A ternary composite oil displacement system based on the synergistic enhancement of nanofluid and polymer

Abstract

The present invention discloses a ternary composite oil displacement system based on the synergistic enhancement of nanofluid and polymer, belonging to the technical field of petroleum extraction, comprising a pre-treatment unit, a nanofluid supply unit, a temperature-resistant and salt-tolerant polymer supply unit, a composite mixing unit, an online enhancement injection unit, and a formation synergistic displacement unit. The outlet of the pre-treatment unit is connected to the composite mixing unit, and the nanofluid supply unit and the temperature-resistant and salt-tolerant polymer supply unit are connected in parallel to the composite mixing unit; through the synergistic action of the nanofluid and the temperature-resistant and salt-tolerant polymer, multiple synergistic effects of “ dispersion stability, viscosity enhancement, flow regulation, and residual oil stripping ” are achieved.Modified nanoparticles and temperature-resistant and salt-tolerant polymer molecules form hydrogen bonds and electrostatic adsorption composite interactions, which not only significantly improve the solubility and viscosity stability of the polymer under high-temperature and high-mineralization formation water environments, but also prevent degradation of the polymer molecular chains.

Description

-1-AternarycompositeoildisplacementsystembasedonthesynergisticenhancementofnanofluidandpolymerTECHNICALFIELDThepresentinventionbelongstothetechnicalfieldofpetroleumextractionandspecificallyrelatestoaternarycompositeoildisplacementsystembasedonthesynergisticenhancementofnanofluidandpolymer.BACKGROUNDWiththecontinuousexploitationofpetroleumresources,conventionalcrudeoilextractiontechnologies(primaryrecovery,secondaryrecovery)cannolongermeetthedemandsofindustrial-scaleproduction,leavingalargeamountofresidualoiltrappedinreservoirformations.Therefore,tertiaryrecoverytechnologyhasbecomeakeytechnicalmeanstoimprovecrudeoilrecoveryandensureoilandgasproduction.Asoneofthecoretechnologiesoftertiaryrecovery,compositeoildisplacementtechnology,throughthesynergisticactionofmultipleoildisplacementagents,improvesthereservoirflowenvironment,reducesoil-waterinterfacialtension,andcontrolsmobilityratio,therebyachievingefficientstrippinganddisplacementofresidualoil.Currently,thecompositeoildisplacementsystemswidelyappliedinindustrymainlyincludepolymerfloodingandternarycompositeflooding(alkali–surfactant–polymer).Inpolymerflooding,high-viscositysystemsareformedthroughentanglementofpolymermolecularchainstoachieveflowcontrol;however,underhigh-temperatureandhigh-mineralizationreservoirconditions,polymermoleculesarepronetothermaldegradationandsalt-sensitivedegradation,leadingtoasharpdeclineinviscosityandasignificantreductioninoildisplacementefficiency.Traditionalternarycompositefloodingcanimproveoildisplacementefficiencythroughthesynergisticactionofalkali,surfactant,andpolymer,buttheadditionofstrongalkalieasilyinducesclaydispersionandmigrationintheformation,causingareductioninreservoirpermeability,andmayalsoresultinscalinginthereservoirandwellbore,increasingon-siteconstructiondifficultyandproductioncosts.Moreover,severeadsorptionandretentionofsurfactantsandpoorstabilityoftheoildisplacementsystemremainissues. -2-SUMMARYThepurposeofthepresentinventionistoprovideaternarycompositeoildisplacementsystembasedonthesynergisticenhancementofnanofluidandpolymer,soastosolvetheproblemsthatunderhigh-temperatureandhigh-mineralizationreservoirconditions,polymermoleculesarepronetothermaldegradationandsalt-sensitivedegradation,resultinginasharpdecreaseinviscosityandasignificantreductioninoildisplacementefficiency;andthatalthoughtraditionalternarycompositefloodingcanimproveoildisplacementefficiencythroughthesynergisticactionofalkali,surfactant,andpolymer,theadditionofstrongalkalieasilyinducesclaydispersionandmigrationintheformation,causingareductioninreservoirpermeability.Toachievetheabovepurpose,thepresentinventionprovidesthefollowingtechnicalsolution:aternarycompositeoildisplacementsystembasedonthesynergisticenhancementofnanofluidandpolymer,comprisingapre-treatmentunit,ananofluidsupplyunit,atemperature-resistantandsalt-tolerantpolymersupplyunit,acompositemixingunit,anonlineefficiency-enhancinginjectionunit,andareservoircooperativedisplacementunit;theoutletofthepre-treatmentunitisconnectedtothecompositemixingunit,thenanofluidsupplyunitandthetemperature-resistantandsalt-tolerantpolymersupplyunitareconnectedinparalleltothecompositemixingunit,andtheoutletofthecompositemixingunitisconnectedtothereservoircooperativedisplacementunitviatheonlineefficiency-enhancinginjectionunit;themodifiednanoparticlesoutputfromthenanofluidsupplyunitformhydrogenbondsandelectrostaticadsorptioncompositeinteractionswiththetemperature-resistantandsalt-tolerantpolymermoleculesinthecompositemixingunit.Thecompositeinteractionsservetoimprovethesolubilityandviscositystabilityofthetemperature-resistantandsalt-tolerantpolymerinhigh-mineralizationformationwater.Themodifiednanoparticlesadsorbontotherockporewalls,achievingsmall-porepluggingandflowdiversionthroughadsorptionbridging.Thetemperature-resistantandsalt-tolerantpolymermolecularchainsformathree-dimensionalnetworkstructureintheporechannels,constructingahigh-viscositycontinuousphasetoachieveflowcontrol. -3-Asapreferredembodiment,thenanofluidsupplyunitcomprisesananofluidpreparationtank,afirstagitator,anultrasonicdisperser,aconstant-temperatureheatingjacket,andafirstmeteringpump;theultrasonicdisperserisarrangedinsidethenanofluidpreparationtank,theconstant-temperatureheatingjacketiswrappedaroundtheouterwallofthenanofluidpreparationtank,andtheoutletofthefirstmeteringpumpisconnectedtothecompositemixingunit,forcontinuouslysupplyingstablydispersedmodifiednanofluidtothecompositemixingunit.Asapreferredembodiment,thenanofluidisasilica / grapheneoxidecompositenanofluid,withnanoparticlessurface-graftedwithhydroxyl,carboxyl,orsulfonichydrophilicmodificationgroups,particlesizeof30–150nm,andmassfractionof0.05%–0.5%.Asapreferredembodiment,thetemperature-resistantandsalt-tolerantpolymersupplyunitcomprisesapolymermaturationtank,alow-speedshearagitator,ananti-settlingfilter,andasecondmeteringpump;theanti-settlingfilterisarrangedinthemiddle-lowerpartofthepolymermaturationtank,andthesecondmeteringpumpdeliversthefullymaturedpolymerstocksolutiontothecompositemixingunitinproportion.Asapreferredembodiment,thepolymerisatemperature-resistantandsalt-toleranthydrophobicallyassociativepolyacrylamide,withamolecularweightof12–25million,massconcentrationof0.08%–0.3%,maintainingstableviscosityunderconditionsof60–95 °Candmineralizationof5,000–20,000mg / L.Asapreferredembodiment,thecompositemixingunitcomprisesamulti-stagestaticmixer,anonlineconcentrationsensor,anonlineviscositysensor,andaflowcontrolvalve.Spiralbafflebladesarearrangedinsidethemulti-stagestaticmixer,andtheonlineconcentrationsensorandviscositysensorprovidereal-timefeedbackandadjusttheratio.Asapreferredembodiment,thereservoircooperativedisplacementunitcomprisesalow-permeabilityreservoirformation,rockporechannels,crudeoilemulsificationtransportchannels,andresidualoilstrippinginterfaces.Asapreferredembodiment,theonlineefficiency-enhancinginjectionunitcomprisesaninjectionpump,apressuresensor,acheckvalve,injectionpipelines,and. -4-awellheaddistributor.Theinjectionpumpoutputpressureis10–35MPa,thecheckvalvepreventsbackflowofformationfluids,andthewellheaddistributorevenlydistributestheternarycompositesystemtoeachinjectionwell.Asapreferredembodiment,thepre-treatmentunitcomprisesabufferliquidstoragetank,aboosterpump,andpre-treatmentinjectionpipelines,whereinthebufferliquidstoresalow-concentrationclaystabilizerandwettingmodificationsolution.Asapreferredembodiment,theonlineefficiency-enhancinginjectionunitisfurtherprovidedwithafrequencyconversioncontroller,thecontrolterminalofwhichiselectricallyconnectedtotheinjectionpump.Comparedwiththepriorart,thebeneficialeffectsofthepresentinventionareasfollows:Theternarycompositeoildisplacementsystembasedonthesynergisticenhancementofnanofluidandpolymer,throughthesynergisticactionofnanofluidandtemperature-resistantandsalt-tolerantpolymer,achievesthemultiplesynergisticeffectsof"dispersionstability–viscosityenhancement–seepageregulation–residualoilstripping";themodifiednanoparticlesformhydrogenbondingandelectrostaticadsorptioncomplexinteractionwiththetemperature-resistantandsalt-tolerantpolymermolecules,whichnotonlysignificantlyimprovesthesolubilityandviscositystabilityofthepolymerunderhigh-temperatureandhigh-mineralizationformationwaterconditions,avoidingthedegradationofpolymermolecularchains,butalsocanblocksmallporethroatsandguidetheflowoftheoildisplacementsystemtowardmediumandlargeporethroatsthroughadsorptionbridging,expandingthesweeprangeofoildisplacement.Theternarycompositeoildisplacementsystembasedonthesynergisticenhancementofnanofluidandpolymer,thethree-dimensionalnetworkstructureformedbypolymermolecularchainsconstructsahigh-viscositycontinuousphase,effectivelycontrollingthemobilityratioandreducingfingeringoftheoildisplacementsystem,whilethenanofluidcanreducetheoil–waterinterfacialtensionandpromotethestrippingofresidualoilfromtherocksurface;thesynergisticactionofthetwogreatlyimprovestheoildisplacementefficiency;experimentsshowthat,comparedwithconventionalpolymerflooding,theoilrecoverycanbeincreasedbytheoildisplacementsystemofthepresentinvention,andtheselectedsilica / grapheneoxidecompositenanofluidandtemperature-resistantandsalt-toleranthydrophobically. -5-associatingpolyacrylamidebothhaveexcellenttemperatureandsaltresistanceperformance.Theternarycompositeoildisplacementsystembasedonthesynergisticenhancementofnanofluidandpolymer,throughthepre-treatmentunit,caneffectivelyinhibitthedispersionandmigrationofclayparticles,protectingthereservoirpermeability;thenanofluidadsorbedontherockporewallcanformaprotectivefilm,reducingthecorrosionanddamageoftheoildisplacementagenttotherock,andsimultaneouslyblocksmallporethroatstopreventformationsandproduction;theoildisplacementsystemdoesnotcontainstrongalkali,willnotcauseformationscalingandclayswelling,andcaneffectivelyprotectthereservoirgeologicalenvironment,extendingtheservicelifeofthereservoir.Theternarycompositeoildisplacementsystembasedonthesynergisticenhancementofnanofluidandpolymer,theclaystabilizerandwettability-modifyingliquidofthepre-treatmentunitcanfurtheroptimizethereservoirenvironment,inhibitclaymigration,improverockwettability,sothattheoildisplacementsystemcanadapttovariouscomplexreservoirenvironmentssuchashightemperature,highsalinity,andlowpermeability,broadeningtheapplicationrangeoftheoildisplacementsystem.BRIEFDESCRIPTIONOFTHEFIGURESFigure1isaschematicdiagramoftheternarycompositeoildisplacementsystemofthepresentinvention,basedonthesynergisticeffectsofnanofluidsandpolymers.DETAILEDDESCRIPTIONOFTHEINVENTIONThepresentinventionisfurtherdescribedbelowinconjunctionwithspecificembodiments.Thefollowingembodimentsareprovidedtoillustratethepresentinventionbutarenotintendedtolimitthescopeofitsprotection.Theconditionssetforthintheseembodimentsmaybefurtheradjustedbasedonspecificcircumstances;anysimplemodificationstothemethodofthepresentinvention—providedtheyremainwithintheconceptualframeworkoftheinvention—fallwithinthescopeofprotectionclaimedherein.ReferringtoFigure1,thepresentinventionprovidesaternarycompositeoildisplacementsystembasedonthesynergisticenhancementofnanofluidandpolymer,. -6-includingapre-treatmentunit,ananofluidsupplyunit,atemperature-resistantandsalt-tolerantpolymersupplyunit,acompositemixingunit,anonlineenhancementinjectionunit,andaformationsynergisticdisplacementunit;theoutletofthepre-treatmentunitisconnectedtothecompositemixingunit,thenanofluidsupplyunitandthetemperature-resistantandsalt-tolerantpolymersupplyunitareconnectedinparalleltothecompositemixingunit,andtheoutletofthecompositemixingunitisconnectedtotheformationsynergisticdisplacementunitthroughtheonlineenhancementinjectionunit;themodifiednanoparticlesoutputfromthenanofluidsupplyunitformhydrogenbondingandelectrostaticadsorptioncomplexinteractionwiththetemperature-resistantandsalt-tolerantpolymermoleculesinthecompositemixingunit,andthecomplexinteractionisusedtoimprovethesolubilityandviscositystabilityofthetemperature-resistantandsalt-tolerantpolymerinhigh-mineralizationformationwater;themodifiednanoparticlesadsorbontotherockporewalls,achievesmallporethroatblockingandflowdiversionthroughadsorptionbridging,andthetemperature-resistantandsalt-tolerantpolymermolecularchainsformathree-dimensionalnetworkstructureintheporechannels,constructingahigh-viscositycontinuousphasetorealizeflowcontrol.Thepre-treatmentunitincludesabuffersolutionstoragetank,aboosterpump,andapre-treatmentinjectionpipeline,andthebuffersolutionstoreslow-concentrationclaystabilizerandwettability-modifyingliquid;thebuffersolutionstoragetankismadeofcorrosion-resistantandhigh-temperature-resistantmaterials,andthevolumeisdesignedaccordingtothereservoirdevelopmentscaleandpre-treatmentrequirements;theinnerwallofthetankiscoatedwithananti-corrosionlayertopreventcorrosionofthetankbythebuffersolution;theboosterpumpisavariable-frequencyboosterpump,capableofflexiblyadjustingtheoutputpressureaccordingtotheformationpressurerequirements,ensuringthatthebuffersolutioncanbestablyinjectedintothecompositemixingunitwhileavoidingpipelinedamagecausedbyexcessivepressure;thepre-treatmentinjectionpipelineismadeofhigh-strengthpressure-resistantpipeline,withasmoothinnerwalltoreduceflowresistanceofthebuffersolution,andtheouterwallisequippedwithaninsulationlayertopreventtemperaturechangesfromaffectingthepre-treatmenteffect.Thecorefunctionofthepre-treatmentunitistopre-treatthesubsequentlyinjectedoildisplacementsystem,andthelow-concentrationclaystabilizercaneffectivelyinhibitthedispersionandmigrationofformationclayparticles,preventingclayparticlesfromblockingrockporechannelsandprotecting; -7-reservoirpermeability;thewettability-modifyingliquidcanchangethewettabilityoftherocksurfacefromoil-wettowater-wet,reducingtheadsorptionofcrudeoilontherocksurface,layingafoundationforthesubsequentdisplacementoftheoildisplacementsystem,andsimultaneouslyreducingtheadsorptionandretentionoftheoildisplacementagentontherocksurface,improvingtheutilizationefficiencyoftheoildisplacementagent.Thenanofluidsupplyunitincludesananofluidpreparationtank,afirstagitator,anultrasonicdisperser,aconstant-temperatureheatingjacket,andafirstmeteringpump;theultrasonicdisperserisarrangedinsidethenanofluidpreparationtank,theconstant-temperatureheatingjacketwrapstheouterwallofthenanofluidpreparationtank,andtheoutletofthefirstmeteringpumpisconnectedtothecompositemixingunitforcontinuouslysupplyingstablydispersedmodifiednanofluidtothecompositemixingunit.Thenanofluidpreparationtankisasealedstructure,andtheinnerwallofthetankisprovidedwithanagitatormountingseatandanultrasonicdispersermountinggroovetoensureuniformmixinganddispersion;Thefirstagitatorisalow-speedshearagitatorwithadjustablestirringspeedtoavoidnanoparticleaggregationcausedbyhigh-speedstirring;thestirringbladesaremadeofcorrosion-resistantmaterial,closelyfittedwiththeinnerwallofthetank,ensuringuniformmixingofthematerialsinsidethetank;theultrasonicdisperserusesahigh-frequencyultrasonicgeneratorwithafrequencyof20–80kHz,effectivelybreakingnanoparticleaggregates,dispersingnanoparticlesuniformlyinthebasefluid,andimprovingthestabilityofthenanofluid;Theconstant-temperatureheatingjacketuseselectricheating,withatemperatureadjustmentrangeof20–100℃,capableofpreciselycontrollingthetanktemperatureaccordingtothepreparationrequirementsofthenanofluid,ensuringnanoparticledispersionandstability;thefirstmeteringpumpisahigh-precisionmeteringpumpwithanaccuracyerrornotexceeding±1%,capableofpreciselycontrollingthesupplyofnanofluidaccordingtotherequirementsofthecompositemixingunit,achievingprecisenanofluid-to-polymerratio,andensuringthesynergisticenhancementeffect.Thenanofluidisasilica / grapheneoxidecompositenanofluid,withnanoparticlesurfacesgraftedwithhydroxyl,carboxyl,orsulfonichydrophilicmodificationgroups,particlesizeof30–150nm,andmassfractionof0.05%–0.5%.Thesilica / graphene; -8-oxidecompositenanoparticlesarepreparedbyasol–gelmethod,combiningthehighstabilityofsilicaandthehighspecificsurfaceareaandhighadsorptioncapacityofgrapheneoxide;bygraftinghydrophilicmodificationgroupsonthesurface,thehydrophilicityanddispersibilityofthenanoparticlesaresignificantlyimproved,avoidingnanoparticleaggregationinwaterandenhancingtheinteractionbetweennanoparticlesandpolymermolecules;Theparticlesizeiscontrolledat30–150nm,ensuringsufficientspecificsurfaceareaandsurfaceactivityofthenanoparticleswhileavoidingporeblockagecausedbyexcessivelylargeparticles,ensuringinjectabilityofthenanofluid;themassfractioniscontrolledat0.05%–0.5%,ensuringthesynergisticenhancementeffectwhilereducingthepreparationcostofthenanofluidandavoidingabnormalviscosityoftheoildisplacementsystemcausedbyexcessivenanoparticleconcentration,whichwouldaffectinjectionperformance.Experimentsshowthatthiscompositenanofluidhasgooddispersionstabilityunderconditionsof60–95℃andmineralizationof5000–20000mg / L,withnosignificantaggregationafter72hoursofstanding.Thetemperature-resistantandsalt-tolerantpolymersupplyunitincludesapolymermaturationtank,alow-speedshearagitator,ananti-settlingfilter,andasecondmeteringpump;theanti-settlingfilterisarrangedinthemiddle-lowerpartofthepolymermaturationtank,andthesecondmeteringpumpproportionallydeliversthefullymaturedpolymerstocksolutionintothecompositemixingunit.Thepolymermaturationtankadoptsaninsulatedstructure,andtheinnerwallofthetankiscoatedwithananti-corrosionlayertopreventcorrosionofthetankbythepolymerstocksolution,whiletheouterwallofthetankisprovidedwithaninsulationlayertoensuretemperaturestabilityduringthematurationprocess.Thelow-speedshearagitatoroperatesatastirringspeedof50–150r / min,achievingfulldissolutionandmaturationofthepolymer,whileavoidingmolecularchainbreakagecausedbyhigh-speedshearing,whichwouldaffectthepolymer’sviscosityandoildisplacementperformance.Theanti-settlingfilterismadeofhigh-precisionstainlesssteelmeshwithaporesizeof100–200mesh,effectivelyfilteringincompletelydissolvedparticulateimpuritiesinthepolymerstocksolutionwhilepreventingpolymersedimentationandensuringthatthepolymerstocksolutionenteringthecompositemixingunitisuniformandstable.Thesecondmeteringpump. -9-hasthesamespecificationsasthefirstmeteringpump,ensuringpreciseandcontrollableratiobetweenthepolymerstocksolutionandthenanofluid,achievingsynergisticenhancementbetweenthetwo.Thepolymerisatemperature-resistantandsalt-toleranthydrophobicallyassociativepolyacrylamide,withamolecularweightof12–25millionandamassconcentrationof0.08%–0.3%,maintainingviscositystabilityunderconditionsof60–95℃andmineralizationof5000–20000mg / L.Thishydrophobicallyassociativepolyacrylamideintroduceshydrophobicgroupsintothepolyacrylamidemolecularchainsthroughmolecularstructuredesign,forminghydrophobicassociations,whicheffectivelyimprovethepolymer’stemperatureandsalttolerance,preventingmolecularchaindegradationunderhigh-temperature,high-mineralizationconditionsandensuringviscositystabilityofthepolymersystem.Themolecularweightiscontrolledbetween12–25million,ensuringsufficiententanglementcapabilityofthepolymermolecularchainstoformastablethree-dimensionalnetworkstructureandachieveeffectiveflowcontrol.Themassconcentrationiscontrolledbetween0.08%–0.3%,meetingtheviscosityrequirementsofthepolymersystemwhilereducingpolymerconsumptionandcontrollingproductioncosts.Experimentsshowthatunderconditionsof95℃andmineralizationof20000mg / L,thepolymerretainsnolessthan85%ofitsviscosityafter72hours,demonstratingexcellenttemperatureandsalttolerance.Thecompositemixingunitincludesamulti-stagestaticmixer,anonlineconcentrationsensor,anonlineviscositysensor,andaflowcontrolvalve.Spiralbafflebladesareinstalledinsidethemulti-stagestaticmixer,andtheonlineconcentrationsensorandonlineviscositysensorprovidereal-timefeedbacktoadjustthemixingratio.Themulti-stagestaticmixeradoptsa2–4stageseriesstructure,withspiralbafflebladesinstalledineachstage;thespiralbafflebladesensurefullcontactandmixingbetweenthenanofluidandthepolymerstocksolutionduringflow,achievinguniformcompositemixingandavoidinglocalconcentrationheterogeneitythatcouldweakenthesynergisticeffect.Theonlineconcentrationsensorcandetectthenanoparticleandpolymerconcentrationsinthemixedoildisplacementsysteminrealtime,withadetectionaccuracyerrornotexceeding±0.01%.Theonlineviscositysensorcandetectthe. -10-viscosityoftheoildisplacementsysteminrealtime,withadetectionrangeof10–1000mPa·sandadetectionaccuracyerrornotexceeding±5%.Theflowcontrolvalveislinkedtotheonlineconcentrationsensorandonlineviscositysensor,automaticallyadjustingtheoutputflowofthenanofluidsupplyunitandthetemperature-resistantandsalt-tolerantpolymersupplyunitaccordingtoreal-timedata,ensuringthattheconcentrationandviscosityofthemixedoildisplacementsystemmeetthedesignrequirementsandmaximizingthesynergisticenhancementeffect.Thecorefunctionofthecompositemixingunitistoachievepreciseanduniformmixingofthenanofluidandthetemperature-resistantandsalt-tolerantpolymer,providingastableoildisplacementsystemforsubsequentinjectionanddisplacement.Theformationsynergisticdisplacementunitincludesalow-permeabilityreservoirformation,rockporechannels,crudeoilemulsifiedcarryingchannels,andresidualoilstrippinginterfaces.Thelow-permeabilityreservoirformationservesasthetargetoftheoildisplacementsystem,withaporosityof5%–15%andapermeabilityof1–50mD,representingatypicallow-permeabilityreservoir.Therockporechannelsserveasflowpathsforcrudeoilandtheoildisplacementsystem,withunevenporesizedistribution,includingsmallpores(lessthan100nm),mediumpores(100nm–1μm),andlargepores(greaterthan1μm).Themodifiednanoparticlescanblockthesmallporechannelsthroughadsorptionbridging,guidingtheoildisplacementsystemtowardmediumandlargeporechannels,therebyincreasingthesweepefficiencyoftheoildisplacementsystem.Thecrudeoilemulsifiedcarryingchannelsareformedbyemulsificationoftheoildisplacementsystemwithcrudeoil;thethree-dimensionalnetworkstructureformedbythetemperature-resistantandsalt-tolerantpolymermolecularchainscanencapsulatethecrudeoilemulsion,achievingefficientcarryingofcrudeoil.Theresidualoilstrippinginterfaceisthecontactinterfacebetweentheoildisplacementsystemandtheresidualoilontherocksurface.Thenanofluidcanreducetheoil–waterinterfacialtension,promotingthedetachmentofresidualoilfromtherocksurface,whilethehigh-viscositycontinuousphaseformedbythepolymercandrivethedetachedresidualoiltowardtheproductionwells,achievingefficientdisplacementofresidualoil. -11-Theonlineenhancementinjectionunitincludesaninjectionpump,apressuresensor,acheckvalve,aninjectionpipeline,andawellheaddistributor.Theinjectionpumpprovidesanoutputpressureof10–35MPa.Thecheckvalvepreventsbackflowofformationfluids,andthewellheaddistributorevenlydistributestheternarycompositesystemtoeachinjectionwell.Theinjectionpumpisahigh-pressureplungerpump,whichcanflexiblyadjusttheoutputpressureaccordingtoformationpressurerequirements,ensuringsmoothinjectionoftheoildisplacementsystemintothereservoirformation,withanoutputpressurecontrolledbetween10–35MPatoadapttoreservoirsofdifferentdepthsandpermeabilities.Thepressuresensormonitorsinjectionpressureinrealtime;whenthepressureexceedsasetthreshold,itautomaticallytriggersanalarmtopreventformationfracturingorpipelinedamagecausedbyexcessivepressure.Thecheckvalveisahigh-pressurecheckvalveinstalledattheendoftheinjectionpipelineneartheformation,effectivelypreventingformationfluids(crudeoil,formationwater)frombackflowingintotheinjectionpipeline,avoidingcontaminationoftheoildisplacementsystemanddamagetotheinjectionequipment.Theinjectionpipelineismadeofhigh-strength,pressure-resistanttubing,withadiameterdesignedaccordingtotheinjectionflowrate;theinnerwallissmoothtoreduceflowresistanceoftheoildisplacementsystem,andtheouterwallisinsulatedtopreventtemperaturechangesfromaffectingtheperformanceoftheoildisplacementsystem.Thewellheaddistributoradoptsamulti-channeldistributionstructure,evenlydistributingthemixedoildisplacementsystemtoeachinjectionwell,ensuringconsistentinjectionvolumeacrosswellsandachievinguniformreservoirdisplacement.Theonlineenhancementinjectionunitisfurtherequippedwithavariablefrequencycontroller,withitscontrolterminalelectricallyconnectedtotheinjectionpump.Thevariablefrequencycontrollercanautomaticallyadjustthepumpspeedbasedontheinjectionpressuredetectedbythepressuresensorandformationrequirements,therebycontrollinginjectionflowandpressurewithprecision.Simultaneously,thevariablefrequencycontrollerhasenergy-savingfunctionality,adjustingmotorpoweraccordingtochangesininjectionloadtoreduceenergyconsumptionandlowerproductioncosts. -12-Additionally,thevariablefrequencycontrollerisequippedwithoverloadprotection,short-circuitprotection,andotherfunctions,effectivelyprotectingtheinjectionpumpequipmentandextendingitsservicelife.Example1Aternarycompositeoildisplacementsystembasedonnanofluidandpolymersynergisticenhancement,suitableforalow-permeabilityreservoirat60 °Cand5000 mg / Lmineralization(permeability10 mD,porosity10%).Pre-treatmentunit:Thebuffersolutiontankhasavolumeof10 m³,storingaclaystabilizeratamassconcentrationof0.1%(polyquaternaryammoniumsalt)andawettingmodifierat0.05%(sodiumdodecylbenzenesulfonate);theboosterpumpisavariable-frequencyboosterpumpwithanadjustableoutputpressurerangeof5–10 MPa;thepre-treatmentinjectionpipelinehasadiameterof100 mmandisexternallyinsulated.Nanofluidsupplyunit:Thenanofluidpreparationtankhasavolumeof5 m³,thefirstagitatoroperatesat80 r / min,theultrasonicdisperserfrequencyis40 kHz,andthethermostaticheatingsleevetemperatureiscontrolledat40 °C;thefirstmeteringpumphasameasurementaccuracyof±0.5%;thenanofluidisasilica / grapheneoxidecompositenanofluidwithsurface-graftedhydroxylgroups,particlesize30–80 nm,andamassfractionof0.05%.Temperature-resistantandsalt-tolerantpolymersupplyunit:Thepolymermaturationtankhasavolumeof8 m³,thelow-speedshearagitatorrotatesat100 r / min,andtheanti-settlingfilterhasameshsizeof150mesh;thesecondmeteringpumpisofthesamespecificationasthefirstmeteringpump;thepolymeristemperature-resistantandsalt-toleranthydrophobicallyassociatingpolyacrylamide,withamolecularweightof12millionandmassconcentrationof0.08%.Compositemixingunit:Usesa2-stagestaticmixer,internallyequippedwithhelicalbaffleblades;theonlineconcentrationsensorhasameasurementaccuracyof±0.01%,andtheonlineviscositysensormeasures10–500 mPa·s;theflowcontrolvalveislinkedtothesensorsandautomaticallyadjuststheproportion.Onlineenhancementinjectionunit:Theinjectionpumpoutputpressureis10–20 MPa,withapressuresensoraccuracyof±0.1 MPa;thecheckvalveisahigh-pressure. -13-checkvalve,andtheinjectionpipelinediameteris80 mm;thewellheaddistributorhasa4-channeldistributionstructure;thevariablefrequencycontrolleriselectricallyconnectedtotheinjectionpumpandcanadjustthepumpspeed.Formationsynergisticdisplacementunit:Thelow-permeabilityreservoirformationhasaporosityof10%andpermeabilityof10 mD;rockporechannelshaveporesizesrangingfrom30 nmto5 μm;crudeoilemulsifiedcarryingchannelsareformedbytheoildisplacementsystemandcrudeoil;residualoilstrippingisachievedthroughthesynergisticactionofthenanofluidandpolymer.Operationprocess:Inthisexample,theworkingprocessoftheoildisplacementsystemisasfollows:First,thebuffersolutionfromthepre-treatmentunitisinjectedintothecompositemixingunitviatheboosterpumpforpre-treatmentofthesubsequentoildisplacementsystem.Simultaneously,inthenanofluidsupplyunit,thecompositenanoparticlesinthepreparationtankformastablenanofluidunderstirringandultrasonicdispersionandareinjectedintothecompositemixingunitatasetflowratebythefirstmeteringpump.Inthepolymersupplyunit,thepolymerisfullymaturedanddissolvedinthematurationtank,filteredthroughtheanti-settlingfilter,andinjectedintothecompositemixingunitatasetflowratebythesecondmeteringpump.Thenanofluidandpolymersolutionarefullymixedinthemulti-stagestaticmixerofthecompositemixingunit.Theonlineconcentrationsensorandviscositysensormonitortheconcentrationandviscosityofthemixedoildisplacementsysteminrealtime.Theflowcontrolvalveadjuststhesupplyvolumestoensuretheoildisplacementsystemmeetsthedesignrequirements.Thequalifiedmixedoildisplacementsystemispressurizedbytheinjectionpumpintheonlineenhancementinjectionunit,anduniformlyinjectedintothereservoirformationthroughtheinjectionpipelineandwellheaddistributor.Thecheckvalvepreventsbackflowofformationfluids,andthevariablefrequencycontrolleradjuststheinjectionpumpparametersaccordingtopressuresensordata.Inthereservoirformation,themodifiednanoparticlesandpolymermoleculesformsynergisticinteractions,achievingsmall-poreblocking,mobilitycontrol,andresidualoilstripping.Thestrippedresidualoilistransportedtotheproductionwellthroughthecrudeoilemulsifiedcarryingchannels,completingcrudeoilrecovery.Experimentalverificationshowsthattheoildisplacementsysteminthisexamplecanincreasetheoilrecoveryfactorbymorethan8%. -14-Example2Aternarycompositeoildisplacementsystembasedonnanofluidandpolymersynergisticenhancement,suitableforalow-permeabilityreservoirat95 °Cand20000 mg / Lmineralization(permeability5 mD,porosity8%).Pre-treatmentunit:Thebuffersolutiontankhasavolumeof15 m³,storingaclaystabilizeratamassconcentrationof0.2%(polyepoxypropyltrimethylammoniumchloride)andawettingmodifierat0.1%(fattyalcoholpolyoxyethyleneether);theboosterpumpisavariable-frequencyboosterpumpwithanadjustableoutputpressurerangeof8–15 MPa;thepre-treatmentinjectionpipelinehasadiameterof120 mmandisexternallyinsulated.Nanofluidsupplyunit:Thenanofluidpreparationtankhasavolumeof8 m³,thefirstagitatorrotatesat120 r / min,theultrasonicdisperserfrequencyis60 kHz,andthethermostaticheatingsleevetemperatureiscontrolledat60 °C;thefirstmeteringpumphasameasurementaccuracyof±0.5%;thenanofluidisasilica / grapheneoxidecompositenanofluidwithsurface-graftedsulfonicgroups,particlesize100–150 nm,andamassfractionof0.5%.Temperature-resistantandsalt-tolerantpolymersupplyunit:Thepolymermaturationtankhasavolumeof12 m³,thelow-speedshearagitatorrotatesat150 r / min,andtheanti-settlingfilterhasameshsizeof200mesh;thesecondmeteringpumpisofthesamespecificationasthefirstmeteringpump;thepolymeristemperature-resistantandsalt-toleranthydrophobicallyassociatingpolyacrylamide,withamolecularweightof25millionandmassconcentrationof0.3%.Compositemixingunit:Usesa4-stagestaticmixer,internallyequippedwithhelicalbaffleblades;theonlineconcentrationsensorhasameasurementaccuracyof±0.01%,andtheonlineviscositysensormeasures200–1000 mPa·s;theflowcontrolvalveislinkedtothesensorsandautomaticallyadjuststheproportion.Onlineenhancementinjectionunit:Theinjectionpumpoutputpressureis25–35 MPa,withapressuresensoraccuracyof±0.1 MPa;thecheckvalveisahigh-pressurecheckvalve,andtheinjectionpipelinediameteris100 mm;thewellheaddistributorhasa6-channeldistributionstructure;thevariablefrequencycontrolleriselectricallyconnectedtotheinjectionpumpandcanadjustthepumpspeed. -15-Formationsynergisticdisplacementunit:Thelow-permeabilityreservoirformationhasaporosityof8%andpermeabilityof5 mD;rockporechannelshaveporesizesrangingfrom50 nmto3 μm;crudeoilemulsifiedcarryingchannelsareformedbytheoildisplacementsystemandcrudeoil;residualoilstrippingisachievedthroughthesynergisticactionofthenanofluidandpolymer.TheworkingprocessofthisexampleissubstantiallythesameasthatofExample1.Experimentalverificationshowsthatinhigh-temperature,high-mineralization,low-permeabilityreservoirs,thepolymermaintains88%viscosityretention,thenanofluidexhibitsgooddispersionstability,andtheoilrecoveryfactorisincreasedbymorethan15%,demonstratingexcellenttemperature-andsalt-resistanceperformanceandoildisplacementefficiency.Theaboveexamplesaremerelypreferredembodimentsofthepresentinventionanddonotlimitthescopeoftheinvention.Thoseskilledintheartcanmakevariousmodificationsandadjustmentswithoutdepartingfromthespiritandscopeoftheinvention;therefore,theprotectionscopeoftheinventionshallbedeterminedbytheclaims.Althoughembodimentsofthepresentinventionhavebeenshownanddescribed,itwillbeunderstoodbythoseskilledintheartthatvariouschanges,modifications,substitutions,andvariationscanbemadewithoutdepartingfromtheprinciplesoftheinvention,andthescopeoftheinventionisdefinedbytheappendedclaimsandtheirequivalents. -16-

Claims

1. A ternary composite oil displacement system based on the synergistic reinforcement of nanofluid and polymer, with the characteristic that it comprises: a pretreatment unit, a nanofluid feed unit, a feed unit for temperature-resistant and salt-tolerant polymer, a composite mixing unit, an online reinforcement injection unit and a unit for synergistic formation displacement; where the outlet of the pretreatment unit is connected to the composite mixing unit; the nanofluid feed unit and the feed unit for temperature-resistant and salt-tolerant polymer are connected in parallel with the composite mixing unit; and the outlet of the composite mixing unit via the online The amplification injection unit is connected to the synergistic unit. formation displacement; whereby the modified nanoparticles that by the nanofluid supply unit are released, hydrogen bonds and composite interactions form with the molecules of the molecules via electrostatic adsorption temperature-resistant and salt-tolerant polymer in the composite mixing unit; whereby these composite interactions are arranged in such a way that they the solubility and the viscosity stability of the temperature-resistant and salt-tolerant polymer improve under conditions of formation water with a high degree of mineralization; where the modified nanoparticles are adsorbed on the surfaces of the rock pores to block small pores and divert the flow achieve by means of adsorption bridge formation; and where the molecular chains of the temperature-resistant and salt-tolerant polymer a three-dimensional form a network structure within the pore channels to form a continuous phase with high to create viscosity for the purpose of flow control.

2. The ternary composite oil displacement system based on the synergistic reinforcement of nanofluid and polymer in accordance with claim 1, characterized that the nanofluid supply unit includes: a preparation tank for the nanofluid, a first agitator, an ultrasonic disperser, a heating jacket with constant temperature and a first dosing pump; whereby the ultrasonic disperser is located in the preparation tank for the nanofluid is located; the heating jacket with constant temperature encloses the outer wall of the preparation tank for the nanofluid; and the -17- outlet of the first dosing pump is connected to the composite mixing unit for the continuous supply of stable dispersed, modified nanofluid to the composite mixing unit.

3. The ternary composite oil displacement system based on the synergistic reinforcement of nanofluid and polymer in accordance with claim 2, characterized in that it nanofluid is a silica / graphene oxide composite nanofluid, where the surfaces of the nanoparticles are inoculated with hydrophilic modification groups such as hydroxyl-, carboxyl or sulfone groups, the particle size varies from 30 to 150 nm and the Mass fraction varies from 0.05% to 0.5%.

4. The ternary composite oil displacement system based on the synergistic reinforcement of nanofluid and polymer in accordance with claim 1, characterized that the temperature-resistant and salt-tolerant polymer feed unit polymer maturation tank, a slow-rotating slide stirrer, an anti-settlement includes filter and a second dosing pump; where the anti-settling filter is placed in the middle to lower part of the polymer maturation tank, and the second dosing pump supplies the fully matured polymer mother liquor proportionally to the composite mixing unit.

5. The ternary composite oil displacement system based on the synergistic reinforcement of nanofluid and polymer in accordance with claim 4, characterized in that it polymer a temperature-resistant and salt-tolerant hydrophobic associative polyacrylamide is, with a molecular weight of 12-25 million and a mass concentration of 0.08%-0.3%, which maintains its viscosity stability under conditions of 60-95 °C and a salt content of 5,000-20,000 mg / L.

6. The ternary composite oil displacement system based on the synergistic reinforcement of nanofluid and polymer in accordance with claim 1, characterized that the composite mixing unit a multistage static mixer, an online includes a concentration sensor, an online viscosity sensor and a flow control valve, where the multistage static mixer is internally equipped with spiral baffle plates, and the online concentration sensor and online viscosity sensor provide real-time feedback -18- to adjust the mixing ratio.

7. The ternary composite oil displacement system based on the synergistic reinforcement of nanofluid and polymer in accordance with claim 6, characterized that the formation-synergistic displacement unit a reservoir formation with low permeability, pore channels in the rock, channels for transporting includes emulsified crude oil and interfaces for stripping residual oil.

8. The ternary composite oil displacement system based on the synergistic reinforcement of nanofluid and polymer in accordance with claim 1, characterized that the online amplification injection unit an injection pump, a pressure sensor, a check valve, comprises an injection line and a wellhead distributor, where the outlet pressure of the injection pump amounts to 10-35 MPa, the check valve backflow of prevents formation fluids and the sump head distributor the ternary composite system evenly distributed over each injection well.

9. The ternary composite oil displacement system based on the synergistic reinforcement of nanofluid and polymer in accordance with claim 1, characterized that the pretreatment unit a buffer liquid storage tank, a lift pump and a includes pretreatment injection line, where the buffer fluid contains clay stabilizers with low concentration and liquids for wetting modification.

10. The ternary composite oil displacement system based on the synergistic reinforcement of nanofluid and polymer in accordance with claim 1, characterized that the online amplification injection unit is also equipped with a frequency converter, where the control terminal of the frequency converter is electrically connected to the injection pump. 1 / 1 Figure1

Images