地球物理测井方法原理和应用课件

地球物理测井方法原理和应用地球物理测井方法原理和应用1总目录第一讲：绪论第二讲：普通电阻率法测井第三讲：聚流电电阻率测井第四讲:自然电位测井方法原理及应用第五讲：感应测井第六讲:声波测井第七讲:自然伽马测井方法原理及应用第八讲:中子测井方法原理及应用总目录2

第一讲：绪论一、地球物理测井的基本概念二、地球物理测井能解决什么问题?三、地球物理测井包括哪些内容？四、地球物理测井的发展历史五、地球物理测井在地球物理探测技术中的位置第一讲：绪论3矿场地球物理油矿地球物理钻井地球物理勘探地球物理测井:钻孔中进行的各种地球物理探测方法的统称.1927年由法国Schlumbeger公司的创始人Schlumbeger兄弟俩创立的.矿场地球物理4地球物理测井是用各种专门的仪器放入井内,沿井身测量井孔剖面上各种物理参数随井深的变化曲线,并根据测量结果进行综合解释,用于判断岩性、确定油气层及其它矿藏的一种间接手段.测井工作分为两个阶段:野外资料录取阶段和资料处理解释阶段.地球物理测井是用各种专门的仪器放入井内,5Theboreholeenvironment

Theboreholeenvironmentinwhichloggingmeasurementsaremadeisofsomeinterestfromthestandpointofloggingtooldesignsandtheoperatinglimitionsplaceduponthem.itisimportantintermsofthedisturbanceitcausesinthesurroundingformationinwhichpropertiesarebeingmeasured.TheboreholeenvironmentTheb6TheBoreholeEnvironmentSomecharacterizationoftheboreholeenvironmentcanbemadeusingthefollowingsetofgeneralizations:WelldepthsThedeviationoftheborehole,whichisbetweenandonshore,andbetweenandoffshore.Thetemperature,atfulldepth,rangesbetweenandFThedrillingfluid,ormud.Thesalinityofthedrillingmudrangesbetween3000and200,000ppmofNaCl,Thiscausesinvasionofaporousandpermeableformationbythedrillingfluid.TheBoreholeEnvironmentSomec7TheBoreholeEnvironmentToaccountforthedistortionwhichisfrequentlypresentwithelectricalmeasurements,asimplifiedmodeloftheborehole/formationhasevolved,whichisshownschematicallyinFig.2-4Itconsiderstheinvadedformationofinterest,ofresistivitytobesurroundedby“shoulder”bedsofresistivitythemudcakeofthicknessandresistivityThenextannularregionofdiameteristheflushedzonewhoseresistivityisdonatedbytheuninvadedorvirginzonewithresistivityTheBoreholeEnvironmentToacc8Figure2-4.Schematicmodeloftheboreholeandformationusedtodescribeelectricloggingmeasurementsandcorrections.Figure2-4.Schematicmodelo9

第一讲：绪论一、地球物理测井的基本概念二、地球物理测井能解决什么问题?三、地球物理测井包括哪些内容？四、地球物理测井的发展历史五、地球物理测井在地球物理探测技术中的位置第一讲：绪论10可以解决的问题:油气储层的评价问题相关的地质问题工程问题及地层的机械性能油气开发问题为地面地球物理勘探资料解释提供参数与其它资料结合进行储层空间描述与盆地分析可以解决的问题:11Introduction

Thissectionpresentsageneraloverviewoftheproblemofloginterpretationandexaminesthebasicquestionsconcerningaformation’spotentialhydrocarbonproductionwhichareaddressedbywelllogs.Theboreholeenvironmentisdescribedintermsofitsimpactontheelectricalloggingmeasurements,andallofthequalitativeconceptsnecessaryforsimpleloginterpretationarepresented.Thelogformatconventionsarepresented,andanexampleisgivenwhichindicatestheprocessoflocatingpossiblehydrocarbonzonesfromlogmeasurements.Theprocessofextractingpetrophysicalparametersfromtheloggingmeasurementsisthesubjectofsubsequentchapters.IntroductionThissection12RudimentaryWellSiteInterpretationLoginterpretation,orformationevaluation,requiresthesynthesisofloggingtoolresponsephysics,geologicalknowledgeandauxiliarymeasurementsorinformationtoextractthemaximumpetrophysicalinformationconcerningsubsurfaceformations.

Inthissection,asubsetofthisprocedureisconsidered:wellsiteinterpretationThissubsetreferstotherapidandsomewhatcursoryapproachtoscanninganavailablesetofloggingmeasurements,andtheabilitytoidentifyanddrawsomeconclusionaboutzonesofpossibleinterest.

RudimentaryWellSiteInterpre13RudimentaryWellSiteInterpretationThemostimportantquestionstobeansweredbywellsiteinterpretationare:1.Doestheformationcontainhydrocarbons?2.Ifso,whatisthequantitypresent?3.Arethehydrocarbonsrecoverable?Inordertoseehowloggingmeasurementscanprovideanswerstothesequestions,afewdefinitionsmustfirstbesetout.1.porosityisthatfractionofthevolumeofarockwhichisnotmatrixmaterialandmaybefilledwithfluids.Fig.2-1illustratesaunitvolumeofrock

RudimentaryWellSiteInterpre14Theporespacehasafractionalvolumedenotedby,thematrixmaterialoccupiestheremainingfractionofthevolume,RudimentaryWellSiteInterpretationFigure2-1.Aunitvolumeofformationshowingtheporosityandthefractionalporevolumeofwater.Thefractionalvolumeofhydrocarbonsis.Theporespacehasafractiona15Note:thefractionalvolumeoccupiedbythewaterisgivenbytheproduct,andthetotalfractionofformationoccupiedbytheoilby2.Watersaturation,isthefractionoftheporositywhichcontainswater.ThisfractionalvolumeisalsoindicatedinFig.2-1.3.Oilsaturation,isgivenbyRudimentaryWellSiteInterpretationNote:thefractionalvolumeoc16Sinceoneoftheprincipalloggingmeasurementsusedforthequantificationofhydrocarbonsaturationiselectricalinnature,itisnecessarytomentionsomeoftheterminologyusedtodescribethesemeasurements.

Theresistivityofaformation

isameasureoftheeaseofelectricconduction.Resistivity,acharacteristicakintoresistance,isdiscussedinmuchmoredetaillater.

Replacingtheconductivebrineofaporousmediumwithessentially

nonconducinghydrocarbons

canbeexpectedtoimpedetheflowofcurrentandthus

increaseitsresistivity.RudimentaryWellSiteInterpretationSinceoneoftheprincipallog17Theresistivityofthe

undisturbedregionofformation,isdenotedbyisderivedfrommeasurementsthatyieldanapparentresistivity.Thesemeasurementscanthenbecorrected,whennecessary,toyieldthetrueformationresistivity.Intheregionsurroundingthewellbore,wheretheformationhasbeen

disturbedbytheinvasionofdrillingfluids,theresistivitycanbequitedifferentfrom.Thiszoneiscalledtheinvadedorflushedzone,anditsresistivityisdonatedby.RudimentaryWellSiteInterpretationTheresistivityoftheundistu18Twootherresistivities:

1.theresistivityofthebrine,whichmaybepresentintheporespace.

2.theresistivityofthefiltrateofthedrillingfluid,,whichcaninvadetheformationnearthewellboreanddisplacetheoriginalfluids.

RudimentaryWellSiteInterpretationReturningtothethreequestionswhichmustbeaddressedbywellinterpretation,refertoFig.2-2,whichattemptstoshowtheinterrelationshipsimplicitinthequestionssite.Twootherresistivities:Rudim19Figure2-2Aschematicrepresentationoftheloggingmeasurementsusedandthepetrophysicalparametersdeterminedforansweringthebasicquestionsofwellsiteinterpretation

Thefirsttaskistoidentifythecleanzones.Thetaskisroutinelyaccomplishedthroughtwomeasurements:GRandSP.Thesecondstepistoanswerthequestion:”Cantheformationcontainhydrocarbons?”Thisconditionwillbepossibleonlyiftheformationisporos.Threecurvesfromthreedifferenttypesofmeasurementswillgiveporosityinformation.Theyarecommonlyreferredtoasthedensity,neutron,andsoniccurves.Figure2-2Aschematicrepres20RudimentaryWellSiteInterpretationOnceaporous,cleanformationisidentified,theanalystisfacedwithdecidingwhetheritcontainshydrocarbonsornot.Thisanalysisisdoneinquiteanindirectway,usingtheresistivityoftheformation.Basically,iftheporousformationcontainsconductivebrine,itsresistivitywillbelow.If,instead,itcontainsasizablefractionofnonconductinghydrocarbon,thentheformationresistivitywillberatherlarge.Anothercommonresistivitymeasurement,whichisusedtogetsomeideaoftherecoverabilityofhydrocarbonsinthefollowingway.

RudimentaryWellSiteInterpre21RudimentaryWellSiteInterpretationIfthethentheoriginalformationfluidsarepresentintheso-calledinvadedzone,indicatingthatnoformationfluiddisplacementhastakenplace.iftheresistivityoftheinvadedorflushedzonecorrespondstotheresistivityexpectedfortheformationinvadedwiththedrillingfluid,thenthedrillingfluidhasdisplacedtheoriginalfluid(someofwhichmaybehydrocarbon).Thereforetheformationfluidsaremoveableandwillprobablybeproducible.

RudimentaryWellSiteInterpre22

第一讲：绪论一、地球物理测井的基本概念二、地球物理测井能解决什么问题?三、地球物理测井包括哪些内容？四、地球物理测井的发展历史五、地球物理测井在地球物理探测技术中的位置第一讲：绪论23地球物理测井包括的内容：测井的方法原理测井仪器与采集技术测井的处理解释及应用根据观测的物理量的性质分：

电－以研究岩石的电学性质为基础的方法声－以研究岩石中的声波传播特性为基础的方法核－以研究物性的原子物理及核物理性质为基础的方法其它－热、重力、磁、地层几何分布特征地球物理测井包括的内容：24QualitativeInterpretationInthisrapidoverview,thebasicrulesforinterpretationaregiven,withoutexplanation.Thereasonsbehindthemarepresentedinlaterchapters.Forthemoment,considerthistobearecipeforansweringthethreebasicquestionsofFig.2-2,fromthephenomenologicalbehaviorofthemeasurementcurespresentednext.QualitativeInterpretationInt25QualitativeInterpretationInordertoassesstheformationforshaliness,twoindicatorscanbeused:thegamma(GR)andthespontaneouspotential(SP).Threeloggingdevicesyieldavalueofporosity.Thatisdensitytool,theneutrontoolandthesonictool.Thepresenceofhydrocarbonisinferredfromthevalueoftheformationresistivity.QualitativeInterpretationIno26QualitativeInterpretationAsummaryoftheserelationsisfoundinTable2-1QualitativeInterpretationAsu27ReadingALogReadingalogwitheaserequiresfamiliaritywithsomeofthestandardlogformats,whichareshowninFig.2-6.Thetopillustrationshowsthenormallinearpresentation,Themiddlefigureshowsthelogarithmicpresentationfortrack2and3.Fourdecadesaredrawntoaccommodatetheelectricalmeasurements,whichcanhavelargedynamicranges.Thebottomillustrationisahybridscalewithalogarithmicgridontrack2andalinearoneintrack3.Electricalmeasurementsthatmayspilloverfromtrack2intotrack3willstillbelogarithmiceventhoughtheindicatedscaleislinear.ReadingALogReadingalogwit28ReadingALogFigure2-6.StandardlogpresentationformatsFigure2-7.PresentationofSPandGRheadingsusedforcleanformationdeterminationReadingALogFigure2-6.Stand29ReadingALogFig.2-7showsthetypicallogheadingpresentationforseveralofthebasiclogsthatwillbeusedshortly.TheuppertwopresentationsshowtwovariationsfortheSP,whichisalwayspresentedintrack1.

theSPbecomeslessnegativeforincreasingshale,thiswillbeseentocorrespondtodeflectionsoftheSPtracetowardtherightforincreasingshalecontent.ThebottompresentationshowsthecaliperandtheGR,whicharealsogenerallypresentedintrack1.TheGRcurvewillalsoproducecurvedeflectionstotherightforincreasingshalecontent.Thusthetwoshaleindicatorscanbeexpectedtofollowoneanotherastheshalecontentvaries.ReadingALogFig.2-7showsthe30ReadingALogOneoftheresistivitylogheadingsisshowninFig.2-8,Theparticulartoolassociatedwiththisformatisreferredtoasthedualinduction.ThetracecodedforILDcorrespondstothedeepestresistivitymeasurementandwillcorrespondtothevalueofwheninvasionisnotsevere.ThecurvemarkedILMisanauxiliarymeasurementofintermediatedepthofpenetrationandishighlyinfluencedbythedepthofinvasion.ThecurvemarkedSFLUcorrespondstotheresistivityoftheinvadedzoneFigure2-8.Theinductionlogheadingandschematicoftheformation,withthreezonescorrespondingapproximatelytothesimultaneouselectricalmeasurementsofdifferentdepthsofinvestigationBycombiningthethreeresistivitymeasurements,itispossibletocompensatefortheeffectofinvasionontheILDreading.ReadingALogOneoftheresist31ReadingALogInFig.2-9,threetypicalheadingsforthethreetypesofporositydevicesareindicated.ThetopheadingshowstheformatforporositiesderivedfromneutronanddensitymeasurementssimultaneouslyThemiddleexampleshows,inaddition,thecorrectincurveforthedensitylog,whichcanbeusedtogetsomeideaofthemudcakeandrugosityoftheboreholeencounteredduringthedensitymeasurement.Thebottomheadingisforthesonictracewiththeapparenttransittimeincreasingtotheleft.Figure2-9.Logheadingsfortheporositydevices.ReadingALogInFig.2-9,three32ReadingALogFortheneutronanddensitylogs,anotherpointtobeawareofthematrixsetting.Thissettingcorrespondstoarocktypeassumedinaconvenientpreinterpretationthatestablishestheporosityfromtheneutronanddensitydevicemeasurements.InbothexamplesshowninFig.2-9,thematrixsettingislistedasSS,whichmeansthattherocktypeistakentobesandstone.Iftheformationsbeingloggedareindeedsandstone,thentheporosityvaluesrecordedonthelogswillcorrespondcloselytotheformationoftheactualformation.iftheactualformationmatrixisdifferent,saylimestone,thentheporosityvalueswillneedtobeshiftedorcorrectedinordertoobtainthetrueporosityinthisparticularmatrix.ReadingALogFortheneutrona33

第一讲：绪论一、地球物理测井的基本概念二、地球物理测井能解决什么问题?三、地球物理测井包括哪些内容？四、地球物理测井的发展历史五、地球物理测井在地球物理探测技术中的位置第一讲：绪论34地球物理测井的发展历史:方法原理及仪器方面：第一阶段:普通电阻率及自然电位等少数几种方法；第二阶段:研究由视参数确定岩层电性参数的方法（横向测井方法）第三阶段:提出一系列带聚焦和贴井壁的测井方法；第四阶段:综合参数解释模型的提出及成像仪的研究开发；仪器的自动化程度：手动－半自动模拟－自动模拟－数字记录－程控数字记录

地球物理测井的发展历史:35

第一讲：绪论一、地球物理测井的基本概念二、地球物理测井能解决什么问题?三、地球物理测井包括哪些内容？四、地球物理测井的发展历史五、地球物理测井在油气勘探开发中的位置第一讲：绪论36地球物理测井在油气勘探开发中的位置：勘探阶段：普查（地质、重磁、电磁、地震）－详查（地质、电磁、地震）－确定目标－钻探－地球物理测井－测试、开发；开发阶段：测试、开发－测井－储层精细研究地球物理测井在油气勘探开发中的位置：37ExamplesOfCurveBehaviorAndLogDisplay

ThefirstexampleistheSP,whichisshownovera150’intervalinFig.2-10.SectionsoflogwithgreaterSPdeflection(i.e.,withamorenegativevaluethantheshalebaseline)aretakenasclean,oratleastcleaner,zones.Onecleansectionisthezonebetween8510’and8550’.Figure2-10.AnSPlogoveracleansectionboundedbyshalesExamplesOfCurveBehaviorAnd38ExamplesOfCurveBehaviorAndLogDisplayNotethesimilaritybetweentheGRtraceofFig.2-11andtheSPtraceofFig.2-10.Inthecleansections.Notealsothatthecaliper,inthisexample,followsmuchofthesametrend.Thistrendresultsfromthefactthattheshalesectionscan“washout,”increasingtheboreholesizecomparedtothecleanersandsectionsthatretaintheirstructuralintegrity.Figure2-11.AGRandcaliperlogoverthesamesectionasFig.2-10ExamplesOfCurveBehaviorAnd39ExamplesOfCurveBehaviorAndLogDisplayTheshallow,deep,andmediumdepthresitivitycurvesareindicate.Inthezonebelow5300’,apossiblewaterzoneisindicated.Atadepthof5275’,apossiblehydrocarbonzoneisnoted.Itisclearthatthedeepresistivityreading(ILD)ismuchgreaterthaninthesupposedwaterzone.However,thisincreaseinresistivitymaynotbetheresultofhydrocarbonpresence.Adecreaseinporositycouldproducethesameeffectforaformationsaturatedonlywithwater.Figure2-12.AninductionlogoverasectionwhichmightbeinterpretedasawaterzonewithahydrocarbonzoneaboveitExamplesOfCurveBehaviorAnd40ExamplesOfCurveBehaviorAndLogDisplayFig.2-13showsatypicallogofaneutronanddensitydeviceincombination.Inadditiontothedensityporosityestimateandtheneutronporosity,thecompensationcurveisalsoshown.

Thiscurveisthecorrectionwhichwasappliedtothedensitymeasurementinordertocorrectforthemudcakeandboreholeirregularities.Figure2-13.Sampleneutronanddensitylogswhichhasbeenconvertedtosandstoneporosity.ExamplesOfCurveBehaviorAnd41ExamplesOfCurveBehaviorAndLogDisplayThepresenceofgasmaybeextremelyeasytospotfromacomparisionoftheneutronanddensitylogs.Inthesimplestofcases,gasisindicatedinanyzoneinwhichtheneutronporosityislessthanthedensityporosity.Fig.2-14showssectionswhichexhibitthisbehavior.Shaleproducestheoppositeeffect.Theneutronporositymayfarexceedthedensityporosity,ascanbeseeninthebehaviorinFig.2-15.Figure2-14.Aneutronanddensitylogexhibitingthecharactersticcrossoverattributedtothepresenceofgasintheformation.ExamplesOfCurveBehaviorAnd42ExamplesOfCurveBehaviorAndLogDisplayFigure2-15.ThesignatureofshaleonaneutronanddensitycombinationlogAllofthesegeneralitiesaretrueonlyiftheprincipalmatrixcorrespondstothematrixsettingonthelog.Theeffectofhavingthewrongmatrixsettingonthelog(orhavingthematrixchangeasafunctionofdepth)isshowninFig.2-16.Severalsectionsshownegativedensityporosity.Theseareprobablyduetoanhydritestreaks,which,becauseoftheirmuchhigherdensity,aremisinterpretedasanegativeporosity.ExamplesOfCurveBehaviorAnd43ExamplesOfCurveBehaviorAndLogDisplayAllofthesegeneralitiesaretrueonlyiftheprincipalmatrixcorrespondstothematrixsettingonthelog.Theeffectofhavingthewrongmatrixsettingonthelog(orhavingthematrixchangeasafunctionofdepth)isshowninFig.2-16.Severalsectionsshownegativedensityporosity.Theseareprobablyduetoanhydritestreaks,which,becauseoftheirmuchhigherdensity,aremisinterpretedasanegativeporosity.Figure2-16.NeutronanddensitycrossovercausedbychangesinlithologyExamplesOfCurveBehaviorAnd44ASampleRapidInterpretation

Inthissectionthestep-by-stepprocessofidentifyinginterestingzonesforpossiblehydrocarbonproductionistraced.thefirststepistoidentifythecleanandpossiblypermeablezones.ThisisdonebyaninspectionoftheSPandGRcurves.Infigure2-17,fourclean,permeablezoneshavebeenlabeledAthroughDbyusingtheSPandGRcurves.inthenextstep,theresistivityreadingsinthefourselectedzonesareexamined.Afirstestimateoffluidcontentcanbeestablishedbylookingatthelowestresistivityvaluesandidentifyingthemaswater,ashasbeendoneinthefigure2-17.ThenthezonessuchasA,B,C,andDmaybesuspectedtobehydrocarbon-bearing.ASampleRapidInterpretation

45ASampleRapidInterpretationWithreferencetotheporosityvaluesintrack3,itisseenthattheporosityoverzoneCandC’isapproximatelyconstant.Inthiscase,theincreaseinresistivityintheupperzone,comparedtothelower,suggeststhepresenceofhydrocarbons.ThecaseforzoneDisnotquitesoclear.Accordingtotheneutronanddensitycurves,theporosityhasbeenconsiderablyreducedinthetransitionbetweenzoneD’andD.Perhapstheincreasedresistivityisduotoapurelywater-saturatedlowporosityformationandnothydrocarbon.Figure2-17.Abasicsetoflogsforperformingawellsiteinterpretation.ASampleRapidInterpretationW46ASampleRapidInterpretationAcarefullookattheneutronanddensitycurvesintrack3canyieldsomeadditionalinformation.NoticethecrossoverbetweentheneutronanddensitycurvesinzoneC.thisisindicativeofthepresenceofgas.ThesameconclusioncanbedrawnforzoneB,whichshowesanevengreaterneutron-densityseparationresultingfromgas.ThehighresistivitystreaksofzoneDarestillquestionable.Thereisnoevidenceofgasfromtheneutronordensitypresentationinthiszone,sothehighresistivityvaluemaysimplybeduotothereducedporosity.AnyfurtherspeculationwilldependontheabilitytobemorequantitativeintheanalysisFigure2-17.Abasicsetoflogsforperformingawellsiteinterpretation.ASampleRapidInterpretationA47ASampleRapidInterpretationSomequestions:

1.Oneofthefirstquestionswhichoccurstotheobservantanalystishowtheporositywasactuallydeterminedinthisexample.Forthisquantivitytobedetermined,someinformationisneededtoidentifythelithology.Intheexamplejustgiven,thematrixwasspecifiedassandstone,However,whatwouldhavebeentheconclusionsifinfacttherockweremainlydolomite?2.Anotherquestionwhichneedstobeexploredistherelationshipbetweentheresistivityofawater-saturatedrockanditsporosity.Thisrelationshipmustbequantifiedinordertounsrambletheeffectsofchangingthesetwovariablessimultaneously.ASampleRapidInterpretationS48ProblemsComputertheporosityofaformationcomposedofuniformsphericalgrainofradiusrarrangedinthemost“open”cubicpacking.(Theunitcubewithsideoflengthof2rspanseightgrains;seeinFig.2-18)IftheformationwerecomposedofthenearlysphericalplanktonofFig.2-19,whatwouldtheporositybeforcubicpacking?Thesphericalvoidatthecenterofeachplanktonseemstohavearadiuswhichis=9/10ofthetotalparticleradius.Mostsandstoneformationshaveporositieswellbelow30%.Canyousuggestseveralreasonswhythisisthecase?Thevolumeofwaterexpelledfromthemud,duringthecreationofthemudcake,willdisplacetheformationfluid,creatingtheso-calledinvasionzone.Thethicknessofthiszone,inwhichtheformationfluidhasbeendisplacedbymudfiltrate,willdependontheformationporosity.Showthattheradiusofinvasionisgivenby:wheredVisthevolumeofmudfiltrate/unitlengthdisplacedintotheformation,istheporosity,andistheboreholeradius.5.Supposethatamudcakeof40%porosityhasbeenformedontheinsideofa6’’borehole,fromamudof80%porosity.Ifthemudcakethicknessis½’’,whatisthediameterofinvasionina2%porosityformation?ProblemsComputertheporosity49ProblemsFigure12-18.Cubicoropenpackingofuniform-sizedsphericalparticles.Figure2-19.Photomicrographofspericalplanktonwhichcontainanearlysphericalvoid.ProblemsFigure12-18.Cubicor50地球物理测井方法原理和应用沈金松石油大学资源与信息学院地球物理系地球物理测井方法原理和应用沈金松51

第二讲：普通电阻率法测井一、电阻率法测井的基本概念二、电阻率测井的基础理论三、视电阻率理论曲线分析四、视电阻率测井曲线的应用五、微电极电阻率测井简介第二讲：普通电阻率法测井52[电阻率法测井]即根据岩石的导电能力的差异，在钻孔中研究岩层性质与划分钻孔剖面的方法。电阻率法测井－普通电极系电阻率法测井、微电极系测井；电阻率法测井的基础是岩石的导电性能的差异，在油气井中研究导电性具有重要意义－判断岩层的含油性[电阻率法测井]即根据岩石的导电能力的差异，在钻孔中研究岩层53

第二讲：普通电阻率法测井一、电阻率法测井的基本概念二、电阻率测井的基础理论三、视电阻率理论曲线分析四、视电阻率测井曲线的应用五、微电极电阻率测井简介第二讲：普通电阻率法测井541.岩石的电阻率－TheconceptofBuckResistivity

Theresistivityisageneralpropertyofmaterials,asopposedtoresistance,whichisassociatedwiththegeometricformofthematerial.ThefamiliarexpressionofOhm’slaw:IndicatesthatacurrentIflowingthroughamaterialwithresistanceRisassociatedwithavoltagedropV.Themoregeneralformofthisequation,usedasanadditionalrelationshipinMaxwell’sequations,is:whereisthecurrentdensity,avectorquantity;istheelectricfield;andtheconstantofproportionalityistheconductivityofthematerial.Resistivity,acommonlymeasuredformationparameter,isdefinedastheinverseofconductivity:Resistivity

1.岩石的电阻率－TheconceptofBuckR55TheconceptofBuckResistivityFigure.3－1A1-metercubeofcharacteristicresistivity1hasaresistanceof1facetoface.TheconceptofBuckResistivit56ElectricalPropertiesOfRocksAndBrines

Therearetwogeneraltypesofconductionofinteresttous:electrolyticandmetallic.Inelectrolyticconduction,themechanismisdependentuponthepresenceofdissolvedsaltsinaliquidsuchaswater.Examplesofelectronicconductionareprovidedbymetals,whicharenotcoveredhere.Thefollowingtableillustratestheresistivityofsometypicalmaterials.ElectricalPropertiesOfRocks57ElectricalPropertiesOfRocksAndBrines

Notice

therangeofresistivityvariationforsaltwater.Typicalrockmaterialsareinessenceinsultors.Thefactthatreservoirrockshaveanydetectableconductivityisusuallytheresultofthepresenceofelectrolyticconductorsintheporespace.Insomecases,theresistivityofarockmayresultfromthepresenceofmetal,graphite,metalsulfides,orclays.Thetableshowsthattheresistivityofformationofinterestmayrangefrom0.5to10**3,nearlyfourordersofmagnitude.ElectricalPropertiesOfRocks58ElectricalPropertiesOfRocksAndBrines

Theconductivityofsedimentaryrocksisprimarilyofelectrolyticorigin.Itistheresultofthepresenceofwateroracombinationofwaterandhydrocarbonsintheporespaceinacontinuousphase.Theactualconductivitywilldependontheresistivityofthewaterintheporesandthequantityofwaterpresent.Toalesserextent,itwilldependonthelithologyoftherockmatrix,itsclaycontent,anditstexture(grainsizeandthedistributionofpores,clay,andconductiveminerals).Finally,theconductivityofasedimentaryformationwilldependstronglyontemperature.Fig.3-5graphicallypresentstheresistivityofsaltwater(NaCl)solutionsasafunctionoftheelectrolyteconcentrationandtemperature.Accordingtotheprecedinganalysis,theresistivityisexpectedtodependinverselyonthechargecarrierconcentrations:ElectricalPropertiesOfRocks59Thechapterfocusesontheevolutionofonetypeofelectricalloggingtool:electrodedevices.Thehistoricalprogressionfromthenormaldevicetostate-of-the-artfocusedlaterologarrayswillbetraced.Anindicationofthemeasurementlimitationsforeachofthesetypesoftoolswillbegivenandrelatestotheirdesignsmethodsusedforthepredictionoftheirresponsewillbediscussed.IntroductionThechapterfocusesontheevo60UnfocusedDevicesTheShortNormal

Theearliestcommercialdevices,theshortnormal,isillustratedinFig.5-1.Asindicatedinthefigure,thespacingbetweenthecurrentelectrodeandvoltageelectrodewad16″,andthusdesignation“short.”Figure5-1.Aschematicrepresentatio