HEAVY AND THERMAL OIL RECOVERY PRODUCTION MECHANIS

HeavyandThermalOilRecoveryProductionMechanismsQuarterlyTechnicalProgressReportReportingPeriod:April1throughJune30,2002PrincipalAuthor:AnthonyR.Kovscek(650)723-1218ReportDate:July2002DOEAwardNumber:DE-FC26-00BC15311NameandAddressofSubmittingOrganization:PetroleumEngineeringDepartmentStanfordUniversity367PanamaStreetStanford,CA94305-22202DisclaimerThisreportwaspreparedasanaccountofworksponsoredbyanagencyoftheUnitedStatesGovernment.NeithertheUnitedStatesGovernmentnoranyagencythereof,noranyoftheiremployees,makesanywarranty,expressorimplied,orassumesanylegalliabilityorresponsibilityfortheaccuracy,completeness,orusefulnessofanyinformation,apparatus,product,orprocessdisclosed,orrepresentsthatitsusewouldnotinfringeprivatelyownedrights.Referencehereintoanyspecificcommercialproduct,process,orservicebytradename,trademark,manufacturer,orotherwisedoesnotnecessarilyconstituteorimplyitsendorsement,recommendation,orfavoringbytheUnitedStatesGovernmentoranyagencythereof.TheviewsandopinionsofauthorsexpressedhereindonotnecessarilystateorreflectthoseoftheUnitedStatesGovernmentoranyagencythereof.AbstractThistechnicalprogressreportdescribesworkperformedfromApril1throughJune30,2002,fortheprojectHeavyandThermalOilRecoveryProductionMechanisms.Weinvestigateabroadspectrumoftopicsrelatedtothermalandheavy-oilrecovery.Significantresultswereobtainedintheareasofmultiphaseflowandrockproperties,hot-fluidinjection,improvedprimaryheavyoilrecovery,andreservoirdefinition.Theresearchtoolsandtechniquesusedarevariedandspanfrompore-levelimagingofmultiphasefluidflowtodefinitionofreservoir-scalefeaturesthroughstreamline-basedhistory-matchingtechniques.Briefly,experimentswereconductedtoimageattheporelevelmatrix-to-fractureproductionofoilfromafracturedporousmedium.Thisprojectisongoing.Asimulationstudiedwascompletedintheareaofrecoveryprocessesduringsteaminjectionintofracturedporousmedia.Wecontinuedtostudyexperimentallyheavy-oilproductionmechanismsfromrelativelylowpermeabilityrocksunderconditionsofhighpressureandhightemperature.Hightemperaturesignificantlyincreasedoilrecoveryrateanddecreasedresidualoilsaturation.Alsointheareaofimagingproductionprocessesinlaboratory-scalecores,weuseCTtostudytheprocessofgas-phaseformationduringsolutiongasdriveinviscousoils.Resultsfromrecentexperimentsarereportedhere.Finally,aprojectwascompletedthatusestheproducingwater-oilratiotodefinereservoirheterogeneityandintegrateproductionhistoryintoareservoirmodelusingstreamlineproperties.ProjectObjectivesTheobjectiveofthisresearchprojectistoimprovetherecoveryefficiencyfromdifficulttoproducereservoirsincludingheavy-oilandfracturedlowpermeabilitysystems.Thisobjectiveisaccomplishedbydevelopinglaboratorytechniquesandapparatusforstudyingmultiphaseflowpropertiesinfracturedandunfracturedporousmedia,identifyingoilproductionmechanismsfromtheporetothecoretofieldscale,andtranslatingthisunderstandingintomathematicalmodelsincorporatingnewlyunderstoodphysics.3Theprojectisdividedinto5mainareas.Theseprojectsandtheirgoalsinclude:1.Multiphaseflowandrockproperties—todevelopbetterunderstandingofthephysicsofdisplacementinporousmediathroughexperimentandtheory.Thiscategoryincludesworkonimbibition,flowinfracturedmedia,andtheeffectoftemperatureonrelativepermeabilityandcapillarypressure.2.Hotfluidinjection—toimprovetheapplicationofnonconventionalwellsforenhancedoilrecoveryandelucidatethemechanismsofsteamdriveinlowpermeability,fracturedporousmedia.3.Mechanismsofprimaryheavyoilrecovery—todevelopamechanisticunderstandingofso-calledfoamyoilanditsassociatedphysicalchemistry.4.In-situcombustion—toevaluatetheeffectofdifferentreservoirparametersontheinsitucombustionprocess.5.Reservoirdefinition—todevelopandimprovetechniquesforevaluatingformationpropertiesfromproductioninformation.Technicalprogressineachoftheseareasisnowdescribedbriefly.Area1.MultiphaseFlowandRockPropertiesWorkinthisprojectareafocusedonamicro-visualanalysisofmatrix-to-fracturetransferintransparent,two-dimensionalreplicasoffracturedsystems.i.e,micromodels.Mostoftheprogressisassociatedwithestablishingtheexperimentalapparatus.(a)(b)Figure1.Schematicofthemicromodel:Thenetworkactsastheporousmediumandtheadjacentchannelsactasthehighconductivityfractures.InletOutlet5cm5cm25µmmatrixfracture4RationaleandSummary–Matrix/FractureTransfer.Understandingandmodelingflowbehaviorinnaturallyfracturedrocks,includingoilandgasreservoirsrequiresadetailedanalysisofthesesystemsatvariouslengthscales.Theultimategoalistoproviderealisticinformationonhowtomodelorsimulatematrixtofracturetransferunderthermalandisothermalconditions.Tounderstandhowfluidscommunicatebetweenthehighconductivityfractureandthelowerconductivitymatrixrequiresbothpore-andcore-scaleanalysisoftheproblem.Thecore-scaleexperimentalworkisdescribedelsewhere(Rangel-GermanandKovscek2002).Ourrecentworkatthepore-levelisconductedusingmicromodelswherematrix-fracturetransferisvisualizedthroughamicroscope.Experimentsareanalogoustothoseconductedwithcores.Etched-silicon-wafermicromodelsofthetypeusedbyGeorge(1999),initiallydeve