Consortium Alumni Association Presents A One-day Course Well... · Consortium Alumni Association Presents. Agenda ... Well-1 Well-2Well-7 GR Res GR Res ... • Modular Formation Test

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  • BasicWellLoggingDesignBasicWellLoggingDesign

    CoordinatedByCoordinatedBy

    SigitSutiyonoSigitSutiyono

    UnocalIndonesiaCompanyUnocalIndonesiaCompany

    A One-day Course on

    Consortium Alumni Association Presents

  • AgendaAgenda

    Introduction(8:15) LectureIBasicTheory/Interpretation Break(10 10:15) LectureIILoggingProgram/Design Break(12:00) Workshop(1:30 4:00) Wrapup(4:00 5:00)

  • ObjectivesObjectives

    Gettoknowvariouslogmeasurements

    Recognizefluidtypeandlithologyofmajorreservoirs,andsomepracticalapplicationoflogdata

    Familiarizewithfactorsaffectingthelogresponse

    Understandthestrategyinwellevaluation

    Gettoknowvariousapproachestowellloggingdesign

    Exercisewithwelllogdesign

  • 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 narrowpaper strip, of observations made on the rocksand fluids of the geologic section exposed inthe well-bore.

    DefinitionDefinition

  • Wireline Logging Logging while Drilling

    Cable

    Tools

    LWD Tools

    Mud inMud out

    Drill Bit

  • WellLoggingHistoryWellLoggingHistory

    Thefirstelectricallogwasintroducedin1927inFranceusingstationedresistivitymethod.

    Thefirstcommercialelectricalresistivitytoolin1929wasusedinVenezuela,USAandIndonesia.

    SPwasrunalongwithresistivityfirsttimein1931 Schlumbergerdevelopedthefirstcontinuousrecordingin1931 GRandNeutronlogswasstartedin1941 Microresistivityarraydipmeterandlateralogwerefirsttimeintroduced

    in1950s

    Thefirstinductiontoolwasusedin1956followedbyFormationtesterin1957,FomationDensityin1960s,Electromagnetictoolin1978andmostofImaginglogsweredevelopedin1980s

    Advancedformationtesterwascommercializedinearly1990s

  • The First Log recorded in 1927

    Well in Pechelbronn - France Surface Recording Instrument

  • LogMeasurementsLogMeasurements

    Logisanindirectmeasurementofformationpropertiesexposedbythewellboreacquiredbyloweringadeviceor

    acombinationofdevicesinthewellbore.

    Practical definition of a log

    A Formation Evaluation Specialist is essential to understand

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

    petroleum reservoirs

  • AdvantagesandLimitationsofWellLoggingAdvantagesandLimitationsofWellLogging

    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

  • BasicTheoryofMeasurementsBasicTheoryofMeasurements

  • LogsareImpliedMeasurementsLogsareImpliedMeasurements

    Logisnotadirectmeasurementofformationproperties,itisanimpliedmeasurementbasedononeorcombinationofthefollowingdevices

    Electrical (Resistivity and Induction)

    Acoustic Nuclear Electromagnetic Magnetic

  • BasicTheoryonResistivityBasicTheoryonResistivity

    Current path

    Unit volume filled with only water

    Current path

    Unit volume with water and matrix

    Rw

    Ro

  • Typical Formation

    Rt

    WaterSand grain

    Grain surface water

    Oil

    Measured by the tool

    Current path

  • ResistivityandMeasurementConceptResistivityandMeasurementConcept

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

    Rw - Formation Water resistivityE - Voltage difference across the formationA - Cross sectional AreaL - Length of brine containerrI - Current

    Rw = E * A

    I * LL

    I E

    ARw

  • ResistivityandMeasurementConceptResistivityandMeasurementConcept

    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 fieldCreated by the ground loop

    Secondary magnetic fieldInduces a current to flow in the receiver

    Transmitter

    Receiver

  • Resistivity is the key to hydrocarbon saturation determination

    ResistivityApplicationResistivityApplication

    Water Saturation EstimationArchies Equation

    Sw = F * Rw

    Rt

    SW - Water saturationRw - Formation water resistivityRt - True Formation resistivity

    ( )1/n where F = 1.0Por m

    Sh = 1 - Sw

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

    F - Formation factorn - Saturation exponentm - Cementation factor

  • SpontaneousPotentialLog(SP)SpontaneousPotentialLog(SP)

    SPmeasurementisbasedonElectricalcurrentsflowinginthemudfromelectrochemicalandelectrokinetic

    Salinitydifferencebetweenmudflitrateandformationwaters,ionsmovementcreatescurrentsmeasuredinmVolt

    NegativeorPositiveSPcurvedeflectionrepresentswhichfluid,formationormudfiltrate,hasmoreioniccharge.

    Itonlyworksinwaterbasedmud!

    TheuseofSPlog;bedboundary,distinguishingpermeablefromimpermeablerock,shalynessindicator,Rwdeterminationandwellcorrelation.

  • SpontaneousPotential(SP)SpontaneousPotential(SP)

    SP

    ShaleSand Thick clean wet sand

    (-) (+)

    - - - - - - -

    - - - - - - -

    Thick shaly wet sand

    Thick clean Gas sand

    Thick shaly Gas sand

    Rmf >> Rw in all sands

    Hydrocarbon effect

  • SpontaneousPotential(SP)SpontaneousPotential(SP)

    20

    40 mV

    7470

    7430

    Given:Rmf = 0.51 at 135 FRm = 0.91 at 135 FTD = 8007 ftBottom hole temp.= 135 FSurface temp. = 60 F

    Determine Rw ?

    SP

    Limitation

    SP is not reliable when you have no or very small contrastBetween Formation water salinity and mud filtrate salinity resulting in no to small SP deflection

  • RwcalculationfromSPlogRwcalculationfromSPlog

    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

  • GammaRayLog(GR)GammaRayLog(GR)

    GRtoolmeasuresnaturalradioactivityoftheformationfromtheemmisionofallthese;(TotalGR)

    Potasium,UraniumandThorium GRlogisusedfor;

    Welltowellgeologicalcorrelation Beddefinition,moreaccuratethanSPlog ShaleVolumeIndicator(mostreliable) Lithologyandmineralogyindicator(NGT)

    IGR = GRlog - GRminGRsh - GRmin

    IGR - Gamma ray indexGRmin - GR cleanGRsh - GR shale baseline

  • GammaRayLog(GR)GammaRayLog(GR)

  • GammaRayLog(GR)GammaRayLog(GR)

    Mineral Density DT GRQuartz 2.64 56 0-15Calcite 2.71 49 0-15Dolomite 2.85 44 0-15Orthoclase 2.52 69 220Micas 2.82 49 275Kaolinite 2.41 - 80-130Chlorite 2.76 - 180-250Illite 2.52 - 250-300Montmorillonite 2.12 - 150-200Anhydrite 2.98 50 lowPyrite 4.99 39 lowCoal 1.47 high low

  • GammaRayLog(GR)GammaRayLog(GR)

    Well-1 Well-2Well-7

    GR ResGR Res

    GR Res

  • NaturalGammaRayLog(NGT)NaturalGammaRayLog(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

  • NaturalGammaRayLog(NGT)NaturalGammaRayLog(NGT)

    0 2 4 6 8 10

    2

    4

    6

    8

    10

    0

    K, Potasium (%)

    Pe

    Kaolinite

    Montmorillonite

    Illite

    Glauconite

    Muscovite

    Biotite

  • DensityLogDensityLog

    Densitytoolisoneofthemostimportantinstrumentsusedtoevaluateformationswhichmeasuresformationdensityanddirectlytiestoformationporosity

    Thedensitytoolmeasurestheelectrondensity,byemittinggammarayfromradioactivesourceandreturningtotwodetectors

    TheamountofGammaraysthatreturndependonthenumberofelectronspresent,electrondensityisrelatedtobulkdensityofmineralorrock

    InmostcasesenvironmentalcorrectionforDensitylogisnotsignificant,fieldlogdensitycanbereadilyusedforinterpretation

  • DensityLogDensityLog

    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 togenerate GR of the Cesium 137 radioactive source at 662 keV

  • DensityLogDensityLog

    Porositydeterminationfromdensitylog:

    POR = RHOBma - RHOBlog

    RHOBma - RHOBfluid

    RHOBma - Matrix densityRHOBfluid - Formation fluid densityRHOBlog - Log densityPORd - Density derived porosity

    Exercise: Determine porosity of limestone with field logdensity inicated 2.5 gr/cc.

  • NeutronLogNeutronLog

    ThetoolmeasurestheHydrogenIndexwhichisthequantityofHydrogenperunitvolume

    Thetoolsemithighenergyneutronseitherfromradioactivesourceorminitron.Theyaresloweddownbycollisionswithformationnuclei,collisionwillresultenergyloss,andtheelementmostlysloweddownisH

    Waterhashighneutroncounts,OilhasalittlelesscountsthanWater,Gaswillhaveverylowneutroncounts

    Neutronlogisverysensitivetoenvironmentchange;boreholesize,mudcake,mudweight,temperature,standoff,pressureandformationsalinity,measurementiscompensationoffarandnearcountrates.

  • NeutronLogNeutronLog

  • NeutronLogNeutronLog

    Neutrontoolhasawiderangeofapplications PorosityDetermination GasDetection Boreholeandformationsalinity ReservoirSaturation ReservoirM