Basic-well-logging-Design (Sigit Sutiyono, Unocal)

7/27/2019 Basic-well-logging-Design (Sigit Sutiyono, Unocal)

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BasicWellLoggingDesignBasicWellLoggingDesign

CoordinatedByCoordinatedBy

SigitSutiyonoSigitSutiyono

UnocalIndonesiaCompanyUnocalIndonesiaCompany

A One-day Course on

Consortium Alumni Association Presents


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gendgend Introduction

(8:15)

LectureI BasicTheory/Interpretation

Break(10 10:15)

LectureII LoggingProgram/Design

Break(12:00)

Workshop

(1:30

4:00) Wrapup(4:00 5:00)


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ObjectivesObjectives

Get

to

know

various

log

measurements Recognizefluidtypeandlithologyofmajorreservoirs,

andsomepracticalapplicationoflogdata

Familiarizewithfactorsaffectingthelogresponse

Understandthestrategyinwellevaluation

Gettoknowvariousapproachestowellloggingdesign

Exercisewithwelllogdesign


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According to

4th Edition of J.A.Jacksons Glossary of Geology:

Log : A continuous record as a function of depth,

usually graphic and plotted to scale on a narrow

paper strip, of observations made on the rocks

and fluids of the geologic section exposed inthe well-bore.

DefinitionDefinition


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Wireline Logging Logging while Drilling

Cable

Tools

LWD Tools

Mud inMud out

Drill Bit


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WellLogging

HistoryWell

Logging

History

Thefirstelectricallogwasintroducedin1927inFranceusingstationed

resistivitymethod.

Thefirst

commercial

electrical

resistivity

tool

in

1929

was

used

in

Venezuela,USAandIndonesia.

SPwasrunalongwithresistivityfirsttimein1931

Schlumbergerdevelopedthefirstcontinuousrecordingin1931

GRandNeutronlogswasstartedin1941

Microresistivityarraydipmeterandlateralogwerefirsttimeintroduced

in1950s

Thefirstinductiontoolwasusedin1956followedbyFormationtester

in1957,

Fomation

Density

in

1960s,

Electromagnetic

tool

in

1978

and

mostofImaginglogsweredevelopedin1980s

Advancedformationtesterwascommercializedinearly1990s


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The First Log recorded in 1927

Well in Pechelbronn - France Surface Recording Instrument


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LogMeasurementsLogMeasurements

Logisanindirectmeasurementofformationproperties

exposedbythewellboreacquiredbyloweringadeviceor

acombinationofdevicesinthewellbore.

Practical definition of a log

A Formation Evaluation Specialist is essential to understand

The theory of measurements, quality control, interpretationprinciples, geophysics and petroleum geology as well as

petroleum reservoirs


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Advantagesand

Limitations

of

Well

LoggingAdvantages

and

Limitations

of

Well

Logging

Advantages:

- Continuous measurements

- Easy and quick to work with

- Short time acquisition

- Better resolution than seismic data

- Economical

Limitations:

- Indirect measurements

- Limited by tool specification

- Affected by environment

- Varying resolution


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BasicTheoryofMeasurementsBasicTheoryofMeasurements


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Logsare

Implied

MeasurementsLogs

are

Implied

Measurements

Logisnotadirectmeasurementofformationproperties,itisanimplied

measurementbasedononeorcombinationofthefollowingdevices

Electrical (Resistivity and

Induction)

Acoustic

Nuclear

Electromagnetic

Magnetic


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BasicTheory

on

ResistivityBasic

Theory

on

Resistivity

Current path

Unit volume filled with only water

Current path

Unit volume with water and matrix

Rw

Ro


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Typical Formation

Rt

Water

Sand grain

Grain surface water

Oil

Measured by the tool

Current path


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Resistivityand

Measurement

ConceptResistivity

and

Measurement

Concept

Resistivity is the ability of a substance to impade the flow of electrical current

Rw - Formation Water resistivityE - Voltage difference across the formation

A - Cross sectional Area

L - Length of brine containerr

I - Current

Rw =

E * A

I * L

L

I E

ARw


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Resistivityand

Measurement

ConceptResistivity

and

Measurement

Concept

Schematic diagram of how an induction tool works

Primary magnetic field

created by transmitter

Magnetic field induces

a current in the ground loop

Secondary magnetic field

Created by the ground loop

Secondary magnetic field

Induces a current to flow in the receiver

Transmitter

Receiver


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Resistivity is the key to hydrocarbon saturation determinationResistivity

ApplicationResistivityApplication

Water Saturation EstimationArchies Equation

Sw =F * Rw

Rt

SW - Water saturation

Rw - Formation water resistivityRt - True Formation resistivity

( )1/n

where F =1.0

Porm

Sh = 1 - Sw

Resistivity is also used for well to well correlation, and to pick fluid contacts

F - Formation factor

n - Saturation exponentm - Cementation factor


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SpontaneousPotential

Log

(SP)Spontaneous

Potential

Log

(SP)

SPmeasurementisbasedonElectricalcurrentsflowinginthe

mudfrom

electrochemical

and

electrokinetic

Salinitydifferencebetweenmudflitrateandformationwaters,

ionsmovementcreatescurrentsmeasuredinmVolt

NegativeorPositiveSPcurvedeflectionrepresentswhichfluid,

formationor

mud

filtrate,

has

more

ionic

charge.

Itonlyworksinwaterbasedmud!

The

use

of

SP

log;

bed

boundary,

distinguishing

permeable

from

impermeablerock,shalynessindicator, Rwdeterminationand

wellcorrelation.


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SpontaneousPotential(SP)SpontaneousPotential(SP)

SP

Shale

Sand Thick clean wet sand

(-) (+)

- - - - - - -

- - - - - - -

Thick shaly wet sand

Thick clean Gas sand

Thick shaly Gas sand

Rmf >> Rw in all sands

Hydrocarbon effect


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SpontaneousPotential

(SP)Spontaneous

Potential

(SP)

20

40 mV

7470

7430

Given:

Rmf = 0.51 at 135 F

Rm = 0.91 at 135 FTD = 8007 ft

Bottom hole temp.= 135 F

Surface temp. = 60 F

Determine Rw ?

SP

Limitation

SP is not reliable when you have no or very small contrast

Between Formation water salinity and mud filtrate salinity resulting in no

to small SP deflection


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Rwcalculation

from

SP

logRw

calculation

from

SP

log

SSP = -K log

Rmfe

Rwe

Steps of Calculation;

- Determine Temperature at Depth of interval

- Correct Rm and Rmf to this temperature (gen-9)

- Determine SP (log) from shale baseline

- Correct SP to SSP using SP thickness corr. chart

- Determine Rmf/Rwe ratio using SP-1 chart- Determine Rwe from above equation or SP-1 chart

- Correct Rwe to Rw using SP-2 chart


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GammaRay

Log

(GR)Gamma

Ray

Log

(GR)

GRtoolmeasuresnaturalradioactivityoftheformationfrom

the

emmision

of

all

these;

(Total

GR)Potasium,UraniumandThorium

GRlogisusedfor;WelltowellgeologicalcorrelationBeddefinition,moreaccuratethanSPlog

Shale

Volume

Indicator

(most

reliable)

Lithologyandmineralogyindicator(NGT)

IGR =GRlog - GRmin

GRsh - GRmin

IGR - Gamma ray index

GRmin - GR clean

GRsh - GR shale baseline


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GammaRay

Log

(GR)Gamma

Ray

Log

(GR)


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GammaRay

Log

(GR)Gamma

Ray

Log

(GR)

Mineral Density DT GR

Quartz 2.64 56 0-15Calcite 2.71 49 0-15

Dolomite 2.85 44 0-15

Orthoclase 2.52 69 220

Micas 2.82 49 275Kaolinite 2.41 - 80-130

Chlorite 2.76 - 180-250

Illite 2.52 - 250-300

Montmorillonite 2.12 - 150-200Anhydrite 2.98 50 low

Pyrite 4.99 39 low

Coal 1.47 high low


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Gamma

Ray

Log

(GR)Gamma

Ray

Log

(GR)

Well-1 Well-2Well-7

GR Res

GR Res

GR Res


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Natural

Gamma

Ray

Log

(NGT)Natural

Gamma

Ray

Log

(NGT)

NGT tool measures the spectrum of

Potasium,Uranium, and Thorium

NGT log is used for;

- Study of Depositional Environments

- Geochemical logging

- Shale typing

- Source Rocks

- Diagenetic History

- Vclay content correction

With combination of Photoelectric curve can be

used for clay and mica type identification


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NaturalGamma

Ray

Log

(NGT)Natural

Gamma

Ray

Log

(NGT)

0 2 4 6 8 10

2

4

6

8

10

0

K, Potasium (%)

Pe

Kaolinite

Montmorillonite

Illite

Glauconite

Muscovite

Biotite


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Density

LogDensity

Log

Densitytoolisoneofthemostimportantinstrumentsusedto

evaluate

formations

which

measures

formation

density

and

directlytiestoformationporosity

Thedensitytoolmeasurestheelectrondensity,byemittinggammarayfromradioactivesourceandreturningtotwodetectors

TheamountofGammaraysthatreturndependonthenumberofelectronspresent, electrondensityisrelatedtobulkdensityofmineralorrock

InmostcasesenvironmentalcorrectionforDensitylogisnot

significant,field

log

density

can

be

readily

used

for

interpretation


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Density

LogDensity

Log

Main categories in the process of GR energy loss due to

collisions with other atomic particles:

Compton Scattering is selected to be the energy level to

generate GR of the Cesium 137 radioactive source at 662 keV


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Density

LogDensity

Log

Porositydeterminationfromdensitylog:

POR =RHOBma - RHOBlog

RHOBma - RHOBfluid

RHOBma - Matrix density

RHOBfluid - Formation fluid density

RHOBlog - Log density

PORd - Density derived porosity

Exercise: Determine porosity of limestone with field log

density inicated 2.5 gr/cc.


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NeutronLogNeutronLog

ThetoolmeasurestheHydrogenIndexwhichisthequantityof

Hydrogenperunitvolume

Thetools

emit

high

energy

neutrons

either

from

radioactive

sourceorminitron.Theyaresloweddownbycollisionswith

formationnuclei,collisionwillresultenergyloss,andthe

elementmostlysloweddownisH

Waterhas

high

neutron

counts,

Oil

has

alittle

less

counts

than

Water,Gaswillhaveverylowneutroncounts

Neutronlogisverysensitivetoenvironmentchange;borehole

size,mudcake,mudweight,temperature,standoff,pressure

andformationsalinity,measurementiscompensationoffar

andnearcountrates.


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Neutron

LogNeutron

Log


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Neutron

LogNeutron

Log Neutrontoolhasawiderangeofapplications

PorosityDetermination

Gas

DetectionBoreholeandformationsalinity

ReservoirSaturation

ReservoirMonitoring

BoreholeFluiddynamics

NeutronradioactivesourceinnormallyusesAm241

Exercise Neutron Log environmental correction

Given: Uncorrected neutron porosity of 34%, 14 borehole size,

0.25 mud cake, 200 kppm borehole salinity, 12 ppg mud at

170 F, 5000 psi pressure, using water based mud with formation

salinity of 50 kppm.


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Acoustic

LogAcoustic

Log Sonictoolgeneratesacousticsignalstomeasurethetimetravelto

passthroughaformation,logmeasurementintimerequiredto

travel

in

one

foot

formation

(microsec/foot) Rockpropertiescanbeimpliedfromsonicmeasurements;

Porosity, Lithology, Gasshows,CompactionandRockstrength

Maincurrentuse: SeismicTie

Mechanical

properties

Fractureidentification

Tooltypes; Boreholecompensatedsonic

Longspacingsonic

Arraysonic

tool

Ultrasonicboreholeimage

Dipoleshearsonicimage


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Acoustic

LogAcoustic

Log


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Acoustic

LogAcoustic

Log


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Special

ToolsSpecial

Tools

Resistivity Based Imaging Tool

- Pad device on 4 to 6 arm caliper, few mm resolution

- Application: Thin bed Evaluation, Dip meter,Paleostream direction, fracture evaluation, stratigraphy.

Nuclear Magnetic Resonance

- Using Permanent magnet to realign hydrogen protons to new

magnetic field, a Lithology dependance porosity, saturartionand permeability estimation

Dipole Shear Sonic

- Shear measurement, AVO and Rock mechanics applications

Borehole sonic imaging- Acustic based bore hole imaging for 360 deg coverage, lower

resolution than resistivity based imaging tools.


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Special

ToolsSpecial

Tools continued

Modular Formation Test

- Very robust formation tester with the capability to take

unlimited pressure tests, pump the fluid into the borehole,identify the fluid type before sampling

Wellbore Seismic

- VSP: Vertical seismic profile surface guns, wellbore detectors

- SAT: Seismic acquisition tool- WST: Well seismic tool

- DSA: Downhole seismic array tool (3 axis geophones)


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WellboreSeismicWellboreSeismic


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Log

and

Seismic

Tie

EffortLog

and

Seismic

Tie

Effort

LogDataValidation

Check

the

log

qualitySeeifthereisanymissinglogdata

Determinewhethersonicpeaks/anomaliesrepresentingformation

Logediting

Velocity

Correction

Sonic

over

VSP

(using

4

2

msec

resolution)

SyntheticSeismicGeneration

AcousticImpedance

ConvolutionWavelettotieseismicandlogpeaks

*ExtractedWavelettoutilizewaveletasseenintheseismic

itis

highly

recommended

(similar

apperance)

*RickrWaveletcommonlyusedtohavezerophase


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Synthetic

SeismogramsSynthetic

Seismograms

SyntheticSeismogramsareusedtocorrelateseismicsections

Theoreticallythis

method

uses

many

simplification

and

assumptions

put

intothemodel

Itprovidesimportantlinktounderstandthetiebetweenseismicdataand

welllogresponses


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VSP&VSP&

SeismicSectionSeismicSection


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Velocity

SurveyVelocity

Survey Velocityorcheckshotsurveysareperformedinthewellboretoobtain

verticaltravelpathsthroughtheformationsbylocatingsourcesand

detectors/receiversat

certain

configuration,

normally

the

receivers

are

placednearthegelogicalhorizons

Thesurveyonlyutilizefirstarrivaltouseintherecordedseismictrace

Firstarrivalsarethenconvertedintoverticaltraveltimesontimedepth

graphswhich

can

be

used

to

calculate

average

velocities

Soniclogcalibrationneedstobedonepriortogenerationofsynthetic

logs,normallyboreholeeffectsarefoundveryoftencausingdrift whichistoberemovedtopreventshiftingintimeofseismicreflectionsor

pesudoevents


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Vertical

Seismic

ProfileVertical

Seismic

Profile VerticalSeismicProfiling(VSP)usesbothentirerecordedseismictraceand

firstbreak. Receiversarespacedatveryclosed intervalsinthewellborein

order

to

get

a

seismic

section

in

the

wellbore Theseismicwaveandalleffectsaremeasuredasafunctionofdepthasit

propagatesthroughtheformations

Thrreceiversareclosetoreflectorswhereupgoinganddowngoingwaves

arerecordedasafunctionofdepth

Thedown

going

wavelets

are

used

to

design

deconvolution

filters

IngeneralVSPprovidemuchbetterspatialandtemporalresolution,the

signalchangesintermofbandwidthandenergylossaremeasured

ApplicatiosofVSParetocorrelatetheactualseismiceventswithmore

confidence,

and

with

much

better

resolution

due

to

shorter

travel

paths

it

canprovideatooltogeneratehighresolutionmaps,andbetterestimateof

rockproperties


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Basic

Concept

of

VSPBasic

Concept

of

VSP


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BasicConceptofVSPBasicConceptofVSP


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Offset

VSPOffset

VSP

OffsetVSPareusedtodetectfaultsandpincouts

developedtoilluminatestructureawayfromthewellbore

Multiple offset and walkaway VSP

Multiple offset VSP were developed to provide high-resolution seismic

structural details in the area where interference from the shallow layers

The disadvantages is very time consuming, it requires few days for the

acquisition by putting multiple source positioned in different locations


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OffsetVSPOffsetVSP


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BasicLog

InterpretationBasic

Log

Interpretation

Logs Data Applications

Determine depth and thickness

Identify productive zones Distinguish fluid types, gas, oil and water

Estimate hydrocarbon reserve

Help geological correlation and subsurface mapping

Determine facies and drilling locations


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Basic

Log

InterpretationBasic

Log

Interpretation Continued

Gamma Rays Self Potential

Resistivity

Induction

Density Neutron

Sonic

Magnetic Resonance

Formation Test

Common Tools in the Logging Industry


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Porosity

Water Saturation

Permeability

Fluid types

Fluid contacts

Lithology

Dip angle

Velocity

Basic Log InterpretationBasic Log Interpretation Continued

Typical properties implied or estimated from

the log Measurements:


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Porosity =Volume of pores

Total Volume of Rock

Porosity is estimated using one or combination of

the followings; - Density

- Neutron

- Sonic

Combination of three inputs will get better estimate

Porosity = Storage Capacity

POR = (DENmatrix DENlog)/(DENmatrix DENfluid)

Density Porosity:

Petrophysical PropertiesPetrophysical Properties


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SW =Formation Water in the pores

Total pore space in the rock

Water Saturation is estimated using combination of

the followings; - Porosity

- Resistivity

It requires formation factor and saturation index

derived from core analysis, and formation water resistivity


Archies Equation

Sw =1/Por * Rw

Rt

SW - Water saturation

Rw - Formation water resistivity

Rt - True Formation resistivity

( )

1/n

n - Saturation exponent

m - Cementation factor

m


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Permeability Estimation from Logs

K=93 * Por

Swi

Permeability (K) is a measure of rock property to get the fluid passes through the rock.

The equations are based on empirical study, accurate K estimation can be obtained from

formation test, drillstem test (DST) or from core analysis

( )2.2 2

K=250 * Por

Swi( )

3 2

Timurs

Tixiers

where Swi = Irreducible water saturation


bj ibj i


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GettoknowvariouslogmeasurementsGettoknowvariouslogmeasurements

Recognizefluid

type

and

lithology

of

major

Recognize

fluid

type

and

lithology

of

major

reservoirs,andsomepracticalapplicationsoflogreservoirs,andsomepracticalapplicationsoflog

datadata

Familiarizewith

factors

affecting

the

log

responseFamiliarize

with

factors

affecting

the

log

response

UnderstandthestrategyinwellevaluationUnderstandthestrategyinwellevaluation

GettoknowvariousapproachestowellloggingdesignGettoknowvariousapproachestowellloggingdesign

Exercisewith

well

log

designExercise

with

well

log

design

Fluid and Lithology Identification From the LogsFluid and Lithology Identification From the Logs


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FluidandLithologyIdentificationFromtheLogsFluidandLithologyIdentificationFromtheLogs

Fluid and Lithology Identification From the LogsFluid and Lithology Identification From the Logs


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FluidandLithologyIdentificationFromtheLogsFluidandLithologyIdentificationFromtheLogs

Gas

Oil

Water

Oil-Water Contact

Gas-Oil Contact

Water filled Sand

Water filled Sand

Water filled Sand

Oil Sand

Gas Sand

Coal

Carbonate/Limestone

Fluid and Lithology Identif ication From the LogsFluid and Lithology Identif ication From the Logs


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RES0.1 100

Fluid and Lithology Identif ication From the LogsFluid and Lithology Identif ication From the Logs

Oil-Water Contact

Gas-Oil Contact

Water filled Sand

Water filled Sand

Water filled Sand

Oil Sand

Gas Sand

Coal

Carbonate/Limestone


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How

Can

We

Remember

These

Easily?How

Can

We

Remember

These

Easily?AboutLithologyInterpretation

Claystone haslargeamountofwater,andradioactivematerials,isdenserwhenithas

lesswater,isnotharderthanlimestoneandisveryconductive.

Sandstone islessdensethanlimestone,haslesswaterthanclay,containmorewater

thanlimestoneexceptwhenitissaturatedwithdrygas,itsconductivityisdependingon

fluidtypeitcontains,hassmalltononeradioactivefragments.

Limestone isharderthanbothclayandsand,containsleastwaterofthethree,very

resistive,ithaslowradioactivitymaterials,fastvelocity,highdensity.

Coal Normalylowradioactive,rarelyradioactive,lowestdensityandveryresistive

How Can We Remember These Easily?How Can We Remember These Easily?


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HowCanWeRememberTheseEasily?HowCanWeRememberTheseEasily?About

Fluid

Interpretation

HighRadioactivity HighGR

VeryConductive LowResistivity

HighWater

High

Neutron

and

Low

Resistivity

HighGas LowNeutronandHighResistivity

HighOil HigherNeutronthanGas,denser

thangasLessNeutronthanwater,

lessdensethanwater,more

resistivethan

water,

less

resistivethangaswhenother

propertiesarethesame

DryGas Veryresistive,largestdensity

neutroncrossover

High

GOR

Larger

density

neutron

crossover

thanoilwithlowGOR

FreshWater Reservoirfilledwithhighresistivewater

Are There Any Anomalies?Are There Any Anomalies?


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AreThereAnyAnomalies?AreThereAnyAnomalies?About

Fluid

Interpretation

InagaszoneMudfiltrateinvasionwillcausetheneutrondensity

crossoverlooks

like

that

of

oil

zone,

the

shallow

investigation

resistivitywillbelessresistivethanthatofdeeperdepthofinvestigation,resistivitydifferenceislargerwhenconductivemudisused

HighIrreduciblewater(waterboundsinclaysandgrains

surface)will

demonstrate

little

density

neutron

crossover

similartothatofoilorwaterzonesbutlessresistivethangasoroilzoneswithlessirreduciblewater

Inanoilzone similartoabove


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How Is Log Analysis Calibrated?How Is Log Analysis Calibrated?

Core Data

Routie Core Analysis - For Porosity and Permeability Calibration

Special Core Analysis - For detailed rock and fluid properties such as

X Ray Diffraction, Scanning Electron Microscopy, Petrophysical

parameters (a,m and n determination), PVT, Gas Analysis and finger

prints of fluid samples, and etc.

Formation Test

Fluid Identification from the logs is not direct, when the parameters are

not well established, formation test fluid samples can be used to

calibrate fluid identification using the logs. Formation test is also usedwhen possible log response anomalies encountered to get conclusive

fluid identification.


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Modern Formation For Fluid IdentificationModern Formation For Fluid Identification

Single Probe Module

Hydraulic Power ModuleHydraulic Power Module

Electric Power Module

Fluid Description ModuleFluid Description Module

MDT String Configuration

Multi sample ChambersMulti sample Chambers

Test ProbeTest Probe

Large sample ChamberLarge sample Chamber

Basic components of the toolBasic components of the tool


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BasiccomponentsofthetoolBasiccomponentsofthetool

Probe

Multi-sample

Chambers

Resist.

sensorPump Out

Module

Pre-Test

Strain Gauge

Quartz Gauge

Isolation

Valve

Optical Fluid

Analyzer

Flow line

Probe

HP GaugeValve

Pre-Test

Two Sample Chambers

OLDOLD NEWNEW


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OFA Gas Detector Optics

Gas Detector SystemGas Detector System

Light Emitting Diode

Cylindrical Lens

Polarizer

Fluid Flow GasLiquid

Gas

Sapphire

Prism

Photodetector

Array

Sapphire window


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OFA Spectrometer

How OFA Divice OperatesHow OFA Divice Operates

Fluid flowSapphire

Lamp

Light

Distributor

Source

Light path

Solenoids

MeasureLight Path

Filter lensPhotodiode

Chopper motor

Filter LensCatridge


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ExampleExample--1 : Gas OFA1 : Gas OFA

ExampleExample--2 : Water OFA2 : Water OFA


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Are There Any Other Logs Applications?Are There Any Other Logs Applications?


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AreThereAnyOtherLogsApplications?AreThereAnyOtherLogsApplications?

VolumeofHydrocarbon

Fluidcontinuity

ReservoirExtent

ReservoirRockProperties

DepositionalEnvirontment

Diagenesisand

Compaction

Trapping

Heterogeneity

Selecting Drilling Location

Well Completion

Subsurface Geological Mapping

Reservoir Characterization

All are useful for

The Logs Can Help Us to Determine:


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Hydrocarbon Reserves EstimateHydrocarbon Reserves Estimate

Oil rec = 7758 * (1-Sw) * h * Por * RF * ABoI

(43560 * DEPTH*0.43)* (1-Sw)* h* Por*RF*A

15

Where : RF - Recovery Factor

h - Thickness, A - Area

BoI - Oil Vol. factorBoI = 1.05 + 0.5 * (Gas Oil Ratio/100)

Gas rec =


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LateralContinuity

?Lateral

Continuity

?

Well-1 Well-2Well-7

GR Res

GR Res

GR Res


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CompactionTrend

?Compaction

Trend

?

GRRes

DT



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Recognizefluid

type

and

lithology

of

major

reservoirs,

and

Recognize

fluid

type

and

lithology

of

major

reservoirs,

and

somepracticalapplicationsoflogdatasomepracticalapplicationsoflogdata

FamiliarizewithfactorsaffectingthelogresponseFamiliarizewithfactorsaffectingthelogresponse


GettoknowvariousapproachestowellloggingdesignGettoknowvariousapproachestowellloggingdesign

ExercisewithwelllogdesignExercisewithwelllogdesign

Depth of Investigation and ResolutionDepth of Investigation and Resolution


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of Logging Toolsof Logging Tools

0 cm50 cm100 cm150 cm200 cm250 cm

2 cm

5 cm

60 cm

20 cm

30 cm

40 cm

80 cm

80 cm

Dipmeter

Micro resistivity

Micro log

Sonic

Density

Gamma-ray

Neutron

Laterolog

Induction

log

Resistivity

Radioactivity

Acoustic

Resistivity

Depth of Investigation

Reso

lution

Tools Size and Measuring point for TypicalTools Size and Measuring point for Typical


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AIT SDT LDT CNT SGT LEH TCC AMS

Additional combinable tools:

- Dipmeter

- Magnetic Resonance

- Borehole Imager

- Dipole Sonic

- Formation Tester

- Others

Oil Based Mud EnvironmentOil Based Mud Environment

Induction S

onic

Density

Neutron

GR

Measuring point from

the bottom of the tool

Tool Length

This slide helps you to configure the tool string that is appropriate for your well


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ResistivityMeasurementProblemsandLimitationsResistivityMeasurementProblemsandLimitations

Resistivity measurements are not reliable when you have:

Severe invasion due to overbalanced mudLarge washed-out borehole

Shoulder bed affects

High content of conductive minerals

Some older tool generations have limited vertical resolution


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Ri

Effectsof

Borehole

EnvironmentEffects

of

Borehole

Environment

Rm

Rxo

Rmf

Sxo

Ri

Rz

Si

Ro

Rt

RwSw

Undisturbed

Formation

InvadedZone

Flushed

Zone

Mud CakeRmc

i

fili

fil


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Invasion ProfileInvasion Profile

Fresh Mud Rmf > RW

Salt Mud Rmf < Rw

Rxo

Rxo

Rt

Rt

Rm

Rm

DMS

D M S

Low High

SPLogLimitationsSPLogLimitations


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The tool is only for water based borehole environment

SP is not reliable when you have no or very small contrast

between Formation water salinity and mud filtrate salinity resulting in no

to small SP deflection

GR Log LimitationsGR Log Limitations

Standard GR tool is not reliable when you log an interval with radioactive

mineral rich rocks. NGT is recommended to use for this type of

Formation to get reliable GR derived clay volume calculation.GR measurements in cased hole environment need to be normalized

due to casing, and cement attenuation

Density Log LimitationsDensity Log Limitations

Density log is a pad device, it is very sensitive to the pad contact with

The borehole wall, make sure to consult with your petrophysicist prior to

using the data for any other applications.


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Wh

Wi li

W ll

l iWh

Wi li

W ll

l i


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WhyWireline Well loggingWhy Wireline Well logging

1. Better Resolution

2. More advanced tools

3. Better depth control

4. Only choice available (certain tools)

5. More certain on data quality

DisadvantagesofWirelineDisadvantagesofWireline

l il i


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logginglogging

1. Invasion effect

2. Hole condition dependant

3. Unable to log in high angle wells (>60 deg)

4. Acquired after drilling, more rig time5. More uncertainty in getting data or good

data in problem prone wells

ImportantIssueswithImportantIssueswith

Running Wireline logsRunning Wireline logs


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RunningWireline

logsRunning

Wireline

logs

1. Borehole fluid type

2. Borehole size3. Well deviation

4. Tool combination5. High Mud Weight resulting in over balanced


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Logging while Drilling

WhyLWD?WhyLWD?


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ReduceRigTime

Real

Time

Decisions MinimizedBoreholeProblems

HighAngle/HorizontalWells


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LWDandWirelineComparisonLWDandWirelineComparison


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X800

X900

InvasionX800

X900

WirelineLogExampleWirelineLogExample


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X400

X450

LWDRealtimeandRecordedLogsLWDRealtimeandRecordedLogs


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GRGR

D. RES

D. RESDEN

DENNEUNEUX500

X600

X700

X500

X600

X700

SelectingtheToolstorunSelectingtheToolstorun


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Itdepends

on

what

type

of

information

you

are

about

to

get

andthecostyouarewillingtospend.

Need

Want

What is the value of information you are getting?

What tools do you run in the hole?

Ability

to

Define

Your

NeedAbility

to

Define

Your

Need


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Ability to Define Your NeedAbility to Define Your Need

Geological

Geophysical

Reservoir

Petrophysical

Mechanical

TypeofInformationtoAcquireTypeofInformationtoAcquire


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GeologyGeology

Sanddevelopmentandsandthickness

Stratigraphic

information

Lateralcontinuity

Hydrocarbonsource

GeophysicsGeophysics

Velocityuncertainty

Well

to

seismic

tie

Seismicandfluids/lithologycorrelation

TypeofInformationTypeofInformation continued

PetrophysicsPetrophysics


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PetrophysicsPetrophysicsPorosityWatersaturation

Permeability

Mineralogy

ReservoirReservoirCompartment

FluidpropertiesReservoirpressureReservoirmonitoring

RockMechanicsRockMechanics

StressdirectionPressureprofileFractureorientation

Understand

the

Scales

Of

ObservationUnderstand

the

Scales

Of

Observation


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Understand the Scales OfObservationUnderstand the Scales OfObservation

Seismic Section

Wireline Logs

Out-Crops/Core

Thin Sections

ScalesOfObservationScalesOfObservation


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Well Logging Design ObjectiveWell Logging Design Objective


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WellLogging

Design

ObjectiveWell

Logging

Design

Objective

The objectives of a well logging design should followyour drilling objectives, if drilling objective is not met,

the objectives of logging program should be adjusted

accordingly.

A logging program would vary depending on drilling

Objectives.

WellLoggingDesignWellLoggingDesign11


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OnshorewellOnshorewell

Adevelopmentwell,A5,istodrillupdipstructureofASandtoaccelerateoil production,theA4wellhasproducedthis

Reservoirforayear,andcurrentlyproduces80%water. The

reservoirhas

astrong

aquiver

drive

mechanism.

WellLoggingDesignWellLoggingDesign11 continued


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DrillingobjectiveistodrillandcompletetheASandLevel

Logging

program

objective

for

this

well

is

then

to

locate

the

topoftheASandandmakesurethattheintervalisstillintheoilcolumn.

Otherinformation:Strongwaterdrivemeansithasgood

pressure

maintenance,

therefore,

no

need

to

take

pressure

data.

Rigtype:OnshoreRig(inexpensive),averticalwell.

LoggingDesign:WirelineGRResistivityNeutronDensity

WellLoggingDesignWellLoggingDesign22


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OffshorewellOffshorewell

Athirdappraisalwellisproposedonthewestflankofthestructure. Firsttwowellssuggestthatwelltowelllog

correlationisnoteasy, howeverpressuredatahashelpedthe

well

to

well

correlation.

This

well

is

to

reveal

the

lateral

continuityandthecompartmentissueofthereservoirs.


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ExampleExample2 LoggingProgram2 LoggingProgram Continued

8 1/2 Hole Section 9000 to 12000 MD


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81/2HoleSection9000to12000MDLWD:GRResistivityDensityNeutron

Wireline:TriplecomboasacontingencywhenLWDfail

WetCase:TriplecomboasacontingencywhenLWDdataisnotreliable

Formation

tests

for

pressures

and

water

samplesH.C.Case:TriplecomboasacontingencywhenLWDdataisnotreliableFormationtestsforpressuresandfluidsamplesBoreholeimagelogfordipandstratigraphicinformationNuclearMagnetictoolwhenconsiderablethickshalysandreservoirsarepenetratedBoreholeseismicforvelocitysurvey

ImportantAspectsToConsiderImportantAspectsToConsider


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Risk

Cost

Environment

HoleSize

WellDesign

ToolSpeed


Some

examplesSome

examples


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Risk

While

we

are

running

in

hole

with

wireline

tools,

the

toolscouldnotgodownatcertaindepth. Thecompany

representativehasdecidedtopulloutofholetorun

differenttoolconfiguration.

Incaseofariskthatwearenotabletogodownpassing

thesamedepthwithnewtoolconfiguration,the

petrophysicist

has

asked

the

log

engineer

to

log

up

while

pullingoutofholetogetdataassurance.


Some

examplesSome

examples

C


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Cost

AfterthewellreachedTDat6000ft,theteamfoundout

thattheydonothaveroomtogetalllogdatatothebaseof

thereservoirnearTDiftheyusetypicaltriplecombination

wirelinetools,todrilladditional50ftwouldtake24hourrig

timeincluding

RIH

and

POOH.

Thepetrophysicisthasthendecidedtosplitthetoolsinto

tworuns,whichonlyrequireadditional6hourrigtimefor

secondwireline

run.

By

doing

that

it

would

have

saved

18

hourrigtimeiftheydrilladditional50fttohaveonlyone

loggingrun


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Some

examplesSome

examples

H l Si


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HoleSize

TheDrillingengineerhassuggestedtorunonlyLWDinthe

121/4holesectiontoreducewellcost.

Thepetrophysicisthasarguedandsuggestedtorun

wirelinebecause

based

on

previous

wells

in

this

field

where

theyhavedrilledataveragerateof300ft/hrresultinginnot

reliabledata.Theteamhassupportedtheirpetrophysicistto

runwirelinebecauseitwouldhelptosupportfield

certification.

ImportantAspectsToConsiderImportantAspectsToConsiderSomeexamplesSomeexamples

Well Design


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WellDesign

AftertheG&Gteamprovidethetargetstothedrilling

engineer,theteamhastoendupwithawelldesignthatit

requiresahighlydeviatedwellexceeding60deg.

LWD

log

data

acquisition

is

then

put

in

their

logging

programbecausebasedontheirexperienceinthisfield50

degwellwasthehighestdeviatedwellthattheycouldlog

withwireline.

ImportantAspectsToConsiderImportantAspectsToConsiderSomeexamplesSomeexamples

Tool Speed


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ToolSpeed

BasedonthestatisticsdrillingthePliocenesectionisvery

quick,averaging400ft/hr,thecompanyisdrillingahorizontalgaswellatabout3000ftTVD.

LWD

engineer

and

the

petrophyscist

have

worked

together

andhavegivenarecommendationtodocontrolleddrillingat

about200ft/hrtogetanacceptablelogdataquality.

Whatdoyouhaveinmind?Whatdoyouhaveinmind?

On Shore Off Shore


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On Shore

Development Well

Off Shore

Deep water

development-well

In respect to Risk, Cost, Environment, Hole Size, Well Design, Tool Speed

ExploratoryWellExploratoryWell

Seismic Information


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SeismicInformation

RegionalGeologyInformation

DrillingthewellusingLearningwhiledoing

concept

HighRiskbutmustbemanageable

MostlyVerticalwell


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AnExampleofrathercomplexLoggingProgramAnExampleofrathercomplexLoggingProgram

DecisionTreeDecisionTree


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West Seno Data Gathering Strategy

Standard

well PAY

Fully

Loaded

Wireline

Full

Cores

SAMPLING

12 1/4

PAY

LWD

SAMPLES

LWD

WIRELINE

PRESSURE

P. O

PEX

MD T

CST

Cores

Special

Logging

Velocity

Uncertainty

UBI or CBL

SAMPLING

Cased Hole GR

CSAT

or VSP

GR to bottom of 13 3/8

STOPSTOP

Objective

driven-logging

Y

N

Y

Y YY

Y

Y

Y

Y

Y

YN

N

N

N

N

N

NN

N

N

N

N

LW D

MD T

Objective

Deepest

WellVSP

STOPN

Another

Way

To

Save

Cost!Another

Way

To

Save

Cost!


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ACQUIREDATAWITHOUTUSINGCOSTLYRIGTIME

(PIPEDECISION

NOT

NECESSARY

NO

DRY

HOLES)

GATHERDATAREALTIMEWHILEDRILLING

GATHERDATA

THROUGH

TUBING

AFTER

COMPLETION

COMBINATIONOFBOTH


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ProjectBaseApproachProjectBaseApproach


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UOMEcompanyhas$200MMprogramfor

exploratorywells

for

the

year

2004.

Asafollowupoftheirexplorationcampaign,

UOMECompany

has

$600

MM

program

for

developinganewdeepwaterfieldfortheyear

2005thatwillhavepeakproductionof100,000

BOPD


Get to know various log measurementsGet to know various log measurements


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Recognizefluidtypeandthelithologyofmajorreservoirs,Recognizefluidtypeandthelithologyofmajorreservoirs,

andpractical

uses

of

log

dataand

practical

uses

of

log

data

FamiliarizewithfactorsaffectingthelogresponseFamiliarizewithfactorsaffectingthelogresponse


Getto

know

various

well

logging

designsGet

to

know

various

well

logging

designs

ExercisewithwelllogdesignExercisewithwelllogdesign

Exercise1

PTIndooilCo.,thesoleownerofmineralrightonBlockA,onshore,2kminadjacenttoaknownoilproducingareaintheBlockB. Thecompanyislookingata


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j p g p y gprospecttodrillthefirstwell,Indoco1,intheblocktargetingforthesameproducingintervalinBlockBatabout4000ftdepth,anditisestimated50ftdown

dip

in

this

block. Thecostsforvariousavailablelogdataacquisitionareasfollow:

WirelineGR$1/ft,Induction$4/ft,BHCSonic$1/ft,Density$2/ft,Neutron$2/ft

Formationtest$100/pressure,$1000/fluididentification,$2000/fluidsample

DepthchargeforeachWirelinetoolisfree.

LWD

GR

and

Induction

$10,000/day,

Density

and

Neutron

$10,000/day Therigcostis$5000/day

1)Whatisyourrecommendeddatagatheringstrategyandwellloggingdesignforthewell?

2)Whiledrilling,thewellpenetrates5thicksandunitswithhighmudloggasfrom3,000to4,200ft. Howdoyourecommendthecompanyontheloggingdesign?

3)After

the

well

reached

the

proposed

TD,

there

were

no

encouragement

seen

from

themudlogsigns,whatwouldyoudoforyourloggingprogram?

Exercise2

Theexercise1wasseismicallytotesttheamplitudeanomalyat Orange horizon equivalent to the Berani Clastic Formation


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atOrangehorizon,equivalenttotheBeraniClasticFormation.TheIndoco1wellencountered300ftofOilcolumnandwas

completedand

produced

from

this

level

for

over

one

year

withcumulativeproductionof4mmbo. Thecompanyislookingatsimilarseismiccharacter11/2kmawayfromIndoco1well,whichwasconnectedbydimeventtotheamplitudeattheIndoco1well. Ithasbeeninterpretedasa

differentchannel

lobe.

The

company

did

low

profile

and

ran

onlysimplewirelineGR,resistivity,density,neutronandsonicontheInoco1well.

WhatisyourdatagatheringstrategyforthisIndoco2well?


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Exercise4

AnoffshorewellisproposedtoredrilltheA5welli h di di i f hi ll h l


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withupdipdirectionfromthiswelltogetthegasleg

of

clean

and

blocky

sand

found

with

gas

water

contactintheA5well. Thecompanyistryingtogetmoregasproduction. Theteamislookingatdrillinghorizontalwellwithabout500ftofproducing

section.

Whatis

your

recommended

logging

programforthiswellandwhy?

Basic-well-logging-Design (Sigit Sutiyono, Unocal)

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Transcript of Basic-well-logging-Design (Sigit Sutiyono, Unocal)