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1、氣體鉆井鉆桿沖蝕規(guī)律研究第31卷第6期20l0年I1月石油ACTAPETROIEISINICAVoI.31No.6Nov.2010文章編號:0253—2697(2010)06—1{/13-05氣體鉆井鉆桿沖蝕規(guī)律研究祝效華劉少胡童華(1.西南石油大學(xué)油氣藏地質(zhì)及開發(fā)工程國家重點(diǎn)實(shí)驗(yàn)室四川成都610500;2.西南石油大學(xué)機(jī)電工程學(xué)院四川成都610500)摘要:針對氣體鉆井巖屑造成鉆柱嚴(yán)重沖蝕的問題,基于氣一固兩相流和沖蝕理論,建立了環(huán)空巖屑運(yùn)移模型.在Eulerian坐標(biāo)系下求解氣體連續(xù)相流場,在Lagrangian坐標(biāo)系下對離散相巖屑粒子
2、進(jìn)行了碰撞求解,采用Grant和Tabakoff公式求解巖屑粒子沖蝕速率,借助實(shí)驗(yàn)數(shù)據(jù)驗(yàn)證了仿真模型.利用該模型研究了氣體鉆井中鉆桿居中以及不同鉆桿偏心率,井徑擴(kuò)大率,注氣量和機(jī)械鉆速下環(huán)空巖屑粒子運(yùn)移規(guī)律和鉆桿沖蝕特性.研究表明,巖屑對鉆桿接頭及下坡面本體的沖蝕比鉆桿本體及接頭上坡面嚴(yán)重;鉆桿偏心和井徑擴(kuò)大都使局部沖蝕速率峰值增大,且偏心越嚴(yán)重,井徑擴(kuò)大越大,局部沖蝕速率峰值增速越大;機(jī)械鉆速增大,導(dǎo)致鉆桿局部沖蝕速率峰值近乎線性增加;在工程常用注氣量范圍內(nèi),注氣量對沖蝕速率峰值和沖蝕速率平均值的影響很小.根據(jù)沖蝕規(guī)律提出如下建議:減小鉆
3、桿斜坡坡度可減少鉆桿接頭及下坡面的局部沖蝕;采用低轉(zhuǎn)速的空氣錘鉆井工藝可減緩因偏心引起的局部沖蝕;井眼擴(kuò)大較大時,增大注氣量,通過改變巖屑粒子軌跡,可減少巖屑對鉆桿本體的多次沖蝕.關(guān)鍵詞:氣體鉆井;氣固兩相流;巖屑運(yùn)移;沖蝕;鉆桿;計(jì)算流體動力學(xué);數(shù)值模擬中圖分類號:TE821文獻(xiàn)標(biāo)識碼:AAstudyonthedrillpipeerosionlawingasdrillingZHuXiaohua,LIUShaohuTONGHua(1.StateKeyLaboratoryofOil—GasReservoirGeology&Exploi
4、tation,SouthwestPetroleumUniversity,Chengdu610500,China:2.MechatronicEngineeringCollege,SouthzvestPetroleumUniversity,Chengdu610500,China)Abstract:Erosionofdrillstringsbycuttingsisveryseriousingasdrilling.Basedonthegasandsolidtwophaseflowdynamicsande—rosiontheory,thepresen
5、tpaperestablishedatransportmodelforannuluscuttings.Acontinuousgasphaseflowfieldwassolvedun—dertheEuleriancoordinatesystem,andthecollisionsolutiontodiscrete—phasecuttingparticleswasobtainedundertheLagrangiancoordinatesbyapplyingtheGrantandTabakoffformulaetocalculatetheerosi
6、onrateofcuttingparticlesandverifyingthesimulatingmodelwiththeaidofexperimentaldata.Then,thismodelwasappliedtostudyvariousproblemsencounteredingasdrilling,suchasthedrill—pipecentralization,differenteccentricityofdrillpipes,enlargementofwellborediameter,volumeofgasinjection,
7、transportlawofannuluscuttingparticlesattherateofpenetration(ROP),anderosionfeaturesofdrillpipes.Thestudiesdemonstratedthatcuttingserodedthedrill—pipejointanditslowerslopingsurfacemoreseriouslythanthedrill—pipebodyandtheupperslopingsurfaceofthejoint.Boththedrill—pipeeccentr
8、icityandtheenlargementofwellborediameterwouldincreasethepeakvalueofthelocalerosionrate,an
