Drilling Engineering(鉆井工程英文課件)

DrillingEngineeringContentsOverviewRigcomponentsDrillstringDrillbitsFormationpressuresWellcontrol1CasingCementDrillingfluidsHydraulicsDirectionaldrillingDirectionalSurveyingMeasurementwhiledrillingSubsea2Chap.1OverviewIntroductionDrillingPersonnelRotarydrillingequipmentThedrillingprocessOffshoredrillingDrillingeconomics3Chap.1Overview1.1ExplorationandproductionlicencesInUK,thesecretaryofStateforEnergyisempowered(授權(quán)),onbehalfoftheGovernment,toinvitecompaniestoapplyforexplorationandproductionlicencesonthe

UnitedKingdomContinentalShelf.Explorationlicencesmaybeawardedatanytime.(mainlyallowtoacquireseismicdata,nottodrillanydeeperthan350meters.)1.Introduction4ProductionlicencesareawardedatspecificdiscreteintervalsknownaslicencingRounds.1.2Exploration,DevelopmentandAbandonmentBeforedrillinganexplorationwell,companyhavetoobtainaproductionlicence.Thelicenceallowthecompanytodrillexplorationwellsintheareaofinterest.Chap.1Overview5TheobjectivesofexplorationwellTodeterminethepresenceofhydrocarbonsToprovidegeologicaldata(core,logs)forevaluation.Toflowtestthewelltodetermineitsproductionpotential,andobtainfluidsample.Chap.1Overview6ThephasesinthelifeofoilfieldExplorationAppraisalDevelopmentMaintenanceAbandonmentChap.1Overview7RoleofDrillingChap.1Overview82.DrillingpersonnelDrillingawellrequiresmanydifferentskillsandinvolvesmanycompanies.Operator：Theoilcompanywhomanagesthedrillingand/orproductionoperations.Injointventuresonecompanyactsasoperatoronbehalfoftheotherpartners.Theoilcompanywillemployadrillingcontractortodrillthewell.Chap.1Overview9ContractingstrategiesDay-ratecontract(日費制)Themostcommontypeofdrillingcontractisaday-ratecontract.TheoperatorpreparesadetailedwelldesignandprogramofworkforthedrillingoperationDrillingcontractorsimplyprovidesthedrillingrigandpersonneltodrillthewell.Thecontractorispaidafixedsumofmoneyforeverydaythathespendsdrillingthewell.Allconsumableitems(e.g.drillingbits,cement),transportandsupportservicesareprovidedbytheoperator.Chap.1Overview10Turnkeycontract(大包)Thedrillingcontractordesignsthewell,contractsthetransportandsupportservicesandpurchasesalloftheconsumables,andchargestheoilcompanyafixedsumofmoneyforwholeoperation.Theroleofoperatoristospecifythedrillingtargets,theevaluationproceduresandtoestablishthequalitycontrolsonthefinalwell.Chap.1Overview11Theoperatorwillgenerallyhavearepresentativeontherig(sometimescalledthe“companyman〞)toensuredrillingoperationsgoaheadasplanned,makedecisionsaffectingprogressofthewell,andorganisesuppliesofequipment.Hewillbeindailycontactwithhisdrillingsuperintendent〔主管〕whowillbebasedintheheadofficeoftheoperator.Theremayalsobeanoilcompanydrillingengineerand/orageologistontherig.Chap.1Overview12Thedrillingcontractorwillemployatool-pusher〔鉆井主管alsocalledsuperintendent〕tobeinoverallchargeoftherig.Heisresponsibleforallrigflooractivitiesandliaises〔保持聯(lián)系〕withthecompanymantoensureprogressissatisfactory.Themanualactivitiesassociatedwithdrillingthewellareconductedbythedrillingcrew.Sincedrillingcontinues24hoursaday,thereareusually2drillingcrews.Eachcrewworksunderthedirectionofthedriller(司鉆).DrillingactivityChap.1Overview13Thecrewwillgenerallyconsistofaderrickman(井架工whoalsotendsthepumpswhiledrilling),3roughnecks(鉆臺工workingonrigfloor),plusamechanic〔機修工〕,anelectrician〔電工〕,acraneoperatorandroustabouts(雜工generallabourers)Servicecompanypersonnelaretransportedtotherigandwhenrequired.Sometimestheyareontherigfortheentirewell(e.g.mudengineer)oronlyforafewdaysduringparticularoperations(e.g.directionaldrillingengineer).Chap.1Overview14PersonnelinDrillingaWell153.DrillingproposalanddrillingprogramTheproposalfordrillingthewellispreparedbythegeologistsandreservoirengineersintheoperatingcompanyandprovidestheinformationuponwhichthewellwillbedesignedandthedrillingprogramwillbeprepared.Drillingproposal:ObjectiveofthewellDepth(m/ft,subsea),andlocation(longitudeandLatitude)oftargetGeologicalcrosssectionPorepressureprofileprediction

16DrillingrigtobeusedforthewellProposedlocationforthedrillingrigHolessizesanddepthsCasingsizesanddepthsDrillingfluidspecificationDirectionaldrillinginformationWellcontrolequipmentandproceduresBitsandhydraulicsprogramDrillingprogram:174.RotaryDrillingEquipment185.DrillingProcessFig.4TypicalwellinNorthSea19Installingthe30inConductorThefirststageistodrivealargediameterpipetoadepthofapproximately100ftbelowgroundlevelusingatruckmountedpile-driver.Thispipe,usuallycalledcasing/conductor,isinstalledtopreventtheunconsalidatedsurfaceformationsfromcollapsingwhistdrillingdeeper.Oncethisconductorisinplacethefullsizedrigisbroughtontothesiteandsetupovertheconductor,andpreparationsaremadeforthenextstageoftheoperation.Overviewoftheprocessofdrilling20Drillingandcasingthe26’holeA26〞diameterbitisgenerallyusedforthefirstholesection(theI.D.ofconductorisapproximately28〞).Thissectionmaybeapproximately2000’.Whistdrillingthe26’hole,drillingfluidiscirculateddownthedrllpipe,acrossthefaceofthedrillbit,anduptheannulusbetweenthedrillpipeandtheborehole,carryingthedrilledcuttingsfromthefaceofthebittosurface.21Atsurfacethecuttingsareremovedfromthemud(tocollectmorecuttings).Whenthedrillbitreachesapproximately2000’thedrillstringispulledoutoftheholeandanotherstringofpipe(surfacecasing)isrunintothehole.Thiscasing,whichgenerally20〞O.D.,isdeliveredtotherigin40ftlengths.Thecasingisloweredintothehole,jointbyjoint,untilitreachesthebottomofthehole.Cementslurryisthenpumpedintotheannularspacebetweenthecasingandtheborehole.22DrillingandCasingthe17?〞HoleOncethecementhassethard,alargespoolcalledawellheadhausing(套管頭)isattachedtothetopofthe20〞casing.Thiswellheadhousingisusedtosupporttheweightofsubsequentcasingstringsandtheblowoutpreventionstack.BOPgenerallyfittedtothewellheadbeforethe17?〞holesectionisstarted.23WhentheBOP’shavebeeninstalledandpressuretested,a17?〞holeisdrilleddownto6000ft.Oncethisdepthhasbeenreachedthetroublesomeformationsinthe17?〞holesection,acasingstringisusedtoisolatetheseformations.Whenthecementhassethard,theBOPstackisremovedandawellheadspoolismountedontopofthewellheadhousing.24DrillingandCasing12?〞HoleWhentheBOPhasbeenre-installedandpressuretested,a12?〞holeisdrilledthroughtheoilbearingreservoir.Whilstdrillingthroughthisformationoilwillbevisibleonthecuttingsbeingbroughttosurfacebythedrillingfluid.IfgasispresentintheformationitwillalsobebroughttosurfacebythedrillingfluidanddetecedbygasdetectorsplacedabovethemudflowlineconnectedtotopoftheBOPstack.25PetrophysicallogsThedrillstringispulledoutandaloggingtoolsispulledintomeasureformationcharacteristics.theelectricalresistance;thebulkdensity;thenaturalradioactiveemissionsfromtherock.Thesetoolsarerunonconductivecablecalledelectricwireline,sothatthemeasurementscanbetransmittedandplottedalmostimmediatelyatsurface.theseplotsarecalledpetrophysicallogsandthetoolsarethereforecallwirelineloggingtools.26CoringInsomecases,itmaybedesireabletoretrievealargecylindricalsampleoftherockknownasacore.Adonutshapedbitisattachedaspeciallargediameterpipeknownasacorebarrelisruninholeonthedrillpipe.Thiscoringassemblyallowsthecoretobecutfromtherockandretrieved.

27Completionthewelltorunandcementproductioncasingacrosstheoilproducingzone.thentorunthetubinginsidethiscasingstring.Theannulusbetweentheproductioncasingandtheproductiontubingissealedoffbyadeviceknownaspacker(onthebottomofthetubing).TheBOP’sarethenremovedandasetofvalvesisinstalledontopofthewellhead.TheXmastressisusedtocontroltheflowofoilonceitreachesthesurface.28Toinitiateproduction,theproductioncasingis“perforated〞byexplosivechargesrundownthetubingonwirelineandpositionedadjacenttothepayzone.Holearethenshotthroughthecasingandcementintotheformation.Thehydrocarbonsflowintothewellboreandupthetubingtothesurface.29306OFFSHOREDRILLINGAbout25%oftheworld’soilandgasisbeingproducedfromoffshorefields.InthenorthSea,explorationwellsaredrilledfromajack-uporasemi-submersibledrillingrig.Ajack-up(自升式鉆井船)hasretractablelegswhichcanbelowereddowntotheseabed.Thelegssupportthedrillingrigandkeeptheriginposition.Suchrigsaregenerallydesignedforwaterdepthupto350ftwaterdepth.Asemi-submersiblerig(半潛式鉆井船)isnotbottomsupportedbutisdesignedtofloat.Semi-submersiblescanoperateinwaterdepthsofupto3500ft.31Inverydeepwaters(upto7500ft),drillshipsareusedtodrillawell.Sincethepositionoffloatingdrillingrigsisconstantlychangingrelativetotheseabedspecialequipmentmustbeusedtoconnecttherigtotheseabedandtoallowdrillingtoproceed.Iftheexplorationwellsaresuccessfulthefieldmaybedevelopedbyinstallinglargefixedplatformsfromwhichdeviatedwellsaredrilled.Oncethedevelopmentwellshavebeendrilledtherigstillhasalotofworktodo.Somewellsmayrequiremaintenance(workovers)orsidetrackstointersectanotherpartofthereservoir.32Awelldrilledfromanoffshorerigismuchexpensivethanalandwelldrilledtothesamedepth.Theincreasedcostcanbeattributedtoseveralfactors,e.g.speciallydesignedrigs,subseaequipment,lossoftimeduetobadweather,expensivetransportcosts(e.g.helicopters,supplyboats).AtypicalNorthSeawelldrilledfromafixedplatformmaybecostaround$10million.33JackUpRig34Semi-submersibleRig35Drillship36FixedPlatform377DRILLINGECONOMICS7.1DrillingcostinfielddevelopmentItisquitecommonfordrillingcosttomakeup25-35%ofthetotaldevelopmentcostsforanoffshoreoilfield.7.2DrillingcostestimatesBeforeadrillingprogramiaapproveditmustcontainanestimateoftheoverallcostsinvolved.Whendrillinginancompletelynewareawithnopreviousdrillingdataavailablethewellcostcanonlybearoughapproximation.Inmostcasessomepreviouswelldataisavailableandareasonableapproximationcanbemade.38Table1Table239Timerelatedcost:drillingcontract,transport,accommodationDepthrelatedcost:

casing,cementFixedcost:wellheadMoresophisticatedmethodsofestimatingwellcostareavailablethroughspeciallydesignedcomputerprogrammes.Whatevermethodisusedtoroducethetotalcostsomeallowancemustbemadeforunforeseenproblems.40Table341Ex1.CostandTimeDistributionRankthemajorcostelementsinthedevelopmentoftheBraeFieldgivenintable1andconsiderthewaysinwhichthecostsdistributionmightchangewithabiggerandsmallerfield.Considerhowthecostsassociatedwithawell(table2)arerelatedtothetimedistribution(table3)forwell.42Platformequipment,developmentdrilling,platformstructure,pipeline,platforminstallation,miscellaneous,onshorefacilities.4344Ex.2ThedrillingprocessYouarerequiredtodrillawellintotheRotliegendesandstoneshownontheattachedgeologicalcrosssection(Appendix1).Considerthefollowingaspectsofthedrillingoperationandhowyouwoulddrillthewell:Therockpenetrationprocess-therockcuttingmechanism/tool-thetransmissionofenergytothecuttingtool-theremovalofdebrisfromthefaceofthecuttingtoolandtheborehole.Thestability/integrityoftheborehole-potentialcausesofinstability-potentialconsequencesofinstability-meansofpreventing/mitigatingproblemsassociatedwithinstability45c)Thesafetyoftheoperation-thegreatestsourceofriskduringthedrillingoperationd)Dataanditsacquisition-datarelevanttothedrillingprocess-datarelevanttoevaluatingthepotentialoilandgasproductionoftheformationse)Thesurfaceequipmentrequirement4647Chap.2RigComponentsIntroductionPowersystemHoistingsystemCirculatingsystemRotarysystemWellcontrolsystemWellmonitoringsystem481.IntroductionSixsub-systems:thepowersystem;

thehoistingsystem;

thecirculatingsystem;therotarysystem;

thewellcontrolsystem;

thewellmonitoringsystem.4950Mostdrillingrigsarerequiredtohaveamethodtogenerateelectricalpower.Theelectricalpowergeneratorsaredrivenbydieselpoweredinternalcombustionengines(primemovers).Electricityisthensuppliedtoelectricmotorsconnectedtothedrawworks(絞車),rotarytable(轉(zhuǎn)盤)andmudpumps(泥漿泵).電驅(qū)動鉆機2.Powersystem51523Hoistingsystem(提升系統(tǒng))Thehoistingsystemisalargepulley(滑輪)systemwhichisusedtolowerandraiseequipment(drillstring/casing)intoandoutofthewell.Thecomponents:Drawworks:drum,drillingline.Crownblock:Travellingblock:Hook:Elevator:Deadline,fastlineDeadlineanchor5354Static:Ff=Fd=W/NNisthenumberoflines,Wisthehookload.Dynamic:Ff=W/EN;Fd=W/NEistheefficiencyofthesystem.Outputpowerofdrawworks(loadonfastlinetimesvelocityoffastline):HPd=FfVf/33,00055Roundtripoperations(起下鉆):DrillingAhead〔鉆進〕RunningCasing〔下套管〕ShortTrips〔短起下鉆〕56ThetotalloadofthederrickisFD=W+Ff+Fd57Ex.1ThehoistingsystemAdrillingstringwithabuoyantweightof200,000lbsmustbepulledfromthewell.Atotalof8linesarestrungbetweenthecrownblockandthetravellingblock.Assumingthatafoursheave,rollerbearingsystemisbeingused.Computethetensioninthefastline.Computethetensioninthedeadline.Computetheverticalloadontherigwhenpullingthestring.584CirculatingsystemThecirculatingsystemisusedtocirculatedrillingfluiddownthroughthedrillstringanduptheannulus,carryingthedrilledcuttingsfromthefaceofthebittosurface.Drillingfluid(mud)isusuallyamixtureofwater,clay,weightingmaterial(Barite)andchemicals.Functionsofmud:tocleantheholeofcuttingsmadebythebittoexertahydrostaticpressuresufficienttopreventformationfluidsenteringtheborehole.59

Themudispumpedthroughthestandpipe,kellyhose,swivel,kellyanddownthedrillstring.Atthebottomofholethemudpassesthroughthebitandthenuptheannulus,carryingcuttingsuptosurface.Onsurfacethemudisdirectedfromtheannulus,throughtheflowlineandbeforeitre-entersthemudpitsthedrilledcuttingsareremovedfromthedrillingmudbythesolidsremovalequipment.Oncethedrilledcuttingshavebeenremovedfromthemuditisre-circulateddownthehole.Themudisthereforeinacontinuouscirculatingsystem.Processofcirculation6061Thepoweroutputofamudpump:HHP=PQ/1714DuplexdoubleactingFlowrateQ=(2d2-dr2)LEvR/147gpmd-linerdiameter,in.;dr-roddiameter,in.;L-strokelength,in.E-efficiencyofpumpR-pumpspeed,spmMudpump62(2)TriplexsingleactingQ=d2LEvR/98.03gpmEx.2ThemudpumpCalculatethefollowing,fortriplexpumphaving6in.linersand11in.strokeoperatingat120spmandadischargepressureof3000psi.Thevolumetricoutputat100%efficviency.Thehorsepoweroutputofthepumpwhenoperatingundertheconditionsabove.635RotarysystemTherotarysystemisusedtorotatethedrillstringandthedrillbit.Thefunctionsofswivel(旋轉(zhuǎn)頭):Supportstheweightofthedrillstring;Permitsthestringtorotate;Allowsmudtobepumpedwhilethestringisrotating.64Kelly(方鉆桿)：thefirstsectionofpipebelowtheswivel.40’longandhexagonalcross-sectionHexagonalshapeisusedtotransmitrotationfromtherotarytabletothedrillstring.Kellysaversub(方鉆桿保護接頭)Kellycock(溢流閥)Rotarytable(轉(zhuǎn)盤)Masterbushing(轉(zhuǎn)盤補心)Kelleybushing(方補心)Astand(立柱，由3根鉆桿組成)Ironroughneck/adrillpipespinner(液壓大鉗)65665.1ProceduresforaddingdrillpipewhendrillingaheadWhendrillingaheadthetopofkellywilleventuallyreachtherotarytable.Atthispointanewjointofpipemustbeaddedtothestringinordertodrilldeeper.1stoptherotarytable,pickupthekellyuntiltheconnectionatthebottomofthekellysaversubisabovetherotarytable,andstoppumping.2setthedrillpipeslipsintherotarytabletosupporttheweightofthedrillstring,breaktheconnectionbetweenthekellysaversubandthefirstjointofpipe,unscrewthekelly.673Swingthekellyovertothenextjointofdrillpipewhichisstoredinthemousehole(小鼠洞，接單根用).4stabthekellyintothenewjoint,screwittogetherandusetongstotighentheconnection.5pickupthekellyandnewjointoutofthemouseholeandswingtheassemblybacktotherotarytable.6stabthenewjointintotheconnectionabovetherotarytableandmakeuptheconnection.7pickupthekelly,pulltheslipsandruninholeuntilthekellybushingengagestherotarytable.8Startpumping,runthebittobottomandrotateanddrillahead.68Proceduresforpullingdrillstringfromthehole695.2procedureforpullingthedrillstringfromtheholeWhenthetimecomestopulloutofthehole,thefollowingprocedureisused.1stoptherotary,pickupthekellyuntiltheconnectionatthebottomofthekellysaversubisabovetherotarytable,andstoppumping.2Setthedrillpipeslips,breakoutthekellyandsetthekellybackintherat-hole(大鼠洞，方鉆桿用).3Removetheswivelfromthehook.704Latchthetheelevatorsontothetopconnectionofthedrillpipe,pickupthedrillpipeandremovetheslips.Pullthetopofdrillpipeuntilthetopofthedrillpipeisatthetopofthederrickandthesecondconnectionbelowthetopofthedrillpipeisexposedattherotarytable.Astandisnowexposedabovetherotarytable.5Roughnecksusetongstobreakouttheconnectionattherotarytableandcarefullyswingsthebottomofthestandovertooneside.Standsmustbestackedinanorderlyfashion.6TheDerrickman,onthemonkeyboard,grabsthetopofthestand,andsetsitbackinfingerboard.71Onsomerigsamechanicaldeviceknownasanironroughneckmaybeusedtomakeupandbreak-outconnections.Thismachinerunsonrailsattachedtotherigfloor,andiseasilysetasidewhennotinuse.Itsmobilityallowsittocarryoutmouseholeconnectionswhenthetracksarecorrectlypositioned.Thedeviceconsistsofaspinningwrenchandtorquewrench,whicharebothhydraulicallyoperated.Advantagesofferedbythisdeviceincludecontrolledtorque,minimaldamagetothreadsandreducingcrewfatigue.5.3IronRoughneck725.4TopDriveSystemsAtopdrivesystemconsistsofapowerswivel,drivenbya1000hpdcelectricmotor.Thispowerswivelisconnectedtothetravelingblockandbothcomponentsrunalongaverticalguidetrackwhichextendsfrombelowthecrownblocktowithin3metersoftherigfloor.Theelectricmotordeliversover25000ft-ibstorqueandcanoperateat300rpm.Thepowerswivelisremotelycontrolledfromthedriller’sconsole,andcanbesetbackifnecessarytoallowconventionaloperationstobecarriedout.Atopdrivesystemreplacesthefunctionsoftherotarytableandallowsthedrillstringtoberotatedfromthetop,usingthepowerswivelinsteadofakellyandrotarytable.73Theproceduresforaddingastand1Suspendthedrillstringfromslips,asintheconventionalsystem,andstopcirculation.2Breakouttheconnectionatthebottomofthepowersub.3Unlatchtheelevatorsandraisetheblocktothetopofthederrick.4Catchthenextstandintheelevators,andstabthepowersubintothetopofthestand.5Makeupthetopandbottomconnectionsofthestand.6Pickupthestring,pullslips,startpumpsanddrillahead.74TheadvantagesofTDS:Itenablescomplete90’standsofpipetobeaddedtothestringratherthantheconventional30’singles.Thissavesrigtimesince2outevery3connectionsareeliminated.Italsomakescoringoperationsmoreefficient.Whendrippingoutoftheholethepowerswivelcanbeeasilystabbedintothestringtoallowcirculationandstringrotationwhenpullingoutofhole,ifnecessary.Whentrippingintotheholethepowerswivelcanbeconnectedtoallowanybridgestobedrilledoutwithouthavingtopickupthekelly.75ThedisadvantagesofTDS:Increaseintopsideweightontherig.Electricandhydrauliccontrollinesmustberunupinsidethederrick.Whendrillingfromasemi-submersibleunderheavingconditionsthedrillstringmaybottomoutduringconnectionswhenthestringishungoffintheslips.Thiscouldbeovercomebydrillingwithdoublesandadrillingsubwhichcouldbebrokenoutlikeakelly.76776WELLCONTROLSYSTEMThefunctionofwellcontrolsystemistopreventtheuncontrolledflowofformationfluidsfromwellbore.Anyinfluxofformationfluidsintheboreholeisknownasakick.Thefunctionofwellcontrolsystem:DetectakickClose-inthewellatsurfaceRemovetheformationfluidwhichhasflowedintothewellMakethewellsafe78Therearemanysignsthatadrillerwillbecomeawareofwhenakickhastakenplace.Thefirstsignthatankickhastakenplacecouldbeasuddenincreaseinthelevelofmudinthepits.Anothersignmaybemudflowingoutthewellevenwhenthepumpsareshutdown.6.1detectingakick796.2ClosinginthewellBlowoutpreventors(BOPs)mustbeinstalledtocopewithanykicksthatmayoccur.OnlandrigsorfixedplatformstheBOPstackislocateddirectlybeneaththerigfloor.OnfloatingrigstheBOPstackisinstalledontheseabed.Ineithercasesthevallvesarehydraulicallyoperatedfromtherigfloor.TwobasictypesofBOP:AnnularpreventorRampreventor(blindrams/piperams/shearrams)80HydrilannularBOP81RAMTypeBOP826.3CirculatingoutakickToremovetheformationfluidsnowtrappedintheannulusahighpressurecirculatingsystemisused.Achokemanifold(溢流管匯)withanadjustablechokeisusedtocontrolflowratesduringthecirculation.Basicallyheaviermudmustbepumpeddownthedrillpipetocontroltheformationpressure,andthefluidsintheannuluscirculatedtosurface.Asthekickstartsmovinguptheholethechokeopeningisrestrictedtoholdenoughbackpressureontheformationtopreventanyfurtherinflux.Thefluidsarecirculatedoutviathechokeline,throughthechokemanifoldouttoagas/mudseparatorandaflarestack.Oncetheheaviermudhasreachedsurfacethewellshouldbedead.837WELLMONITORINGSYSTEMSafetyrequiresconstantmonitoringofthedrillingprocess.Ifdrillingproblemsaredetected,earlyremedialactioncanbetakenquickly,therebyavoidingmajorproblems.Driller’sconsole(司鉆控制臺)Mudlogging〔泥漿錄井〕84BOPStackup85Chapter3Thedrillstring86ContentsIntroductionDrillpipeTooljointsHeavywalldrillpipeDrillcollarsOtherdrillstringcomponentsDrillstringdesign87Drillstring:Thetubularsandaccessoriesonthedrillbit.Thedrilldtringconsistsof:drillpipe,drillcollar,thekellyandvariousotherpiecesofequipmentsuchasstabilisers(穩(wěn)定器)andreamers〔擴眼器〕.BottomholeAssembly:thedrillcollarsandtheotherequipmentwhichismadeupjustabovethebit.1Introduction88Componentsofdrillstring89Thefunctionsofdrillstringare:Tosuspendthebit;Totransmitrotarytorquefromthekellytothebit;Toprovideaconduit(通道)forcirculatingdrillingfluidtothebit.902drillpipeDrillpipeisaseamlesspipewiththreadedtooljoints.Oneendisthebox,theotherispin.Eachlengthofdrillpipeisknownasajointorasingle(單根).SinglesareinthreeAPIlength“ranges〞.Buttheexactlengthofeachsinglemustbemeasuredontherig-site.Drillstringmustbemeasuredandrecordedonadrillpipetally(標簽)91TooljointPipebody92Thedrillpipeismanufacturedwithdifferentouterdiameters,weightsandmaterials.Specifications:5〞19.5ib/ftGradeSRange293weightinair:Theweightofdrillpipesuspendedinair.wetweight:Theweightofdrillpipesuspendedinafluid.weightinair=weightperfootlengthofpipeWetweight=weightinairBuoyancyFactorEx.1dimensionsandweightofpipe(seetable13)Whatistheweightinairofajoint(30’)of5〞19.5lb/ftGradeGdrillpipewith4?〞IFconnections?Whatisthewetweightofthisjointofdrillpipewhenimmersedinadrillingfluidwithadensityof12ppg?942.1drillpipestressandfailureDrillpipeisexposedtothefollowingstresses:Tension--Theweightofsuspendeddrillstringexposeseachjointofdrillpipetoseveralthousandpoundsoftensileload.Torque—duringdrilling,rotationistransmitteddownthestring.Gain,poorholeconditioncanincreastheamountoftorqueortwistingforceoneachjoint.Cyclicstress—indeviatedhole,thewallofthepipeisexposedtocompressiveandtensileforcesatpointsofbendinginthehole.

95Cyclicstress96Corrosionofadrillstring:OxygenCarbondioxideDissolvedsaltsHydrogensulphideOrganicacids97Itisextremelydifficulttopredicttheservicelifeofadrillstringsincenotwoboreholesexperiencethesamedrillingconditions.Asaroughguide,thelengthofholedrilledbyapieceofdrillpipewillbe:Softdrillingareas:220000-250000ftHardordeviateddrillingareas:180000-210000ftThemethodsusedtoinspectdrillpipearesummarisedintable4.2.3DrillpipeInspection98993tooljoint(鉆桿接頭)Tooljointsarelocatedateachendofalengthofdrillpipeandprovidethescrewthreadforconnectingthejointsofpipe