(石油地质及储油层).ppt

1,Chapter2PetroleumGeologyandReservoirs石油地質及儲油層,References石油地質及儲油層PetroleumGeologyandReservoir,Textbook1FundamentalsofPetroleum,PetroleumExtensionService,TheUniversityofTexasatAustin,Austin,Texas,1979.–chapter1Textbook2Archer,J.S.,andWall,C.G.,PetroleumEngineeringprinciplesandpractice,Graham4.2,2,3,PetroleumGeology石油地質,Geology地質---研究1地球的歷史及構造2記錄在岩石的生物命形式PetroleumGeology石油地質---研究地質以預測石油累積之處所,4,地球的形成及構造,地球的形成40～50億年前由宇宙塵Cosmicdust的凝結而成地球內部大構造Core---heavy4,400milesMantle---Lighter1,800milesCrust---1030miles,5,地球內部大構造,,Core--heavy4,400milesMantle--Lighter1,800milesCrust---1030miles,在地球上，不管您走到哪裡，你都是在岩石（Rock）的上面。在加州的某些地方，你是站有岩石的上面20哩處,20哩是多少,6MILES9.6KILOMETERS20MILES32KILOMETERS,喜馬拉雅山大約有6哩高,所以20哩是喜馬拉雅山的3倍高，其間有很多的岩石。,7,地球表面的變化--Rockcycle,,,Magma岩漿,Igneousrocks火成岩,Sediments沉積物,Sedimentaryrocks,Metamorphicrocks,地球內部,Watervaporandgases,Prim初期的Atmosphere大氣,地殼冷卻,地殼收縮變形而皺摺,噴出,,形成,,,,,,,,,heat,heatpressure,erosion,erosion,pressurecementation,erosion,,,,,,下雨,,,Cool,8,沉積岩的分類,,9,ReservoirRockSedimentaryRock,,10,地球的歷史,寒武紀Cambrian【約5.5億年前】開始在海洋裡有大量的生物生命在寒武紀之前為前寒武紀Precambrian地質年代自寒武紀開始地質代年表GeologicTimeScale泥盆紀Devonian時期【約3.3億年前】陸上有大量植物及動物,11,GeologicalTimeScale,12,地層年代表,,13,,,14,Petroleumaccumulation石油累積Petroleumreservoir石油油藏;油藏;油層,Petroleumaccumulation必須具備1Oil＆gas之來源2具有孔隙porosity及滲透率permeability之ReservoirRock3要有trap封閉以阻擋流體的流動,15,石油的來源,16,石油的來源,－石油來自沈積岩的有機物質－海洋裡大量的生物不停的，緩慢的掉落到海底。雖然在掉落的過程中，有部分被吃掉或被氧化掉，但另部份動物或植物掉落海底而埋在沼澤或泥濘之海底－海底繼續被Sand砂，Clay黏土及debris等沈積物埋沒一直到幾千英呎－沈積物的壓力開始作用。細菌由殘餘的有機物質中，用掉氧而分解物質，使其僅存碳及氫－在高度的壓力及重量的地層影響之下，Clays變成Shales→石油產生,砂、淤泥及泥土的顆粒沉到水裡，蓋在死的矽藻類以及其他的動植物之上。而且，水被夾在這些砂、淤泥及泥土的顆粒之中。,不久，這些顆粒，又被其他的動植物殘骸覆蓋。這個過程，一再的重複，最後，泥、砂及水累積達幾千呎厚。,這些砂、泥在堆積過程中，底部的砂、泥受到上部砂、泥而擠壓,在河流、湖及海底的泥、砂、水及動植物殘骸所受的覆蓋壓力逐漸的變大,當覆蓋深度加大而變深，其溫度也增加。經過幾百萬年之後，在適當的壓力及溫度之下，這些泥砂顆粒就變硬而成為岩石，類似褐色或灰色的水泥。當動植物的殘骸腐朽之後，形成石油及天然氣，大部分的石油及天然氣係由相當微小的動植物殘骸而來的確實的石油及天然氣之形成原因仍不清楚。但是，溫度、壓力及細菌是很重要的因素。,18,,Petroleumationrequiresthatorganicsourceclaysbecomematurebysubjectiontopressureandtemperature.,19,石油形成的重要條件,225℉500℉有機物質碳化，不能形成石油,20,Generationofgasandoil,,21,22,,Ingeologyandoceanography,diagenesisisanychemical,physical,orbiologicalchangeundergonebyasedimentafteritsinitialdepositionandduringandafteritslithification,exclusiveofsurfacealterationweatheringandmetamorphism.,23,,CatagenesiscanrefertoCatagenesisgeology–Thecrackingprocessinwhichorganickerogensarebrokendownintohydrocarbons;Catagenesisbiology–Retrogressiveevolution,ascontrastedwithanagenesis.,24,,Metamorphismcanbedefinedasthesolidstaterecrystallisationofpre-existingrocksduetochangesinheatand/orpressureand/orintroductionoffluidsi.ewithoutmelting.Therewillbemineralogical,chemicalandcrystallographicchanges,25,,Prolongedexposuretohightemperatures,orshorterexposuretoveryhightemperatures,mayleadprogressivelytothegenerationofhydrocarbonmixturescharacterizedascondensates,wetgasesandgas.Theaverageorganiccontentofpotentialsourcerocksisabout1byweight.TheKimmeridgeclay,theprincipalsourcerockforNorthSeaoilaverageabout5carbon7organicmaterwithlocalrichstreaksgreaterthan40.Thehydrogencontentoftheorganicmattershouldbegreaterthan7byweightforpotentialasanoilsource.,26,,Itisaruleofthumbthatforeachpercentagepointoforganiccarboninmaturesourcerocks,some13001500cubicmetersofoilperkm2-mor1040barrelsofoilperacre-ft;or56-225ft3/43560ft3ofsedimentcouldbegenerated.1.31.5m3oil1,000m3rockItisnot,however,necessarilytruethatalltheoilgeneratedwillbeexpelledortrappedinporousrock.,27,石油移棲,,Themigrationprocessinvolvestwomainstages,namelyfromthesourcerockandthenthroughapermeablesystem.,28,Migrationofpetroleum--fromthesourcerock,29,Migrationofpetroleum--fromthesourcerock,**Capillaryeffect**MicrofracturesSincethegenerationofpetroleumisaccompaniedbyvolumechangeswhichcanleadtohighlocalpressures,theremaywellbeaninitiationofmicrofractureswhichprovideanescaperouteintopermeablesystemssuchassedimentaryrocksorfaultplanes.Thesourcerockmicrofracturesarebelievedtohealaspressuresaredissipated.,30,Migrationofpetroleum--throughapermeablesystem,**FluidpotentialgradientorgravityeffectInthepermeablesystemthetransportoccursunderconditionsofafluidpotentialgradientwhichmaytakethehydrocarbontosurfaceortosomeplacewhereitbecomestrapped.Itmightbeassumedthatlessthan10ofpetroleumgeneratedinsourcerocksisbothexpelledandtrapped,asshownintheexampleofFig.2.5.,31,32,Petroleumtraps石油封閉,Thecharacteristicsofpetroleumtrapareknownasstructuraltraps構造封閉andstratigraphictraps地層封閉,withthegreatmajorityofknownaccumulationbeingintheerstyle.,33,地質構造（GeologicalStructures）,,34,,Figure1.12.TwogeneralkindsofunconitiesaredisconityAandangularunconitiesBandC.,Figure1.13.Basichydrocarbonreservoirsarestructuraland/orstratigraphictraps.,35,封閉traps,,Combinationtraps,36,Caprockandfluiddistribution,Impermeablerocksprovidesealaboveandbelowthepermeablereservoirrocks.Atequilibriumconditions,thedensitydifferencesbetweentheoil,gasandwaterphasescanresultinboundaryregionsbetweenthemknownasfluidcontacts,i.e.gas-oilandoil-watercontacts.,37,Structuraltrap構造封閉--Anticline,,Longitudinalviewofatypicalanticline.Theoilcannotescapeupwardbecauseoftheimperviousshalebedabovetheoilsand;neithercanittraveldownwardbecauseofthewaterthatisassociatedwithanaccumulationofthistype.,Anticlines－Ofthemanytypesofstructuralfeaturespresentintheupperlayersoftheearthscrustthatcantrapoil,themostimportantistheanticlines－thetypeofstructurefromwhichthegreaterpartoftheword’soilhasbeenproduced.Anticlinesareupfoldsofbedsintheearth’scrust,and,whentheproperconditionsarepresent,oilaccumulateswithintheclosureoftherefolds.,38,Structuraltrap--Anticline,,Lateral,orendview,ofatypicalanticline.,Planviewofatypicalanticline,showinglocationsoflongitudinalviewA-BandlateralviewC-D.,39,Structuraltraps,Figure1.7.Schematiccrosssectionshowsdeationofearth’scrustbybuckingoflayersintofolds,Figure1.8.SimplekindsoffoldsaresymmetricalanticlineA,plungingasymmetricalanticlineB,plungingsynclineC,anddomewithdeepsaltcoreD.,Figure1.9.SimplifieddiagramoftheMilano,Texas,fault.,40,Structuraltraps–domesurfaceerosionOsmosisbetweenwatershavingdifferentsalinity,thesealingshaleactingasthesemipermeablemembraneinthisionicexchange;ifthewaterwithinthesealismoresalinethanthesurroundingwatertheosmosiswillcausetheabnormalhighpressureandviceversa.,91,,,92,,,93,,,94,,,95,Abnormalhighpressure,Allshowsimilarsalinitygradientsbutdifferentdegreesofoverpressure,possiblyrelatedtodevelopmentinlocalizedbasins.Anyhydrocarbonbearingstructureofsubstantialreliefwillexhibitabnormallyhighpressureatthecrestwhenthepressureatthehydrocarbon-watercontactisnormal,simplybecauseofthelowerdensityofthehydrocarboncomparedwithwater.,96,Causesofabnormalpressure,Abnormalfluidpressuresarethosenotininitialfluidequilibriumatthediscoverydepth.Magara1978hasdescribedconditionsleadingtoabnormallyhighandabnormallylowpressures.Someexplanationslieinreservoirsbeingfoundatpressuredepthshigherorlowerthanthedepthsatwhichtheybecamefilledwithhydrocarbon.Thismaybetheresultofupthrustordownthrownfaulting.,97,Causesofabnormalpressure,Overpressurefromtheburialweightofglacialicehasalsobeencited.InGulfcoastandNorthSeareservoirs,overpressureismostfrequentlyattributedtorapiddepositionofshalesfromwhichboundwatercannotescapetohydrostaticequilibrium.Thisleadstooverpressuredaquifer-hydrocarbonsystem.,98,2.3Fluidpressuresinahydrocarbonzone,99,Arethewaterbearingsandsabnormallypressured,Ifso,whateffectdoesthishaveontheextentofanyhydrocarbonaccumulations,100,PressureKick–OilandWater,,,,,Ppsia,5000,,,,,,,,5200,5500,5600,,,oil,,water,OWC,D5500ft,,,,,,,,Pw2265,,Po2315,Pw2355,Po2385,,PwPo2490,,Pw2535,Depthft,101,pressurekick-gasandwater,,,,,,,,Gas,,,Ppsia,5000,,,,,,,5200,5500,5600,,,,Pw2265,Pg2450,,,Pg2466,Pw2355,PwPg2490,Pw2535,Depthft,,,GWC,water,D5500ft,102,pressurekick-gas,oilandwater,,,,,,,,,,,,,Ppsia,,,,,,,5000,5200,5300,5400,5500,5600,,,,,,,,Pw2265,Pg2396,Pw2355,Pg2412,Pw2400,PoPg2420,Pw2445,Po2455,,PwPo2490,Pw2535,Depthft,,,Gas,GOC,oil,OWC,water,D5500ft,D5300ft,103,PressureKick,AssumesanormalhydrostaticpressureregimePω0.45D15Inwaterzoneat5000ftPωat500050000.45152265psiaatOWC5500ftPωatOWC55000.45152490psia,,,104,PressureKick,InoilzonePo0.35xDCatD5500ft,Po2490psi→C2490–0.355500565psia→Po0.35D565atGOC5200ftPoatGOC0.3552005652385psia,,,105,PressureKick,IngaszonePg0.08D1969psiaat5000ftPg0.08500019692369psia,,,106,PressureKick,IngaszonePg0.08DCAtD5500ft,PgPω2490psia24900.085500CC2050psia→Pg0.08D2050AtD5000ftPg2450psia,,,Overburdenpressure,ThereisabalanceinareservoirsystembetweenthepressuregradientsrepresentingrockoverburdenGr,porefluidsGfandsedimentgrainpressureGg.Theporefluidscanbeconsideredtotakepartoftheoverburdenpressureandrelievethatpartoftheoverburdenloadontherockgrains.GrGfGg,Overburdengradient,Themagnitudeoftheoverburdengradientisapproximately1psi/ft22.6kpa/m.For100rocksandGg0.433x2.71.169psi/ftFor100waterGf0.433psi/ftFor20rockGr0.2x0.4330.8x1.1691.022psi/ft,,FluidPressureRegimes,Thetotalpressureatanydepthweightoftheationrockweightoffluidsoil,gasorwater[]1psi/ft*depthft,FluidPressureRegimes,Densityofsandstone,,,,Pressuregradientforsandstone,Pressuregradientforsandstone,,,,Overburdenpressure,OverburdenpressureOPFluidpressureFPGrainormatrixpressureGPOPFPGPInnon-isolatedreservoirPWwellborepressureFPInisolatedreservoirPWwellborepressureFPGP’whereGPGPInaperfectlynormalcase,thewaterpressureatanydepth,Normalhydrostaticpressure,Inaperfectlynormalcase,thewaterpressureatanydepthAssume1Continuityofwaterpressuretothesurface2Salinityofwaterdoesnotvarywithdepth.[]psiapsi/ftforpurewaterpsi/ftforsalinewater,,,,GWCerrorfrompressuremeasurement,Pressure2500psiaPressure2450psiaatD5000ftatD5000ftingas-waterreservoiringas-waterreservoirGWCGWCSol.Sol.Pg0.08DCPg0.08DCC2500–0.085000C2450–0.0850002100psia2050psia→Pg0.08D2100→Pg0.08D2050WaterpressurePω0.45D15WaterpressurePω0.45D15AtGWCPgPωAtGWCPgPω0.08D21000.45D150.08D20500.45D15D5635ftGWCD5500ftGWC,ResultsfromErrorsinGWCorGOCorOWC,GWCorGOCorOWClocationaffectingvolumeofhydrocarbonOOIPaffectingOOIPorOGIPaffectingdevelopmentplans,2.4ReservoirTemperature,Reservoirtemperaturemaybeexpectedtocontotheregionalorlocalgeothermalgradient.Inmanypetroliferousbasinsthisisaround0.029k/m1.6oF/100ft.Theoverburdenandreservoirrock,whichhavelargethermalcapacities,togetherwithlargesurfaceareaforheattransferwithinthereservoir,leadtoareasonableassumptionthatreservoirconditionprocessestendtobeisothermal,118,,119,,,120,Reservoirpressures,Hydrocarbonreservoirsarefoundoverawiderangeofpresentdaydepthsofburial,themajoritybeingintherange500–4000mss.Inourconceptofthepetroliferoussedimentarybasinasaregionofwaterintowhichsedimenthasaccumulatedandhydrocarbonshavebeengeneratedandtrapped,wemayhaveanexpectationofregionalhydrostaticgradient.,121,,Theprimarydepositionalprocessesandthenatureofthesedimentshaveamajorinfluenceontheporosityandpermeabilityofreservoirrocks.,122,,Secondaryprocesses,includingcompaction,solution,chemicalreplacementanddiageneticchanges,canacttomodifyfurthertheporestructureandgeometry.Withcompaction,grainsofsedimentaresubjecttoincreasingcontactandporefluidsmaybeexpelledfromthedecreasingporevolume.Iftheporefluidscannotbeexpelled,theporefluidpressuremayincrease.,123,Abnormalpressure,Undercertaindepositionalconditions,orbecauseofmovementofclosedreservoirstructures,fluidpressuresmaydepartsubstantiallyfromthenormalrange.OneparticularmechanismresponsibleforoverpressureinsomeNorthSeareservoirsistheinabilitytoexpelwaterfromasystemcontainingrapidlycompactedshales.AbnormalpressureregimesareevidentinFig.2.11.,124,PressureKick–OilandWater,,125,Pressurekick--gasandwater,,126,Pressurekick--gas,oilandwater,,