鉆頭選型中的因素分析詳解演示文稿

鉆頭選型中的因素分析詳解演示文稿當(dāng)前第1頁\共有42頁\編于星期四\13點(diǎn)（優(yōu)選）鉆頭選型中的因素分析當(dāng)前第2頁\共有42頁\編于星期四\13點(diǎn)RotaryConsideration

旋轉(zhuǎn)因素RotaryBit旋轉(zhuǎn)鉆頭Theprofilefortherotarydesignsisrelativelyflatandthenoseisatarelativelylargeradius,allowingsecondarybladestooriginatefurtherfromthebitcentralregion.Thisgeometricarrangementkeepsthefaceofthebitmoreopenforimprovedhydraulics.旋轉(zhuǎn)外形設(shè)計(jì)為是扁平狀，但前端的半徑較大，能使二級(jí)刀片從鉆頭的中心部位伸出來。這種幾何設(shè)計(jì)使鉆頭的表面更加開闊，以提高液壓。當(dāng)前第3頁\共有42頁\編于星期四\13點(diǎn)TurbineConsideration

渦輪機(jī)因素TurbineBit渦輪機(jī)鉆頭Somebitdesignshavebeenoptimizedforusewithahighspeedturbine.Normallytheyhaveaparabolicprofile,withalongtaper.Thenoseofthebitisveryclosetothebit'scentralaxesbecausetheRPMwillbehigheronaturbinethanonnormalrotary,thecutterswillhavehighervelocityresultinginacceleratedheatgenerationaswellasashallowerdepthofcuttoachievethesameROP.有些鉆頭設(shè)計(jì)已經(jīng)完善，以便同高速渦輪機(jī)一起使用。它們的外形通常呈拋物線形狀，還帶一個(gè)長錐拔。鉆頭前端與鉆頭的中心軸非常接近，因?yàn)闇u輪機(jī)鉆頭比普通旋轉(zhuǎn)鉆頭的轉(zhuǎn)速（RPM）更高，刀具的速度更快，不斷加速發(fā)熱過程，從而切削深度更淺，這樣才能獲得相同的機(jī)械鉆速（ROP）。Tocompensate,aturbinePDCbitisbuiltwithanextendedprofiletopermitmorecutterstobesetinthebitwithlargeredundancyincluded.Therefore,eachcutterdoeslessworkindividually,asitisbackedupbyothercutters,resultinginincreasedcutterlife.Ifoneortwocuttersshouldfail,thebitwillstillbeabletocontinuedrilling.為彌補(bǔ)這一缺點(diǎn)，渦輪機(jī)PDC鉆頭表面延長，以便在鉆頭上安裝更多的刀具，這樣鉆頭上就留有很大的冗余部分。因此，刀具之間就能互相協(xié)助，從而減少每個(gè)刀具單獨(dú)的工作量，延長刀具的壽命。若一個(gè)或兩個(gè)刀具發(fā)生故障，鉆頭仍能繼續(xù)工作。當(dāng)前第4頁\共有42頁\編于星期四\13點(diǎn)SteerableSystemsTheory

導(dǎo)向系統(tǒng)理論MotorsTheory電動(dòng)機(jī)理論Motorsweredesignedtomeettheruggedrequirementsofdirectionaldrillersandclients.TheSurface-AdjustableBent(SAB)housinggivesthedrilleravarietyofmotorbendanglesthatareessentialtosteeringandcontrollingwelldeviation.Howthisbendinfluencesthewellprofiledependsuponthedrillingmode.電動(dòng)機(jī)應(yīng)滿足定位鉆井工和客戶對(duì)于礦井表面不平的要求。表面可調(diào)彎（SAB）殼體允許鉆井工從各種角度彎曲電動(dòng)機(jī)，這對(duì)操縱和控制井斜非常重要。而這種彎曲對(duì)礦井結(jié)構(gòu)的影響取決于鉆井方式。當(dāng)前第5頁\共有42頁\編于星期四\13點(diǎn)MotorsTheorycont.

電動(dòng)機(jī)理論（續(xù)）FrictionalForces摩擦力ThedrawbackofthePDMsisthatinordertosteer,thedrillstringcannotberotated,andthisdecreasestheamountofWeightonBit(WOB)thatcanbetransmittedtothebit,inturndecreasingROP.Forthisreason,PDMshavelimitedusageinExtendedReachDrilling(ERD)applications,especiallyastheinclinationofwellsincreases.容積式電動(dòng)機(jī)（PDM）的缺點(diǎn)在于，為了實(shí)現(xiàn)操控鉆頭之目的，不能旋轉(zhuǎn)鉆柱，這將減少能傳遞到鉆頭的鉆壓（WOB）數(shù)量，從而降低機(jī)械鉆速。因此，在大位移延伸井鉆井（ERD）應(yīng)用中，尤其是在礦井傾斜增多的情況下，PDM的使用有限。Thebitsteer-abilityinslidingmodeisoneofthemajorconcernstodirectionalcompaniesaswellastotheclient.滑動(dòng)模態(tài)中鉆頭的導(dǎo)向能力是定向公司和客戶的主要憂慮之一。當(dāng)前第6頁\共有42頁\編于星期四\13點(diǎn)RotarySteerableMethods

旋轉(zhuǎn)導(dǎo)向方法Pointthebit指向式Thismethoddictatesthedirectionofbuildbypointingthebitofftheaxisoftherestofthetool.Thisway,thetrajectoryissetbythreetouchpoints;theupperstabilizer,thenear-bitstabilizer,andthebit.

本方法通過指示鉆頭遠(yuǎn)離其它工具的軸線來規(guī)定建立方向，這樣就能通過三個(gè)觸點(diǎn)（即上部穩(wěn)定器、近鉆頭穩(wěn)定器和鉆頭）來設(shè)定軌道。當(dāng)前第7頁\共有42頁\編于星期四\13點(diǎn)Point-the-BitSystem

指向式系統(tǒng)BenefitsofthePoint-the-BitSystem指向式系統(tǒng)的優(yōu)點(diǎn)Point-the-Bitsystemsputtheoperatingmechanismsinsidethecollarinoilchambersisolatedfromthemudandfromcontactwiththewellbore.Additionally,therearenorotatingormovingo’ringsealsinitssteeringunit.PointthebitsystemshavealsolessworktodooncetheBHAhasentereditsnaturaltrajectory.Themajorityoftheworkisdonewhenthedirectionischanged.指向式系統(tǒng)將操作機(jī)構(gòu)置于儲(chǔ)油器中的套圈內(nèi)，遠(yuǎn)離泥漿和鉆井孔。此外，導(dǎo)向裝置中無旋轉(zhuǎn)式或可移動(dòng)O型環(huán)密封件。一旦井底鉆具組合（BHA）進(jìn)入其自然軌道，指向式系統(tǒng)的工作量則減小。而大多數(shù)工作已在方向改變時(shí)完成。當(dāng)前第8頁\共有42頁\編于星期四\13點(diǎn)RotarySteerableMethods

旋轉(zhuǎn)導(dǎo)向方法Pushthebit.推靠式Pushthebitsystems;useeitheranon-rotatingsleeveorpistonsontheODofthetooltopushthebitinthedesireddirection.推靠式系統(tǒng)：在工具的外直徑（OD）上使用非旋轉(zhuǎn)套筒或活塞，將鉆頭向目標(biāo)方向推進(jìn)。Itisarotarysteerablesystemthatcontrolsthedirectioninwhichawellisdrilled,in3–D,whilerotatingthedrillstring.Thetoolusesmudactuatedpadstodeviatethedirectionofdrillingbypushingagainsttheformation.

旋轉(zhuǎn)導(dǎo)向系統(tǒng)，可在旋轉(zhuǎn)鉆柱時(shí)從三個(gè)方向控制鉆井。該工具使用泥漿驅(qū)動(dòng)式襯墊通過推動(dòng)地層而改變鉆井方向。當(dāng)前第9頁\共有42頁\編于星期四\13點(diǎn)Push-the-BitSystem

推靠式系統(tǒng)BenefitsofthePush-the-BitSystem推靠式系統(tǒng)的優(yōu)點(diǎn)Thepush-the-bitsystem,workstopushthebitatalltimes,andevenharderwhenaskedtobuild,becauseithastolifttheweightofthetool.Nodissipatedtimeforslidingandtool-faceadjustments,itusesadesiredInclinationandAzimuthtofollowtheplantrajectorymoreaccurately.推靠式系統(tǒng)的工作是一直推動(dòng)鉆頭，在需要承重時(shí)要有足夠的硬度，因?yàn)樵撓到y(tǒng)必須舉起工具的重量。無需浪費(fèi)時(shí)間進(jìn)行滑動(dòng)和工具表面的調(diào)整，它也能通過理想的傾角和方位更加精確地跟隨規(guī)劃的軌道移動(dòng)。當(dāng)前第10頁\共有42頁\編于星期四\13點(diǎn)BitDesignforRSS

RSS鉆頭設(shè)計(jì)Steer-ability導(dǎo)向能力Bitprofile,gaugelength鉆頭外形，保徑長度Aggressivesidecuttingability鋒利面切削能力Stability穩(wěn)定性Lateral側(cè)面Torsional扭矩Durability耐久性ShoetoTD管靴至TDExtendbitlife延長鉆頭壽命當(dāng)前第11頁\共有42頁\編于星期四\13點(diǎn)DesignFeaturesforRSSApplication

RSS應(yīng)用的設(shè)計(jì)特點(diǎn)SecondaryCutters二級(jí)刀具ImprovedSecondaryCutterscountenablesuseofshort,steerableprofilewhilstmaintainingcutterdensity增加二級(jí)刀具的數(shù)量，能使用外形短小、易操縱的刀具，且能保持刀具的密度。Fieldrunsdisplay50%lesswear現(xiàn)場(chǎng)運(yùn)行顯示磨損小于50%Extendedbitlife延長鉆頭壽命當(dāng)前第12頁\共有42頁\編于星期四\13點(diǎn)RotarySteerableBitGaugeDesign

旋轉(zhuǎn)導(dǎo)向鉆頭保徑設(shè)計(jì)ActiveGaugeBit有效保徑鉆頭Sincedrillbitsusedwiththerotarysteerablesystem(RSS)arelaterallyresponsiveforgenerationoftherequireddoglegs,manytimesitisrequestedtheyhaveactivegauges,whicharecriticalforeffectiveside-cutting.由于旋轉(zhuǎn)導(dǎo)向系統(tǒng)（RSS）中使用的鉆頭是側(cè)面反應(yīng)轉(zhuǎn)向要求的軌道，很多時(shí)候都需要有效保徑，才能有效地完成側(cè)向切削。Anactivegaugebitconsistsofcuttersontheleadingedgeofthegaugepadsandapassivepadtrailingthecutters.Theside-cuttingpotentialofthebitcanbeadjustedbychangingthelength,width,andlevel,relativetothecuttingedgeofthepassivepad.有效保徑鉆頭包括保徑襯墊前緣的刀具和刀具后面的無源襯墊?？赏ㄟ^改變相對(duì)于無源襯墊切削刃的長度、寬度和水平面來調(diào)節(jié)鉆頭的側(cè)向切削能力。當(dāng)前第13頁\共有42頁\編于星期四\13點(diǎn)DesignFeatures-ActiveGaugeforRSSApplication設(shè)計(jì)特點(diǎn)——RSS應(yīng)用中的有效保徑Conventionalgaugecutterplacement-non-aggressive.常見的邊刀配置——非侵蝕性CuttersinanActiveGauge:有效保徑中的刀具：Heavyset沉重的Lowbackrake后傾角低Highexposure暴露量高Improvedsidecuttingability提高側(cè)向切削能力Advantages:優(yōu)點(diǎn)：Increasedgaugedurability提高保徑耐久性Aggressivegauge,increasedsidecuttingability侵蝕性保徑，提高側(cè)向切削能力LowfrictionresistancefrompointcontactwithTCimpregswillimprovepotentialROP.與TC浸漬木接觸點(diǎn)產(chǎn)生的低摩擦阻力能提高潛在的機(jī)械鉆速。Fluidflowtoaidcoolingandcleaningaroundthegaugecuttersandimpregs.液體流動(dòng)能促進(jìn)冷卻且能清潔邊刀和浸漬木。.當(dāng)前第14頁\共有42頁\編于星期四\13點(diǎn)DesignFeatures–ProfileforRSSApplication

設(shè)計(jì)特點(diǎn)——RSS應(yīng)用簡(jiǎn)介Steerable:Shortroundedtaper,shallowconeandshortbitlength.導(dǎo)向：短圓形錐拔，淺圓錐體，鉆頭長度短Sidecutting:Maximizationofcuttersinshoulder&gauge側(cè)向切削：刀具的肩部和保徑部位增加到最大程度Stable:Stabilityenhancedbyincreasedcontactwithboreholeviaspiraledgaugepads,andflatterprofile.穩(wěn)定：通過螺旋形保徑襯墊與井眼的接觸增多，穩(wěn)定性增強(qiáng)，且表面更加平滑。當(dāng)前第15頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations

鉆頭設(shè)計(jì)因素BitBody鉆頭體Profile外形Cutters刀具RakeAngles傾角BitLength鉆頭長度Gauge保徑BladeHeight刀片高度Vibrations振動(dòng)當(dāng)前第16頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations-BitBody

鉆頭設(shè)計(jì)因素——鉆頭體Themainfactorsinfluencingthechoiceofmaterialare:影響材料選擇的主要因素包括：A.Life‐incertainapplicationsbodylifeisdictatedbyerosionresistance,notstrength.Steelislesserosionresistantthanmatrix,butwithcarefuldesignofthebodygeometryanduseofhardfacing,thisshortcomingcanbereduced.A.壽命——在某些應(yīng)用中，鉆頭體的壽命取決于抗腐蝕性，而非強(qiáng)度。雖然鋼材的抗腐蝕性不如脈石強(qiáng)，但只要仔細(xì)設(shè)計(jì)鉆頭體的幾何排列和表面硬化處理，就可以彌補(bǔ)該缺點(diǎn)。B.Strength‐matrixisnotasstrongintensionassteelandconsequentlythisisreflectedinthebodydesign.Steelbitscanbedesignedtoincorporatehigh,relativelythinbladeswhichcanbeusefulespeciallyinwaterbasedmud,softformationapplications.Suchdesignsaregenerallynotfeasibleifthebitismanufacturedfrommatrixbecauseoftheriskofbladebreakageifaharderstringerisencountered.B.強(qiáng)度——脈石的張力不如鋼材強(qiáng)，這點(diǎn)在鉆頭體的設(shè)計(jì)中不難看出。鋼鉆頭上可安裝較薄的高刀片，尤其適用于水基泥漿和軟地層。若鉆頭由脈石制成，此種設(shè)計(jì)則不可行，因?yàn)殂@頭遇到較硬的細(xì)脈時(shí)刀片可能會(huì)斷裂。當(dāng)前第17頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–BitBodyCont.

鉆頭設(shè)計(jì)因素——鉆頭體（續(xù)）C.BitLength‐matrixproductsmusthaveaseparatepiecefortheAPIpinwhichisthenweldedontothesteelblankcastintothematrixcrownand,therefore,amatrixbitisinherentlylongerthantheequivalentone‐piecesteelbit.C.鉆頭長度——脈石產(chǎn)品必須包括一個(gè)單獨(dú)的部件，以便隨后將API銷焊接在鑄成脈石冠部的鋼鐵坯料上，因此，脈石鉆頭會(huì)比相同的鋼鉆頭更長。

D.Repair‐Worncutterscanbereplacedwithconsiderablymorereliabilityinasteelbodiedbitbecauseoftheoriginalattachmenttechniqueutilized.Inmostcases,cuttersareinterferencefittedintoasteelbitwhereasbrazingsecuresthePDCinamatrixproduct.Replacingcuttersinamatrixbitinvolvestheapplicationoflocalizedheat,whichcanhavedetrimentaleffectsonthesurroundingPDCwhichisnotbeingreplaced.D.修理——由于使用了原始連接技術(shù)，磨損的刀具可被更換為鋼制鉆頭體鉆頭中可靠性更高的刀具。在大多數(shù)情況下，刀具通過過盈配合被安裝在鋼鉆頭上，而銅焊卻能將PDC緊固于脈石產(chǎn)品中。更換脈石鉆頭中的刀具時(shí)需局部加熱，這對(duì)周圍未被更換的PDC有不利影響。當(dāng)前第18頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–BitProfile

鉆頭設(shè)計(jì)因素——鉆頭外形Cone圓錐體Theconeofthebitprovidesadegreeofstabilitywhenthebitisdrilling,duetotheresultantcuttingforcesfromthePDCsetwithintheconegenerallyurgingthebittorotateaboutitscentralaxes.鉆頭的圓錐體使鉆頭工作時(shí)保持穩(wěn)定，原理在于圓錐體中的PDC組產(chǎn)生的切削合力驅(qū)動(dòng)鉆頭圍繞中心軸旋轉(zhuǎn)。Nose前端Itisdesirabletohavearelativelylargenumberofcutterssetonthenosetopreventoverloadingduringthetransitiontoaharderformation.鉆頭前端最好能攜帶較多刀具，以防止轉(zhuǎn)換到較硬地層時(shí)刀具超負(fù)荷工作。當(dāng)前第19頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–BitProfileCont.

鉆頭設(shè)計(jì)因素——鉆頭外形（續(xù)）Taper錐拔Thetaper(orflank)ofthebitisthesectionbetweenthenoseandthegauge.Itmayprovideadegreeofstabilityanditslengthisusuallygovernedbythecutterdensityrequirement.鉆頭的錐拔（或側(cè)翼）指位于前端和保徑之間的部位，能使鉆頭保持穩(wěn)定，其長度通常取決于刀具密度的要求。However,analternativewaytoachieveahighercutterdensitywithoutextendingthetaperistoincreasethenumberofblades.然而，另一種方法無需延長錐拔即可實(shí)現(xiàn)較高刀具密度，那就是增加刀片的數(shù)量。當(dāng)前第20頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–BitProfileCont.

鉆頭設(shè)計(jì)因素——鉆頭外形（續(xù)）OuterDiameterRadius(ODR)外直徑區(qū)域（ODR）TheODRreferstothatregionofthebitprofilewheretheradiusattheendoftheflankleadsintothegaugeofthebit.ODR指鉆頭剖面區(qū)域，即側(cè)翼末端到鉆頭保徑的區(qū)域。Thisregionofabitisextremelyimportant,especiallyinmotororturbineapplicationswhererotatingspeedsarehigh,asthecuttersmustwithstandtheeffectsofhighvelocityduetotheirradialpositiononthefaceofthebit.Althoughtheangularvelocityofcuttersatthebitgaugeisidenticaltothatofcutterswithinthecone,thetangentialvelocityisgreatersinceitisafunctionofradiallocation.該區(qū)域在鉆頭上極其重要，尤其是在電動(dòng)機(jī)和渦輪機(jī)的應(yīng)用中轉(zhuǎn)速很高時(shí)，由于刀具處于鉆頭表面上的徑向位置，它們必須承受高速度的影響。雖然鉆頭保徑處刀具的角速度與圓錐體中的刀具相同，但由于徑向位置的作用，保徑處刀具的角速度更高。當(dāng)前第21頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–Cutters

鉆頭設(shè)計(jì)因素——刀具CutterCount刀具數(shù)量ThenumberofcuttersonaPDCbitisaprimarydeterminantofhowthebitperforms.PDC鉆頭上的刀具數(shù)量是鉆頭性能的主要決定因素。

Inanidealworldthebitdesignerwantstodesignaproductwhich:在理想環(huán)境中，鉆頭設(shè)計(jì)師想要設(shè)計(jì)出擁有下述特點(diǎn)的產(chǎn)品：Candrillabroadrangeofformationsincludinghardandabrasivestringers,能在各種地層中工作，包括較硬的和研磨性細(xì)脈，Canprovideaconsistentlyhighrateofpenetration,能持續(xù)提供較高的機(jī)械鉆速，Hasalongbitlifeandcanbebuiltatalowcost.鉆頭壽命長，且制造成本低。當(dāng)前第22頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–CuttersCont.

鉆頭設(shè)計(jì)因素——刀具（續(xù)）Unfortunately,thereareperformanceandcosttradeoffsinvaryingcuttercount.Usingmorecuttersallowsabittodrillharder,moreabrasiveformationsandgenerallyresultsinalongerbitlife.但不幸的是，產(chǎn)品的性價(jià)比隨刀具數(shù)量的變化而變化。若使用較多刀具，鉆頭則能在較硬的、研磨性更強(qiáng)的地層中工作，鉆頭壽命也更長。However,ahighercuttercountalsomakesabitmorecostly(particularlysincePDCcomponentsconstituteahighpercentageofthetotalbitcost)and,ingeneral,causethebittodrillataslowerrateofpenetration.Asthenumberofcuttersisreduced,thedirectionofthetradeoffreverses.然而，刀具越多也會(huì)使成本增加（特別是當(dāng)PDC部件在鉆頭總成本中占有很高比例時(shí)），而且，通常使鉆頭的機(jī)械鉆速更低。若刀具數(shù)量減少，情況則相反。當(dāng)前第23頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–CuttersCont.

鉆頭設(shè)計(jì)因素——刀具（續(xù)）CutterSize刀具尺寸AvarietyofPDCcuttersizesareavailable.ThemajorityofPDCproductsincorporatePDCofdiameters9mm,13mm,16mmand19mm.PDC刀具有各種不同的尺寸。大多數(shù)PDC產(chǎn)品的PDC直徑為9毫米、13毫米、16毫米和19毫米。Small小型Cuttersof9mmdiameterhavebeenusedonproductsdesignedforharderformations.刀具直徑為9毫米的產(chǎn)品設(shè)計(jì)用于較硬的地層。Medium中型13mmand16mmcuttersaremostsuitableforcuttingmediumtomedium-hardformationsaswellasabrasiverock.直徑為13毫米和16毫米的刀具最適用于切削中等到中等硬度的地層以及研磨性巖石。當(dāng)前第24頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–CuttersCont.

鉆頭設(shè)計(jì)因素——刀具（續(xù)）Large大型Generallyassociatedwithfastdrilling,19mmcuttersaremostsuitablefordrillingsofttomediumformationswhenmountedinhighbladedfishtailstylebits.Becauselargercuttersproducelargecuttingsintherightapplication.將直徑為19毫米的刀具安裝在高刀片魚尾形鉆頭上時(shí)，通常鉆速都很快，最適用于軟到中等地層，因?yàn)檩^大的刀具在適當(dāng)?shù)膽?yīng)用中會(huì)產(chǎn)生較大的鉆屑。VeryLarge超大型PDCcomponentsofupto48mmdiameterhavebeenusedinsoftformationbits.Spaceislimitedonthebitfaceandbyusingsuchlargecuttersthereisonlysufficientroomtomounttheminimumnumberofcutterstocutafullborehole.Wereonecuttertofail,thebitwouldbeunabletoproceed.Additionally,asverylargecutterswear,theverylargewearflatsproduceconsiderableheatwhichcancausecatastrophicdamagetothediamondlayer.直徑達(dá)48毫米的PDC部件適用于軟地層鉆頭。鉆頭表面的空間有限，若使用此類大型刀具，鉆頭上的空間只夠安裝最少的刀具，這樣才能切削出完整的井眼。若有一個(gè)刀具發(fā)生故障，則整個(gè)鉆頭都不能工作。此外，若超大型刀具磨損，那么，磨損的平面則會(huì)產(chǎn)生相當(dāng)高的溫度，這會(huì)嚴(yán)重?fù)p壞金剛石焊層。當(dāng)前第25頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–CuttersCont.

鉆頭設(shè)計(jì)因素——刀具（續(xù)）CutterDistribution刀具分布Cuttersaredistributedacrossthebitfaceinsuchawayastosatisfyvariousrequirements.刀具在鉆頭表面的分布方式能滿足各種要求。A.EvenWear‐thedesignertriestoachieveevenwearacrossthebit,sothatnoonecutterwearsappreciablymorethantherestwhichwouldresultinaweakspot.Additionally,evenwearresultsintheefficientutilizationofthePDC.A.均勻磨損——設(shè)計(jì)師試圖通過鉆頭實(shí)現(xiàn)均勻磨損，這樣就不會(huì)出現(xiàn)某一個(gè)刀具明顯比其它刀具磨損得更嚴(yán)重的情況，也不會(huì)產(chǎn)生薄弱環(huán)節(jié)。此外，均勻磨損能實(shí)現(xiàn)PDC的高效利用。B.OptimumLife‐basedontargetformationsand,therefore,operatingconditions,thecuttersarearrangedacrossthebitinsuchawayastoprovidemaximumbitlifeandtotakeintoaccountexpectedratesofpenetrationandproductcost.B.最長壽命——按照目標(biāo)地層和工作條件，刀具在鉆頭表面的分布方式能使鉆頭的壽命最長，且考慮了機(jī)械鉆速和產(chǎn)品成本等因素。當(dāng)前第26頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–CuttersCont.

鉆頭設(shè)計(jì)因素——刀具（續(xù)）C.Balance‐thelateralimbalanceforce,resultingfromthevectorialadditionofallthecuttingforcesasthebitisdrilling,iscalculatedatthedesignstagetoreducetheincidenceofbackwardwhirling,adetrimentalmotionofthebitwhichcanoccurundercertainconditions.Onmostproducts,however,itisdesirabletominimizethislateralforceandthecuttersarepositionedaccordingly.C.平衡——應(yīng)在設(shè)計(jì)階段計(jì)算好鉆頭工作時(shí)所有切削力的向量相加而產(chǎn)生的側(cè)向不平衡力，以減小某些情況下鉆頭反向旋轉(zhuǎn)和有害運(yùn)動(dòng)的發(fā)生率。然而，對(duì)多數(shù)產(chǎn)品而言，最好能使側(cè)向力減到最小，并將刀具放置在相應(yīng)位置。當(dāng)前第27頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–CuttersCont.

鉆頭設(shè)計(jì)因素——刀具（續(xù)）對(duì)PDC刀具的更高效利用——若PDC鉆頭設(shè)計(jì)中鉆頭全表面的刀具磨損相對(duì)一致，則能實(shí)現(xiàn)對(duì)PDC的最高效利用。制造鉆頭時(shí)避免易磨損區(qū)域是延長鉆頭壽命的一大要素?！硐氲哪p曲線中，鉆頭中心的磨損最小，在鉆頭表面則大面積迅速上升直到達(dá)到一個(gè)很高的穩(wěn)定水平，而在關(guān)鍵的保徑保護(hù)區(qū)域則下降到較低水平。1.減小中心刀具被損壞的可能性。2.提高鉆頭表面的刀具磨損率，延長鉆頭壽命。3.減少鉆頭關(guān)鍵外直徑區(qū)域（ODR）的嚴(yán)重磨損。4.大大地提高邊刀的有效性。當(dāng)前第28頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–RakeAngles

鉆頭設(shè)計(jì)因素——傾角Therakeanglesofacuttingtooldefinetheanglesatwhichthetoolispresentedtotheworkpiece.切削工具的傾角指工具與被加工件之間的角度。PDCelementscanhavebackrakeandsiderake,eachofwhichcanbepositive,negativeorzero.PDC元件可有后傾角和側(cè)傾角，二者都可為正角、負(fù)角或零角。Cutterbackrakeissaidtobemoreaggressivewhenthecutterispositionedsuchthatagivenweightonabitgivesagreaterdepthofcut.Themoreaggressivethebackrakeangle,thesmalleritsvaluebecomes.Henceacutterwithbackrakeof20°willbelessaggressivethanonewitha15°angle,butmoreaggressivethananothercuttersetat25°.若刀具放置的位置有利于施加在鉆頭上的重量使鉆頭制造更大的切削深度，刀具后傾角據(jù)說有具有更大的攻擊力。后傾角的攻擊力越大，其價(jià)值則越小。因此，后傾角為20°的刀具比后傾角為15°的刀具的攻擊力小，但卻比后傾角為25°的刀具的攻擊力大。當(dāng)前第29頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–RakeAnglesCont.鉆頭設(shè)計(jì)因素——傾角（續(xù)）Ingeneral,asthebackrakeofaPDCcutterbecomesmoreaggressive(i.e.asthetoprakeisreduced)itismoresuitableforsofterformations.Ifbackrakeistooaggressive,drillingharderformationsmightresultinchatteringofthecutter(andhencethebit),followedbychippingofthediamondandperhapscatastrophicfailureofthePDC.一般而言，由于PDC刀具后傾角的攻擊力較大（即，前傾角減?。?，此類鉆頭更適用于較軟的地層。若后傾角的攻擊力過大，在較硬的地層中工作可能會(huì)使刀具（以及鉆頭）震顫，然后導(dǎo)致金剛石碎裂，也許還會(huì)使PDC產(chǎn)生嚴(yán)重故障。Lessaggressivebackrakeswillreducetorqueforagivenweight-on-bit,butattheexpenseofpenetrationrate.Thus,onceagain,thedesignerisfacedwithadecisionbasedonconflictingrequirements.Themajorityofbitshavebackrakesof15°to30°.Althoughothervalueshavebeentested,the15°to30°rangeappearstoprovidethebestbalancebetweenrateofpenetrationandbitlife.攻擊力較小的后傾角能減小給定鉆壓的扭矩，但卻會(huì)減小機(jī)械鉆速。因此，設(shè)計(jì)師再次面臨就沖突要求作出決定的難題。大多數(shù)鉆頭的后傾角為15°到30°。盡管設(shè)計(jì)師也對(duì)刀具其它數(shù)值的后傾角做過試驗(yàn)，但只有15°到30°范圍內(nèi)的后傾角似乎才能使機(jī)械鉆速和鉆頭壽命達(dá)到最佳平衡。Mostdesignsvariesbackrakeascutterpositionincreasesfromthecentralaxesofthebit.LowerbackrakeonthebitfacemakesthebitmoreaggressiveforfasterROPandincreasedbackrakeattheODRreducesthelikelihoodthatbitwhirlwillbeinitiated.在大多數(shù)設(shè)計(jì)中，后傾角隨刀具位置與鉆頭中心軸之間距離的增加而變化。若鉆頭表面的后傾角減小，鉆頭的攻擊力則變大，機(jī)械鉆速也提高；若外直徑區(qū)域的后傾角增大，則可減小鉆頭旋轉(zhuǎn)的可能性。當(dāng)前第30頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–RakeAnglesCont.鉆頭設(shè)計(jì)因素——傾角（續(xù)）Siderakeisameasureofcutterskewrelativetoalinenormaltothedirectionoftravel.側(cè)傾角指刀具與鉆頭行進(jìn)方向標(biāo)準(zhǔn)直線之間的傾斜度。Negativesiderakepositionsthecutterfacetowardsthebit'scentralaxesandresultsincuttingsbeingurgedinward,insteadoftowardsthejunkslots.若側(cè)傾角為負(fù)角，則刀具的位置為表面朝向鉆頭中心軸，這樣就會(huì)將鉆屑推入鉆頭內(nèi)部而非垃圾槽中。Positivesiderakepositionsthecutterfacetowardstheoutsidediameterandproducestheoppositeeffect.若側(cè)傾角為正角，則刀具的位置為表面朝向外直徑，并能產(chǎn)生與上述相反的效果。Differentcompanieshaveexperimentedextremelyhighsiderakeangles,bothpositiveandnegative,butnoadvantageswereseen.Assiderakeincreases,theeffectiveoperatingwidthofthecutterdecreases,necessitatingmorecutterstoobtainthesamecoverage.個(gè)別公司嘗試過使用極其大的側(cè)傾角（包括正角和負(fù)角），但并未無任何優(yōu)勢(shì)。因?yàn)閭?cè)傾角增大，刀具的有效操作寬度則減小，這樣則需使用更多的刀具才能完成相同范圍內(nèi)的工作。InlightoftheabovemanybitcompaniescurrentlyorientsallPDCcuttingelementswithzerosiderake.鑒于上述原因，許多鉆頭公司目前都將所有PDC切削元件的側(cè)傾角設(shè)定為零。當(dāng)前第31頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–BitLength

鉆頭設(shè)計(jì)因素——鉆頭長度Wesupposethatthedistancefromthefacewherebittouchesthedriveshafttothebitcuttingfacemayvaryfrom1to2ofnominalbitdiameter.我們假設(shè)鉆頭接觸驅(qū)動(dòng)軸的表面與鉆頭切削表面之間的距離可有1至2個(gè)公稱鉆頭直徑的差異。Theoverallbitlengthisimportantfromasteer-abilityperspective.Shorterbitsaremoresteerable,astheyreducetheradiusofthepossibleturn.就導(dǎo)向能力而言，鉆頭的整體長度非常重要。鉆頭越短則越容易被操縱，因?yàn)樗鼈兡軠p少可能轉(zhuǎn)動(dòng)的半徑。ThelengthofaPDCbitisgovernedbythelengthofthebitgaugedesiredfortheapplication,thebladeheightandthebitcuttingprofile.PDC鉆頭的長度取決于應(yīng)用中理想鉆頭保徑的長度、刀片高度和鉆頭的切削剖面。當(dāng)前第32頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–BitGauge

鉆頭設(shè)計(jì)因素——鉆頭保徑GaugeProtectionMaintainingthefullgaugediameteroftheholebeingdrillediscrucial.Ifthebitlosesgaugeandbeginstodrillanundersizedhole,avarietyofproblemscanfollow,includingthebottomholeassemblybecomingstuckinthewell.保徑保護(hù)——維持鉆孔的全尺寸直徑至關(guān)重要。若鉆頭為安全保徑而開始鉆尺寸過小的孔，各種問題將會(huì)接踵而至，包括井底鉆具組合陷在井內(nèi)。Itis,therefore,imperativethebithassufficientprotectionatgaugetoavoidexcessivewear,whilestillbeingofreasonablelengthtoallowfordirectionalwork.因此，充分保護(hù)鉆頭保徑避免過度磨損非常必要，但仍需利用合理的長度以完成定向工作。InmyexperienceaPDCbitwilltypicallyhaveagaugeofsomewhereintheregionof1“to5".OnaverageIwouldsaythatthemajorityofbitsrunwiththeRSStoolhaveagaugeof1.5"to3.5",andthemajorityofbitsrunonmudmotorshaveslightlylongergaugesof2"to4".以我之見，PDC鉆頭的保徑通常為1"至5"。大多數(shù)應(yīng)用RSS工具的鉆頭的保徑通常為1.5"至3.5"，而大多數(shù)應(yīng)用井下動(dòng)力鉆具的鉆頭的保徑稍長，為2"至4"。當(dāng)前第33頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–BitGaugeCont.

鉆頭設(shè)計(jì)因素——鉆頭保徑（續(xù)）Forspecificapplicationssuchassidetrackingthebitgaugemaybeevenlessthan1"andforenvironmentswherebitstabilityisveryimportantextendedgaugesof>5"maybeutilized.在特殊應(yīng)用中，比如側(cè)向鉆，鉆頭保徑可能小于1"，而在鉆頭穩(wěn)定性極其重要的環(huán)境中，也可使用大于5"的延長保徑。

Itisgenerallyconsideredthatlongergaugelengthsprovidemorestabilityinrotationduetoincreasedsurfacecontactbetweenbitandborehole.一般而言，保徑越長，鉆頭與井眼的接觸面越大，則旋轉(zhuǎn)穩(wěn)定性越高。當(dāng)前第34頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–BladeHeight

鉆頭設(shè)計(jì)因素——刀片高度Thebladesofabitservethreemainfunctions:鉆頭的刀片有三個(gè)主要功能：

1.Givesupporttothecuttingstructures,1.支撐切削結(jié)構(gòu)，

2.Definethehydraulicflowpaths2.規(guī)定液流路徑，

Asoftformationbitwillbenefitfromtallblades,givingthebitmaximumopenfacevolume.

軟地層鉆頭最好使用高刀片，這會(huì)使鉆頭的露面體積達(dá)到最大。

3.ProvideincreasedfrontalexposureforthePDC.3.增加PDC的正面暴露量。當(dāng)前第35頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–BladeHeightCont.鉆頭設(shè)計(jì)因素——刀片高度（續(xù)）Exposure暴露量ExposureisdefinedasthedistancebetweenthetopofthePDCandthebottomofthewaterwayinfrontofthebladeasillustratedinthefigurebelow.暴露量指PDC頂部和刀片前面水道底部之間的距離，如下圖所示。Insoftformationdrilling,wheredepthofcutandpenetrationratearehigh,increasedexposurebecomesanadvantage,asthehighvolumeofcuttingsproducedcanberemovedfromthePDCfacemoreeasilyduetothelargecrosssectionalareaofwaterway.Thishighexposuregreatlyreducestheriskofbitballingwhendrillingsoft,stickyformationswithwaterbasedmud.在切削深度和機(jī)械鉆速都很高的軟地層鉆井中，暴露量增加是一大優(yōu)勢(shì)，因?yàn)樗赖臋M切面積較大，更易于將產(chǎn)生的大量鉆屑從PDC表面移除。在帶水基泥漿的軟粘性地層中鉆井時(shí)，高暴露量大大地減小了鉆頭泥包的風(fēng)險(xiǎn)。當(dāng)前第36頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–Vibrations

鉆頭設(shè)計(jì)因素——振動(dòng)Bitstability鉆頭穩(wěn)定性VibrationscancausehighimpactloadsonindividualPDCcutterswhichoftenresultinchipping,andreducedcutterlife.振動(dòng)可對(duì)單個(gè)PDC刀具造成高沖擊負(fù)載，這常常導(dǎo)致碎裂并縮短刀具壽命。Acceleratedwearofevenjustafewcuttersincriticalareasofabitcangreatlyreduceoverallbitlife.鉆頭關(guān)鍵部位的刀具，即使僅有幾個(gè)刀具加速磨損都能在很大程度上縮短整個(gè)鉆頭的壽命。Therearetwodistincttypesofvibrationwhichmustbeconsidered:必須考慮以下兩種不同的振動(dòng)類型：

1.Lateralvibration側(cè)向振動(dòng)

2.Axialvibration軸向振動(dòng)當(dāng)前第37頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–VibrationsCont.

鉆頭設(shè)計(jì)因素——振動(dòng)（續(xù)）Lateralvibration,sometimesreferredtoasbitwhirl,istheperiodicsidewaysmovementofthebitinthe"x-y"plane.Bitwhirlisaspecificphenomenonthatoccurswhenthedownholedynamicforcescausethebit'sinstantaneouscenterofrotationtomovefromitsgeometriccenter.側(cè)向振動(dòng)指鉆頭在“x-y”平面上的周期性側(cè)向運(yùn)動(dòng)，有時(shí)也指鉆頭的旋轉(zhuǎn)運(yùn)動(dòng)。鉆頭旋轉(zhuǎn)是一種特殊現(xiàn)象，通常在井下動(dòng)力使鉆頭的瞬時(shí)旋轉(zhuǎn)中心偏離其幾何中心時(shí)發(fā)生此現(xiàn)象。WhenanindividualPDCcutter"grabs"theformation,thebit'sinstantaneouscenterofrotationisshiftedtothepointofcutter/formationcontact.ThisinturncreatesabackwardwhirlingmotionwhichimpartsimpactloadingonthePDCcuttersonthesideoppositethecenterofrotation.當(dāng)單個(gè)PDC刀具“鉆入”地層時(shí)，鉆頭的瞬時(shí)旋轉(zhuǎn)中心移至刀具與地層的接觸點(diǎn)，從而產(chǎn)生反向旋轉(zhuǎn)運(yùn)動(dòng)，使旋轉(zhuǎn)中心反側(cè)的PDC刀具承受沖擊荷載。當(dāng)前第38頁\共有42頁\編于星期四\13點(diǎn)BitDesignConsiderations–VibrationsCont.

鉆頭設(shè)計(jì)因素——振動(dòng)（續(xù)）Axial