INRODUCIONODRILLINGBI鉆頭英文簡介

DRILLBITSELECTION

Oneofthemoreconfusingaspectsofoilwelldrillingtotheyoungandoldalikeisthenumeroustypesofdrillbits.Thelargestmanufacturerofdrillbitsmakes34typesand33sizes(diameters)andmanymoreonrequest.IADCorganizationhasasystemofassigningadesignationcodetoeachbittype.ROLLERCONESeriesTypeFeatureFeature(2)ROLLERCONEExample

Code:522R

5=codefor"insertbits“2=codefor"softtomediumformation“2=codefor"rollerbearingaircooled“R=codefor"reinforcedwelds"

FIXEDCUTTERSCuttertypeandbodymaterial,Cross-sectionprofile,Hydraulicdesign,andCuttersizeanddensityFIXEDCUTTERSFirstcodedesignationsareD-naturaldiamond/matrixbodyM-polycrystallinediamondcutters/matrixbodyS-polycrystallinediamondcutters/steelbodyT-thermallystablepolycrystallinediamondcutters/matrixbodyO-otherSecondcodedesignationsarelongtaper/deepconelongtaper/mediumconelongtaper/shallowornocone(parabolic)mediumtaper/deepconemediumtaper/mediumconemediumtaper/shallowornocone(rounded)shorttaper/deepcone(inverted)shorttaper/mediumconeshorttaper/shallowornocone(flat)Thirdcodedesignationsarebladed/changeablejetsbladed/fixedportsbladed/openthroatribbed/changeablejetsribbed/fixedportsribbed/openthroatopenface/changeablejetsopenface/fixedportsopenface/openthroatalternativecodesradialflowcrossflowotherFourthcodedesignationsarecuttersize;large,medium,andsmallcutterdensity;light,medium,heavyExampleCode:M582M=codefor"polycrystallinediamondcutters/matrixbody““5=codefor"mediumtaper/mediumcone““8=codefor"fixedports/openface““2=codefor"mediumcuttersize/lightcutterdensity"DrillBitCharacteristicsTeethlengthandsizeNumberofteeth(indexing)ConeoffsetConebearingtypeHeelrowteethconfigurationGaugeconfigurationJournalshaftangle(howflatorroundthebottomholepattern)TheteethlengthandsizeandconeoffsetaffecttheROPThenextthreeitemsonthelisthavealargeaffectonthebitlife.Item7affectsholestraightness.Rollerconedrillbitcharacteristicsofimportanceinregardtoselectionare:ROCKFAILUREMODELSTworockfailuremodelsarerecognized:thetensionandshearIthasbeenarguedthatthesheartypeactionismoreefficientthanthetensionmodel.DRILLBITSELECTIONCRITERIAApopularequationforcostcomparisonsisthetotalcostperfootequation.Ifthebitwereoperatedtoitsoptimallifeatitsoptimumweightandspeed,thenthecostwouldbethelowestcostperfootforthebit.IsthebitlifeifthebitisterminatedbyBearingfailure,Totaltoothwear,orThereductionofitsdrillingratetoanuneconomicalone.p.s.Formationchangesoftenmaskthelatteroptimallifeandcaremustbeexercised.OPTIMALLIFEExampleFollowingperformancedataisgiven:ITEMSTEELTOOTH INSERTTOOTHBitCost$277.88 $1521.32Trip6:18hrs/min6:32hrs/minRotationTime10:01hrs/min 58:42hrs/minDownTimeNoneNoneBitFootage 180ft880.5ftRigCostRate375$/hrSameFractionToothWear1/2NotApplicableFractionBearingWear 6/8 8/8AverageDrillingRate 18ft/hr12.5ft/hrBitSize7-7/8in.7-7/8in.BitWeight30,000lbs 40,000lbsRotarySpeed 85rpm60rpmTheplotshowsthathadthesteeltoothbitbeenpulledatitsoptimallife(6hoursand34minutes)itwouldhavehadalowercostperfoot:$34.05/ftversus$35.47/ft.TriptimesmaybetakenfromtheIADCtoursheetormaybetakenfromtheGeolographunitorsomeotherdevice.Achartversusdepthmustbeconstructedforeachrigforultimateanalyses.TRIPTIMEExampleAbitisrunatadepthof8,000feetandpulledatadepthof8,500feet.Howmanyhoursisthetriptimeforthisbit?TripT=(5.2+5.7)/2=5.45hrFromthechartaroundtripsat8,000feetand8,500feetrequire5.2hoursand5.7hours,respectively.OPTIMALWOB&RPMThepurposeofselectingbitweightandrotaryspeedsareto1. producethelowestdrillingcostperfoot2. controlthedirectionofthedrillhole3. findoverpressuredzones4. satisfyequipmentlimitations(solidsremoval,BHA,etc.)5. developasatisfactorycuttingsdescriptionlogCONTOURMETHODThemethodconsistsofconstructingthepreviousfigureinatwodimensionalpresentation.ExampleSixinsertbitshavebeenrunandtheirperformanceandtotalcostperfootdataarelistedinthetable.BIT#ROT.TIMEFOOTAGETCFHr:Min$/FT158:42 734 35.28239:05 360 51.513 101:2185548.99462:07 614 44.24547:16 517 41.27656:33 658 38.14TheoptimalWOBandRPMare40,000lband50rpm($35.00/ft)ANALYTICALMETHODThesameprocedurecouldbeusedfordeterminingoptimalWOB,andRPMforthesteeltooth,rollerbearingbit;however,anGalleandWoods’analyticalmethodisavailableforthesebits.DEFINITIONOFTERMSBS =Bitdiameter;inchW' =Actualweightonbit;1000poundsW =Equivalentweightona7-7/8inchbit;1000poundsTT =Triptime;hrsR =Costrateofthedrillingoperation;$/hrsT =Time;hrsG =BitCost+TripCost;$TC =Tripcost;R*TT;$D =Fractionoftoothheightwornaway;8thsB =Fractionofbearinglifeconsumed;8thsDT =Downtime;hrsRT =Rotationtime;hrsF =Bitfootage;ftGalleandWoodspublishedthefollowingrelationshipsfortherateoftoothwear.TOOTHWEARA= CorrelationcoefficientfortoothwearandiscalledtheformationabrasivenessfactorIntegrationofthetoothwearequationgivesbitrotationtimeToothwearEquationRotarySpeed,N=80BEARINGWEARS= correlationcoefficientcalledthedrillingfluidfactorOtherspublishedthefollowingrelationshipfortherateofbearingwear.RotarySpeed,N=80RATEOFPENETRATIONC= correlationcoefficientcalledtheformationdrillabilityfactorThevaluesofandaredeterminedfromdrill-offtestandrangebetween.6<<1.0.4<<1.0p= 1.0ifflattoothwear(non-sharpening)p= 0.5ifselfsharpeningBitfootage(F)isequaltoRateofPenetrationxRotationTimeEquationofROPSofar,RTisdeterminedeitherbysettingD=1(completebittoothwear)orB=1(completebearingwear)Whichevercomesfirst.DRTFDRTFDRTFDRTFDRTFDRTFDRTFRotarySpeed,N=80ThetotalcostperfootequationisDRTFTCFDRTFTCFDRTFTCFDRTFTCFDRTFTCFDRTFTCFRotarySpeed,N=80TheparametersA,C&Sareusuallycomputedwithdatagatheredfromothersimilardrillbitswhichwereruninsimilarformations,atsimilardepths,withsimilarbottomholeassemblies,withsimilarhydraulics,withsimilarmuds