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1、CHAPTER13DeepwaterRiser1.essBestPracticeNote:Chaptersarenotdefinitive.Regiona1.know1.edgeandexperiencesha1.1.a1.waysbeusedtoassurebestwe1.1.practicesareapp1.ied.TOPANDSURFACEHO1.EOBJECTIVESTheriser1.essobjectivessha1.1.beexecutedinaccordancewithSEEprincip1.esandassurethatprimarywe1.1.contro1.ismaint
2、ainedthroughouta1.1.activitiesconductedtode1.iverprogram,design,engineering,andoperatingva1.ueasp1.anned.Pi1.ot-ho1.etopandsurface-ho1.eprogramobjectivesgenera1.1.yconsideredare:Pi1.ot*Ho1.eObjective1. Gatherdatatodetect,identify,eva1.uate,p1.an,prevent,andmitigateunknownhazardsandoperationa1.riskst
3、hatexist2. Obtaingeo1.ogica1.,porezandfracturepressuredatatomakemoreinformedandva1.ueadditiondecisions.3. Determineandeva1.uateoptima1.designzengineering,andoperatingrequirements.Note:Forwi1.dcatorimportantexp1.orationand/orappraisa1.we1.1.szacquiringpressureand1.oggingwhi1.edri1.1.ing(PWD/1.WD)data
4、isoftenakeywe1.1.objectivetobeobtainedfromthepi1.ot-ho1.e.TopandSurfaceHo1.eObjective1. MaintainVertica1.ityandoptima1.cy1.indrica1.we1.1.borequa1.ity.2. Providestructura1.integritytotrip,run,insta1.1.,andcementa1.1.structura1.casingstrings.3. Affordsufficientshoestrengthtosafe1.ydri1.1.thefirstinte
5、rmediatesectiontoitsrequireddepth.4. Incurnooperationa1.damage,fai1.ure1.oss,orharmtotheenvironment.Note:Optima1.we1.1.de1.iveryrequiresa“higauge“symmetrica1.andcy1.indrica1.we1.1.borethatisreadi1.ytripped,casedrun,andcementedatA1.ARPoperationa1.1.oss.IvpuucDttghttpsd0iar1.l 016B97S4)X)4 022825.0001
6、324772019 Ekcvicr 1.ed. All rights reserved.HAZARDSANDRISKSHazardsandrisksdri1.1.ingsha1.1.owwe1.1.boreinterva1.s(asi1.1.ustratedinTab1.e13.1)isthefocusofthissectioninregardstothekeyandcritica1.issuesthatcancause,affect,andimpactdeepwateroperationa1.methodsthemostBestpracticesconsideredtopreventandm
7、itigatedetrimenta1.hazardeffectsasopposedtoremedia1.curesarepresentedinthischapter.Priortodri1.1.ingwe1.1.s,afu1.1.hazard,riskanduncertaintyassessment,andrequiredsensitivityana1.ysisiswarranted.Practica1.stepsthenaretakentopreventand1.imita1.1.operating1.ossthatshou1.dinc1.udeanappraisa1.processmeth
8、odofhowtomode1.,monitorandcontro1.insituwe1.1.borestressbehaviorfora1.1.operationsconducted.Thatisthroughgatheringthecritica1.we1.1.sdataandevidentinformationprovidedtoderiveformation(sand)strengths,sha1.1.owX1.o1.1.OTdata,formationporepressure,andseismicpropertiesofanypressuredpackage.FromTab1.e13.
9、1,itisconc1.udedthateachinterva1.unitisindividua1.risked,assessedthroughtheuseoff1.uidmechanics,petrophysics,geoscience,geomechanics,pressureeva1.uation,andmateria1.(formation)strengthandstressregimefactors.Note:Riskc1.assifications(whereinterpretationcanbespurious)werepresentedinChapter2,p.11.TAB1.
10、E13.1I1.1.ustrativeDeepwaterPresha1.1.owHazardandRiskAssessmentHorizonDepthBe1.owSeaF1.oorUnitSeismicStratigraphicInterpretation1.itho1.ogyRiskAssignedSeaf1.oorOft,SeawatergradientandpressurebasedonwaterdepthA0-199ftIHemipe1.agicmudsCIayA1.199-429ft,IIDebrisf1.owsands1.umpedturbiditefeaturesC1.ay,si
11、1.tB429-479ft,IIISandrichbasinf1.oofanturbiditesSand,c1.ayandsi1.y1.owBsandtop479-1106ft.IVupperS1.umpedturbiditesC1.aysi1.tandsandNeg1.igib1.eBsandbase1106-1196ft,IVaTurbiditechanne1.fi1.1.SandMediumC96-1556ft,IV1.owerS1.umpedturbiditesC1.aysi1.tandsandNeg1.igib1.eH1556-2002ftzVS1.umpedandchanne1.e
12、dturbiditesC1.aysi1.tandmar1.H1.2002-2362ftzVIMids1.opeturbiditesCIayandmar1.BaseOfstudy2362-3600ft,VIIDeepmarineturbiditesSandzsha1.eandsi1.tNeg1.igib1.eSource:KingdomDri1.1.ingReconstruction2078.HazardOperatingStrategiesGenera1.strategiestopreventkeysha1.1.owhazardprob1.emsresu1.tingcanbec1.assedi
13、norderas:1. Avoidthehazard2. Setcasingabovethehazard3. Tagthehazard4. Maintainprimarywe1.1.contro1.throughthehazards5. Trainpersonne1.withthewiderski1.1.ssetdemanded.Thekeyissueinrespecttoaworstcasepermeab1.eporouspressurizedhazardousinterva1.isthatthesearegenera1.1.ytheweakestfracturezones.C1.ayint
14、erva1.sofferstrongerfracturestrengthsandwhycasingshoesarepreferredtobesetthere.Settingcasingabovehazardinterva1.scan1.eaveweakerformationsinterva1.exposedbe1.owthatsti1.1.remaintobedri1.1.edcasedandcemented.Settingbe1.owdoesiso1.atethesectionandinspecificcasescanaffordasaferand1.owerriskOfsettingcas
15、ingshoesdeeper.Thekeydeterminantisfactoringthatprimarywe1.1.contro1.risk,confidence,oruncertain1.ysha1.1.notbecompromisedthrougha1.1.we1.1.activities,noton1.ydri1.1.ingbutoftenmoreimportant1.yduringcementing.Ina1.1.cases,contingentoptionsandhavingasaminimumap1.anBarerecommended.AvoidWe1.1.-Deve1.ope
16、dHazardsSitessha1.1.beavoidediftheriskprobabi1.ityofsha1.1.owhazardsishigh.Insomeareasz1.ocationcanbemovedashortdistancetomissanoma1.ieswithoutprogramcompromise.SetCasingAbovetheHazardWhengeopressuredhazardscannotbeavoidedbywe1.1.p1.acement,andoperatingmethodstomaintainprimarywe1.1.contro1.isimpract
17、icab1.e.Casingmustbesetabovethezone,anothersectiondri1.1.ed,acontingentcasingsetand/ortheriserrun.TagtheHazardIfthereisariskofoverpressure,itmaybenecessarytosetcasingassafeoperatingmarginscannotbemet.Ifitissafeandpracticab1.etoweighupandtagtheinterva1.priortopenetrating,thiscana1.sobeaviab1.eoption.
18、MaintainPrimaryContro1.WithintheHazardWhenA1.ARPdecisionscannotbereadi1.ymet,thebestrisked-basedoptionmaybetosetthesurfacecasingthroughthehazardinterva1.s).Thisshou1.dbequa1.itative1.yandquantitative1.ysurmisedastherightthingtodo.TrainingofPersonne1.Deepwaterhazardseventsmaynotfitwithtraditiona1.we1
19、.1.boreinf1.uxesandrequiremorespecifictrainingdeve1.opmentandski1.1.sresponsethatisusua1.1.ya1.ignedtoanemergencyresponsep1.an.Tbassurebestpracticesresu1.tpersonne1.mustbeeducatedandski1.1.edtounderstanda1.1.centra1.aspectsofsha1.1.owhazards,withemergencyresponseassuredtobewe1.1.rehearsedbya1.1.Regu
20、1.ations&Vesse1.AspectsOperatorsandcontractorsmusttakemeasurestoassurethathazardsaremanagedatA1.ARP1.eve1.s.Regu1.ationsoftensupp1.ementbest-practiceindustrystandards,ru1.es,andguide1.inesintermsofhowhazardsandrisksaremitigated,e.g.z1. Useofoverba1.ance(mud)asabarrieragainstunintentiona1.outf1.ow.2.
21、 Useofasuitab1.yengineeredsubseariser1.ess(dua1.gradient(DGD)ormanagedpressuredri1.1.ing(MPD)methods)orasubseaseabeddivertersystemtominimizethewe1.1.operationa1.safetyrisksofapossib1.eriser1.essorundergroundb1.owout.Otherimportantsubjectstoconsidera1.soviewedas:3. RequirementsOfcontro1.systemforacti
22、vationandre1.easeOfsubseasystems4. Pi1.ot-ho1.ebenefits,prosandcons5. Operatingbestpracticesused/app1.iedinconjunctionwithpressureand1.oggingdri1.1.ingequipmentmeasurement6. Useandapp1.icationofdua1.gradientandmanagedpressuredri1.1.ing,techno1.ogies.Theessentia1.soffshorearethatb1.owouts(notab1.ysha
23、1.1.owgasinsha1.1.owerwaters)haveresu1.tedinmoremobi1.eoffshoredri1.1.ingunitstobe1.ost,withconsequentia1.1.ossofIiveszthananyothertypeofsha1.1.owwe1.1.contro1.accidenta1.1.osstimeevents.Indeewaterzduetothemorefavorab1.e1.engthanddistanceofthedri1.1.ingvesse1.totheseaf1.oorinconjunctionwiththemetoce
24、anconditionsandfactspresented,sha1.1.owgasriskstotheinsta1.1.ationandpersonsonboardaresignificant1.y1.ess.Thequestionab1.econdition,hazards,andriskaspectstoaddressaretherigequipment,mringzstationkeeping,andsystemscapabi1.itytosafe1.ymoveandwhetheremergencyresponsep1.ansaresuitab1.yinp1.ace.Rigandwe1
25、.1.1.ocationse1.ectionforhazardousareasmustaccountfor:1. Se1.ectionofasafeoperatingwe1.1.1.ocation.2. Awe1.1.-engineereddri1.1.ingprogramandwe1.1.designthataffordsprioritytomaintainandassureprimarywe1.1.contro1.3. Vesse1.andpersonne1.capabi1.ities,ofbestpracticeandemergencyresponsecomp1.iance.4. Rig
26、equipmentandsystemsa1.1.evident1.ywork,arere1.iab1.ewithnoidentifiedriskeditemsshou1.dawe1.1.sitehavetobeabandonedimmediate1.yduetoahazardouseventSha1.1.ow(Water)F1.owTypesofsha1.1.owf1.owsinc1.udeinducedfractures,inducedstorage,geopressuredformations(sands),andthetransmissionOfgeopressureformations
27、throughcementchanne1.s.Geopressuredinterva1.scanoriginatefromsevera1.differentmechanismsthemostcommonisthroughrapidsedimentation.Note:Themostcommonf1.uidoweventsthatresu1.tinthesephasesareinfactthroughinducedfracturesresu1.tingviainappropriatepracticesormisunderstandingsthatarise.Majorsha1.1.owf1.ow
28、eventsarewe1.1.documentedtohigh1.ightthemagnitudeandextentof1.osttimeandassociatedconsequentia1.prob1.emsthatcanresu1.t.Primeexamp1.esare:Asha1.1.owwaterf1.owresu1.tedduringadeepwaterwe1.1.operationa1.phasewheretheoperator1.ostacomp1.etedeve1.opmenttemp1.atesiteconsistingofsevera1.we1.1.satsignifica
29、ntcapita1.,operatingandproductionexpenditure1.oss.DeepiuaterstudiesfromtheGu1.fofMexicointhe1.ate1990sa1.soestimatedanaverageof$1.6mi1.1.ionWnS1.ostpere1.1.duetosha1.1.owwaterf1.ows.Tbpreventtheseprob1.ems,preventionandmitigatingareastoconsiderare:1. Assessment,site-specificsurveys,andaddedp1.anning
30、forthepurposesofidentifyingsha1.1.owgeopressuredsandsandsafe1.y1.ocatingwe1.1.stopriortodri1.1.ing.2. Theuti1.izationofmeasurementandpressurewhi1.edri1.1.ingtoo1.s,personne1.3. Therequirementtodri1.1.,trip,run,insta1.1.andcementmoresurfacecasingstrings.4. Pi1.otho1.eswhen/asrequired.5. Moretime-cons
31、umingandmorecontro1.1.edbestpracticesz,demanded.6. Theuseofspecia1.izeddri1.1.ing,operating,andcementingmethods.7. Theuseofamarinerisertodri1.1.somespecificdeepersha1.1.owsections.8. A1.ternativeriser1.esswe1.1.operatingmethodsandtechno1.ogies.Note:Insomeregionsdependentuponsubsurfacehazardspresente
32、d.Accurate1.ypredictedandmode1.edminorf1.owsinexp1.orationorappraisa1.canbeto1.erated.Eg,sma1.1.thin1.ensesarecommon1.ydri1.1.edarereadi1.ynauvedtof1.owtodep1.eteinafezhourswithnorma1.dri1.1.ingresumingthereafter.Minorf1.owsindeve1.opmentwe1.1.sontheotherhandmustbefu1.1.yriskedassessed.Sha1.1.owF1.o
33、wOperatingMethodsBestPracticetechniquesandmethodstocomp1.ywithandassureare:1. Provideinformationaboutthequa1.ityandpositionofsha1.1.owf1.owporous,permeab1.eformationinterva1.s,2. Identifyanappropriatecasingpointinre1.ationtoasha1.1.owf1.owzone,3. E1.iminate/minimizechargingnorma1.1.ypressuredformati
34、onsands,si1.tsorporous,permeab1.ezones,4. Checkforsha1.1.owf1.ow,and5. Providemudpropertiesforcementing.Thedesiredoutcomeistominimizeasha1.1.owhazardeventoccurrencethroughassuringthatprimarycontro1.ismaintainedthroughout.Bestpracticesaretobeapp1.iedthrougheva1.uatinga1.1.aspectsof:1. Geophysica1.pre
35、diction2. Porepressureandfracturepressureprediction3. Dri1.1.ingandcementingtechniques4. Mechanica1.shutoffdevices5. Externa1.casingpackers6. Subsea-diverterdevices7. Pumpanddumpandmoreadvancedpressuremanagement(e.g.DGD,MPD)methods8. Casingwhi1.edri1.1.ing9. Chemica1.a1.ternatives.Note:Detai1.softhe
36、sepracticesarewe1.1.referencedwithincurrentindustrystandards,journa1.papers,andthird-partypub1.ications.Items1-4forexamp1.eareout1.inedintheIADCDeepwaterwe1.1.contro1.guide1.ines,1998,1stEdition;Chapter1We1.1.p1.anning,Section1.2,Sha1.1.owwaterf1.owguide1.ines,pp.1-33to1-65.Remedia1.Sha1.1.owF1.owCo
37、ncernsTbc1.ose,itisgenera1.1.ydifficu1.ttodynamica1.1.yki1.1.andstopasha1.1.owhazardf1.owonceun1.oaded.PressureIdentificationandunderstandingoftheowinterva1.andmechanismthatdrivebestpracticestoprohibitanddetectowear1.yisparamount.Iftheprecisedepthcannotbedeterminedtoprevent,mitigateandstopthef1.ow.O
38、riff1.owhas1.aterinthewe1.1.cyc1.eresu1.tedbehindcasing,duetoafai1.edcementjob.Thiscanbeextreme1.ytimeconsuming,cost1.y,andhigh1.yprob1.ematica1.Onceowhasstopped,operationsthatfo1.1.ow,casingandcementmustbesuitab1.yp1.acedtoset,andsea1.theannu1.uszonefortheexpected1.ifeofwe1.1.Thiscementingcanbejust
39、asifnotmorecha1.1.engingthanthestandardnorm.Providingapp1.icationfordesignercementsthatnowexist,e.g.zfoamand1.ightweightmixturestobeusedwhengreaterriskanduncertaintyexiststoiso1.atesha1.1.owdeepwaterriser1.essdri1.1.edhazardouszonesinterva1.sthatareregardedasdifficu1.ttocement.Sha1.1.owGasSha1.1.owg
40、ascanpotentia1.1.ybeahazardousrisk-basedeventinspecificdeepwaterenvironments.Rea1.ismmusttakeprecedencefora1.1.offshoreemergencyscenarios.Casehistoriesdisc1.osethat,onceawe1.1.hasun1.oadedtogas,thereisa1.owerprobabi1.itytorecoverprimarywe1.1.contro1.,beforethewe1.1.mayco1.1.apseatcost1.yremediatione
41、xpense.Tbpreventsha1.1.owgasesca1.ation,theoperatorsha1.1.constructwiththedri1.1.ingcontractorrea1.isticemergencyproceduresthatworkinherent1.yandinconjunctionwithear1.yf1.owdetection.Offshoreoperatingbestpracticemustaccountandcontemp1.atetopreventasha1.1.owgasevent.Inaddition,prespudmeetings,dri1.1.
42、s,etc.shou1.dbeauthorizedandconductedtoenforceemergencyproceduresareknown,understood,andimp1.emented,andassurancestakenthatemergencyequipmentisworkingandre1.iab1.e.Sha1.1.owGasDefinedSha1.1.owgasisdefinedasbiogenic(methanegas)resu1.tingfrom(name1.y,sand)proneinterva1.sencounteredatcontaineddepthsbe1
43、.owtheseaf1.oorwherefracturegradientsare1.owerandwherekickscannotbecontro1.1.edthroughconventiona1.BOPshutintechniques.Sha1.1.owGasOriginsGenera1.izedoriginsofoffshoresha1.1.owgasare:1. Trappedaccumu1.ationscanexistin“Norma1.orAbnorniaVfpressureregimes.2. Accumu1.ationsexistinvaryingquantities,press
44、ures,andinformationswithdifferentporositiesandpermeabi1.ities.Notes:Nomattertheconditions,sha1.1.owgasisA1.WAYStobetreatedwithcaution.Sha1.1.owGasInterpretationSha1.1.owgasinterpretationderivedfromseismicdataandinvo1.vestheaccumu1.ationofa1.1.predictiveevidence.Themoreanoma1.oustheseismicindicatorso
45、fgaspresence,raisestherisk.Factorsbrandingsha1.1.owgasareasasmoredifficu1.tandoperationa1.1.ycha1.1.engedare:1. Uncertainprognosisofthepressureatthetopofthepotentia1.gasbearingzone(s)zoftenduetothe“gaseffect“dictatedbyzonethicknessand/ornatura1.dip.Pressuresinexp1.orationareunknon,unti1.dri1.1.ed,se
46、ismicsurveys,genera1.1.ycannotofferaccurateinterva1.section1.engthorinsitugas(pressurecharge)concentrations.2. 1.owformationfracturegradientsthatpredominant1.yfactorinsha1.1.owgasoperations.3. Uncertaintyandassociatedrisksbecauseunti1.dri1.1.edthereisnocertaintytowhatexists.Bestpracticesmustbeincorp
47、oratedintode1.iveryp1.ans.Factorsstatedintheprevioussectionsonsha1.1.owf1.owa1.1.simi1.ar1.yaretobeapp1.iedtoreduceoperatingrisk1.ossandwastethatcanquick1.yresu1.tshou1.dwe1.1.sun1.oadthrough:1. Minorhydrostatichead1.oss,2. Errorsinequiva1.entmudweight,mudweightanda1.1.otherpressuremanagementp1.anni
48、ng,3. Uncontro1.1.edratesofpenetration,too1.owwe1.1.f1.ows,toohighannu1.uscanover1.oadoren1.arge,withfurtherprob1.emsofco1.1.apse,bridging,oranundergroundb1.owoutresu1.ting.4. Poorqua1.ityandre1.iabi1.ityofkickdetectionsha1.1.on1.yservetoincreaserisks.Emphasisofdetai1.edcarefu1.p1.anningandcomp1.iantbestoperatingpracticemustthereforebefu1.1.yaffordedthroughouta1.1.we1.1.p1.anning,execution,andde1.iveryactivities.Sha1.1.owGasDetectio
