对稠油的开采一直w来都是研巧的热点,目前我国许多稠油油藏己经进入开 发中后期,地层天然能量不足,导致稠油采收率下降,开采成本上升,经济效益 直线下滑,随着开发进程的进一步深入,开发难度越来越大。目前开采稠油油藏 的常规技术是注蒸汽热采,但由于蒸汽密度和粘度均较低,容易发生重力超覆和 气窜现象,从而产生不均匀的垂直扫油效率,导致地层中残余油饱和度高、蒸汽 波及系数小、驱油效率和采收率降低。常规技术只是暂时降低了稠油粘度,随着 稠油离开地层后环境温度的降低,及生产后期地层温度的降低,造成稠油温度 降化。当稠油温度低于其拐点温度时,稠油粘度迅速恢复,造成渗流阻力増大, 含水迅速上升,严重影响了后期井筒举升和集输工艺。现阶段的研究采用了渗热 流体等伴送工艺,但是降粘效果有限,同时采取的加热、惨降粘剂和注高压水等 措施,使开采成本大大增加,严重影响了稠油的开采效果和经济效益。因此,有 必要研究有效的稠油热采技术,从而进一步提高稠油采收率。 本文研究内容来自潮海旅大油田化学辅助热采提离稠油采收率可行性研究课 题,主要目的是为海上稠油开发中后期提供可行的开采方案,本文针对旅大27-2 油田的具体情况,进行了一系列的工作,具体如下; 首先调研了国内外研究人员在稠油热采方面做的研究,熟悉稠油热采的理论 知识及其发展现状,通过分析国内外稠油热采的研巧现状,可W看出,大多数研 究化学辅助热采得出的结果都是在蒸汽驱或者蒸汽吞吐的过程中加入表面活性剂 或者泡沫,可W有效的增加蒸汽的波及范围,提高驱油效率,对提高采收率有一 定的帮助。但是也存在一定的问题,并不是所有的地区都可W进行化学辅助热采 来进行开发,不同地区的不同油藏要进行具体的分析。 其次,对稠油热采主要的开采方式机理进行分析,主要针对蒸汽吞吐和蒸汽 驱提高采收率的生产机理W及各自应用情况进行描述,指出存在的缺点,针对缺 点给出有效的建议。同时对稠油热采的影响因素进行讨论,主要有稠油粘度、地 层粘±矿物、生产井出砂会对稠油的开采产生影响。 第H,根据油田地质及流体性质结合化学剂设计了一部分实验,主要进行了 化学剂和地层原油之间的界面张力分析,发现当界面张力大于l〇-2mN/m级别时, 随着界面张力的降低,采收率逐渐提高。随后进行了实验室岩必驱替物理模巧实 验,主要研究了不同注入方式对采收率的影响、不同渗透率地层对采收率的影响、 化学剂浓度对采收率的影响、不同化学剂对采收率的影响W及化学剂波及系数的 研究。得到的认识如下:(1)实验所用的化学剂与旅大油田原油之间界面张力大 多在l(Ti~l〇-2mN/m之间,当界面张力大于10、nN/m级别时,随着界面张力的降 I低,采收率逐渐提島。(2)化学辅助稠油热采的稠油最终采收率比单纯注蒸汽驱 的稠油最终采收率要髙接近10个百分点;对于不同渗透率的填砂管,髙渗填砂管 最终采收率要髙于低渗填砂管,但是会出现稳定压差偏大的倩况。(3)在化学剂 相同情况下,浓度大的化学剂对采收率提島效果好,但是化学剂浓度减半之后注 入压差相对较低,在采收率影响不大的情况下可W适当考虑注入压差较小的化学 剂进行实验。(4)在參透率同为lOOOmD的地层中采用不同药剂进行先注化学剂 后注蒸汽驱油的方案驱油,其采收率都比单纯注蒸汽驱油方案采收率髙,其中全 部药剂原浓度方案驱油采收率最高。筛选出来的化学剂在后续2000mD和4000mD 填砂管实验中,取得了不错的实验效果,稠油最终采收率很高。(5)通过填砂管 并联研究化学剂波及系数的实验发现,实验所用的化学剂在渗透率不同的地层中 能够暂时封堵髙渗地层,保证低渗地层出油,从而提髙整体原油采收率。 通过W上各方面的研究,认识到常规的蒸汽驱对现在稠油开采提高采收率的 效果不是特别明显,而采用化学辅助蒸汽驱可W有效的提髙稠油最终采收率,油 田在实际应用中要根据实际情况进行经济可行性评价,选出最佳方案进行生产。 关巧词:化学辅助蒸汽驱,界面张力,物理模巧,提高采收率 II1 Abstract Thee邱loitatio打ofheavyoilisalwaysthefocusofresearch^atpresent泣lotof heavyoilreservoirinChinahasenteredthelaststageofdevelopment,thefonnationof naturalenergyshortage,resultinginheavy0。recoverydecline,risingproductio凸costs, economicbenefitsplummeted,withthefurtherdeepeningofthedevelopmentprocess, thedevelopmentbecomesmoreandmorediffi圳t.Atpresent,化eexploitationofheavy oilreservoirbyconventionaltechniquesisthethermalrecoverybysteaminjectio凸,but 化edensityandviscosityofvaporwerelower,itisprone化gravityoverrideandgas 浊annding,resultinginunevenverticalsweepefficiencyofoil,andthenlead化high residual0。saturatio打intheformation,steamsweepcoefficient^0。displacement efficiencyandrecoveryrateisreduced.Conventionaltechniquesonlytemporarily reducetheviscosityofheavyoil,whentheheavyoilleavethefonnation,withthe decreaseoftheenvironmenttemperatureandthedecreaseofformationtemperaturein thelaterstage,resultinginheavyoiltemperaturedecreases.Whenthetemperatureis belowtheinflectionpointtemperatureofheavyoil,heavyoilviscosityquicklyrestored, resiiltingintheincreaseofseepageresistanceandtherapidincreaseofwatercontent, seriouslyaffect化elateshaftKftingandgatheri凸gandtransportationtechnology. Presetstudymixedwithhotflmdsdeliveryprocess,butthedropofviscosityeffectis limited,andthenheating》addingadhesiveandhi班pressxureinjectio打water,leadtothe CO巧greatlyincreased,化eexploitationeffectandeconomicbenefitofheavy0。are seriouslyaff说ted.Therefore,itisnecessary化study化eeffective化ermalrecovery technology,soas^fUrtherenhancetherecoveryofheavyoil. Thecontentsofthispaperisfromtheresearchonfeasibilityofimprovingoil recoveryofchemicalauxiliaryheatrecoveryinBohaiOil巧eld,themainpurposeisU) providethefeasibleminingplanforoffshoreheavyoildevelopmentinthelaterstage, accordingtothespecificcircumstancesofLD27-2oilfield,wecarriedoutaseriesof work,asfollows: Firstlyweinvestigatedsomeresearchof化e化ermalrecoveryofheavy0。has done,familiarwiththeheavyoilthermalrecoveryoftheoreticalknowledgeandits developmentstatus,throu^analysisoncurrentsituationofheavyoilthermalrecovery, itcanbeseen化at化eresultsofmo巧studieschemicalauxiliaryheatrecoveryisin steamfloodingorsteamhuffandpuffin化eproc朗sofaddingsurfaceactiveagentor foam,caneffectivelyincreasethesteamsweeprange,improvestheefficiencyofoil IIIdisplacement,forimprovingtherecoveryrateofsomehelp.Buttherearealsosome problems,and打otalloft;heregionscanbethedevelopmentofchemicalassist:ed thermalrecovery,differentregionsofdifferentreservoirstocarryoutspecificanalysis. Secondly,weanalysistheheavyo。thermalrecoverymainminingwayof mechanismanalysis,itismai打lyaimedattheproductio打mechanismandtheapplication ofs1:eaminjectio打andst:eamfloodingtoimproveoilrecovery,andpoi打touttheir shortcomi打gs,givin呂effectiverecomme打dations,atthesametime,theinfluencefactors ofthethermalrecoveryofheavyoilarediscussed.Themai打factorsaretheviscosityof heavyoil,theclaymineralsoftheformatio打a打dthesandproduction. Thirdly,according化theoilfieldgeologyand打uidpropertiescombi打edwith chemicalagentsdesignedpartoftheexperiment,mainlyfortheinterfkcialtension betweencrudeoilandchemicalagents,whentheinterfacialtensionisgreaterthanthe 10 ~^ mN/mlevel,withthereductionofinterfacialtension,therecoveryrategradually increased.Then,wecarryoutlaboratorycorefloodingphysicalsimulationexperiments, studied化eeffectsofdifferentinjectio打me化odsonrecovery,也eeffectsofdifferent permeabilityformationsforrecovery,theeffectofchemicalagentconcentratio打onthe recovery,theeffectsofdifferentchemicalage打tso打recoveryandthestudyonthe chemicalagentsweepcoefficient.Theresultsareasfollows;(1)thechemicalagent usedi打theexperimentwithLudaoilinterfacialte打sionisl〇-il〇-2mN/m,whenthe interfacialte打sio打isgreaterthanthel〇-2mN/inlevel,withthereductionofinterfacial tension,therecoveryrategraduallyi打creased.(2)theheavyoilultimaterecoveryof chemicallyassiskdthermalrecoveryishigherthansimplys1:eamfloodin呂打early10 percentagepoints,fordifferentpermeabilitysandfilledtube,the巧打alrecoveryrateof thehighpermeabilitysandfilledtubeishigherthanthatofthelowpermeabilitysand filli打gpipe,but化estabilitypressureistoolar呂e.(3)In化esamecaseofchemical agents,alargeCO打ce打tratio打ofchemicalage打tsforenhancedoilrecoveryisgood,but afterthechemicalconcentrationhalvedtheinjectio打pressureisrelativelylow,inthe caseofli行leeffecto打oilrecovery,itisappropriatetoCO打sideranexperimentwitha smallerinjectionpressure.(4)Inpermeabilityfortheformatio打oflOOOmD,using differentrea呂entsto行rstchemicalinjectionthentheinjectionofs化amfloodingforoil displacement,oilrecoveryarehigher化anpurest;eamdrive,among化em,化eoil i ^ ecoveryefficiencyof化ewholedrugis化ehigl化stScreenedoutof化echemicalagent i打化efollow-up2000mDand4000mDsandfilledtubeexperiment,achievedgood IVresuhs,orecoveryrateisveryhigh巧)By巧llingsandtubeparallelresearch chemicalssweepefficiencyitwasfomidthatt