国外某大学石油工程系油藏工程考试试题

Course:-28117Class:-289013HERIOT-WATTUNIVERSITYDEPARTMENTOFPETROLEUMENGINEERINGExaminationfortheDegreeofMEnginPetroleumEngineeringReservoirEngineering1Tuesday6thJanuary199809.30-13.30NOTESFORCANDIDATES1.ThisisaClosedBookExamination.2.15minutesreadingtimeisprovidedfrom09.15-09.30.3.ExaminationPaperswillbemarkedanonymously.SeeseparateinstructionsforcompletionofScriptBookfrontcoversandattachmentofloosepages.Donotwriteyournameonanyloosepageswhicharesubmittedaspartofyouranswer.4.ThisPaperconsistsof3Sections:-A,BandC.5.SectionA:-AttemptallQuestionsSectionsB&C:-Attempt4numberedQuestionswithatleast1QuestionfromeachSection6.SectionA:-20%ofmarksSectionB/C:-80%ofmarksMarksforQuestionsandpartsareindicatedin[brackets]7.ThisExaminationrepresents100%oftheClassassessment.8Stateclearlyanyassumptionsusedandintermediatecalculationsmadeinnumericalquestions.Nomarkscanbegivenforanincorrectanswerifthemethodofcalculationisnotpresented.9.Answersmustbewritteninseparate,colouredbooksasfollows:-SectionA:-BlueSectionB:-GreenSectionC:-YellowSECTIONAA1Define:-(i)Gasformation-volumefactor(ii)Oilformation-volumefactor(iii)Totalformation-volumefactor(iv)Solutiongas-oilratio[2]A2Explainbrieflywhatyouunderstandby:-(i)Compositionalmodeldescriptionforthecharacterisationofareservoirfluid.(ii)Blackoildescriptionforthecharacterisationofareservoirfluid.[3]A3Drawthepressure-temperaturephasediagramforagascondensatereservoirindicatingthefollowing:-(i)Bubblepointanddewpointlines(ii)Criticalpoint(iii)Cricondentherm(iv)Linesofconstantproportionofliquid-gas(v)Regionofretrogradecondensation.[3]A4Deriveanequationfortheaveragepermeability,resultingfromradialcircularflowintoawellfromlayersofdifferentpermeabilitiesandthicknesses.Fromwherewouldsuchanaveragebeobtained?[3]A5Listtherockpropertiesthatshouldbedeterminedinarock-mechanical-oriented,specialcoreanalysisprogramme.[3]A6Describethenatureofapartiallycommunicatingfaultandhowpressuredatamaybeusedtoidentifythetransmissibilityindexofsuchfeatures.[3]A7Explainthedifferencebetweenasteady-stateandasemi-steady-stateproductivityindex.[3]SECTIONBB8(a)Methaneisasignificantcomponentinreservoirfluids.Usingasketchforabinaryofmethaneandn-decane(C10),illustratetheimpactofmethaneonthecriticalpointlociofC1-C10binarymixtures.Whatisthesignificanceofthisdiagram?[6](b)Awetgasisproducingat40,000SCF/STB,fromareservoirwhichhasbeenestimatedfrompetrophysicstohaveavolumeof1.1x1010cuft.andhasapressureof3,000psiaandatemperatureof250°FThecompositionoftheproducinggasisgivenbelow:-Component(MW)Composition(Molefraction)GasCondensateMethane(16.04)0.84-Ethane(30.07)0.07-Propane(44.09)0.050.16N-butane(58.12)0.020.34N-pentane(72.15)0.020.31Hexane(86.17)-0.10Heptaneplus(114.2)-0.09(equivalenttooctane)(i)Whatisthecompositionofthereservoirgas?(ii)Whatarethereservesofgasandcondensateat3,000psia?(iii)Howmuchgaswillhavebeenproduced,whenthepressurehasdroppedto2,000psia?[14]R=10.72cuft.psi/lbmole.°R1lbmole=379.4SCF1bbl=5.615cuftB9(a)YouhavebeengivenaPVTreportforanoilsample.Listtheproceduresandcalculationsyouwouldtaketodetermine:-(i)Thebubblepointpressureatreservoirtemperature(ii)Thesolutiongas-oilratiosandtheoilformationvolumefactorsabovethebubblepointandbelowthebubblepoint.[10](b)Alaboratorycell,contained290ccofreservoirliquidatitsbubblepointof2100psiaat145°F.21ccofmercurywereremovedfromthecellandthepressuredroppedto1700psia.Mercurywasthenre-injectedatconstanttemperatureandpressureand0.153SCFofgaswasremovedleaving270ccofliquidinthecell.Theprocesswasrepeatedreducingthepressureto14.7psiaandthetemperatureto60°F.Then0.45SCFofgaswasremovedand207.5ccofliquidremainedinthecell.Determine:-(i)BoandRsatthebubblepoint.(ii)Bo,Bt,Bg,Rsandzat1,700psiaand145°F(iii)Btat2100psiaand145°F[10]B10Usingfieldexamples,describethevariousrock-mechanicalphenomenawhichcanbeactivatedinproducingreservoirs,andexplaintheimpactofthesephenomenaonreservoirdevelopmentandmanagementstrategies.[20]B11(a)Forlowpermeabilityrocks,themeasuredpermeabilityoftherock,usinggasasthefluidismorethanitisusingaliquid.Commentbrieflyonthisandhowthepermeabilityofarockcanbeobtainedusinggasasthefluid.[4](b)Thesystembelowrepresentsthecommonarrangementformeasuringthepermeabilityofacoreplugusingagas.Deriveanequationtocalculatethegaspermeabilitiesofarockusingtheabovesystem.[6](c)Whatisthefreewaterlevel?Explainbrieflywhy,becauseofcapillarypressure,itispossibletohavewatersaturationsoflargevalues,upto100%,abovetheoil-watercontactandabovelayerswithlowerwatersaturations.[4](d)Capillarypressuredataareobtainedfromcoresampleswhichrepresentasmallpartofthereservoir.Leverettderiveda“J”FunctionusingthePoiseuilleequationforlaminarflow:-qrPL=πμ48ΔtorelateCapillarypressure(Pc),toPermeability(k),andPorosity(ø).Derivethe'J'functionandcommentononeofitslimitingassumptions.[6]B12(a)Identifythevariouselementsinthematerialbalanceequationbelow:-()[()][()]()()()NNBNBBNRNNRGGGBGBWWBNBmpcScSWBGBpooigsipspspcggiepwoifwcwwcinjwinjg-=----------++-⎡⎣⎢⎤⎦⎥-+11Δwithalineabovethesymbolsoftheequatione.g.()infWWBnetwaterluxepw-=[3](b)Simplifythemate