海底多相泵模块化设计

:[e-mail],[e-mail],[e-mail]es——especiallythosediscoveredindeepwater——willbeimportantinmeetingfutureglobaloildemand.Asoilcompaniesstepoutintodeeperwaters,operatorsmaydiscoverthatfindingoilandgasistheeasypart——therealchallengeliesinmovingproducedfluidsfromthereservoirtotheprocessingfacility.Multiphasesubseapumpingrepresentsakeydevelopmentneed.Whilemultiphasepumpinghasbeenprovenonshore,operatorshavebeenhesitanttodeploythistechnologysubseaduetoitscostsaving.Thispaperpresentthestateofartinsubseamultiphaseboosting.Thisincludesthesubseapump,subseaintegration,powerandcontrolsystem,andintervention,installation.Therearealsoseveralexamplesofsubseamultiphasemodulesasproductionenablingequipment.Someexperienceandlessonswillbeaddressed.Althoughmultiphasepumpsinmostcasesareusedindividually,theymaybeusedincombinationwithotherartificiallifttechnologylikedownholepumpstoofferintegratedsystemswithpremiumreliabilityandeconomics.ThelastpartofpresentationwillberelatedspecificallytotheprototypesubseamultiphasepumpdesignedbyChinaUniversityofPetroleum(beijing),themotor-drivenpumpmoduleispresentedforverticalsubseainstallationontheseabottom.Detailsofdesignlikepumpparameters,hydraulicparts(impellers,diffusers),coolingsystem,bearings,mixerwillbepresented.Keywords:multiphasepump;subsea;module;artificiallift;prototype1IntroductionDeepwateroildepositsandstrandedgasreservoirsrepresentsignificantworld-classenergysourcesthathaveonlyrecentlybecomeaccessiblethroughremarkableadvanceintechnology[1].Modernoffshoredevelopmentstrategiesmakeextensiveuseofsubseawellandflowlines,therebyenablingaccesstoremoteresources.Oneoftheforcesdrivingincreaseduseofsubseaproductionsystemisthedramaticreductionindevelopmentcostswhencomparedwithconventionalmethods.Subseamultiphasepumpingisalsoanenablingtechnology[2,3].Multiphaseproductionsystemseliminatetheneedofseparationandinsteadboosttheproducedstreamdirectlytothegatheringfacility.Thisreducestheamountofequipmentrequiredandalsoreducesthefootprintandemissions,bothveryfavorabletraitswhenitcomestocompliancewithenvironmentalregulations[4].Thereducedspaceisalsoaplusinoffshoreproduction,duetothelimitedspaceonplatformsandvessels.Systemsforsubseapumpingofrawflowwerefirstdeveloped20yearsago.Theinitialmotivationwastoenableeconomicalproductionratesfromnewoftenmarginalsubseafieldstiedbacktoexistingproductionfacilities.Thefirstsubseamultiphasepumpwasinstalledin1993,followedbyanelectric-drivenversionin2000[5].Itisessentiallyaproventechnologyandisbecomingtheconventionalmethodforincreasingrecoveryinsubseawells,severalpumpsarenowcapableofdeliveringwellstreamswithgas–volumefractionsof95%,sometimeshigher.Howeverspecialchallengesarestillhavingtobetakenintoaccount.Forexamplethepowertransmissionandpumpcontrol.Also,topicslikereliability,redundancyandinterventionbecomeevenmoresignificantwhenequipmentisoperatedinoneofthemostremotelocationsonearth.1ThisprojectissupportedbyNationalHi-techResearchandDevelopmentProgramofChina(863Program,2007AA09Z316)andChinaNationalPetroleumCorporationyoungandmiddle-agedInnovationFund(07E1039)(oil+gas+water)atadifferentialpumppressureof500psishouldsatisfymostrequirements.Therewill,ofcourse,beapplicationthatcallforhigherflowsandpressures.Thepumpmustbecapableofhandlingvoidfractionsintherange0to0.9onthecontinuousbasisandmustalsobecapableofhandlingavoidfractionof1.0forshorttermtransientconditions.Fluidspumpedwillbehot,gaseoushydrocarbons,producedwater,possibleh2sandco2pluscorrosionandscaleinhibitors.Producedfluidsmayalsocontainsolids,soresistancetoabrasionisalsoaprimeconsideration[6].Thepumpmustbeabletooperatemaintenance–freeaslongaspossible.3SystemdescriptionThepumpsmaybeintegratedwithexistinginfrastructuresuchastheChristmastreeormanifold.However,themostcommonsolutionistoinstallcompletelyself-containedpumpmodulesontheseabedwithassociatedpipingandvalvestoallowremoteoperationofoneortwopumpsfromthehostplatform(Fig1).Suchasystemtypicallycomprises:motor,pumpanddrivesystem,coolingsystem,controlsystemandintervention[7].Fig1.Typicalmultiphasesubseasystem3.1SubseapumpmoduleThesubseapumpmodulecontainsthemultiphasepumpandmotorcartridge,processpiping,andisolationvalvesaswellasthecontrolpodforvalveoperation(Fig2).Forlongtiebackdistances,therealsowillbeastep-downtransformerincludedinthesubseapumpmodule.Typically,themodulewillbesupportedonmudmatsorasinglepile.(Fig3)aremostattractive.Theirtorquecharacteristicsareideallysuitedtoprovideautomaticspeedchangeinsympathywithchangeinpumpingconditions.Powerl