)

measuring capacitanceof detecting diaphragm

(psi or bar)

PROXIMITY SWITCH

measuring crown sensor counter

(logic condition: 0 or 1)

HYDRAULIC

ELECTRIC

Hydraulic system

TRQ Torque .... .... .... .... rotary table (RT)

Electrical lineCURRENT TRANSDUCER

HALL effect: measuring electrical fieldflowing in motor cable (Amp)

items mounting on

MEASUREMENT

method principle


34/167


MUD SENSORS

SENSORS

Flow Rate .......................................................flowline

Potentiometer (floater)

Potentiometer (paddle)

Platinium resistance

HYDRAULIC

ELECTRIC

items mounting on

MEASUREMENT

method principle

Echo pulse (ultrasonic) ACOUSTIC above mud tank

PITS Volume ..............................

inmud tank

IN ...... ..suction pitTEMP° ...................................

OUT .... ...possum belly

IN ...... ..suction pitCOND. / RESIST...................

OUT .... ...possum belly

Toroidal induction coil

Differential pressure

Gamma ray absorption (NUCLEAR)

IN ...... ..suction pit

OUT .....gas trapMud Weight / DENSITY.....

IN ..... .. stand pipe

OUT .......possum belly


35/167


SENSORS MEASUREMENT & SPECIFICATION

P

R

I

N

C

I

P L

E

WOH / WOBSPP

CP / WHP

TRQ (diaphragm)DENS. / MW

TRQ (Hall effect)

PITS Volume(ultrasonic)

(DENS. / MW )

MUD &DRILLING

sensors

HYDRAULIC ELECTRIC ACOUSTIC NUCLEAR

M E T H O D

RADIOACTIVE

RESISTIVITY

Pressure

Current

TRANSDUCERT

10

PROXIMITY switch

(counter)

POTENTIOMETER

ULTRASONIC

ROP / Depth

HKPos

RPM

SPM

COND. / RESIST.TEMP°

PITS Vol. (floaters)FR (paddle)


36/167


G A S : DEFINITION & MEASUREMENT S U M M A R Y (1/2)

DEFINITION

- GAS SAMPLING HISTORY- GAS TYPES RECORDED- GAS SHOWS: Definition

Origin … or sourcesSwab & SurgeGas Events vs … warning!Main ranges

- MUD DEGASSING ON SURFACE

MEASUREMENT- GAS MEASUREMENT CHAIN- DEGASSER TYPES- GAS LINES:efficiency

main & back-up- DETECTOR:principles- DETECTORS for ACID GASES- H2S: HYDROGEN SULPHIDE => the Killer gas- CHROMATOGRAPHY: problems to solve

principles & efficiency- FID: total gas & chromatography- TCD: total gas & chromatography


37/167


G A S : INTERPRETATION

S U M M A R Y (2/2)

INTERPRETATION

- LOG/LOG DIAGRAM (SNPA)

- PIXLER PLOT (BAROID)

- TRIANGLE METHOD (GEOSERVICES)

- Wh, Bh, Ch RATIOS (EXLOG)

- LIGHT HYDROCARBON RATIOS: interpretation

- RATIOS ACCURACY

- GAS NORMALISATION: AIM

- GAS NORMALISATION: magic! or bluff?


38/167


GAS Sampling: HISTORY

< 1930’s > 1930’s (1980’s) -> PRESENT FUTURE

«rule of thumb method»

Based on

. shows estimation

. depth levels

uncertainty

oily appearance,

petroleum odor,

...

Qualitative method:

=> Identification by

. centrifugation (oil)

. ignition (gases)

=> no quantitative evaluation

«Mudlogging Blooming»

Lagged depths with

associated lithology

(off-line Cabin)

=>Degaser calibration: Steam Still analysis

(VMS 1950’s, constant vol)

=>«Hot Wire» systems:(Thermal Conductivity Detector)

(Catalytic Combustion Detector)

.total gas detection and

.components identification

Combustibles: C1...C4, H2 .Other gases: H2S,CO2,N2,

«R & D»

Micro-indices

on surface:

. detection

. analysis

(geochemistry)

borehole &

fluid travel

contamination?

Downhole

measurements

. in-situ data(?)

&. horiz. wells

(geosteering)

« Fast & Accurate ...»

Integrated

services

(on-line Unit)

=> Degasser efficiencyimprovement

(constant flow & vol)

=> FID system:(Flame Ionisation Detector)

from > 5 min to < 1 min

only forcombustible gases

(C1 ... C5)and optional «hot wire»

for other gases


39/167


GAS TYPES RECORDED

HYDROCARBON Gas NON-HYDROCARBON Gas

N2 Nitrogene

H2 Hydrogen

He ? Helium

(Rn Radon)

Inert gas

H2S Hydrogen Sulfid

CO2 Carbon Dioxide

Polar gas or «acid gas»

C1 Methane

C2 EthaneC3 Propane

iC4 iso -Butane

nC4 normal-Butane

iC5 iso -Pentane

nC5 normal-Pentane

(C6 Hexanes )

alkanes series(CnH2n+2)

DRY

HUMID

POLAR

INERT


40/167


41/167


ORIGIN of GAS SHOWS

. GAS from Gas

. GAS from Oil

. GAS from Water

( Dissolved)

GAS from CUTTINGS

GAS from SHALE

(cavings)

GAS from Fault

GAS RECORDED on surface

NON DRILLED GASNON DRILLED GAS

RECYCLED(R)

PRODUCED (P)

&CONTAMINATED(C)

DRILLED GASDRILLED GASLIBERATED (L)

Surface mixingNew additives

Downhole chemicalreactions

...

affecting

BACKGROUND GASL

L

L

P

P

P

Other Produced GAS: Pipe Connection, Swabbing/LCT, Trip Gas, ...

R

C


42/167


SWAB & SURGE

POOH

SWAB & SURGEfunction of:

- pipe velocity- annulus diameter (hole, pipes)

- mud rheology

(MW,Visc)

imbalance between mud pressure and formation fluid pressure

and possible KICK

final

CONSEQUENCE

on both cases

EMW

RIH

delta Pmud LOSSES

delta Pmud GAINS

suction

injection


43/167


SAFETY: GAS EVENTS … WARNING!

. . . based on gas observationswhen circulation stopped

INFORM and Precise:

• Change to new baseline (based on MW)

• Lithology (Phi-K) associated to peaks• Gas observed= BKG + ‘Gas event’ origin

Phenomena emphasized IF:• cumulative gas events• recycled gas• rig degasser OFF(‘Poor Boy’)

I n i t i a l B a s e l i n e

Peak heights increase=> back to baseline

between each gas event

(peaks becoming wider)

BKG increase=> back to new baseline

- shifted between each gas event

- increased between

each gas event

nil

traces

A S Y

M M E T R I C p e a k s

S Y M M E T R I C A L p e a k s

Qualitative ALERTQualitative ALERT methodmethod

GAS EVENTS reflect

PressureRegime and/or Formation fluid content

∆P > 0

∆P < 0

∆P ≈ 0

IDENTIFY Origin of gas observed INDICATORS (possible gas origin)

- PIPE CONNECTIONS- SWAB GAS TEST- LCT (Long Connection Test)- TRIP GAS- BACKGROUND GAS (BKG)

Miscell: surveyfalse connectionscarbide (Lag-Time check)

FORMATION Gas

Total Gas (TG)

1 std

B K G

B K G


44/167


GAS SHOWS: scale range

-50 0 50 100delta P (bars) influence

too late!

-> Life jacket

0

20

40

60

80

100

Delta P > 0

Delta P < 0

Spectacular => Muster point

Exceptional to Dramatic

Risky to Hasardous

Daring to Lucky

Questionable

Delightful to Interesting

Promising

Nice (or Lovely)

Fair to Slightly

Weak to Poor

Disappointing

Nil

=> Blow-out => Kick

?

Gas (%)observed


45/167


MUD DEGASSING on surface

DEGASSER

Drill String

Bell Nipple

MUD PIT(s)

ShaleShakers

GAS

BUBBLES

and

CUTTINGS

GAS LINE

to Unit

Gas

Trap

Possum

Belly

loss of free gas

F l o w l i n e

loss of free gas

(=> recycled in part)

AIR

inlet

(Air + Gas)

Decanting tube

(water)


46/167


47/167


DEGASSER TYPES

GAS TRAP

EFFICIENCY (%)

(50) -

(100) -

SUCTION PROBEConstant mud flow &

Constant volumeQantitative Gas

Trap MeasurementConstantmud flow

BASICVariable mud flow

STEAM STILLConstant mud volume

(reference degasser )

ContinuousDiscontinuousGAS EXTRACTING

MODE

EFFICIENCY = fct ( degasser location , chamber volume vs degassing time, mud type, ...)

THE LONGER THE MUD

UNDER AGITATOR,THE GREATER THE EFFICIENCY

immersed

types


48/167


DEGASSER

DETECTOR

DEGASSER

DETECTOR

GAS LINES EFFICIENCYDEGASSER DETECTOR

NEITHER TOO LONG ...(C3+ analys is)

LENGTH

NEITHER TOO FAST ... ...NOR TOO SLOW

FLOW RATE

APPROPRIATE GAS LINES LENGTH => TRANSIT TIME TO UNIT < 100 sec

depending on «AIR + GAS» mixture flow rate through Monoflexand on motor pump suction efficiency

...NOR TOO SHORT(safety reasons)


49/167


50/167


DETECTORS: principles

TOTAL GAS

CONTINUOUS PROCESSfor

UNDIFFERENTIATED GASES

QUANTITATIVE measure

CHROMATOGRAPHY

BATCH PROCESSfor

INDIVIDUAL COMPONENTS

QUALITATIVE measure

CCDCATALYTIC COMBUSTION(NO LONG EXISTS)

Low threshold detection

(100ppm)

Poor detection for

non-combustible

C6+ cause breakdown of filament (Platinum)

High T° filament (800°C)

ADVANTAGES

+

DISADVANTAGES

-

FIDFLAME IONISATION

Very low threshold

(5-20ppm)

High repeatability

Accurate only for

combustible gases

Need continuous

H2 supply

TCDTHERMAL CONDUCTIVITY

No combustion

Detection of

non-combustible gases

High threshold (>500ppm)

Very high sensitivity to H2Low sensitivity to Hcb

other than Methane


51/167


ACID GASES DETECTORS

Infra-Red ABSORPTION principle

CO2 ATTENUATES the «IR» RADIATION

EMITTED BY THE SOURCE (IR beam)

Voltage proportional to CO2 content

=> accuracy: 1000 ppm (0.1%)

warning: CO2 highly absorbed by basic

water contained in WBM and also

in OBM (water phase)

CO2

1- SEMICONDUCTOR principleH2S REDUCES THE METAL OXIDE COATING

TO METALLIC SULPHIDES

Conductivity proportional to H2S content

=> accuracy: 1 ppm (0.0001%)

warning: humidity reduces sensor sensibility

2- DELPHIAN MUD DUCKIDENTIFY SOLUBLE SULPHIDES IN THE MUD

related to mud pH (>10) & temperaturewarning: operating ONLY in water base mud

H2S

DRAEGER hand-held (QUALITATIVE RESULTS)

graduated tube filled with

silicagel impregnated

with LEAD ACETATE... turning to DARK-BROWN

( +/- 10 ppm)

graduated tube filled with

HYDRAZINE

(N2H4)... turning to BLUE-PURPLE

( +/- 10 %)

** DETECTOR AVAILABLE FOR ALL GASES (various reactants) with various SENSITIVITY RANGES **

CO2 H2S


52/167


Hydrogen Sulfide (H2S) SAFETY

odour

ROTTEN EGGS

0.1 1000

0.001 10

0.01 100

0.05 500

0.07 700

0.02 200

0.002 20

H 2

S

c o n c

e n t r a t i o n

H2S effects

% ppm

’safe’for 8 hours

STINGS EYES & THROAT

within 3-5 min

HEADACHE

KILL SMELL

DIZZINESS

UNCONSCIOUSNESS

breathing ceases after 30 min

DEATH => 15 min

DEATH => 1 min

H2SACID GAS

COLORLESS

DEADLY GAS

FLAMMABLE ( blue flame )

sg=1.18 (heavier than air)

Highly CORROSIVE to certain metals

permanent cerebral injury

=> prompt artificial respiration

THETHE KILLER GASKILLER GAS

ROTTEN EGGSodour


53/167


CHROMATOGRAPHY: problems to solve

Question: HOW TO BE FAST AND ACCURATE FOR

SEPARATING GASEOUS COMPONENTS MIXTURE (AT A MAXIMUM MUD FLOW)

and for

AVOIDING CONTAMINATION BY SUCCESSIVE & REPEATING MEASURES ?

Heu!

it depends ...

IF THERE IS WIND,

IF IT’ S HOT ...

hey, guys!

SAMPLING RATE

(TEMPERATURE& PRESSURE)

PROCESS ACCURACY

(COLUMNS and/or CAPILLARY TUBES)

Answer : yes, absolutely right, Mr O’NURB,IT DEPENDS ON ANALYSIS SYSTEM

EFFICIENCY ... mainly BASED ON ...

and

on


54/167


CHROMATOGRAPHY:principles & efficiency

=> DIFFERENTIAL DISTRIBUTIONS OF THE

SAMPLE COMPONENTS BETWEEN 2 PHASES:

ONE ST ATIONARYsolid phase

as

SILICAGEL,SQUALANE, ...

packing (coatingfilm thickness)

ONE MOBILEliquid phase

with

GAS SAMPLE+CARRIER(Air, He)

percolating throughor over the solid phase

stainless

or

aluminiummade

COLUMNS

Length: 6-20 ft

ID: 0.125 - 0.25 inch

CAPILLARY TUBES

Length > 300 ft

ID < 0.03 inch

=> bent or coiled

for compactness

TEMPERATURE & PRESSURE EFFECT S

Temp° & Press. Temp° & Press.

QUICK and POOR ELUTION

C1C2 C3 C4 C 5

SLOW and GOOD ELUTION

C1 C 2 C 3 C 4 C 5

12

3


55/167


total gas & chromatography : FID

ionisation

chamber iC5

C1

C2nC4iC4

C3

iC5nC5

peak

area

BASELINE

Retention

time for C1

response(mV)

time

analysis

# 300 sec

SCHEMATIC CHROMATOGRAM(after Geoservices)

(*) Backflush starts only when compoundsof interest have passed

through the PRECUT column (depending on selection of cycles)

Gas line

manual

injectionTOTAL GAS detection line

GAS «in»(mixture)

waste

effluent

H2Air

C1

C2C5 C3

C4Precutelution

Main elution(separation)

backflush(*)

P2 > P1

P1

signal

purge speed up

C1C2 C5C3

C4C6+


56/167


57/167


LOG/LOG Diagram (SNPA)

S.N.P.A. (1950’s), now ELF

developed over Lacq gas& oil field (France)

gas ratios used:

(C2 /C1) x 103

(C3 /C1) x 103

… based on production gas data (DST)

1 10 100 1000 10000 100000

1

10

100

1000

10000

100000

(C2 /C1)x103

(C3 /C1)x103

3

4

1

2

4

3

2

1 DRY GAS dissolved in water

GAS with CONDENSATE

GAS with OIL

... grading to TARS & BITUMEN


58/167


PIXLER PLOT (Baroid)

PIXLER (1969) modified FERRIE (1981)

gas ratios used:

C1/C2

C1/C3

C1/(iC4+nC4)

C1/(iC5+nC5)

=> LINES ARE DRAWN BY CONNECTING

INDIVIDUAL RATIOS

Comments:

- Plot basically based on C1/C2 ratio

(see ratios accuracy)

- Steep slopes are usually

a «tight reservoir» criteria- Negative slope might be a «water zone»

Texas and Louisiana experiences

Non-productive Gas

Productive Gas

Non-productive Oil

Productive Oil

(wet gas)

(dry gas)

(volatile oil)

(heavy oil)

(tars, bitumen)

(no free gas)

C1 /C2 C1 /C3 C1 /C4+ C1 /C5+

… based on production

gas data (DST)


59/167


60/167


Wh, Bh and Ch ratios (EXLOG)

EXLOG (1985), now BHI

gas ratios used … based on drilling:

1 - WETNESS

2 - BALANCE

3 - CHARACTER

W hC C C C

C C C C C=

+ + +

+ + + +

( )

( )*

2 3 4 5

1 2 3 4 5

1 0 0

B hC C

C C C=

+

+ +

( )

( )

1 2

3 4 5

C hC C

C=

+( )4 5

3

(*) N/A => incompatible

Wh < 0.5 0.5 - 17.5 17.5 - 40 > 40

Fluid DRY GAS GAS OIL Residual Oil

Bh Fluid

> 100 dry Gas

> Wh GAS

Bh Fluid

>>Wh coal bed

> Wh GAS

= Wh lt G / Cond

Bh Fluid

> Wh coal -N/A*

< Wh OIL


61/167


LIGHT HYDROCARBONS ratios INTERPRETATION

1001 10 0 1 2 3

VERY LIGHTDRY GAS

LIGHT GAS

GAS &

LIGHT OIL

COAL-BED

EFFECT

MEDIUMGRAVITY OIL

RESIDUALOIL

Wh ratio

Bh ratioCh ratio

Non-productive Gas

Productive Gas

Non-productive Oil

Productive Oil

1 10 100 1000 10000 100000

1

10

100

1000

10000

100000

(C2 /C1)x103

(C3 /C1)x103

C2 /C(1-5)

C 4 / C

( 1 - 5 )

C 3 / C

( 1 - 5 )

WHICH PLOT

to trust ?

NONE or ALL !

NO MIRACLE METHOD

WHY ?

... based on

RATIOS ACCURACY

CALIBRATED IN SPECIFIC AREAS


62/167


63/167


64/167


GAS NORMALISATION: magic!

CGI (Corrected GasIndex)

CGIGas FR

HV ft ROP ft(%)

(%)* (bbl/ min)

(bbl / )* ( /min)=

approximate normalisation for changes

of flow rate (FR), of hole volume (HV) and of ROP

(equivalent to SPI)

Recommended DEGASSERS: steam still (Cst volume) and/or suction probe (Cst flow)

SPI (Surface Potential Index)

SPIGas FR l ROP m

inches

= 197100 2

. *(%)* ( / min) * (min/ )

* (BS )( )

SPI estimates, at SURFACE CONDITIONS,the m3 of gas per m3 of rock

(dimensionless value)

THE MOST REALISTIC INDEX

FOR FAST & EASY COMPARISONS

BS: bit size

CGS (Calculated Gas Saturation)

CGS SPIPa

Pu

Tu

TaZ

kg cm

kg cm

K

K

= °

°

1002

2* * * *

( / )

( / )

( )

( )

Pa: ambiant surface pressure=1 Ta: ambiant surf. temp° (AMST)

Pu: estimated fluid pressure Tu:estimated bottom temp(BHT)

Z: deviation coefficient from Ideal Gas Law («gas compressibility»)

CGS estimates, at BOTTOM CONDITIONS,the m3 of gas per m3 of rock (dimensionless value)

Gas saturation affected bydrilling conditions (flushing)

VGN (Volumetric Gas Normalisation)

VGN GasROP

ROP

HV

HV

FR

FR E

normal

actual

normal

actual

actual

normal

(%) (%) * * * *=1

(ROP in m/hr HV inbbl/ft E=degasser efficiency in decimal %)

«normal» conditions derived froma specific field, basin or region (!)

Similar to CGI, more rigorousbut incomprehensible!

MAGIC!

tremendously


65/167


S U M M A R Y (1/2)

GENERALITIES

ConceptsPressure Regime status

HYDROSTATIC Pressure

OVERBURDEN: Definition

OVERBURDEN: Calculation

OVERBURDEN: Evaluation

PORE Pressure:Definition

Overburden and Pore PressureCOMPACTION: Normal & Abnormal

LUCKY & UNLUCKY: examples

FORMATION PRESSUREAcquisitionIndicatorsEvaluationSwab Gas Test & LCT

Drilling pressure evolution‘ROP’ normalized … storyAdvanced ‘ d ’ exp ./.

Generality & Formation PRESSURES


66/167


S U M M A R Y (2/2)

FORMATION PRESSURE (suite)

Normal Compaction Trend ‘dCn’Rock bit types vs ROP curve vs ’d’ expCompaction vs Drilling parametersCompaction vs LithologyCompaction Trend Observed ’dCo’Shale Pore Pressurecomputed: Eaton methodPore Pressure:Eaton formula (dC, ∆tcl, Rcl) and OverlaysEATON Overlays: isodensity (EMW)

’dCo’ OVERLAYS example: Excel worksheetFracturation pressureevaluation

WELL PRESSURE MEASUREMENTS

THEORETICAL TESTS: CSG, SBT, LOT, FIT(Casing, Shoe Bond Test, Leak Off Test, Formation Integrity Test)

PRESSURE RECORDING PLOT

Equivalent Mud Weight (EMW)

CHARACTERISTIC PROFILESANALYSES & INTERPRETATIONS

Formation & Well PRESSURES


67/167


68/167


PRESSURE REGIME STATUS

ABNORMAL

pressureH Y D R O S T A T I C

LITHOSTATIC

pressure

G E O S T A T I C SUBNORMALpressure

0 200 400 600 800 1000

0

1000

2000

3000

4000

5000

0 2000 4000 6000 8000 10000 12000 14000

0

2500

5000

7500

10000

12500

15000

D e p t h ( m

e t e r s )

D e p t h

( f e e t )

Pressure (psi)

Pressure (kg/cm2)

E q .D e n s = 2 .3 1 g / c c ( 1 p s i / f t )

E q . D

e n s =

1 . 0 0 g / c c ( 0

. 4 3 3 p s i / f t )

E q . D

e n s = 1 . 0 8 g

/ c c ( 0 . 4 6 8 p s i / f t )


69/167


HYDROSTATIC PRESSURE

Pressure exerted by a static fluid at a given point in a column

MW g/cm 3

TVD meter HP = 1850 psi

theoretically

Ph = (d . h) / 10

practically

HP = (MW x TVD) x 1.422

1000m TVD

mud

weight: 1.30g/cm3

TMDh

water

density: 1.00g/cm3

0 m

1000m

1300m

Pressure depends on vertical height (1) and on fluid density (2)Note: 130 kg/cm

2

= 1850 psi

Ph = 130 kg/cm2 d g/cm 3

h meter (1)

(2)

FLUID


70/167


OVERBURDEN PRESSURE

OBG Pressure exerted by the total weight of overlying sediments

(sea water + matrix + fluids into porous medium)

EMW

Cumulative Geostatic pressure

( ) in

i

ii

i

OBG Z Z Z

S ρ**11

1∑= −−=

( )Z Z erval usually m TVDi i− = ≈−1 50int

( )ρ i average density litho y

along erval

= ∀ log

int

SOBG expressedin EMW TVDTVD

EMW

cumulative

SOBG

air gap

ρ i

Zi

Zi - 1 cumulative

SOBG

sea water


71/167


OVERBURDEN CALCULATION

Air gap

Sea water

Litho 1

Litho 2

0m RTE

25m AMSL

125m Sea bed

pb= 0

pb= 1.03

pb= 1.65

S1= (0 x 25) / 25 = 0.000 EMW

S2= [(0 x 25) + (100 x 1.03)] / 125 = 0.824 EMW

S3= [(0 x 25) + (100 x 1.03) + (175 x 1.65) ] / 300 = 1.306 EMW

S4= [(0 x 25) + (100 x 1.03) + (175 x 1.65) + (150 x 1.75)] / 450 = 1.454 EMW

300m Unit 1

pb= 1.75

450m Unit 2

and so on ...


72/167


OVERBURDEN EVALUATION

BULK DENSITY EVALUATION

directly from DENSITY log:average value along constant interval

=> NOT ACCURATE in case of

heterogeneousformations

OVERBURDEN EVALUATION

• known regionally, ie from logs ( ∆t )

• unknown (ie exploration: wildcat) => rough approximation:

=> parabolic equation

with

in feet A B Csoft 0.01304 -0.017314 1.4335hard 0.01447 -0.018350 1.4846

in meters A B Csoft 0.01304 -0.014215 1.2462hard 0.01447 -0.014912 1.2870

=> or regional equation/parameters

( ) in

i

ii

i

OBG Z Z Z

S ρ**1

1

1∑=

−−=

( ) C Z B Z AS TVDBRT TVDBRT OBG ++= ln*ln*2

derived from SONIC log:

Sonic velocity (µsec/ft), computed

whatever formations: AGIP formula

• If SOFT form. ( > 70 µsec/ft)

• If HARD form. ( < 70 µsec/ft)

( )( )200

50*11.275.2

+∆−∆

−=t

t bρ

8928.3 t b ∆−=ρ

( )( )

( ) 3.28*ZZ

1000*TTI? t

1ii

msec

µsec/ft

−−

=

50m)Z(Zinterval:note1ii ≈− −


73/167


PORE PRESSURE

Po Pressure exerted by fluids density into pore space

Po

SUBNORMAL

Po < PhNORMAL

Po = PhABNORMAL

Po > Ph

- for SHALE => Po corresponds to Pp (d’exp, Sigmalog) - for RESERVOIR => Po corresponds to Pf (formation testers)

EQUILIBRIUM GAINSLOSSES


74/167


75/167


COMPACTION

pore

pore

pore

pore

... ONLY

BY

GRAIN TO GRAIN CONTACT

... BY GRAIN CONTACT

AND

... BY PORE FLUIDS

NORMAL

He-he!

WEIGHT

TRANSMITTED

...

Oooh

ABNORMAL


76/167


77/167


Formation PressureACQUISITION

1 - CONTRACTORS INVOLVED vs DATA MODES

REAL TIME DRILLING POST DRILLING

RECORDING

MUD LOGGINGCREW controlled (DST)uncontrolled (FFT)

On SURFACE

DOWNHOLE

(transmitted to surface)

ACQUISITION

LOGGING WHILE DRILLING

CREW

and

WIRELINE LOGGING

CREW

DATA


78/167


Formation PressureINDICATORS

2 - DATA INVOLVED and RESULTS

RESULTS

THROUGH

GAS

DRILLING

CUTTINGS

Well Temp°

NUCLEAR

ELECTRIC

ACOUSTIC

BKG, LCT, SwG, PCG, Ratio, …

ROP, WOB, Bit type, TRQ, Drag

Shape, Size, Density (shale)

Thermal gradient: (T°IN, T°OUT)

none

none

none

none

ROP, CAL, Rotary/Sliding modes

none

BHT, Mud T°, Tool T°

GR, Density (RhobCL), Neutron (PhiNCL)

Resistivity (RCL)

SONIC Transit Time (deltaTCL)

PARAMETERS

COMPACTION TREND SOBGPORE PRESSURE(PP) Psh, Pf

’d’ exp, Sigmalog, Form. testers

Empirical formula or laws Direct physical measurements

F ti P EVALUATION


79/167


Formation PressureEVALUATION

3 - DATA RESPONSES versus SHALE POROSITY INCREASE EFFECTS

GAS BKG PCG LCT

DRILLING ROP WOB TRQ

CUTTINGS Cavings Size Shape

Well Temp° Thermal gradient

NUCLEAR RHObCL PHINCL

ELECTRIC ResCL

ACOUSTIC DeltaTCL

NORMAL ABNORMAL

WHOLE CRITERIA MAY or MAY NOT REACTand IF ONLY 1 => ALERT

(diversity)

Swab Gas Test & Long Connection Test


80/167


Swab Gas Test & Long Connection Test

AIM ANTICIPATE the ARRIVAL OF the TRANSITION ZONE with the lowest MW

PC

PC

1 std (Top Drive)1 single (Kelly)

time

Hook height

SPMSwGT

• Stop drilling

• Stop circulating

• ‘Off Bottom’ 3-5m

swabbing time < 1min

• Resume circulation

• Back to drillingTotal DURATION: 5-10min

PSWB


81/167


z

DRILLING PRESSURE EVOLUTION

D E P

T H

PRESSURE (EMW)

O V E R B U R D E N F R A C

MWH y

d r o

s t a t i c

P r e s s .

PPECD

2

3

4

3

5 5

1too early (?) for - setting Casing- rising MW(possible LOSSES)

too late (?) for rising MW => KICK(if porous reservoir)

PP = MW, but still < ECDUnsafe drilling …

=> well in equilibrium (in static conditions)

ECD > PFRAC ( or ≥ PLOT)=> LOSSES(slow pump rate: reduce ECD and pump LCM)

2

1

4

• drilling conditions => LOSSES (ECD > PFRAC)• static conditions (PP > MW)

=> GAIN to KICK… depending on permeability

THE WORST SITUATION!

What to do?


82/167


’ROP’ NORMALIZED … STORY!

• BINGHAM (1964, Gulf coast): relationships between LITHOLOGY and DRILLING PARAMET ERS

’d’ exponent empirical formula

=

BS inches

WOB lbs K

RPM ROP hr ft

)(

)(.

)/(

BS

WOB RPM

ROP

inches

lbs

*

hr ft

d

* )(

* )(

10

)/(

10

6

''

10

12log

60log

=

• JORDEN & SHIRLEY (1966) solved this equation for a constant lithology (K=1 for shale)

with d = compaction exponent(=> ‘ d ’ exp)

and K = lithological constant

Any decrease in ‘ d ’ exp

(expressed in EMW)

when drillinga shaly sequenceis a function of the degree

of undercompaction

• REHM & McCLENDON (1971): ‘ d ’ exp corrected for mud weight (∆P function of Shale pore presure)

ECD

Phydro

EMW

EMW d dc

)(

)('.''' =

Parameters not takeninto account:

- ∆P, not known accurately- bit type and bit wear

- mud hydraulics when drilling with jetting (unconsolidated Clay)

Why only for

SHALE ?

)*(exp*@ Z Cst surfacedepthCLAY Z −=φφ

RUBEY & HUBBERT law (1959)

φ

Ζ

CLST

SST

easy,

Man?

Yeah!

Fair enough?NO !

d

UPGRADED ADVANCED ’d ’


83/167


UPGRADED or ADVANCED ’d ’ exp

How to restitute an almost true normalized ROP ?

)(

)(

)(

)(

)(min/*

*026469.0log

**3048.0log

EMW

EMW

inches

T

m

p

c ECD

Ph RPMc

BS WOB

ROP a

d =

corrected for ROCK BITS

as new ones

for each depth drilled

)(*

8

1*3*31.0

18

*3

8*31.0

)(?0.0)(2.01.0)(5.03.01*6*93.0

)09.1*10*8(

2

2

2

4

drilled Interval

depth Bit depth Bit BW x

and

RPM RPM and x x

BW BW

Z

with

bit PDC bit insert bit teeth pand Z Z a

where

IN OUT

RPM

corrected

−=

=++

++=

−−=++=

+− −

WELLSITE GEOLOGIST& MUDLOGGING Crew

MUDLOGGING UnitCOMPUTER

dCndCo

YES!

HELP!

è … and ‘dCn’ still not drawn !

NORMAL COMPACTION TREND ’d ’


84/167


NORMAL COMPACTION TREND ’dCn’

• RUBEY & HUBBERT ⇒ log(φ ) = -c.Z + log(φo) => linear relations hip between Depth (Z) and Porosity (φ )

• ZAMORA: the ‘ d ’exp (proportional to porosity), follows the same law for claystone/shale:

Slope A

( )

12

12 /log

Depth Depth

d d A CnCn

−=

[ ] Depth Ad Cn

Cn

B

Depth Ad B

*)log(

10

*)log()log(

−=⇒

−=

In tercept B

Example:

@ 1500m dCn= 1

@ 4500m dCn= 2

slope A= 1.003*10-4

intercept B= 0.707Computer job(MUDLOGGING CREW)

Geologist job

log(dCn) = A.(DEPTHTVDBRT) + B

0

1000

2000

3000

4000

5000

3 5 2 31.00

*

*

S L O P E

INTERCEPT

dCn

dCo

dc(EMW)

D e p t h

( T V D B R T

)

[ ])log(*10 B Depth ACnd +=⇒ At any depth:

ROCK BIT t ROP ’d’


85/167


ROCK BIT types vs ROP curve vs ’d’ exp

Cone bitsNOZZLES

3 x ?? /32’’

Fixed head bitsNOZZLES or

TOT AL FLOW AREA

TEETH bit INSERT bit PolycrystallineDiamond Compact

Rock is SHATTERED by pressure Formation is CUT with cutters

• ROP curve CONTRASTED:

drilling parameters relativelysteady

• Cuttings shape & size generally

well representative of rock compaction

• ROP curve SMOOTHED:

parameters adjustedvs lithology

• Cuttings shape & size fairly to non

representativeof rock compaction

NOZZLES

3 x …/32’’

TFA inch2

converted

to equiv.

nozzles

+ -


86/167


COMPACTION TREND and Drilling param ’s

COMPACTION TREND

assumed to reflect a normalized ROP

with constant (!)

DRILLING & MUD

parameters

WOB

RPM

Bit type

Bit size

OBM

WBM

MW

ECD

è ADJUST ‘END to END’ SHIFTS

è WITHOUT CHANGING SLOPE(S)

Fast ROP (min/m) Slow

Depth

OBM effect

WBM effectDCn

TEETHtricone bit

èPDC bit

ç Core bit

Worn bit

è

ç

ç

INSERTtricone bit

IT WORKS!


87/167


COMPACTION TREND and LITHOLOGY

è check LITHOLOGY

è check CALCIMETRY

Fast ROP (min/m) Slow

DCn

Sand

baseline

DCo

SILT effect CO3 effect

Depth

Shale

baseline

Dco => OBSERVED

COMPACTION TREND

assumed to reflect a normalized ROP

based on pure (!)

CLAYSTONE / SHALE

Dcn => NORMAL

COMPACTION TREND OBSERVED ’d ’


88/167


COMPACTION TREND OBSERVED ’dCo’

’dCo’reflects a ‘Normalized ROP’

corresponding to:

normalcompaction

dCo= dCn

0

1000

2000

3000

4000

5000

3 5 2 3

1.00

dCn

d(EMW)

D e p t h

dCo

abnormalcompaction

dCo < dCn

porepore

pore

poreThe increase in pressure is

proportional to the difference

dCn and dCoPRESSURE

SHALE COMPUTED


89/167


SHALEPore PressureCOMPUTED

Shale Pore Pressure (PP)

EATON method

( )2.1

trend)(normal

trend)(observed

(EMW) chydrostatiOBGOBG

−−=Cn

Co P

d

d P S S P

0

1000

2000

3000

4000

5000

3 5 2 31.00

dCn

d(EMW)

D e p t h

dCoExample

at 4000m: dCo = 1.50 g/cc (EMW)

Ph = 1.00 g/cc (function of water salinity)

dCn = 10(1.003*10-4*4000 + log(0.7)) = 1.76 g/cc (EMW) at 4000m

SOBG = 0.01447*(ln4000)2 + (-0.014912*ln4000) + 1.287 = 2.16 g/cc

PP = 2.16 - (2.16-1.00)(1.50/1.76)1.2 = 1.20 g/cc (EMW)

Pore Pressure & Overlays


90/167


Pore Pressure & Overlays

EATON formulas

While drilling

During logging

Overlaysisodensity EMW

( )2.1

trend)(normal

trend)(observed

hydro

−−=

Cn

Co P

d

d P S S P

( )3

trend)(observedl

trend)(normal

hydro

∆∆

−−=o

n P

t

t P S S P 3*

p

h

no P S

P S t t

−−

∆=∆

2.1*h

p

nCnCo

P S

P S d d

−−

=

(Pp sucessively taken to1.00, 120, 1.40, …)

( )

5.1

)(observedl

)(normal

hydro −−= on

clay

clay P

R R P S S P

’d’ exp

∆t clay

Resclay 5.1*h

p

no

P S P S Rcl Rcl −−=


91/167


EATON Overlays: isodensity (EMW)

0

1000

2000

3000

4000

5000

2 3 5 2 3

1.00d (EMW)

d e p t h

1.00

1.20

1.40dCn

dCo

2.00

1.80

1.60

Isodensity lines for ’d’ exp

1 - Determine the ’dCn’ trend:

( slope & intercept)

2 - Compute at each depth, knowing

- the SOBG (regional or recomputed)

- the Ph hydrostatic gradient (1.00 to 1.08)

the theoritical values of the ’dCo’ for different pressure gradients (1.20, 1.40, 1.60, … )

⇒ using Eaton ’s formula:

2.1*h

p

nCnCo

P S

P S d d

−−

=

Quick look method for Shale Pp

Note: Eaton exponents may vary(1.1 - 1.5)

’d ’ OVERLAYS example (Excel worksheet)


92/167


dCo OVERLAYS example (Excel worksheet)

NORMAL TREND dcn:log(dcn)=A*depth+B A=(log(dcn2/dcn1))/(depth2-depth1) OVERBURDEN:

dcn1 = 0.75 sgEMW 0.00010557 => slope S=a*(ln(depth)) 2̂+(b*(ln(depth))+c

dcn2 = 0.9 sgEMW B=10 (̂log(dcn1)-A*depth1) depth in meter

depth1 = 250 m 0.70577702 => intercept a => 0.01447ept = m => dcn at depth: => - .

dcn=10 (̂A*(depth)+log(B)) c => 1.28700

Pr.hydr. = 1.01 sgEMW => OVERLAY at depth: or enter newcoefficientsEATON exp' 1.2 dco= dcn*[ (S-Pp)/(S-Ph)] (̂1/Eaton exp' or enter local OBG formula

SHALE PORE PRESSURE at depth: S = 2.129 SHPP= S-(S-Ph)*[dco/dcn] 1̂.2

dco = 1.35 dcn = 1.65 => 1.249 sgEMW

DEPTH dcn= 1,00 SOBG RLAYS (sgEMW

(mTVDBRT) 1.00 (EMW) 1.20 1.40 1.60 1.80 2.00 2.20

100 0.723 1.525 0.493 0.222 #NOMBRE! #NOMBRE! #NOMBRE! #NOMBRE!

250 0.750 1.646 0.558 0.340 0.084 #NOMBRE! #NOMBRE! #NOMBRE!

500 0.797 1.753 0.623 0.429 0.214 #NOMBRE! #NOMBRE! #NOMBRE!

750 0.847 1.822 0.678 0.491 0.288 0.043 #NOMBRE! #NOMBRE!1000 0.900 1.874 0.732 0.546 0.346 0.117 #NOMBRE! #NOMBRE!

1250 0.956 1.916 0.786 0.598 0.398 0.173 #NOMBRE! #NOMBRE!

1500 1.016 1.952 0.842 0.651 0.447 0.222 #NOMBRE! #NOMBRE!

1750 1.080 1.983 0.901 0.705 0.496 0.268 #NOMBRE! #NOMBRE!

2000 1.148 2.010 0.963 0.760 0.546 0.312 0.024 #NOMBRE!

2250 1.220 2.034 1.028 0.818 0.596 0.356 0.071 #NOMBRE!

2500 1.296 2.056 1.097 0.879 0.649 0.401 0.113 #NOMBRE!

2750 1.377 2.076 1.169 0.942 0.704 0.447 0.153 #NOMBRE!

3000 1.463 2.095 1.247 1.010 0.761 0.495 0.193 #NOMBRE!

3250 1.555 2.113 1.328 1.081 0.821 0.544 0.232 #NOMBRE!

3500 1.653 2.129 1.415 1.156 0.885 0.596 0.273 #NOMBRE!

3750 1.756 2.144 1.507 1.236 0.952 0.650 0.315 #NOMBRE!

4000 1.866 2.159 1.605 1.321 1.024 0.708 0.359 #NOMBRE!4250 1.983 2.172 1.709 1.411 1.099 0.768 0.404 #NOMBRE!

4500 2.107 2.185 1.819 1.506 1.179 0.832 0.452 #NOMBRE!

4750 2.239 2.198 1.937 1.607 1.264 0.900 0.503 #NOMBRE!

OPEN

FILE

FRACTURATION evaluation

http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/http://ml-obg-%26-overlays_1098.xls/


93/167


FRACTURATION evaluation

WHY ?

TO DETERMINE the MAXIMUM:

- Mud Weight (ECD) permitted during drilling

- Annular surface pressureallowed during kick

- Casing shoe settings

FRACTURE gradients depend on:

- stress conditions in the wellbore (σx, σy, σz)

- Hole geometry & orientation (FRACHORIZ. WELL K

with 0.33


94/167


WELL PRESSURE MEASUREMENTS

Theoretical Pressure tests types

TO CHECK

possible leaks

along casing or liner

equipments

before

drilling out

cement

Casing and/or

Liner Test

TO CHECK

possible leaks

at casing shoe

(cement: presence

and hardness)

after drilling out

casing shoe

SBT

Shoe Bond Test

TO DETERMINE

the maximun pressure

up to ‘‘leak off’’ = PLOT

which can be applied

at the firstpermeable level

below the shoe

(or no more than 50m)

LOT

Leak Off Test

FIT

Form. Integrity T.

Equivalent to LOT,

TO CONFIRM

the validity of former

LOT at shoe

with cracking theformation PFIT PLOT

while drillingthe new section

≤

DRILLER interest DRILLER & GEOLOGISTinterest

PracticallyPERFORM IN A ROW (‘RAT HOLE’ DRILLED)

UP TO FRACTURATION/INJECTIVITY THROUGH THE FORMATION

OR at a LOWER PRESSURE (assumed to be valid as PLOT),DEPENDING ON EXPECTED FORM. PRESS. ALONG THE SECTION



95/167



Measurementsfor the determination of the maximun mud weight

permitted for drilling (ECD) without loss of circulation

METHOD: Increasing the mud pressure,generally using CementUnit pump(s),by shut-in-well (well closed)

P

r e s s u r e ( p s i )

Volume (bbl) Time (min)

THEORITICAL

PUMPING BLEED OFF

1

1LINEAR INCREASE IN ANNULAR PRESSURE,

PROPORTIONAL TO THE VOLUME PUMPED,

AT CONSTANT MUD FLOW RATE

PLOT

2

2

DEPARTURE FROM LINEAR SLOPE:

START OF ‘LEAK OFF’ =>PLOT => AS PUMPING CONTINUES, MUD

PENETRATING/INJECTING THE FORMATION

PINJECTIVITY

3a

3aCRACKING and INJECTIVITY THROUGH

THE FORMATION => STOP PUMPING

3b

3bEND OF INJECTIVITY (fracture propagation)WELL STILL CLOSED (TIME > 15min)

4

4END OF TEST: PRESSURE PURGE

=> COMPARE VolPUMPED vs VolRETURNED

paper print

screen plot

computer

MUDLOGGING UNIT

+

++

CEMENT UNIT

+

--

Pressure outputs


96/167


EQUIVALENT MUD WEIGHT: EMW

P

r e s s u r e ( p s i )

Time (min)Volume (bbl)

PUMPING

PLOT

PINJECTIVITY

FRACTUREPROPAGATION

BLEED OFF

In OBM well, the ‘pumping phase’

might be smoothly curved,

due to fair oil compressibility

EMW PTVDBR

MWLOT= +* .07032(g/cc) (g/cc)

(m)

(psi)

(conversion

factor)

example

PLOT = 1250 psi

Shoe = 1820 mTVDBRT

MW = 1.22 g/cc

VolPUMPED = 5.50 bblVolRECOV = 4.25 bbl

CONVERSION: 1 14 2210

142207032

1 42 160

2psi kg cm

bbl gal liters

= =

≈ ≈

. / (.

. )

EMW = 1.70 g/cc

Injected through formation:

=> 1.25 bbl = 200 liters


97/167


98/167


PRESSURE ANALYSES

CEMENT

RAT HOLE

CASING

SHOE

FRACTURE

PROPAGATION

P (psi)

Volume (bbl) Time (min)

B

A

PLOT > Ppropag.1

VOLRECOV


99/167


S U M M A R Y

SAMPLING PROCESS:

- SAMPLES: Why? and Types?- SAMPLES: Preservation ... what for?

SAMPLING: BASIC RULESCUTTING PREPARATION

WASH OUT SAMPLE EVALUATION

CUTTING PERCENTAGE ACCURACY and VISUAL ESTIMATION

DESCRIPTION and Order Standardization:

General RECOMMENDATIONS

1 - ROCK NAME

2 - COLOUR3 - HARDNESS / INDURATION

4 - TEXTURE: General

Summary

SEDIMENTARY PARTICLES

CARBONATE DESCRIPTION

5 - MATRIX and CEMENT

6 - FOSSILS and ACCESSORIES

7 - Apparent POROSITY

8 - OIL SHOWS: GeneralitiesObservation

Comments

SAMPLE PROCESSING


100/167


SAMPLING PROCESS (1)

AIM OBSERVATION and EVALUATION OF FORMATION DRILLED,

SUMMARIZED IN MUDLOG DOCUMENT, ON RIGSITE

SOLIDS samples FLUIDSsamples

=> to rebuiltlithological

column

=> to visualise

reservoir

characterisation

=> to identify

true

formation fluids

=> to precise

rheology(drilling fluid)

CUTTINGS

Unwashed (UNW)

Washed & Wet (W&W)Washed & Dried (W&D)

( + spot samples)

CORES

+

wax preserved

samples

FORMATION SAMPLES MUD SAMPLES

Prior logging job,New mud type

(per Drlg phase)...

WHY?

SAMPLES

TYPES?Liquids

Cond

OilWater

Gas

S G OC SS


101/167


SAMPLING PROCESS (2)

PRESERVATION

MODE

SAMPLES

LABORATORY

STUDIES

measurement

(on rigsite)

&

analysis(in town)

BAGScotton, paper,

plastic,aluminium,

glass pills

CORESCUTTINGS

BOXES

wooden(preferably)

or plastic

W&DW&W

UNW

=>Accurate DESCRIPTION

Lithology

CALCIM., FLUO.,

Shale density

Thin sections, ...

HCb extraction, TOC (W&W)Heavy Mals identification

Microfauna, ...

=> Rough description

CHIPS observation

CALCIM., FLUO.

(thin sections)

PETROPHYS. on Plugs

SCAL (Phi-K, matrix, Sw)SEDIMENTOLOGY

on slabbed core

MUD

SAMPLES

Liquids

jerricans

bottles

Gas

PVT cells

chamber

FORMATION

SAMPLES

CANS

Jerricans

Quick look

Density (API),

Pour Point,

Resistivity

& Salinity, ...

Component

C1 ... C5CO2, H2S

same analysismore accurate+ Volume Factor (Bo, Bg)

+ Gravity, Finger prints, ...

Mud weight

OBM: Elect. stability

O/W ratio, ...

WBM: Rm, Rmf, Rmc

Visc, Gels, ...

rarely to none

SOLIDS samples FLUIDSsamples

SAMPLING: BASIC RULES


102/167


SAMPLING: BASIC RULES

«UNFORESEEN EVENTS OCCUR ONLY ONCE DURING WELL DURATION»

NEVER MISS OPPORTUNITY TO COLLECT SAMPLES

S

OTHERWISE

YOU CAN BE TRAPPED !AND LOOSE SOME IMPORTANT WELL DATA

SOLID SAMPLES LIQUID SAMPLES

=> WHILE TRIPPING/FISHING ...

rock samples remainingstuck on BHA:

- bit (tricone)

- stabilizers

- junk basket

- ...

Bigger cuttings for

nicer thin sections

=> WHILE TESTING ...

no flow on surface or

nothing while reverse circulation

(but test «technically successful!»)

CHECK below DST string

=> WHILE DRILLING ...

... Oil on Shale-Shakers

(fractures indicator ?)

THUS

. . .

CUTTINGS PREPARATION


103/167


CUTTINGS PREPARATION

UNWASHED sample WASHED sample

DEPTH

COARSEsieve

MEDIUMsieve

FINEsieve

WRITTEN WITH PENCILTHROUGH SIEVES COLUMNFROM SHALE SHAKERS SIEVES

RAW & MIXED CUTTINGS

EMBEDDED

WITH MUD including

ADDITIVE PRODUCTS

(Polymers, LCM, ...)

• FOR CHECKING POSSIBLE CAVINGS

• BIGGER CUTTINGS MAY BE USED for:

- SELECTIVE CALCIMETRY

- THIN SECTIONS

FOR PERCENTAGE EVALUATION

& FOR DESCRIPTION(Medium and Fine granulometric sizes

may be mixed)SUCK EXTRA WATER

with towel,

sponge,paper filter, ...

STEEL / INOX

flat area

GLASS-WATCH

curved

ALUMINIUM DISH

undulatedarea

SAMPLE TRAYS

RECOMMENDED . . . . . . . . . . . . IF NOTHING ELSE

GEOLOGICAL WASH OUT


104/167


GEOLOGICAL WASH OUT

WASH OUT EVALUATION

• Possible ORIGIN:

. formations poor ly cemented, indurated, .... and/or inappropriate drilling fluid (mud)

• PHENOMENA:

Drilling with almost no WOB (‘jetting’) => vf-f SD/SST

Washable CL/CLST, SLST, ...

• Surface DETECTIONin Mudlogging unit:

Samples do not reflect the expected lithology

Volume cuttings recovered Miss DATA, borehole instability

• How to solve the situation?Wash samplesyourself & check residue inside sink

Look for ‘lost’ samples: flow-line, sand-trap, ...

Washed out evaluation:

• Other: unexpected SALT, drilled ... with WBM not saturated

Mudlogging crew => DECIDE & ACTthen ... INFORM => Drlg Supervisor %606.02.0

%404.08.0

=>=

−+

=

=>=

=

H h H

H h xCLAY

H

h xSAND

H

Height BEFORE ...

h

Height AFTER ...

WASHINGsieves set

coarse

medium

fine

Raw percentage

after washing:

SAND: 80%

CLAY: 20%

CUTTING PERCENTAGE ACCURACY


105/167


ACCURACYEXPECTED ?

±1000

remember:

5% TRACES

CUTTING PERCENTAGE ACCURACY

CUTTING PERCENTAGE ESTIMATION


106/167


CUTTING PERCENTAGE ESTIMATION

SAMPLE DESCRIPTION (1):


107/167


WELLSITE GEOLOGIST

=> EXAMINE SEVERAL SAMPLES IN A ROW ... for updating the

interpretated lithological column ... and KEEP LAST SIGNIFICANT ONES

BUT AVOID T O «fill up volume» for the base Geologist!

OBSERVE under

«same conditions»

TIME =>hardness

LIGHT => colour

FOCUS => texture

. . .

USE

«usual codification»

STANDARD

ABBREVIATIONS

REPORT

MAIN

ROCK

FEATURES

RECOGNIZE and

DISREGARD

CAVINGS and

«other

contaminants»

BE CONSISTANT BE HOMOGENEOUS BE ACCURATEBE SELECTIVE BE CONCISE

NOTE

DOMINANT

SIGNIFICANT

DETAILS

limestone

LMST

LST LSLime-stone


GENERAL RECOMMENDATIONS



108/167


1 - ROCK NAME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . and abundance (estim.%)

2 - COLOUR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . under Cst lighting

3 - HARDNESS / INDURATION . . . . . . . . . . . . . . . .

subjective appreciation

4 - TEXTURE: rock’s components . . . . . . . . . . . . characteristic elements

5 - MATRIX and/or CEMENT . . . . . . . . . . . . . mechanical/chemical process

6 - FOSSILS & ACCESSORIES . . . . . . . . . . . . . . secondary rock particles

7 - POROSITY (apparent) . . . . . . . . . . . . . . . . . . . . . . qualitative evaluation

8 - OIL SHOWS . . . . . . . . . . . . . . . . . . . . ephemeral approach fct(rock Phi,K)

DESCRIPTION ORDER

SAMPLE DESCRIPTION (2):BASIC RULES or STANDARDISATION



109/167



1 - ROCK NAME

Six (6) BASIC

CATEGORIES OF ROCKS

ARGILLACEOUS

SH ShaleCLST ClaystoneMRL Marl

CARBONATES

LS/LMST LimestoneDOL DolomiteCHK Chalk

SILICEOUS

SLST SilstoneSD SandSST SandstoneCHT Chert

ANH AnhydriteGYP GypsumSA or HAL Salt

EVAPORITES

COAL CoalLIG LigniteBIT Bitumen

ORGANICS

BM BasementBAS BasaltGRT Granite

SSDD - SXST

Miscellaneous

NOTE: DIATOMITE and RADIOLARITEmay be encountered,

but «FORAMINIFERITE» generally corresponds to

an intensive washing of Argillaceous deposits !

PERCENTAGE QUALIFIERSLess than 5 = TRACES



110/167



2 - COLOUR

SAMPLE TRAY:a- MUSHROOMS, TOMATO, ...b- CHEESE, NODDLES, ...c- MEAT, PAPRIKA, ... , Oil

ROCK COLOUR DEPENDS ON:

a- CONSTITUENT GRAINS

b- MATRIX and/or CEMENT

c- STAINING (mud products, iron, ... , OIL)

STRESS ON PREDOMINANT COLOURSTRESS ON PREDOMINANT COLOURREDDISH to LIGHT BROWN

(rdsh-lt brn)

BROWNISH to ORANGE

(brnsh-or)

TRAFFIC LIGHTS

for

COLOUR BLIND WSG

for more details, see the

ROCK COLOR CHART

(The Geological Society of America)

representing the:

U.S. Geological Survey, AAPG, ...


111/167



112/167



4 - TEXTURE: GENERAL

ORGANISATION of the COMPONENT ELEMENTS ofthe ROCK

(simplified WENTWORTH scale)

SIZE ARRANGEMENT

extr wl srt

v wl srt

wl srt

mod srt

pr srt

v pr srt

mono-

modal

poly-

modal

ROUNDNESS:

edges sharpness

v ang

ang

sbang

sbrnd

rnd

wl rnd

v elong

elong

sli elong

sli spher

spher

v spher

SHAPE

SPHERICITY:

shape of the grain(ratio width/length)

CLAST ICS size of CARBONATES

Grains element Crystals

Mud - Clay < 20µ crpXln - mXln

Silt 20 - 63µ extrXln

vf - f 63 - 250µ vfXln - fXln

med - v crs 250µ - 2mm medXln - vcrsXln

Granule-Boulde 2 - 256mm extrcrsXln

SORTING:

grains range size

pr gdfr



113/167



4 bis - TEXTURE summary

ROCK GRAINS / CRYSTALS ORGANISATION

SIZE SORTING

SHAPE

ROUNDNESS

SPHERICITY

TEXTURE: SEDIMENTARY PARTICULES


114/167


TEXTURE: SEDIMENTARY PARTICULES

very coarse

coarse

medium

fine

very fine



115/167


CLASSIFICATION according to

DEPOSITIONAL TEXTURE

Structures of ELEMENTS




116/167



5 - MATRIX and/or CEMENT

M A T R I X C E M E N T

OF SMALL INDIVIDUAL GRAINS,

BETWEEN LARGER GRAINS ,

FILLING INTERSTICES

AROUND GRAINS or CRYSTALS,

OFTEN BOUNDED TO THE SEDIMENT ,

FILLING INTERSTICES and/or VOIDS

Silica, Calcite, Dolomite,Pyrite, Salt, ...

MECHANICAL

DEPOSIT

CHEMICAL

PRECIPITATE

Silt, Clay

BOTH REDUCING

POROSITY



117/167


F O S S I L S A C C E S S O R I E S

EASY TO RECOGNISE, DIFFICULT TO IDENTIFY

MINOR ROCK PARTICLES ARE USEFUL

FOR CORRELATIONS and FOR ENVIRONMENT INDICATORSeven if it is A SPECIALIST ’S job

=> INFORMATION on ORIGIN and HISTORY of the SEDIMENT

FORAMINIFERAGASTROPODS

PELECYPODS

CORALS

ALGAE

OSTRACODS

BRYOZOA

. . .

(crystal, framboid) PYRITE => DIAGENETIC, CONFINED DEPOSITSGLAUCONITE

=> MARINE: EXTERNAL SHELF

CALCITE => FAULT, RECRYSTALL

(BIOT, MUSC => detrit acid rocks) MICA (CHLORITE =>fluvio -marine)SCATTERED GRAINS (Org.Mat, Coal, Gyps., ...l

HEAVY MINERALS (APATITE: detritic, PO4 deposits)

«lithics rock fragments»magnet => Fe-Mg minerals

. . .

MINERALSORGANISMS

PERCENTAGE QUALIFIERS

> 10 % Abundant

5-10 % Minor

1-5 % Rare

< 1 % Trace

and COLOUR

DON’T FORGET

( )

6 - FOSSILS & ACCESSORIES



118/167


soft

sediments

solid or

liquid ?

0 - 5% negligable visual porosity(n vis por: nvp)

5 - 10% poor porosity (p vis por)

10 - 15% fair/medium visual porosity (fr/med vis por)

15 - 20% good visual porosity (g vis por)

20 - 25% very good visual porosity(vg vis por)

PERCENTAGE QUALIFIERS

I N T E R G R A N U L A R

INTRAGRANULAR

MOLDIC

VUGGYINTERCRYSTALLINE

FRACTURE

CONNECTED or ISOLATED network ?

cuttings?CORE => OK

( )

7 - APPARENT POROSITY



119/167


STRONGEST SHOWS

DO NOT NECESSARILY REFLECT

THE BEST RESERVOIR

- mud weight flushed while drillingmud types (WBM, OBM) samples washing- bits used cuttings size

SHOWS ARE FUNCTION OF:

DESCRIPTION ORDER

FLUORESCENCE (direct)

ODOUR & COLOUR: intensity

DISTRIBUTION:staining & bleeding

FLUORESCENCE(cut, residual)

ONE OF THE MAIN INTEREST OF A WELL

knowing that:

SHOWS ARE

EPHEMERAL

(highly volatile)


8 - OIL SHOWS: Generalities



120/167


( )

8bis - OIL SHOWS: Observation

SOLVENT FLUORESCENCE (crushed sample)

OIL ODOUR & OIL COLOUR

the stronger, the darker (dk brnsh), the lower °API

the fainter, the lighter (lt yelsh), the higher °API

3

OIL ST AINING & BLEEDING

DISTRIBUTIONEVEN

MOTTLED very good >40%

PATCHY good 20-40%

SPOTTY fair 10-20%

SPECKLED poor 1-10%

PINPOINT very poor 1-2 grains

NIL

(RATING roughly= 1/permeability)

2

BRIGHT => DULL => PALE => FAINT

(strong to weak)

INTENSITY

+ -

CUT 1 SPEED flash: instant.

fast: < 5sec

slow: 5-10sec

crush:‘needle’

2 STRENGTH

01_ml for dummies(geolog)

Documents