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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