EVALUATION OF TECHNICAL DRILLING OPERATION – CASE STUDY IN INDONESIA.docx

EVALUATIONOFTECHNICALDRILLINGOPERATION-CASESTUDYININDONESIAFinalExaminationReportBy:ALRisAlfharisiNIM.12211014GUSTiArdiansahNIM.12211039AstiDamayantiNIM12211063SubmittedasthefinalexaminationofDrillingEngineeringLectureDepartmentofPetroleumEngineeringFacultyofMiningandPetroleumEngineeringInstitutTeknologiBandungDEPARTMENTOFPETROLEUMENGINEERINGFACULTYOFMININGANDPETROLEUMENGINEERINGInstitutteknologibandung2014VALIDATIONSHEETEVALUATIONOFTECHNICALDRILLINGOPERATION-CASESTUDYININDONESIAFinalExaminationReportBy:ALRisAlfharisiNIM.12211014GUSTiArdiansahNIM.12211039AstiDamayantiNIM12211063SubmittedasthefinalexaminationofDrillingEngineeringLectureDepartmentofPetroleumEngineeringFacultyofMiningandPetroleumEngineeringInstitutTeknoIogiBandungApproval,Date:Supervisor,Dr.Ing.BOnarTUaHaIOmoanMarbUnN1P.197512222009121002EVALUATIONOFTECHNICALDRILLINGOPERATION-CASESTUDYININDONESIAA.Alfahrisi*,G.Ardiansah*,A.Damayanti*,InstitutTeknologiBandungCopyright2014zInstitutTeknologiBandungThisreportwaspreparedtofulfilldrillingengineeringlecturefinalexaminationattheDepartmentofPetroleumEngineering,InstitutTeknologiBandung.ThisreportwaswrittenusingstandardSPEPublicationStylein2013.AbstractWellplanningisanessentialpartindrillingengineeringbecauseitwillbethebackboneofeveryotherprocessthatwearegoingtodowiththeoilfieldthatwearedealingwith.Processsuchasreservoirsimulation,productionengineering,orevensurfacefacilitiesoperationwillbeaffectedbythewellplanningprocess.Wellplanningprocessareconstitutedbyseveralstepswhichstartfromdeterminingtheporepresureandfracturepressureinordertodeterminethecasingdesign.Casingdesignisthenimportanttodeterminethecasingsettingdepth,andalsotocreatethemostefficientcosttobepaidforthecasingoperation.Afterthecasingdesignisfinished,thewellplanningprocesswillgotothenextstepwhichismuddesignprocess.Themuddesignistheheartofdrillingengineeringbecauseit'sthemaincomponenttomaintainboreholestabilitytopreventblowoutfromhappening.Becauseofthat,muddesignisconsideredtobeveryimportant.Otherthanmuddesign,anotherdesignthatwehavetodoisthecasingdesigninordertoprovidestrongmixtureofcementthatcanholdthecasingweight.Nexttothatisbitchoosingbytakingintoaccounttheboreholesize,formationcharacteristic,andalsotheeconomiccost.Incasingdesignprocess,weneedtotakeintoaccountburst,collapse,andtensionloadofthecasingtodeterminethesizeofthecasingandalsocasingsettingdepth.Thisisveryimportanttoensurethecasingcanwithstandtheloadthatwillbehandledduringthewelllifetimeperiod.Afterthat,weneedtoproceedwiththedrillstringdesigninordertodesignthetypeofdrillpipetobeusedandthesize.Thisisimportanttomakethedrillingprocessmoreefficientbecausethewrongselectionofdrillpipemaycreateeconomiclossthat,sveryimportanttothecompany.Thecasinganddrillstringdesignareverynecessarytocalculatethemaximumloadtobeheldbytherigthatwecanuseindeterminingtherightypeandsizebecauserigrentingisoneofthemajorbudgetportionineverydrillingoperation.Allthedesignprocessthataredescribedabovearethenintendedtoavoidthenon-productivetimeofdrillingoperationtocreatemoreefficientdrillingprocess.Additionalanalysisisthenrequiredtodeterminewhetherweneeddirectionalorhorizontaldrillingoperationbasedongeologicalconsiderationsandeconomicreasonstorecovermoreoilandgas.BackgroundWellTM-19isaverticalwellwithtotaldepthof3610feet.Thedrillingactivityisintendedtoevaluatethehydrocarbonappearanceonsandstoneformation.Thewellwasdrilledon7thAugust2009andreached3610feeton18,hAugust2009byusing2PDCdrillingbits(bothofthemaresecond-hand).Thecompanystartedtheoperationfrom572feet(hole12¼tttrajectory)until3610feet(TD).The12xtrajectorystartedfrom572feetuntil1874feetbyusingmudof8.8-9.2ppgdensity.Onthistrajectorythereadingofbackgroundgasisontheintervalof10-30unitswithmaximumgasof411unitson1724feet.Bygettingin49jointsofK-55,36ppfR3BTCcylinder95/8"withoatshoeseton1870feet.The8%”holetrajectorystartedfrom1874feetdeepuntil3610fetbyusingmudweightof9.2-9.4ppg.Onthistrajectory,thebackgroundgasisaround5-15unitswithmaximumgasof172unitson2065feet.TherecordingdataElectricLoggingisdonebySchlumbergerwhichisPEX-BHC-AIT-GR;GR-RFT;CST-GR.Gettingin97jointsK-55,23ppf,R-3,BTCCylinderof7,'withfloatshoeseton3610feet.Thisstudyisintendedtoanalyzewhehterthemeasurethathavebeendonebythecompanyisefficientenoughtothedrillingprocessandgiveabetterrecommendationthatwillfinallyleadtoeffectivenessofthedrillingoperation.Inordertodothat,thisstudywillbeusingtheoreticalapproachandcalculationthatwillhopefullyhelpthecompanytoevaluatetheinefficientmeasuresintheTM19WellProjectandputabettermeassurebasedonouranalysisontheirnextproject.Theevaluationalanalysiswillincludeonthefollowingmeasures:porepressure,fracturegradient,casingsettingdepth,holegeometryselection,mudplan,cementplan,bitprogram,casingdesign,drillstringdesing,rigsizingandselection,fieldperformance,anddirectionaldrilling.TheoreticalBackgroundAliteraturereviewwasperformedtogainknowledgeofdifferentporepressureandfracturegradientpredictionmethodsandeconomicaldesigninanefforttofindthebeststrategyforthisareaPorePressure.Formationpressure(porepressure)isanimportantfactorthataffectsthedrillingoperation,duetoimproperevaluationmayleadtodrillingproblemssuchaslostcirculation,blowout,stuckpipeandholestability.Foroptimizationofthedrillingprocess,sowhendeterminingfonationpressureshouldwefocusondeterminingtheareaswherethereareformationsthathaveanoverpressure,itrequiressomemethodstodetectandpredictwherethepressurewillbeencounteredover.Basicallyitisaidedbytheseismicdata,butitisnotveryaccurateprecisionandaccuratebecausethedataobtainedisdatathatisrough.Therefore,weneedtomakeobservationsofcertainparametersrecordedduringdrillingunderwaythatwillhelpinpreventingtheoccurrenceofwildbursts(blow-out)asaresultofthedetectionarea/zoneoverpressure.Drillingparametersthatneedtobeconsideredinclude:drillingpenetrationrate(rateofpenetration/ROP),rotationalspeed(RPM)andloadonthechisel(WOB),inwhichtherelationshipofthethreeparametersshowninthefollowingformula.where:d=drillingexponentR=rateofpenetration(ROP),ft/hrsN=rotarySpeed(RPM)W=weightofbit(WOB),lbsB=bitdiameter/bit(inchi)Thevaluefromaboveequationstillneedstobecorrectedagainagainstthenormalgradientandthedensityofthemud,sothat:d-=dfc)2)where:dcorr=d-exponentIerkoreksipmn=muddensityonnormalformation(normalgradient),lbgalPmC=circulationmuddensity,lbgalInIndonesia,especiallyinSumateraandthesurroundingsareahavenormalvalueofthegradientaround1.06SG(8.8ppg).Inthesewellsestimateformationpressureorporepressurebasedon:backgorundgas,gasconnection,temperatureout,theinteretationoflithology,observationwellsandd-exponenl.Valueofporepressurecanbeobtainedfromthedatad-exponentoftheresultdcorrplotagainstgasconnection.Ifthereisaconnectiontoagasdrillingcontinuouslymudweightindicatesthatweuseisapproximatelyequaltotheporepressureoftheformation,meanporepressureoftheformationisequivalenttotheweightofthemudthatweuse.Atthetimeofthegasdrillingtakesplacedoesnotlookgreat,becausecoveredbyECD(EffectiveCirculatingDensity)ofmudwhosemagnitudedependsonthepropertiesofthemud.ECDvalueitselfisaffectedbythedensityofthemudusedandthepressurelossintheannulusalongthecircuitasafunctionofdepth,canbecalculatedbythefollowingequation:ECD= MW +6p0.052*D3)where:ECD=EffectiveCirculatingdensity,lbgalMW=muddensity,lbgal£6p=totalpressurelossesinannulus,psiD=depth,ftFracturePressure.Pressurefracturing(fracturegradient)isthehydrostaticpressureoftheformationofthemaximumthatcanbedetainedwithoutduecausefracturingincaseoffracturefearedtobetheinclusionofaninfluxofgasthatcancausekick.Inaddition,byknowingthefracturingpressuregradientisveryusefulwhenresearchingthebasicstrengthcasing(casing),whereaswhenthefracturingpressuregradientisnotknownitwillfinditdifficulttocloakingwellcementingandcasingormounting.Thevalueofthefracturingpressureisaffectedbyoverburdenpressure,formationpressureandrockstrengthconditions.ThecalculationofthegradientestimationoffracturingwellsusingthecalculationmethodofMatthewsandKelly.ThiscalculationisbasedonthevalueofKi(matrixstresscoefficient)derivedfromtheresultsLeakOffTest.Fracturinggradientcalculationformulais:4)F=P/D+KiDwhere:F:fracturegradient,psi/ftP:formationporepressure,psi:matrixstressatpointofinterest,psiD:depthatpointofinterest,TVD,ftKi:matrixstresscoefficient,dimensionlessCasingDesignDepth.Casingsettingdepthisdeterminedbasedondownholeconditionsuchasporepressure,fracturepressure,andpressurewindow.Fromthepressurewindowwehaveconstructedwecananalyzetheintervalofourcasingused.Afterdeterminingcasingsizeanddepthforeverycasingstring,anddesigndrillingoperation,loadtowardsthecasingcanbecalculated.Weightandgradeofcasingthatissuitabletocounteraloadcanbecalculated.1. CollapseLoadCasingwillreceivemaximumloadiftheexternalradialforceismorethaninternalradialforce.Maximumcollapseloadoncasingcanbecalculatedbyassuminginnercasingisinemptycondisiton.Collapseloadoneverypointalong5)thecasingcanbecalculatedwith:PColIaPSe=externalinternal2. BurstLoadCasingalsowillgainaburstloadiftheinternalradialloadisbiggerthanexternalradialload.Burstloadalongcasing,canbecalculatedwith:6)PCollaPSeinternalPeXternal3. AxialLoadAxialLoadoncasingcanbeintheformoftensileloadandcompressiveload,dependsontheoperation.Axialloadoncasingcanhaveaveryvarietyvalue.Axialloadwillappliedonsomeoperationsandhavetocalculatedandsumtodeterminetotalaxialloadtowardthecasing.HoleGeometrySelection.Bitandcasingsizeselectioncanmeanthedifferencebetweenawellthatmustbeabandonedbeforecompletionandawellthatmustbeabandonedbeforecompletionandawellthatisaneconomicandengineeringsuccess.Impropersizeselectioncanresultinholessosmallthatwellmustbeabandonedduetodrillingorcompletionproblems.Thedrillingengineer(andwellplanner)isresponsiblefordesigningtheholegeometrytoavoidtheseproblems.However,asuccesfulwellisnotnecessarilyaneconomicsuccess.Forexample,awelldesignthatallowsforsatisfactory,trouble-freedrillingandcompletionmaybeaneconomicfailurebecausethedrillingcostsaregreaterthanbeexpectedreturninvestment.Holegeometryselectionisacriticalpartoftheengineeringplanthatcanmakethedifferencebetweeneconomicandengineeringfailureorsuccess.RigSizingandSelection.Rigisoneofthemostimportantcomponenttodrillawell,andthefirstcomponentthatweneedtopreparebeforedrilling.UsuallyRigDesignisrelatedtoitsmaximumloadtoruninacasingoradrillstring.7)casing的”casing(ft)x3.281Where:WIOtaI=Totalweightofcasing(Ibs)WCaSing=Weightofcasing(lbft)hcasing=Casingdepth(ft)MaxRigLoad=wtal(n+2)8)Where:WtOtai=Totalweightofcasing(Ibs)n=Numberofcoileddrillinglineinthecrownblock(Assume:n=l()MudPlan.Ingeotechnicalengineering,drillingfluidisusedtoaidthedrillingofboreholesintotheearth.Drillingmudisoneofthemostimportantelementondrillingoperation.Drillingfluidhasmanyfunctionswhichneedtobeoptimizedtoovercomeholeproblem.Failureofthedrillingfluidtomeetitsdesignfunctionscanproveextremelycostlyintermsofmaterialsandtime,andcanalsojeopardisethesuccessfulcompletionofthewellandmayevenresultinmajorproblemssuchasstuckpipe,kicksorblowouts.Sotypeplanning,additiveandvolumeofdrillingfluidisimportanttomakethedrillingoperationsucceed.Oftenusedwhiledrillingoilandnaturalgaswellsandonexplorationdrillingrigs,drillingfluidsarealsousedformuchsimplerboreholes,suchaswaterwells.Liquiddrillingfluidisoftencalleddrillingmud.Thethreemaincategoriesofdrillingfluidsarewater-basedmuds(whichcanbedispersedandnon-dispersed),nonaqueousmuds,usuallycalledoil-basedmud,andgaseousdrillingfluid,inwhichawiderangeofgasescanbeused.Themainfunctionsofdrillinguidsincludeprovidinghydrostaticpressuretopreventformationfluidsfromenteringintothewellbore,keepingthedrillbitcoolandcleanduringdrilling,carryingoutdrillcuttings,andsuspendingthedrillcuttingswhiledrillingispausedandwhenthedrillingassemblyisbroughtinandoutofthehole.Thedrillingfluidusedforaparticularjobisselectedtoavoidformationdamageandtolimitcorrosion.Hp=0.052xMw(ppg)xD=Psi8)where:Hp=Hydrostaticpressurefromthemud,psi.Mw=Muddensity,ppg/pcfD=Depth,ft.Therearemanydrillingfluidadditiveswhichareusedtodevelopthekeypropertiesofthemud.Thevarietyoffluidadditivesreeclthecomplexityofmudsystemscurrentlyinuse.Thecomplexityisalsoincreasingdailyasmoredifficultandchallengingdrillingconditionsareencountered.Weshalllimitourselvestothemostcommontypesofadditivesusedinwater-basedandoilbasedmuds.Theseare:1. WeightingMaterialWeightingmaterialsordensifersaresolidsmaterialwhichwhensuspendedordissolvedinwaterwillincreasethemudweight.MostweightingmaterialsareinsolubleandrequireViscosiferstoenablethemtobesuspendedinafluid.Exampleofweightingmaterialsare:barite,hematite,magnetite,etc.2. ViscosifiersTheabilityofdrillingmudtosuspenddrillcuttingsandweightingmaterialsdependsentirelyonitsviscosity.ExampleofViscosifiersare:bentonite,CMC,PAC,XanthanGum3. StarchesStarchisanaturalpolymerusedindrillingmudsprimarilytoreducefiltratelossandtoprovideviscosity.CementPlan.Inordertoplancementwemustdeterminetopofcement(TOC)isthepointwherethecementbegantobepumpedorcementtopspot.Incementingoperationsweknowthetermsqueezecementingisaconditioninwhichthehydraulicpressureisusedtopushthecementpassesthroughtheholeinthecasingandintotheannulus.Inanycementingoperation,decisivestepbysubtractingtheTOCissqueezecementinginten,alswith50fttoobtaintheTOCvalue.Inthiscase,becausethecasingisinstalledat571ft,thentheselectedTOCat521ft.Topofcementcanbedeterminedby2ways: SurveiTemperaturThisinvolvesrunningathermometerinsidethecasingjustafterthecementjob.Thethermometerrespondstotheheatgeneratedbythecementhydration,andsocanbeusedtodetectthetopofthecementcolumnintheannulus.Figure-1.DeterminingTopofCementbyusingtemperaturelog(Source:Heriolt-WattUniversity,DrillingEngineering) RadioactiveSurveyRadioactivetracerscanbeaddedtothecementslurrybeforeitispumped(Carnoliteiscommonlyused).Aloggingtoolisthenrunwhenthecementjobiscomplete.Thistooldetectsthetopofthecementintheannulus,byidentifyingwheretheradioactivitydecreasestothebackgroundnaturalradioactivityoftheformation.Figure-2.DeterminingTopofCementbyusingRadioactivelog(Source:Heriott-WaitUniversity,DrillingEngineering)Incementingoperationsrecognizedtwotypesofcementnamelyleadandtailcementcement.Bothtypesofcementhavedifferencesintermsofdensityandalsothepenyemenannya.Headcementisthecementthatwasfirstpumpedatthelopofthedrillholeastemperatureandlowerpressuresothatthequalityofcementevenworsethanthetailcement.Whilethetailcementiscementwhichislocatedinthedeeperpartsothatithasbetterqualitybecausetheyhavetowithstandtemperaturesandhigherpressures.Figure-3.LeadcementandTopcementSource:http:WWWFigure-3.PartitionofCementingProgramSource:Source:http:WWWdrillin>formulascon¾/What-areleadand-tail-cement/accessedon10,hMay2014BitProgram.ADrillbit,isadeviceattachedtotheendofthedrillstringthatbreaksapart,cut