Baker-钻井手册-——-钻具基础

第四章DrillstringBasics钻具基础Uponcompletionofthissectionyouwillbeableto:读完这一部分后，你可以1、Explainhowdrillpipegradesdefinetheyieldstrengthandtensilestrengthofsteel.1、解释钻杆钢级是如何定义钢材的屈服强度和抗拉强度的；2、Explainhowdrillpipeisclassified.2、解释钻杆是怎么分类的；3、Calculatetotalyieldstrengthforaspecificgrade/classofdrillpipe.3、计算特定钢级和类别钻杆的屈服强度；4、Explaintheeffectsofbuoyancyonthedrillstring.4、解释浮力对钻具的影响；5、Calculatethebuoyedweight(orhookload)inaverticalhole.5、计算直井中钻具的浮重（或称悬重）；6、Explainthecausesofvaryinghookloadduringthedrillingprocess.6、解释钻进过程中大钩悬重变化的原因；7、Explainoverpullandcalculatethemaximumpermittedpull.7、解释过提、计算昀大许用上提力；8、CalculaterequiredBHAairweightforapplicationswheredrillpipeistoberunincompression.8、计算在允许钻杆受压的钻井过程中，需要的井下钻具组合净重；9、Calculatecriticalbucklingforceandexplainthefactorsinvolvedwhenrunningdrillpipeincompression.9、计算压曲临界力并解释压缩钻杆的钻井过程中的原理；10、Explaincausesandeffectsofsinusoidalandhelicalbuckling.10、解释正弦和螺旋弯曲的起因及影响因素；11、Explainneutralpointandcalculatetheapproximatelocationoftheneutralpointinarotarydrillstring.11、解释中和点并计算其在转动钻具中的大概位置；12、Explaintherelationshipbetweencyclicbendingstressanddrillpipefatigue.12、解释周期性的弯曲应力和钻杆疲劳的关系；13、Describesomeofthefactorsaffectingaxialdragandtorque,andtheeffectofdragonweightonbit.13、描述一些影响轴向摩擦力和扭矩的因素以及摩擦力对钻压的影响。Tubulars管件Introduction介绍Drillpipeandcollarsaredesignedtosatisfycertainoperationalrequirements.Ingeneral,downholetubularsmusthavethecapabilitytowithstandthemaximumexpectedhookload,torque,bendingstresses,internalpressure,andexternalcollapsepressure.OperationalcapabilitiesofdifferentsizesandgradesofdrillpipeandcollarsaretabulatedintheAPIRP7Gtoassistthedrillingengineerinselectionofpipeandcollarsforagivendrillingsituation.Otherconcerns,suchasthepresenceofH2S,mustalsobeconsideredintheselectionprocess.钻杆和钻铤是为满足特定作业需求而设计的。总体来说，入井管件必须禁得起预期的昀大悬重、扭矩、弯曲力、内压力和外挤力。不同尺寸和钢级的钻杆和钻铤的工作能力记录于API标准RP7G，以帮助钻井工程师在特定钻井条件下选择钻杆和钻铤。在选择过程中，诸如存在H2S等具体情况也要加以考虑。DrillPipeYieldStrengthandTensileStrength钻杆的屈服强度和抗拉强度Ifdrillpipeisstretched,itwillinitiallygothrougharegionofelasticdeformation.Inthisregion,ifthestretchingforceisremoved,thedrillpipewillreturntoitsoriginaldimensions.TheupperlimitofthiselasticdeformationiscalledtheYieldStrength,whichcanbemeasuredinpsi.Beyondthis,thereexistsaregionofplasticdeformation.Inthisregion,thedrillpipebecomespermanentlyelongated,evenwhenthestretchingforceisremoved.TheupperlimitofplasticdeformationiscalledtheTensileStrength.Ifthetensilestrengthisexceeded,thedrillpipewillfail.Tensionfailuresgenerallyoccurwhilepullingonstuckdrillpipe.Asthepullexceedstheyieldstrength,themetaldistortswithacharacteristicthinningintheweakestareaofthedrillpipe(orthesmallestcrosssectionalarea).Ifthepullisincreasedandexceedsthetensilestrength,thedrillstringwillpart.Suchfailureswillnormallyoccurnearthetopofthedrillstring,becausethetopofthestringissubjectedtotheupwardpullingforceaswellasthedownwardweightofthedrillstring.如果钻杆受拉，起初，它会在一定拉力范围内发生弹性形变。在这个范围内，如果拉力消失，钻杆能恢复原状。这个范围的上限称为屈服强度，可用psi衡量。超过这个范围后，存在一个塑性形变范围。在这个范围内，钻杆被永久拉长，即使拉力消失也不恢复。这个范围的上限称为抗拉强度，如果拉力超过抗拉强度，钻杆会被拉断。钻杆被拉断的情况一般发生在上提被卡钻具的时候。如果拉力超过屈服强度，钻杆昀薄弱处（或昀小截面积处）的金属会变细。如果拉力继续上涨并超过抗拉强度，钻具会断裂。这样的断裂通常发生在钻具上部，因为管柱的上部不但要承受向上的拉力，还要承受其下钻具的重量。DrillPipeGrades钻杆钢级Therearefourcommongradesofdrillpipewhichdefinetheyieldstrengthandtensilestrengthofthesteelbeingused.钻杆有4个常用钢级，定义了所用钢材的屈服强度和抗拉强度。钢级EX-95G-105S-135昀小屈服强度（psi）7500095000105000135000昀小抗拉强度（psi）100000105000115000145000GradeE,composedofalowergradeofsteel,issometimesreferredtoas“mild”steel,becauseithasthelowestyieldstrengthperunitarea.Assuch,mildsteelisgenerallydefinedassteelwithayieldstrengthoflessthan80,000psi.Ascanbeseen,GradeEdrillpipehasaloweryieldstrengthinpsithanthehighstrengthdrillpipegrades,howeveroncetheyieldstrengthisexceeded,itcanwithstandagreaterpercentageofstretchor“strain”priortoparting.LowergradesofsteelsuchasGradeEarealsomoreresistanttocorrosionandcracking.GradeEhasbeenutilizedinmediumdepthwells(10,000to15,000feet).E级钻杆使用较低等级的钢材制造，这种钢材有时被称为“温和”金属，因为它在单位面积上具有昀低的屈服强度（psi）。温和金属通常定义为单位面积屈服强度在80,000psi以下的金属。众所周知，E级钻杆较高钢级的钻杆具有更小的单位面积屈服强度（psi），然而，一旦拉力超过屈服强度，它在破断前，可以禁受更大比率的拉力或“张力”。同样，像E级钻杆这样低等级的钢材对腐蚀和破裂有更强的抵抗能力。E级钻杆一般应用于中等深度的井（10,000ft~15,000ft）。Inthe1980's,ashorizontaldrilling,highinclinationextendedreachwellsanddeepholedrillingapplicationsincreased,sohasthedemandforhighstrengthdrillpipe.Itiscommonindeepholeapplicationsforhighstrengthdrillpipetobeutilizedintheupperportionofthestringtokeepthetensionloadwithinthecapabilitiesofthesteel.Inhighdoglegenvironments,suchasthoseencounteredinmediumandshortradiushorizontalwells,highstrengthdrillpipecanwithstandtheassociatedbendingstresses.Inhighinclinationandhorizontalwells,highstrengthdrillpipeisalsocommonlyrunincompression.Onedrawbackofhighergradesofsteelisthattheyaregenerallylessresistanttocorrosion,likethatcausedbyhydrogensulfide(H2S).Limitedavailabilityalsocontributestothehighercost.80年代，随着水平井、大斜度井和深井钻井的更多应用，对高强度钻具的需求也在提升。通常在深井的上部使用高强度钻杆来保证拉力在钢材许用范围之内。在大狗腿度井况下，比如造斜段较短的水平井，高强度的钻杆可以承受因此带来的弯曲力。在大斜度井和水平井中，高强度钻杆也经常会受到压缩力。高等级钢材的一个缺点是，它们对腐蚀环境的抵抗能力较差，比如受H2S影响的情况。数量的有限同样导致了其昂贵的价格。Theyieldandt