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英文文献.docx

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英文文献

Methodofcontinuousdissolutionofpolyacrylamideemulsionsforenhancedoilrecovery（EOR）

EP2283915A1

Abstract

Enhancedoilrecoverymethodconsistingincontinuouslydissolving,intheinjectionwater,astableinvertemulsionofacrylamide（co）polymercontainingatleastoneinvertingagent,andawatersolublepolymer,whereby:

-inafirststep,theemulsionispredilutedinafirststaticmixertoa（co）polymerconcentrationofatleast5g/l,thedifferenceofpressurebetweenthemixeroutletandinletbeingatleast2bar,

-inasecondstep,thesuspensionfromthefirstmixerisdilutedinasecondstaticmixertoaconcentrationcorrespondingtotheinjectionconcentrationofthewaterinthewellofbetween500and3000ppm,thedifferenceofpressurebetweenthemixeroutletandinletbeingatleast1bar.

Claims

1.Enhancedoilrecoverymethodconsistingincontinuouslydissolving,intheinjectionwater,astableinvertemulsionofacrylamide（co）polymercontainingatleastoneinvertingagent,whereby:

-inafirststep,theemulsionispredilutedinafirststaticmixermountedonabypassofthemaininjectionwatercircuit,toa（co）polymerconcentrationofatleast5g/l,thedifferenceofpressurebetweenthemixeroutletandinletbeingatleast2bars,

-inasecondstep,thedispersionmixturefromthefirstmixerisdilutedinasecondstaticmixermountedonthemaininjectionwatercircuit,toaconcentrationcorrespondingtotheinjectionconcentrationofthewaterinthewellofbetween500and3000ppm,thedifferenceofpressurebetweenthemixeroutletandinletbeingatleast1bar.

2.MethodaccordingtoClaim1,characterizedinthatthe（co）polymerconcentrationinthefirststepisbetween5and20g/l,advantageouslyabout20g/l.

3.MethodaccordingtoClaim1,characterizedinthatthedifferenceofpressurebetweentheoutletandinletofthefirstmixerisbetween2and10bars,advantageously10bars.

4.MethodaccordingtoClaim1,characterizedinthatthedifferenceofpressurebetweentheoutletandinletofthesecondmixerisbetween1and3bars,advantageously3bars.

5.MethodaccordingtoClaim1,characterizedinthattheinjectionwaterflowrateinthemaincircuitisbetween100and200m3/hatapressureofbetween40and200barsgovernedbythefieldpressure.

6.MethodaccordingtoClaim1,characterizedinthatthe（co）polymercontentintheinvertemulsionbeforepredilutionisbetween20and50%.

7.InstallationimplementingthemethodaccordingtooneofClaims1to6.

Description

∙[0001]

Polyacrylamidesareproducedindustriallyinvariousforms:

powders,water-in-oilemulsions,polymerizedbeadsinsuspension,water-in-wateremulsions,aqueoussolutions,water-alcoholsuspensions,etc..

∙[0002]

Thesepolymersmayhavesimilarphysicochemicalpropertiesandareusuallyselectedontwocriteria:

oCostand,inthiscase,powdersareselected,

oTheireaseofhandlingand,despitehighercosts,emulsionsareselected.

∙[0003]

Theseemulsionswerediscoveredin1957byJ.W.VanderhoffandR.M.Wiley（USP3284393）.

∙[0004]

TheseearlyemulsionscontainedmicroparticlesofpolymersemulsifiedinanoilbymeansofoneormoresurfaceactiveagentshavingalowHLB（hydrophilic-hydrophobicbalance）ofabout2to6.Fortheseemulsionshavingsuchcomposition,,itwasverydifficulttodilutethepolymermicrogelsdirectlyinasolution.Indead,thedissolutionwaterhavedifficultiestopenetratethesurfaceactiveagentsbarriers.

∙[0005]

Theywerethereforeusuallydriedbyspraydryingtoyieldapowderwhichdissolvedmoreorlesssatisfactorily.

∙[0006]

In1970,D.R.AndersonandA.J.Frisque（patentUSP3624019）discoveredthatitwaspossibletoinverttheseemulsions,byaddingahydrophilicsurfaceactiveagent（HLB>8）.Thisratherhydrophilicsurfaceactiveagentenabledthewatertopenetrateintothepolymersphericalmicroparticuleandtodissolveitinafewminutes.

∙[0007]

Initially,thissurfaceactiveagentwasdeliveredandaddedseparatelytothedilutionwater.

∙[0008]

Butveryquickly,theproductioncompaniesdevelopedformulationsinwhichitwaspossibletoincorporateinvertingsurfaceactiveagentsintheemulsionitself,withoutlattercoagulatingorbeingdestabilized.

∙[0009]

Thisoperationwasarealtechnicalchallengebecauserequiredquantityofhydrophilicsurfaceactiveagentaddedwaslimitedbycoagulationordestabilizationeitherduringproductionorinstorage.

∙[0010]

Theindustrialimplementationofthismethodwasthesubjectofconsiderablesuccessiveresearchesandnumerouspatents.

∙[0011]

However,eventoday,limitationtoproperlyinvertanemulsionexist,withtwomainfactors:

oThequantityofhydrophilicsurfaceactiveagentthesystemcansustaintoavoidcoagulationoftheemulsionduringproductionorinstorage,

oTheconcentrationofpolymerreachedwhendissolvingtheemulsioninwater.

∙[0012]

Itiscommonlyfoundthatthemaximumquantityofhydrophilicsurfaceactiveagent,allsystemscombined,compatiblewiththestabilityoftheemulsion,isabout5%oftheemulsion.

∙[0013]

ThisquantityistheoneobservedwiththemosteffectiveNPD（ethoxylatednonylphenol9EO）surfaceactiveagentsorethoxylatedalcoholscontaining7-9EO.Largerquantitiesoflesseffectivesurfaceactiveagentscanbeadded,butwithoutimprovingthedissolution.

∙[0014]

Withsuchaconcentrationofreversingsurfaceactiveagents,itisfoundthattheemulsioncannotdissolvecompletelyinthewaterinlessthan5minutes,inanemulsionconcentrationlowerthan9-12grams/litreoronstandardcommercialemulsions,about4-5grams/litre（4to5000ppm）ofactivepolymer.

Particularcaseofenhancedoilrecovery

∙[0015]

Duetotheproductcosts,EORmainlyusespowderstoviscosifythewaterinjectedintotheoilwells.Thesepolyacrylamidepowdersaredissolvedtoafinalconcentrationof500to2000ppmforinjectionintotheoilwellatthefieldpressure.

∙[0016]

Incertaincases,andparticularlywhentheproductisusedonboats（FPSO）oroffshoreplatforms,thehandlingofverylargequantitiesofpowderbetweenaserviceboatandtheFPSOortheplatformraisesseverelimitationsassociatedwithairlifttransport,difficulttosolvetoday.

∙[0017]

Inthesesituations,theend-usersprefertouseanemulsionthatiseasiertotransferbystandardoffshorepumpingmeans.

∙[0018]

Therequirementsoftheend-usersareverystrict:

totaldissolutioninlessthan5minutes,completelyandcontinuously.

∙[0019]

Itisthereforenecessarytodissolvetheemulsiontoafinalconcentrationof500to2000ppminapipeinline,whichcannotbeobtainedwithastableemulsionincorporatedwithainvertingsurfaceactiveagentinconcentrationsensuringthestabilitythereof.

∙[0020]

Thetestaccordinglyusedconsistsinmeasuringthetimetakenbygivenvolumesofsolutioncontaining1000ppmofactivepolymertoflowthroughafilter.Thesolutioniscontainedinacellpressurizedto2barsandthefilterhasadiameterof47mmandaporesizeof5microns.

∙[0021]

Thetimesrequiredtoobtain100ml（t100ml）;200ml（t200ml）and300ml（t300ml）offiltratearethereforemeasuredandafiltrationquotient（orfilterratiodenoted"FR"）isdefined,expressedby:

FR=t300ml-t200mlt200ml-t100ml

∙[0022]

Thetimemeasurementaccuracyis0.1second.

∙[0023]

TheFRthusrepresentsthecapacityofthepolymersolutiontoplugthefilterfortwoequivalentconsecutivevolumes.AtypicalacceptabilitycriterionoftheindustryisFR<1.5.

∙[0024]

Itisclearthatthisleveloffilterabilitycannotbereachedevenafterseveralhoursofstirringinthelaboratory,andevenlessinindustrialconditionsforthedesiredconcentrationsof500and2000ppm.

∙[0025]

TheusualsolutionistofurtherincorporateaNP9type（nonylphenol9EO）surfaceactiveagentorethoxylatedoralkoxylatedalcoholordioctylsulphosuccinateorotheranionicsurfaceactiveagentinaproportionfarabove5%inthedilutionwater.Intheseconditions,theemulsionmaypassthefilterabilitytest.

∙[0026]

Thissolutionisdifficulttoacceptbytheuserbecause:

oTwodifferentchemicalsmustbehandledandstoredindifficultconditions,addyinganon-negligibleinvestmentcost,

oThecostofthesurfaceactiveagentpossiblyjeopardisestheprofitabilityoftheproject.

∙[0027]

Tosumup,willingtoimplementtheuseinvertemulsionstoday,apersonskilledinthearthasthereforethechoicebetween:

othefurtheradditionofinvertingsurfaceactiveagentwiththeabovementioneddrawbacks;

olargescalecontinuousorbatchinstallationsallowinglongresidencetime,implyinghighcostsininvestment,volumeandmaintenance.

∙[0028]

Theinventionreferstoamethodfordissolving,inlineandcontinuously,areverseemulsionofacrylamide（co）polymertotheactivepolymerinjectionconcentrationof500to2000ppm,inordertoobtainthefilterabilitylowerthan1.5inlessthan5minutesofmixingcontacttime.

∙[0029]

Forthispurpose,theapplicanthasdevelopeda2-phasesinlinedissolution:

oAinlinedispersionphaseathighconcentration,

oAsubsequentinlinedilutionphaseatthefinaldesiredconcentration.

∙[0030]

Moreprecisely,theinventionrelatestoanenhancedoilrecoverymethodconsistingincontinuouslydissolvingastableinvertemulsionofacrylamide（co）polymercontainingatleastoneinvertingagent,whereby:

oinafirststep,theemulsionispredilutedinafirststaticmixermountedonabypassofthemaininjectionwatercircuit,toa（co）polymerconcentrationofatleast5g/l,preferablybetween5and20g/l,advantageouslyab