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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
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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)
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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
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’STONE AGE’ BIBLES ...
USEFUL, BUT:- DIFFICULT TO MANAGE (heavy, huge, ...)
- BORING RESEARCH & READING M
d i u L n
go g g
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... 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
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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
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Mudlogging KEYWORDS index research
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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
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Geological Well Report
TOOLBOX - module 7.0
TEXT.doc
PRESSURE MEASUREMENTS
SAMPLING SEQUENCE
MUDLOG
PORE PRESSURE
DATA TRANSFER(ASCII)
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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
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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
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TOOLPUSHERGEOLOGIST
CO- MANMUDLOGGING
LOGGING(WL & LWD)
DIRECTIONALDEVIATION
POSITIONING
CORINGMWD
DRILLINGMUD
CEMENT
CASINGROV, ...
DRILLING
&
RIGMAINTENANCE
RIGSITE CONTRACTORS
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RIGSITE RESPONSIBILITIES
Rigsite
role
TOOLPUSHERCO-MAN
GEOLOGISTMUDLOGGING
Rigsite
position
ACQUISITION
EVALUATION
DECISION
EXECUTION
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MUDLOGGING «Householder»
DATAENGINEER
MUDLOGGER
SAMPLE-
CATCHER
OUR TEAM
YOURBOSS?
MY BOSS
YEAH!
WELLSITE
GEOLOGIST
MUDLOGGING
CREW
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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
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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 ...
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MUDLOGGING : JOB PURPOSES
MONITORING
&DETECTION
QUICK
UNDERSTANDING
& FASTREACTING
RECORDING REPORTING
PARAMETERS EVENTS
DATAACQUISITION DOCUMENTS
WELL FOLLOW UP ...
?
... ON A ROUTINE BASIS
BS
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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
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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
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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
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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
...
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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
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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
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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
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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.
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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
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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
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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, ...
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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
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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
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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)
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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
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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?
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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
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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
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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
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TEP/DEG/CEF/SUB. . . Natters Around Field . . .
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
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TEP/DEG/CEF/SUB. . . Natters Around Field . . .
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
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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
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TEP/DEG/CEF/SUB. . . Natters Around Field . . .
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)
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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
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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)
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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
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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
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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
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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
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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
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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+
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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
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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)
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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
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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
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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
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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
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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
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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 )
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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
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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
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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 ...
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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 ≈− −
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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
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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
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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
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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
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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
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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
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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?
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’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 ’
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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 ’
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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’
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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
+ -
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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!
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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 ’
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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
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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
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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 −−=
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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)
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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/
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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
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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
PRESSURE RECORDING PLOT
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PRESSURE RECORDING PLOT
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
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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
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PRESSURE ANALYSES
CEMENT
RAT HOLE
CASING
SHOE
FRACTURE
PROPAGATION
P (psi)
Volume (bbl) Time (min)
B
A
PLOT > Ppropag.1
VOLRECOV
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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
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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
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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
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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
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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
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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
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ACCURACYEXPECTED ?
±1000
remember:
5% TRACES
CUTTING PERCENTAGE ACCURACY
CUTTING PERCENTAGE ESTIMATION
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CUTTING PERCENTAGE ESTIMATION
SAMPLE DESCRIPTION (1):
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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
SAMPLE DESCRIPTION (1):
GENERAL RECOMMENDATIONS
SAMPLE DESCRIPTION (2):
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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
SAMPLE DESCRIPTION (3):
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SAMPLE DESCRIPTION (3):
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
SAMPLE DESCRIPTION (4):
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SAMPLE DESCRIPTION (4):
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, ...
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SAMPLE DESCRIPTION (6):
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SAMPLE DESCRIPTION (6):
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
SAMPLE DESCRIPTION (7):
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SAMPLE DESCRIPTION (7):
4 bis - TEXTURE summary
ROCK GRAINS / CRYSTALS ORGANISATION
SIZE SORTING
SHAPE
ROUNDNESS
SPHERICITY
TEXTURE: SEDIMENTARY PARTICULES
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TEXTURE: SEDIMENTARY PARTICULES
very coarse
coarse
medium
fine
very fine
CARBONATE DESCRIPTION
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CLASSIFICATION according to
DEPOSITIONAL TEXTURE
Structures of ELEMENTS
CARBONATE DESCRIPTION
SAMPLE DESCRIPTION (8):
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SAMPLE DESCRIPTION (8):
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
SAMPLE DESCRIPTION (9):
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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
SAMPLE DESCRIPTION (10):
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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
SAMPLE DESCRIPTION (11):
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STRONGEST SHOWS
DO NOT NECESSARILY REFLECT
THE BEST RESERVOIR
- mud weight flushed while drilling- mud 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)
SAMPLE DESCRIPTION (11):
8 - OIL SHOWS: Generalities
SAMPLE DESCRIPTION (12):
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( )
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