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1、本科毕业设计(论文)题目提高顶替效率的钻井液性能要求的理论探索摘要在固井施工前,为提高顶替效率,一般均要求对钻井液的性能进行调整。而对钻井液性能的参数具体调整到什么数值,目前现场大多是凭经验给出,也有一些关于钻井液性能调整的理论和原则,但总的来说理论根据仍比较缺乏。选择本课题的目的就是:针对直井层流顶替情形,从理论上探索性地研究提高顶替效率的钻井液性能要求的计算方法,为生产现场固井前调整钻井液性能提供理论依据。本文针对直井、层流、套管居中的情况,在对顶替时钻井液与水泥浆受力分析的基础上,建立了钻井
2、液与水泥浆之间顶替的数学模型。通过推导,最终给出了钻井液不发生滞留的流变性能要求的计算表达式。文中分析了钻井液流变性能与水泥浆和钻井液之间的密度差、水泥浆动切力、井眼与套管尺寸组合等因素的关系。研究结果表明:增加水泥浆与钻井液的密度差、增加水泥浆的稠度系数或钻井液的流性指数、增加水泥浆的塑性粘度、以及增大水泥浆或钻井液的动切力,都有利于提高顶替效率;反之,增加水泥浆的流性指数或钻井液的稠度系数,或增加钻井液的塑性粘度,会使水泥浆的顶替效率降低。研究结果有助于明确注水泥过程中环空顶替机理,为注水泥设
3、计与施工提供必要的理论依据。建议在固井施工中,尽量降低钻井液的稠度系数,以降低钻井液的动切力,同时扩大水泥浆与钻井液的正密度差,可提高顶替效率。关键词:固井;顶替效率;钻井液性能要求;计算方法AbstractBeforecementing,itisnecessarytoadjusttheabilitiesofdrillingfluidinordertoimprovethedisplacementefficiency,butthereisnoclearvalues.Atthemoment,theva
4、luesarealmostgivenbyexperiences,andtherearesometheoriesandrulesabouttheadjustingfortheabilitiesofdrillingfluid.Generallyspeaking,thebasisfortheoriesareyetlacked.Theaimofthistopicis:beingaimedatthedisplacementofstraightwell,lamellarflow,tostudythecalcu
5、lationmethodabouttherequirementforthetheabilitiesofdrillingfluidontheory,itwillsupplythetheoreticalcriterionofadjustingtheabilitiesofdrillingfluidforcementing.Inthispaper,beingaimedatthesituationofstraightwell,lamellarflowandthecasingpipebeinginthemid
6、dle,themechanicalmodelofdisplacementbetweencementslurryanddrillingfluidwerebuiltup,onthebaseofanalysingtheforceofdisplacementbetweencementslurryanddrillingfluid.Accordingtoderiving,thefinalcalculationexpressionisobtainedforcementingwithoutdrillingflui
7、dretention.Thentherelationshipsareanalyzedabouttherheologicalofdrillingfluidwiththedensitydifferences,thedrillingfluid’syieldpoints,theconsistencyindex,thecombinationsofholesizeandcasingsize.Researchresultsdemonstratethatincreasingthedensitydifference
8、betweenthecementslurryandthedrillingfluid,theconsistencycoefficientofcementslurryortheliquidityindexofdrillingfluid,theplasticviscosityofcementslurry,andtheyieldpointofcementslurryordrillingfluid,allhelptoimprovethedisplacementefficiencyofceme