Federal Government Issues Report on Causes of BP Oil Spill

8/4/2019 Federal Government Issues Report on Causes of BP Oil Spill

1/217

THEBUREAUOFOCEANENERGYMANAGEMENT,

REGULATIONANDENFORCEMENT

REPORTREGARDINGTHECAUSESOFTHEAPRIL20,2010

MACONDOWELLBLOWOUT

September14,2011


2/217

i

TABLEOFCONTENTS

ExecutiveSummary................................................................................................1

I. Introduction ..................................................................................................... 10

A. TheInvestigation ......................................................................................... 10

B. BackgroundRegardingDeepwaterDrillingintheGulfofMexico ............ 13

C. CompaniesInvolvedintheMacondoWell .................................................. 16

D. TheDeepwaterHorizon ............................................................................... 18

E. TheMacondoWell ....................................................................................... 19

F. TheBlowout ................................................................................................. 23

II. WellDesign...................................................................................................... 25

A. CostoftheMacondoWell ............................................................................ 25

B. DrillingMargin........................................................................................... 27

C. CasingProgram ........................................................................................... 31

D. MudProgramandType .............................................................................. 32

E. MudLosses .................................................................................................. 33

F. WellBallooning ........................................................................................... 34

G. PlannedandActualTotalDepth ................................................................. 34

H. DesigningtheProductionCasingLongStringversusLiner................... 36

III. Cementing ........................................................................................................ 40

A. CementingProcess....................................................................................... 40

B. CementDesignandModeling ..................................................................... 41

C. GasFlowPotential....................................................................................... 46

D. Centralizers .................................................................................................. 47E. FloatCollar .................................................................................................. 49

F. CementingtheMacondoProductionCasing .............................................. 53

G. IndustryStandardsforCementing.............................................................. 57

IV. PossibleFlowPaths ........................................................................................ 61

V. ConclusionsonWellDesign,Cementing,andFlowPath ........................ 68

A. CauseoftheFailureoftheCementBarrier.................................................. 68

B. ContributingCausesoftheCementBarrierFailure ................................... 68

C. PossibleContributingCausesoftheCementBarrierFailure ..................... 70

D. FlowPathCause .......................................................................................... 73

VI. ChallengesattheMacondoWell .................................................................. 75

A. KicksandStuckDrillPipe .......................................................................... 75

B. SchedulingConflictsandCostOverruns .................................................... 78

C. PersonnelChangesandConflicts ................................................................ 79

D. SafetyStanddown....................................................................................... 83

VII. TemporaryAbandonmentoftheMacondoWell ....................................... 85


3/217

ii

A. InstallingtheLockDownSleeve ................................................................. 85

B. SettingtheCementPlug.............................................................................. 86

C. TheUseofLostCirculationMaterialasSpacer .......................................... 87

D. WellIntegrityTesting ................................................................................. 88

VIII. KickDetectionandRigResponse................................................................. 98

A. KickDetectionMethodsandResponsibilities.............................................. 98

B. MultipleSimultaneousOperationsThatHamperedtheCrewsAbilityto

DetectKicks ................................................................................................. 99

C. RigFloorResponse .................................................................................... 103

D. TheUseoftheMudGasSeparator ............................................................ 104

E. ActivityontheBridge................................................................................ 106

F. EmergencyDisconnectSystem.................................................................. 107

IX. ConclusionsonTemporaryAbandonment,KickDetection,andthe

EmergencyResponse................................................................................... 109

A. KickDetectionandResponseFailureCause ............................................. 109B. KickDetectionFailureContributingCauses ............................................ 109

C. KickDetectionFailurePossibleContributingCauses .............................. 110

D. ResponseFailureContributingCauses ..................................................... 112

E. ResponseFailurePossibleContributingCauses ....................................... 113

X. IgnitionSource(s)andExplosions .............................................................. 115

A. MainEnginesandEngineSwitchGearRooms ........................................ 115

B. MudGasSeparator .................................................................................... 119

C. OtherPossibleIgnitionSources ................................................................ 122

XI. Conclusionson

Ignition

Source

and

Explosion........................................ 125A. IgnitionSources ......................................................................................... 125

B. ContributingCausesoftheExplosion ....................................................... 125

C. PossibleContributingCausesoftheExplosion ......................................... 126

D. OtherPossibleIgnitionSources ................................................................ 127

XII. TheDeepwaterHorizonBOPStack............................................................... 129

A. DesignandConfiguration ......................................................................... 129

B. ControlandPowerSystems....................................................................... 132

C. EmergencyDisconnectSystem.................................................................. 133

D. AutomaticModeFunction(Deadman) ................................................. 134

E. AutoshearFunction ................................................................................... 134

F. ForensicExaminationoftheBOP ............................................................. 135

G. ExaminationMethodsUsedbyDNV........................................................ 137

H. DNVsForensicExaminationFindings .................................................... 138

I. EvaluationofOtherPossibleFailures ....................................................... 142

J. StudiesEvaluatingtheReliabilityofBOPs .............................................. 144

K. MaintenanceoftheDeepwaterHorizonBOP ........................................... 146


4/217

iii

L. BOPSystemLeaks ..................................................................................... 151

M. ROVInterventions .................................................................................... 153

XIII. BOPStackConclusions ................................................................................ 155

A. CauseoftheBOPStackFailure................................................................. 155

B. BOPStackFailureContributingCauses .................................................. 155

C. BOPStackFailurePossibleContributingCauses..................................... 155

XIV. RegulatoryFindings ..................................................................................... 157

A. PermittingProcess..................................................................................... 158

B. WellActivityReports ................................................................................ 161

C. MacondoDeparturesandAlternativeProcedures .................................... 161

D. MMSDrillingInspections ........................................................................ 162

E. PotentialIncidentofNoncomplianceGuidelines ...................................... 162

F. InspectionForms........................................................................................ 164

G. MMSDeepwaterHorizonInspectionsatMC252 ................................... 164

H. SafeDrillingMargin ................................................................................. 165I. WellControl............................................................................................... 165

J. SubseaBOPRegulatoryRequirements ..................................................... 167

K. RegulatoryImprovements ......................................................................... 172

L. IncidentsofNonCompliance .................................................................... 173

XV. PoliciesandPracticesofInvolvedCompanies ......................................... 175

A. BPsPoliciesandPractices ........................................................................ 175

B. TransoceansPracticesandProcedures ..................................................... 185

C. BPandTransoceanBridgingDocument................................................... 189

D. StopWork

Authority ................................................................................. 189

XVI. ConclusionsRegardingInvolvedCompaniesPractices......................... 191

XVII.SummaryofPanelConclusions.................................................................. 194

A. WellDesignandCementing...................................................................... 194

B. FlowPath ................................................................................................... 195

C. TemporaryAbandonment,KickDetection,andEmergencyResponse ..... 195

D. IgnitionSource .......................................................................................... 197

E. BlowoutPreventer ..................................................................................... 198

F. CompanyPractices .................................................................................... 199

XVIII.Conclusion ..................................................................................................... 200

XIX. Recommendations......................................................................................... 202

A. WellRecommendations.............................................................................. 202

B. KickDetectionandResponseRecommendations ...................................... 203

C. IgnitionSourceRecommendations ............................................................ 205

D. BlowoutPreventerRecommendations ....................................................... 206

E. RegulatoryAgencyRecommendations ...................................................... 207

F. OCSCompaniesPracticesRecommendations.......................................... 209


5/217

iv

Dedication .............................................................................................................211

Acknowledgement...............................................................................................212


6/217

1

ExecutiveSummary

Atapproximately9:50p.m.ontheeveningofApril20,2010,whilethe

crewoftheDeepwaterHorizonrigwasfinishingworkafterdrillingtheMacondo

exploratorywell,

an

undetected

influx

of

hydrocarbons

(commonly

referred

to

as

akick)escalatedtoablowout. Shortlyaftertheblowout,hydrocarbonsthat

hadflowedontotherigfloorthroughamudgasventlineignitedintwo

separateexplosions. Flowinghydrocarbonsfueledafireontherigthat

continuedtoburnuntiltherigsankonApril22. Elevenmendiedonthe

DeepwaterHorizonthatevening. Overthenext87days,almostfivemillion

barrelsofoilweredischargedfromtheMacondowellintotheGulfofMexico.1

AfteranextensiveinvestigationconductedbytheJointInvestigation

TeamoftheBureauofOceanEnergyManagement,RegulationandEnforcement

(BOEMRE)(formerlytheMineralsManagementServiceorMMS)andthe

UnitedStatesCoastGuard,theBOEMREpanelofinvestigators(thePanel)has

identifiedanumberofcausesoftheMacondoblowout.

ThePanelfoundthatacentralcauseoftheblowoutwasfailureofa

cementbarrierintheproductioncasingstring,ahighstrengthsteelpipesetina

welltoensurewellintegrityandtoallowfutureproduction. Thefailureofthe

cementbarrierallowedhydrocarbonstoflowupthewellbore,throughtheriser

andontotherig,resultingintheblowout. Theprecisereasonsforthefailureof

theproductioncasingcementjobarenotknown. ThePanelconcludedthatthefailurewaslikelydueto:(1)swappingofcementanddrillingmud(referredtoas

fluidinversion)intheshoetrack(thesectionofcasingnearthebottomofthe

well);(2)contaminationoftheshoetrackcement;or(3)pumpingthecementpast

thetargetlocationinthewell,leavingtheshoetrackwithlittleornocement

(referredtoasoverdisplacement).

ThelossoflifeattheMacondositeonApril20,2010,andthesubsequent

pollutionoftheGulfofMexicothroughthesummerof2010weretheresultof

poor

risk

management,

last

minute

changes

to

plans,

failure

to

observe

and

respondtocriticalindicators,inadequatewellcontrolresponse,andinsufficient

1Thisestimateisbaseduponpressurereadings,data,andanalysisconductedbyU.S.scientific

teamscommissionedbytheNationalIncidentCommander. See

http://www.doi.gov/news/pressreleases/USScientificTeamsRefineEstimatesofOilFlowfrom

BPWellPriortoCapping.cfm.


7/217

2

emergencybridgeresponsetrainingbycompaniesandindividualsresponsible

fordrillingattheMacondowellandfortheoperationoftheDeepwaterHorizon.

BP,asthedesignatedoperatorunderBOEMREregulations,was

ultimatelyresponsibleforconductingoperationsatMacondoinawaythat

ensuredthesafetyandprotectionofpersonnel,equipment,naturalresources,

andtheenvironment. Transocean,theowneroftheDeepwaterHorizon,was

responsibleforconductingsafeoperationsandforprotectingpersonnelonboard.

Halliburton,asacontractortoBP,wasresponsibleforconductingthecementjob,

and,throughitssubsidiary(SperrySun),hadcertainresponsibilitiesfor

monitoringthewell. CameronwasresponsibleforthedesignoftheDeepwater

Horizonblowoutpreventer(BOP)stack.

Atthetimeoftheblowout,therigcrewwasengagedintemporary

abandonmentactivitiestosecurethewellafterdrillingwascompletedandbeforetheDeepwaterHorizonleftthesite. InthedaysleadinguptoApril20,BP

madeaseriesofdecisionsthatcomplicatedcementingoperations,added

incrementalrisk,andmayhavecontributedtotheultimatefailureofthecement

job. Thesedecisionsincluded:

Theuseofonlyonecementbarrier. BPdidnotsetanyadditionalcementor

mechanicalbarriersinthewell,eventhoughvariouswellconditions

createddifficultiesfortheproductioncasingcementjob.

Thelocationoftheproductioncasing. BPdecidedtosetproductioncasingin

alocationinthewellthatcreatedadditionalriskofhydrocarboninflux.

Thedecisiontoinstallalockdownsleeve. BPsdecisiontoincludethesetting

ofalockdownsleeve(apieceofequipmentthatconnectsandholdsthe

productioncasingtothewellheadduringproduction)aspartofthe

temporaryabandonmentprocedureatMacondoincreasedtherisks

associatedwithsubsequentoperations,includingthedisplacementof

mud,thenegativetestsequenceandthesettingofthesurfaceplug.

Theproductioncasingcementjob. BPfailedtoperformtheproduction

casingcementjobinaccordancewithindustryaccepted

recommendations.

ThePanelconcludedthatBPfailedtocommunicatethesedecisionsand

theincreasingoperationalriskstoTransocean. Asaresult,BPandTransocean


8/217

3

personnelonboardtheDeepwaterHorizonontheeveningofApril20,2010,did

notfullyidentifyandevaluatetherisksinherentintheoperationsthatwere

beingconductedatMacondo.

OnApril20,BPandTransoceanpersonnelonboardtheDeepwaterHorizon

missedtheopportunitytoremedythecementproblemswhenthey

misinterpretedanomaliesencounteredduringacriticaltestofcementbarriers

calledanegativetest,whichseekstosimulatewhatwilloccuratthewellafterit

istemporarilyabandonedandtoshowwhethercementbarrier(s)willhold

againsthydrocarbonflow.

Therigcrewconductedaninitialnegativetestontheproductioncasing

cementjobthatshowedapressuredifferentialbetweenthedrillpipeandthekill

line,whichisahighpressurepipeleadingfromtheBOPstacktotherigpumps.

Thiswasaseriousanomalythatshouldhavealertedtherigcrewtopotentialproblemswiththecementbarrierorwiththenegativetest. Aftersome

discussionamongmembersofthecrewandasecondnegativetestonthekill

line,therigcrewexplainedthepressuredifferentialawayasabladdereffect,a

theorythatlaterprovedtobeunfounded. Around7:45p.m.,afterobservingfor

30minutesthattherewasnoflowfromthekillline,therigcrewconcludedthat

thenegativetestwassuccessful. Atthispoint,therigcrewmostlikely

concludedthattheproductioncasingcementbarrierwassound.

Thecement

in

the

shoe

track

barrier,

however,

had

in

fact

failed,

and

hydrocarbonsbegantoflowfromtheMacondoreservoirintothewell. Despitea

numberofadditionalanomaliesthatshouldhavesignaledtheexistenceofakick

orwellflow,thecrewfailedtodetectthatthewellwasflowinguntil9:42p.m.

Bythenitwastoolatethewellwasblowingdrillingmudupintothederrick

andontotherigfloor. Ifmembersoftherigcrewhaddetectedthehydrocarbon

influxearlier,theymighthavebeenabletotakeappropriateactionstocontrol

thewell. TherewereseveralpossiblereasonswhytheDeepwaterHorizoncrew

didnotdetectthekick:

Therigcrewhadexperiencedproblemsinpromptlydetectingkicks. TheDeepwaterHorizoncrewhadexperiencedakickonMarch8,2010thatwent

undetectedforapproximately30minutes. BPdidnotconductan

investigationintothereasonsforthedelayeddetectionofthekick.

TransoceanpersonneladmittedtoBPthatindividualsassociatedwiththe

March8kickhadscrewedupbynotcatchingthekick. Tenofthe11


9/217

4

individualsondutyonMarch8,whohadwellcontrolresponsibilities,

werealsoondutyonApril20.

Simultaneousrigoperationshamperedtherigcrewswellmonitoringabilities.

Therigcrewsdecisiontoconductsimultaneousoperationsduringthe

criticalnegativetests includingdisplacementoffluidstotwoactivemud

pitsandcleaningthepitsinpreparationtomovetherig complicated

wellmonitoringefforts.

Therigcrewbypassedacriticalflowmeter. Atapproximately9:10p.m.,the

rigcrewdirectedfluiddisplacedfromthewelloverboard,which

bypassedtheSperrySunflowmeter,whichisacriticalkickdetectiontool

thatmeasuresoutflowfromthewell. TheDeepwaterHorizonwas

equippedwithotherflowmeters,butthePanelfoundnoevidencethat

thesemeterswerebeingmonitoredpriortotheblowout.

Oncethecrewdiscoveredthehydrocarbonflow,itsenttheflowtoamud

gasseparator,apieceofequipmentnotdesignedtohandlehighflowrates. The

mudgasseparatorcouldnothandlethevolumeofhydrocarbons,andit

dischargedagasplumeabovetherigfloorthatignited.

ThePanelfoundevidencethattheconfigurationoftheDeepwaterHorizon

generalalarmsystemandtheactionsofrigcrewmembersonthebridgeofthe

rigcontributed

to

a

delay

in

notifying

the

entire

crew

of

the

presence

of

very

highgaslevelsontherig. TransoceanhadconfiguredtheDeepwaterHorizons

generalalarmsystemininhibitedmode,whichmeantthatthegeneralalarm

wouldnotautomaticallysoundwhenmultiplegasalarmsweretriggeredin

differentareasontherig. Asaresult,personnelonthebridgewereresponsible

forsoundingofthegeneralalarm. Personnelonthebridgewaited

approximately12minutesafterthesoundingoftheinitialgasalarmstosound

thegeneralalarm,eventhoughtheyhadbeeninformedthatawellcontrol

problemwasoccurring. Duringthisperiod,therewereapproximately20

alarmsindicatingthehighestlevelofgasconcentrationindifferentareasonthe

rig.

TheDeepwaterHorizonsBOPstack,amassive,360tondeviceinstalledat

thetopofthewell,wasdesignedtoallowtherigcrewtohandlenumeroustypes

ofwellcontrolevents. However,onApril20,theBOPstackfailedtosealthe

welltocontaintheflowofhydrocarbons. Theexplosionslikelydamagedthe

DeepwaterHorizonsmultiplexcablesandhydrauliclines,renderingthecrew


10/217

5

unabletoactivatetheBOPstack. TheBOPstackwasequippedwithan

automaticmodefunction,whichuponactivationwouldtriggertheblindshear

ram(BSR),twometalblockswithbladesontheinsideedgesthataredesignedto

cutthroughthedrillpipeandsealthewellduringawellcontrolevent.

ThePanelconcludedthatthereweretwopossiblewaysinwhichtheBSR

mighthavebeenactivated:(1)onApril20,bytheautomaticmodefunction,

immediatelyfollowinglossofcommunicationwiththerig;or(2)onApril22,

whenaremotelyoperatedvehicletriggeredtheautoshearfunction,whichis

designedtoclosetheBSRifthelowermarineriserpackagedisconnectsfromthe

restoftheBOPstack. RegardlessofhowtheBSRwasactivated,itdidnotseal

thewell.

AforensicexaminationoftheBOPstackrevealedthatelasticbucklingof

thedrillpipehadforcedthedrillpipeupagainstthesideofthewellboreandoutsidethecuttingsurfaceoftheBSRblades. Asaresult,theBSRdidnot

completelyshearthedrillpipeanddidnotsealthewell. Thebucklingofthe

drillpipe,whichlikelyoccurredatornearthetimewhencontrolofthewellwas

lost,wascausedbytheforceofthehydrocarbonsblowingoutofthewell;bythe

weightofthe5,000feetofdrillpipelocatedintheriserabovetheBOPforcingthe

drillpipedownintotheBOPstack;orbyacombinationofboth. Asaresultof

thefailureoftheBSRtocompletelycutthedrillpipeandsealthewell,

hydrocarbonscontinuedtoflowaftertheblowout.

PriortotheeventsofApril20,BPandTransoceanexperiencedanumber

ofproblemswhileconductingdrillingandtemporaryabandonmentoperations

atMacondo. Theseproblemsincluded:

Recurringwellcontroleventsanddelayedkickdetection. Atleastthree

differentwellcontroleventsandmultiplekicksoccurredduring

operationsatMacondo. OnMarch8,ittooktherigcrewatleast30

minutestodetectakickinthewell. ThedelayraisedconcernsamongBP

personnelabouttheDeepwaterHorizoncrewsabilitytopromptlydetect

kicksandtakeappropriatewellcontrolactions. Despitethesepriorproblems,BPdidnottakestepstoensurethattherigcrewwasbetter

equippedtodetectkicksandtohandlewellcontrolevents. AsofApril20,

TransoceanhadnotcompleteditsinvestigationintotheMarch8incident.

Schedulingconflictsandcostoverruns. Atthetimeoftheblowout,

operationsatMacondoweresignificantlybehindschedule. BPhad


11/217

6

initiallyplannedfortheDeepwaterHorizontomovetoBPsNilewellby

March8,2010. Inlargepartasaresultofthisdelay,asofApril20,BPs

Macondooperationsweremorethan$58millionoverbudget.

Personnelchangesandconflicts. BPexperiencedanumberofproblems

involvingpersonnelwithresponsibilityforoperationsatMacondo. A

reorganizationthattookplaceinMarchandApril2010changedtheroles

andresponsibilitiesofatleastnineindividualswithsomeresponsibility

forMacondooperations. Inaddition,thePanelfoundevidenceofa

conflictbetweentheBPdrillingandcompletionsoperationsmanagerand

theBPwellsteamleaderandevidenceofafailuretoadequatelydelineate

rolesandresponsibilitiesforkeydecisions.

Atthetimeoftheblowout,bothBPandTransoceanhadextensive

proceduresinplaceregardingsafedrillingoperations. BPrequiredthatitsdrillingandcompletionspersonnelfollowadocumentedandauditablerisk

managementprocess. ThePanelfoundnoevidencethattheBPMacondoteam

fullyevaluatedongoingoperationalrisks,nordiditfindevidencethatBP

communicatedwiththeTransoceanrigcrewaboutsuchrisks.

Transoceanhadanumberofdocumentedsafetyprogramsinplaceatthe

timeoftheblowout. Nonetheless,thePanelfoundevidencethatTransocean

personnelquestionedwhethertheDeepwaterHorizoncrewwasadequately

preparedto

independently

identify

hazards

associated

with

drilling

and

other

operations.

EveryoneonboardtheDeepwaterHorizonwasobligatedtofollowthe

TransoceanstopworkpolicythatwasinplaceonApril20,whichprovided

that[e]achemployeehastheobligationtointerruptanoperationtopreventan

incidentfromoccurring. DespitethefactthatthePanelidentifiedanumberof

reasonsthattherigcrewcouldhaveinvokedstopworkauthority,noindividual

ontheDeepwaterHorizondidsoonApril20.

ThePanelfoundevidencethatBPand,insomeinstances,itscontractorsviolatedthefollowingfederalregulations:

30CFR250.107BPfailedtoprotecthealth,safety,property,andthe

environmentby(1)performingalloperationsinasafeandworkmanlike

manner;and(2)maintainingallequipmentandworkareasinasafe

condition;


12/217

7

30CFR250.300BP,Transocean,andHalliburton(SperrySun)failedto

takemeasurestopreventtheunauthorizedreleaseofhydrocarbonsinto

theGulfofMexicoandcreatingconditionsthatposedunreasonablerisk

topublichealth,life,property,aquaticlife,wildlife,recreation,navigation,

commercialfishing,orotherusesoftheocean;

30CFR250.401BP,Transocean,andHalliburton(SperrySun)failedto

takenecessaryprecautionstokeepthewellundercontrolatalltimes;

30CFR250.420(a)(1)and(2)BPandHalliburtonfailedtocementthe

wellinamannerthatwouldproperlycontrolformationpressuresand

fluidsandpreventthereleaseoffluidsfromanystratumthroughthe

wellboreintooffshorewaters;

30CFR250.427(a)BPfailedtousepressureintegritytestandrelated

holebehaviorobservations,suchasporepressuretestresults,gascut

drillingfluid,andwellkickstoadjustthedrillingfluidprogramandthe

settingdepthofthenextcasingstring;

30CFR250.446(a)BPandTransoceanfailedtoconductmajor

inspectionsofallBOPstackcomponents;and

30CFR250.1721(a)BPfailedtoperformthenegativetestprocedures

detailedinanapplicationforapermittomodifyitsplans.

AlthoughthePanelfoundnoevidencethatMMSregulationsineffecton

April20,2010wereacauseoftheblowout,thePanelconcludedthatstronger

andmorecomprehensivefederalregulationsmighthavereducedthelikelihood

oftheMacondoblowout. Inparticular,thePanelfoundthatMMSregulationsin

placeatthetimeoftheblowoutcouldbeenhancedinanumberofareas,

including:cementingproceduresandtesting;BOPconfigurationandtesting;

wellintegrity

testing;

and

other

drilling

operations.

In

addition,

the

Panel

found

thattherewereanumberofwaysinwhichtheMMSdrillinginspections

programcouldbeimproved. Forexample,thePanelconcludedthatdrilling

inspectionsshouldevaluateemergencydisconnectsystemsand/orotherBOP

stacksecondarysystemfunctions. BOEMREhasalreadyimplementedmanyof

theseimprovements.


13/217

8

ThisReportsetsforthindetailthePanelsinvestigativefindings,

conclusions,andrecommendations. ThePanelsfindingsandconclusionsare

presentedinthefollowingsubjectareas:welldesign;cementing;possibleflow

paths;temporaryabandonmentoftheMacondowell;kickdetectionandrig

response;ignitionsourceandexplosion;thefailureoftheDeepwaterHorizon

blowoutpreventer;regulatoryfindingsandconclusions;andcompanypractices.

ThisReportconcludeswiththePanelsrecommendations,whichseekto

improvethesafetyofoffshoredrillingoperationsinavarietyofdifferentways:

Welldesign. Improvedwelldesigntechniquesforwellswithhighflow

potential,includingincreasingtheuseofmechanicalandcementbarriers,

willdecreasethechancesofablowout.

Wellintegritytesting. Betterwellintegritytestpractices(e.g.,negativetestpractices)willallowrigcrewstoidentifypossiblewellcontrolproblemsin

atimelymanner.

Kickdetectionandresponse. Theuseofmoreaccuratekickdetectiondevices

andothertechnologicalimprovementswillhelptoensurethatrigcrews

candetectkicksearlyandmaintainwellcontrol. Bettertrainingalsowill

allowrigcrewstoidentifysituationswherehydrocarbonsshouldbe

divertedoverboard.

Rigengineconfiguration(airintakelocations). Assessmentandtestingof

safetydevices,particularlyonrigswhereairintakelocationscreate

possibleignitionsources,maydecreasethelikelihoodofexplosionsand

fatalitiesintheeventofablowout.

Blowoutpreventers. ImprovementsinBOPstackconfiguration,operation,

andtestingwillallowrigcrewstobebetterabletohandlewellcontrol

events.

Remotelyoperatedvehicles(ROVs). StandardizationofROVinterventionpanelsandinterventioncapabilitieswillallowforimprovedresponse

duringablowout.

ThePanelbelievesthattheadoptionoftheproposedrecommendations

willimprovethesafetyofoffshoreoperationsandwillhelptoreducethe


14/217

9

likelihoodoftheoccurrenceofanothertragiceventsimilartotheMacondo

blowout.


15/217

10

I. Introduction

A.

TheInvestigation

OnApril

27,

2010,

the

Secretaries

of

the

Department

of

Homeland

Security

andtheDepartmentoftheInteriorconvenedajointinvestigationofthe

explosionandsinkingofthemobileoffshoredrillingunitDeepwaterHorizon2by

theBureauofOceanEnergyManagement,RegulationandEnforcement

(BOEMRE)andtheUnitedStatesCoastGuard(USCG). TheConvening

OrderdirectedtheJointInvestigationTeam(JIT)toissueajointreportwithin

ninemonths. ThisdeadlinewasextendedtoallowtheJITtocompletethe

investigation.

OnApril29,2010,anMMSAssociateDirectorappointedtheMMS(now

BOEMRE)membersoftheJIT.3 ThisReportisbasedontheinvestigativerecord

developedbytheJITandcontainsthePanelsfindingsandconclusions.

BOEMREsInvestigationsandReviewUnit(IRU),inclosecoordinationwith

thePanel,hadasubstantialroleinthedraftingandpreparationoftheReport.4

TheConveningOrderprovidesthatrelevantstatutesandregulations

relatingtoboththeUSCGandBOEMREgoverntheJITandthattheJITspublic

hearingsbeconductedinaccordancewiththeUSCGsrulesandprocedures

relatingtoMarineBoardsofInvestigation. Undertheserules,theJITwas

requiredto

formally

designate

certain

companies

and

individuals

involved

with

theDeepwaterHorizonoperationatthetimeoftheblowoutaspartiesininterest

(PIIs)andalsoretainedtheauthoritytodesignateotherPIIsatitsdiscretion.

TheJITdesignatedthefollowingentitiesandindividualsasPIIs:BP,Transocean,

Halliburton,MISWACO,Weatherford,AnadarkoPetroleum,MOEXUSACorp.,

DrilQuip,JimmyHarrell(Transocean),CurtKuchta(Transocean),Douglas

HaroldBrown(Transocean),SteveBertone(Transocean),MikeWilliams

2Joint

Department

of

the

Interior

and

Department

of

Homeland

Security

Statement

of

Principles

andConveningOrderRegardingInvestigationintotheMarineCasualty,Explosion,Fire,

Pollution,andSinkingofMobileOffshoreDrillingUnitDeepwaterHorizon,withLossofLifein

theGulfofMexico,April2122,2010(theConveningOrder). ByorderoftheSecretaryofthe

Interior,datedJune18,2010,BOEMREreplacedtheformerMineralsManagementService

(MMS)astheUnitedStatesoffshoreresourcemanagerandsafetyauthority.3PanelmembersincludedDavidDykes(cochair),GlynnBreaux,JohnMcCarroll,Kirk

Malstrom,andJasonMathews.4IRUmembersincludedMichaelFarber,LisaScanlon,andKishanNair.


16/217

11

(Transocean),PatrickOBryan(BP),andRobertKaluza(BP).5 UndertheMarine

Boardrulesandothergoverningauthorities,thePIIspossessedcertainrights

relatingtotheinvestigation.6

UndertheConveningOrder,theJITwasgiventhefullinvestigative

authorityofboththeDepartmentoftheInteriorandtheDepartmentof

HomelandSecurity.7 TheJITheldsevenpublichearingsandheardtestimony

frommorethan80witnesses.8 Threewitnesseswhosetestimonywassoughtby

theJITinvokedtheirFifthAmendmentrightsagainstselfincriminationand

refusedtotestifyduringtheJIThearings,andtwootherwitnessesclaimedthey

wereunabletotestifyformedicalreasons.9 Inadditiontothepublichearings,

BOEMREinvestigatorsalsoconductedinterviewsofmorethan25individuals

throughouttheinvestigation.

TheJITcollectedandreviewedlargevolumesofelectronicandwrittenmaterial,includingdata,emailsandotherrecordsrelatedtothePIIsequipment,

managementsystems,supervisionofemployeesandcontractors,

communications,performanceandtrainingofpersonnel,relevantcompany

policiesandpractices,andworkenvironment. TheJITissuedmorethan90

subpoenasfordocumentsandotherinformationandcollectedover400,000

pagesofevidence.

Duringthecourseoftheinvestigation,theJITcommissionedseveral

entitiesand

qualified

individuals

to

conduct

expert

analyses

of

evidence.

Dr.

JohnSmith,apetroleumengineerwithPetroleumConsultingLLC,reviewed

5AttherequestoftheRepublicoftheMarshallIslands,theJITdesignateditasaSubstantially

InterestedState. TheDeepwaterHorizonwasaforeignflaggedvesselthat,atthetimeofthe

blowout,wasflaggedundertheRepublicoftheMarshallIslands.6See46U.S.C.6303;46CFR.4.0310,4.0735,4.0915.7ConveningOrder,at1.8RetiredUnitedStatesDistrictJudgeWayneAndersen,whoservedwithoutcompensation,

joinedtheJITinAugust2010topresideoversubsequenthearings. BOEMREisgratefulforJudge

Andersens

assistance

during

the

hearings

and

in

meetings

with

counsel

for

the

PIIs.

9BrianMorelandRobertKaluzaeachinvokedhisFifthAmendmentRightsandrefusedtotestify

duringJIThearings. Aftertestifyingatonehearing,MarkHafleinvokedhisFifthAmendment

Rightsandrefusedtotestifyasecondtime. Throughhisattorney,DonaldVidrineclaimedthat

hecouldnottestifyduetomedicalreasons. EachofthesefourindividualswasaBPemployeeat

thetimeoftheblowoutandcontinuestobeemployedbyBP. Inaddition,twoTransocean

witnessesdeclinedtocooperatewiththeinvestigation,citingtechnicalreasonsfortheirdecisions

nottotestify. Transoceandeclinedtoencouragethesewitnessestocooperatewiththe

investigation.


17/217

12

wellconditiondatacollectedbySperrySunduringthetemporaryabandonment

procedureandreportspreparedbytheInternationalAssociationofDrilling

Contractors(IADC)tohelpreconstructandidentifykeyissuesduringthe24

hoursimmediatelypriortotheblowout. KeystoneEngineeringconducteda

casingbuoyancyanalysis.10 OilfieldTestingandConsultingconductedacement

blendanalysisonsamplesprovidedbyHalliburton. DetNorskeVeritas

(DNV)conductedtheforensicexaminationoftheDeepwaterHorizonsBOP

stackandsectionsofdrillpipeandprovidedaforensicanalysisreportdetailing

theinformationandconclusionsdevelopedbasedonthisexamination.11 These

expertreportsareattachedasappendicestothisReport.

Thepurposeofthisinvestigationwastoidentifythecausesofthe

Macondoblowoutandissuerecommendationsinordertoreducethelikelihood

ofasimilareventinthefuture. Throughoutthisreport,thePanelclassifiesthe

factorsthatcontributedtotheblowoutinthefollowingcategories:

Causesarethosefactorsthatmostimmediatelyandproximatelycaused

theblowout;thatmostdirectlyledtothecircumstancesunderlyingthe

blowout;orthatallowedtheblowouttohappen. Butforthesefactors,

therewouldnothavebeenablowout. Thesefactorsmaybespecific

eventsorconditionsthatexistedinthewellorontherigatthetimeofthe

blowout.

Contributing

Causesare

those

factors

that

alone

would

not

have

led

to

theblowout,butthatweresignificantincontributingtotheeventsor

conditionsthatgaverisetotheblowout. Forafactortobeclassifiedasa

contributingcauseofanevent,theremustbecompellingevidence

supportingboththeexistenceofthefactorandthatitmaterially

contributedtotheoccurrenceorseverityoftheevent.

PossibleContributingCausesarethosefactorsthateitherwereminor

contributingcausesoftheblowoutorforwhichtheevidencesuggeststhe

factorscontributingroleintheblowoutisweakerorlesscompelling.

10Thecasingbuoyancyanalysisevaluatedwhethertheproductioncasingfloatedupthewellbore

aresultoftheblowout.11

Asdiscussedinmoredetaillaterinthisreport,aBOPstackisalargedevicethatsitsontopofa

wellandisdesignedtoassistrigcrewsinmaintainingcontrolofthewell. VariousBOPstack

componentscanbemanuallyorautomaticallyoperatedtosealthewellandprotectagainsta

blowout. ThecentralissueinvestigatedbytheJITregardingtheDeepwaterHorizonBOPwaswhy

theBOPfailedtostoptheflowofhydrocarbonsfromtheMacondowell.


18/217

13

B. BackgroundRegardingDeepwaterDrillingintheGulfof

Mexico

Thegoalofdeepwaterdrillingoperationsistolocateandextractoiland

gas(collectivelyreferredtoashydrocarbons)fromreservoirslocatedbeneath

theseafloor. Insomereservoirs,thehydrocarbonsbecometrappedbeneath

impermeablerock;whenthishappens,thehydrocarbonsseepintosurrounding

porousrock. Drillingoperationsseektopenetratetheimpermeablerocktogetto

hydrocarbonbearingreservoirsorpayzones.

TheGulfofMexicoishometoalargenumberofhydrocarbonreservoirs.

Since1947,morethan50,000wellshavebeendrilledintheU.S.GulfofMexico.

Approximately97%oftheoilproducedontheU.S.OuterContinentalShelf

(OCS)isproducedintheU.S.GulfofMexico. Therearecurrentlynearly7,000activeleasesintheU.S.GulfofMexico,64%ofwhichareindeepwater.12

Since1995,deepwaterdrillingactivityhasincreasedsignificantlyinthe

Gulf. In2001,U.S.deepwateroffshoreoilproductionsurpassedshallowwater

offshoreoilproductionforthefirsttime. AsofMay2010,operatorsdrilled

approximately700wellsinwaterdepthsequaltoorgreaterthan5,000feet,the

approximatedepthoftheMacondowell.13 Deepwaterreservoirscanyieldahigh

volumeofoilandgas. Productionratesfordeepwaterwellsaretypicallymuch

higherthan

in

shallow

water

wells.

Theinitialwellorwellsdrilledintoaformationarereferredtoas

exploratorywells,whichanoperatordrillstodeterminewhetherareservoir

containssufficientvolumesofhydrocarbonstowarrantinvestmentinthe

12SeeDepartmentofInterior,IncreasedSafetyMeasuresforEnergyDevelopmentontheOuter

ContinentalShelf,(May27,2010). Althoughthereisnosingleaccepteddefinitionof

deepwater,acommonuseofthetermistorefertolocationswherethewaterdepthisatleast

1,000feet.

13Id.Operatorsarethepersonsthelessee(s)designatesashavingcontrolormanagementofoperationsontheleasedareaoraportionthereof. Anoperatormaybealessee,theMMS

approveddesignatedagentofthelessee(s),ortheholderofoperatingrightsunderanMMS

approvedoperatingrightsassignment. Lesseemeansapersonwhohasenteredintoalease

withtheUnitedStatestoexplorefor,develop,andproducetheleasedminerals. Thetermlessee

alsoincludestheMMSapprovedassigneeofthelease,andtheownerortheMMSapproved

assigneeofoperatingrightsforthelease. 30CFR250.105.


19/217

14

installationofequipmentrequiredforproduction. Atthisstage,theoperator

mayhavelimitedinformationaboutthegeologicalcharacteristicsofthereservoir

andsurroundingformations. Suchinformation,includingdataaboutthe

surroundingformations,porepressures,14reservoirconfigurationandreservoir

volumes,isdevelopedduringtheexploratorydrillingoperationandmayleadto

changesinthedrillingplanandwelldesignastheoperationproceeds.

Onceanoperatorfinishesdrillinganexploratorywellandperformingits

initialevaluationofthewell,ittypicallysealsthewellbypumpingcementand

installingmechanicalplugs. Thisprocedureiscommonlyreferredtoas

pluggingandabandoningthewell. Iftheoperatorbelievesthatiteventually

willbeabletoproducehydrocarbonsfromtheexploratorywell,itmaychooseto

performtemporaryabandonmentprocedures,whichareproceduresthatallow

thedrillingrigtomoveoffofthewellsothattheoperatorcanreturnatalater

datetocompletethewellandprepareitforproduction.

Atypicaldeepwaterwellisdrilledusingthefollowingprocess:

Adrillingrigmovesonthelocationofthewell. Manyrigsoperatingin

deepwateraredynamicallypositioned,whichmeansthattheyarenot

mooredtotheseafloorbutinsteadholdtheirpositionoverthewell

throughacombinationofsatellitetechnologyanddirectionalthruster

activity. TheDeepwaterHorizonwasadynamicallypositionedrig.

Theriglowersdrillpipe(alsoknownasadrillstring)withadrillbit

attachedtoitsend. Thedrillbitboresintotheseafloorandthesubsea

formationtomakeahole. Thatholeisreferredtoasthewellbore.

Theriginstalls,orsets,alargediameterpipeknownascasinginto

thewellboretoestablishabarrierbetweenthewellboreandthe

surroundingformationandtoensurethatcontinueddrillingdoesnot

resultinthecollapseofthewellbore. Theinitialcasingthatissetinthe

wellboreiscalledconductorcasing.

Therigthenusesthemarineriserorriser,whichisalargepipethat

surroundsthedrillpipe,tolowerthesubseaBOPstackontothewell.

ThesubseaBOPislatchedtothewellheadontheconductorcasing.

14Porepressureisthepressureoffluidswithintheporesofareservoir.


20/217

15

Asdrillingprogresses,therigsetsadditionalcasings(sectionsofpipe)

thatareslightlysmallerindiameterthantheholecreatedbythedrillbit.

Thecombinationofcasingsisreferredtoasthecasingstring. The

casingsarebondedintoplaceusingcement. Thecasingstringmaintains

theintegrityofthewellborebyprotectingthesidesofthewellborefrom:

(1)pressureexertedfromthedrillingmud;(2)collapseoftheholealready

drilled;and(3)influxoffluidsfromthesurroundingformation.

Theoutermostcasingnearthetopofthewellcanbeuptofourfeetin

diameter,andtheinnermoststringofcasingnearthebottomofthewell

canbelessthansixinchesindiameter. Thesizeoftheinitialandfinal

casing,thetypesofcasing,andthetypeofcementusedaredetermined

bytheprofileofthewellbeingdrilled,includingfactorssuchaswell

depth,temperatures,andwellpressures. Oncethewellisinproduction,

hydrocarbonsareextractedthroughatubingstringthatisrundownthroughthemiddleoftheproductioncasingstring.

Duringdrilling,therigcrewpumpsafluid,calleddrillingmudor

muddownthedrillpipeandthroughthedrillbitnozzles. Althoughthefluid

isreferredtoasmud,itisactuallyacomplexsystemcomprisedofcomponents

thataredesignedinlightof,andtailoredto,avarietyofwellconditions. The

mudsprimaryfunctionistoassistdrillcrewsinmaintainingwellcontrol.

Drillingmudexertshydrostaticpressureinthedrillpipeandannulus(thespace

betweenthe

drill

pipe

and

the

walls

of

the

casing

strings

or

open

hole)

that

is

equaltoorgreaterthanthepressuresencounteredinthewellbore,thereby

keepingthewellbalancedandundercontrol. Drillingmudalsocoolsthedrill

bitandliftscuttingstothesurfaceasthemudiscirculatedduringdrilling.15 By

closelymonitoringwellpressure,rigcrewsmaintainthewellborefluidpressure

sothatitisequaltoorslightlygreaterthanthepressuresfromtheformation.

Thistypeofpressurebalanceisreferredtoasanoverbalancedcondition. By

contrast,awellisinanunderbalancedconditionwhentheformationpressures

exceedthewellboredrillingfluidpressures. Rigcrewsrelyuponanumberof

indicatorstotrackfluidpressures.16

15Operatorsroutinelyrelyupondrillingmudsupplierstoprovideassistancewithchoosingan

appropriatedrillingmud. Drillingrigcrewsincludemudloggerswhomonitordrillingmud,

wellborepressures,andotherdata.16Thisprocessofmonitoringwellpressuresisreferredtoasmeasurementwhiledrilling.

Operatorsalsoroutinelyrelyupondrillingmudsupplierstoprovideassistancewithchoosingan

appropriatedrillingmudandtoprovidemudloggersontherigtomonitordrillingmud,

wellborepressures,andotherdata.


21/217

16

Cementingisanimportantfactorinwelldesignandtheexecutionofa

safedrillingprogram. Aftereachcasingstringisset,cementispumpeddown

thedrillstring,outthebottomofthecasingandbackupintotheannularspace.

Thecementreinforcesthecasingstringandsealsofftheannularspace,

preventinghydrocarbonsfromflowingthroughthespace. Aproperlycemented

annularspaceissaidtohaveachievedzonalisolation. Operatorsoftenwork

withcontractorsthatpossessspecificcementingexpertisetodeveloptheoptimal

typeofcementforaparticulardrillingoperation. Cementingcompaniesalsocan

helpmodeldifferentanticipatedwellconditionstohelpdrillingengineersto

designasuccessfulcementjob. Thereareanumberofdifferentteststhatcanbe

performedtoassessthequalityofacementjob.

Duringthedrillingprocess,pocketsofoil,naturalgas,orwaterthatare

encounteredinporouslayersoftheformationcanexertpressureintothewellborethatmaysuddenlyforcemudbackupthewellborewithconsiderable

forcethisiscommonlyreferredtoasakick. Tohandlekicksandtomaintain

wellcontrol,drillingcrewsusevariousmechanisms,including,underextreme

circumstances,activationoftheBOPstackanddiverters. Ifakickoverwhelms

thecontrolmechanisms,ablowouttheuncontrolledflowofhydrocarbons

throughthewellborecanoccur.

C.

CompaniesInvolvedintheMacondoWell

BPandTransoceanweretheprimarycompaniesinvolvedindrillingthe

Macondowell. BPwasthemajorityowneranddesignatedoperatorofthelease.

BPidentifiedtheprospectanddesignedandplannedthewell. Transoceanwas

thedrillingcontractorengagedbyBPtodrilltheMacondowellandprovidethe

DeepwaterHorizon,adynamicallypositioned,mobileoffshoredrillingunit(DP

MODU),aswellasthedrillingpersonnel.

BPisaglobaloilandgascompanyheadquarteredinLondon,England.

BPoperatesinmorethan80countriesandisinvolvedinoilandgas

exploration,production,andrefining,aswellastheoperationofservicestationsworldwide. BPholdsmorethan500activeleasesin

theGulfofMexico,morethananyotherlessee. From2005through

2009,BPwastheleadingproducerofoilandgasintheGulfofMexico,

producing559,336,436barrelsofoiland846,352,047MCF(thousand

cubicfeet)ofgasduringthatperiod.


22/217

17

Transoceanistheworldslargestoffshoredrillingcontractor. Basedin

Switzerland,Transoceanownsmorethan140drillingrigsandoperates

inthemajoroffshoreoilandgasfieldsintheworld. Transoceanhas

grownsubstantiallythroughaseriesofcorporateacquisitions,

includingtheacquisitionofReading&BatesFalcon(R&BFalcon)in

2000andGlobalSantaFein2007. TransoceanownedtheDeepwater

Horizonrig,whichwasunderalongtermleasetoBPatthetimeofthe

Macondoblowout. TheleaseagreementrequiredTransoceanto

manageandoperatetheDeepwaterHorizononbehalfofBP.

Offshoredrillingoperationsarecomplexandnormallyinvolvethework

ofmanydifferentspecialists. InadditiontoBP,theleaseholderandthe

designatedoperatoroftheMacondowell,andTransocean,thefollowing

companiesalsohadsignificantrolesintheoperation:

Halliburton,whichprovidesproductsandservicestotheenergy

industryworldwideandisoneoftheworldslargestcementing

contractorstotheoilandgasindustry,providedcementplanning,

products,andservicesatMacondo.

AnadarkoE&PCompanyLP,AnadarkoPetroleumCorporationand

MOEXwereBPspartnersintheMacondowell. AnadarkoE&P

CompanyLPowned22.5%,andAnadarkoPetroleumCorporation

owned2.5%.

17Both

Anadarko

companies

are

U.S.

oil

and

gas

explorationcompanies.18 MOEXOffshore2007,aJapaneseoil

explorationfirm,owneda10%shareofthewell.19 Thecompanies

sharedinBPscoststodrilltheMacondowellandwouldhaveshared

inanyprofitsfromthewell.

Cameron,whichisaTexasbasedmanufacturerofoilandgaspressure

controlequipment,manufacturedtheDeepwaterHorizonsBOPstack.

MISWACO,whichprovidesdrillingsuppliesandservices

worldwide,developedthemudprogramandprovideddrillingmudandpersonneltooperatetheDeepwaterHorizonrigsmudsystem.

17BP-HZN-MBI-00192559.18BPHZNMBI00177777.19Id.


23/217

18

Schlumberger,whichprovidesoilfieldservicesthroughouttheworld,

providedwellloggingservicesfortheMacondowell.

SperryDrilling(SperrySun),asubsidiaryofHalliburtonthat

providesdrillingdatasystemsandpersonneltothedrillingindustry,

equippedtheDeepwaterHorizonwithSperrydatasensorsandSperry

mudloggerstomonitorandevaluatewellconditiondata. The

DeepwaterHorizonwasalsooutfittedwithTransoceanpaddleflow

meterstomonitorflow.

Weatherford,whichprovidesavarietyofdrillingservicesand

components,providedthecasing,casingcentralizers,andfloat

conversionequipmentusedontheDeepwaterHorizon.

D.

TheDeepwater

Horizon

TheDeepwaterHorizonwasadeepwater,columnstabilized,semi

submersibleDPMODU,designedtodrillsubseawellsforoilandgas

explorationanddevelopment. TheDeepwaterHorizonwasbuiltforR&BFalcon

(whichlaterbecamepartofTransocean)byHyundaiHeavyIndustriesinUlsan,

SouthKorea. ConstructionstartedinDecember1998,andtherigwasdelivered

onFebruary23,2001,afterTransoceanacquiredR&BFalcon. Atthetimeofthe

blowout,theDeepwaterHorizonwasregisteredinMajuro,MarshallIslands,and

leasedto

BP.

TheDeepwaterHorizonsdayrateatthetimeoftheblowoutwas$533,495

andtherigstotalestimateddailyoperatingcostswereapproximately$1

million.20 Asiscommonintheindustry,underitscontractwithBP,Transocean

wasallowedaspecificamountoftime(inthiscase,uptotwentyfourhoursper

calendarmonth)formechanicaldowntimetoperformmaintenanceandrepairs

withamaximumaccumulationof12daysofdowntimeperyear.21 Transocean

wasnotpaiditsdayrateiftherigwasnotoperationalduetoequipmentrepairs

fortimeperiodsbeyondthisallotment.22

20TRNUSCG_MMS00040941.21TRNUSCG_MMS00040482.22Id.


24/217

19

E. TheMacondoWell

BPacquiredLeaseOCSG32306inanMMSCentralGulfofMexicolease

saleonMarch19,2008. Thisleasecovers5,760acresandextendsfor10years,

beginningonJune1,2008. BPisthedesignatedleaseoperatorandshares

ownershipoftheleasewithAnadarkoandMOEX.

TheMacondowellislocatedapproximately48milesfromthenearest

shoreline,114milesfromtheshippingsupplypointofPortFourchon,Louisiana,

and154milesfromtheHouma,Louisianahelicopterbase. BPbegandrillingthe

Macondowell(referredtoasspuddingthewell)onOctober7,2009,using

TransoceansMarianasrig. AftertheMarianassustaineddamageduring

HurricaneIdainNovember2009,BPmovedtheDeepwaterHorizontothe

Macondowell. TheDeepwaterHorizoncrewresumeddrillingoperationsat

MacondoinFebruary2010.

BPandTransoceanexperiencedseveralchallengesindrillingthe

Macondowell. InOctober2009,thewellexperiencedakickduringdrilling

operations.23 ThedrillingcrewexperiencedanotherkickonMarch8,2010. Asa

resultoftheMarch8kick,thedrillpipebecamestuckinthewellbore,andtherig

crewcouldnotpullthepipefree.24 Thecrew,therefore,hadtoseverthedrill

pipeanddrillabypassaroundtheportionofthewellwiththestuckpipe.25 The

wellalsoexperiencedseverallostreturnincidentsduringdrilling,when

drillingmud

pumped

down

the

wellbore

did

not

return

to

the

surface

as

expectedbecausesomevolumeofthemudflowedintoandwaslostinthe

formation.26 Lostreturnsarenotuncommonandcanoccurforavarietyof

reasons,suchasafractureintheformationordrillinginoverbalanced

conditions.27 Becauseoftheseandotherchallenges,onApril20,2010,the

Macondowellwasabout38daysbehindscheduleandapproximately$58

millionovertheoriginalbudget.28

23MC252WellActivityReport,10/25/2009.24IADCReports,3/8/10 3/12/10.25Abypassisasecondarywellboredrilledawayfromtheoriginalhole. Itisnotuncommonfor

anoperatortodrillabypasswhileexperiencingproblemsduringthedrillingofawell.26IADCReports,3/8/10 3/12/10.27AsdiscussedthroughouttheReport,thelostreturnsattheMacondowellwereofnotebecause

oftheirfrequencyandbecausetheyoccurredalongwithotheranomalies.28BPHZNMBI00125958;BPHZNMBI0019553;BPMBHZN00192599.


25/217

20

Despitetheseproblems,byApril14,theDeepwaterHorizoncrew

successfullydrilledtotheM56sand,oneofthehydrocarbonbearingzones

thatBPgeologistsandengineershadtargetedforthewell.29 Althoughthe

originalwellplanwastodrillapproximately1,800additionalfeet,theBPdrilling

teaminHoustonoptedtostopdrillingthewellatatotaldepthof18,360feet

becauseBPbelievedthewellhadreachedthebaseofthetargetreservoirandthat

ithadrunoutofdrillingmargin.30 Inotherwords,BPconcludedthatitcouldno

longersafelydrillintotheformationwithoutcreatinganunderbalancedwell(if

themudwastoolight)orriskingfracturingtheformationandthreateningwell

integrity(ifthemudwastooheavy). BPplannedtorunproductioncasingand

temporarilyabandonMacondobysealingitwithasurfacecementplugsothat

anotherrigcouldreturntothewelllaterandtakethestepsnecessarytocomplete

thewellforproduction.

OnApril19,theDeepwaterHorizoncrewrantheproductioncasingstringintothewell.31 BPsengineeringteamhadengagedinsignificantdebateoverthe

appropriatedesignofthecasingtoruninthefinalwellsection. Therewas

additionaldebateamongBPpersonnelaboutthenumberofcentralizers,which

arepiecesofequipmentusedtokeepthecasingcenteredinthewell,touseon

thefinalcasingstring. Thecrewpumpedcementintotheannulusandintothe

shoetrack,thesectionofthecasingbetweenthebottomofthewellandthefloat

valveinstalledinthewell(alargevalvedesignedtoallowfluidstoflowdown

thewellwhilepreventingfluidsfromflowingbackupthewellboreduring

cementingoperations).

Thepurposeofthecementjobwastoestablishanisolationbarrieracross

thehydrocarbonzoneatthebottomofthewellsothathydrocarbonscouldnot

enterthewell. InthelatehoursofApril19andintothemorningofApril20,the

rigcrewandBPscementcontractor,Halliburton,pumpedcementintothe

Macondowelltoisolatethehydrocarbonzones.32 BasedondataprovidedbyBP,

Halliburtondesigned the cement slurry, whichisamixtureofcement,waterand

29BPHZNMBI00126338.30Id. AsdiscussedindetaillaterinthisReport,drillingmarginisthedifferencebetweenthe

weightofthemudusedtodrillrelativetotheporepressuresandthefracturegradientofthe

formation. Commonindustrypracticeistouseadrillingmarginof0.5ppgmudweightunder

thefracturegradient.31IADCReport4/19/10.32HalliburtonPostJobCementReport,BPHZNCEC011406.


26/217

21

assorteddryandliquidadditives.33 After BP approved the design, Halliburtonbegan pumping the cement.

Inadditiontocementing,theprocessofpreparingawellfortemporary

abandonmentincludesfurtherprocedurestosecurethewellsothattherigsBOP

stackandrisercanberemovedastherigpreparestomoveoffthelocation. BP

engineersinHoustondevelopedtemporaryabandonmentprocedures(different

fromtheMMSapprovedprocedure)fortheMacondowellthatincludedthe

followingsteps:performingapositivepressuretest;34displacingmudinthewell

from8,367feettothewellhead;performinganegativepressuretest;35settinga

300footcementpluginthewellapproximately3,300feetbelowtheseafloorand

settingalockdownsleevetolockthefinalcasingintoplace.36 BPengineers

changedtheorderofthesestepsseveraltimesinthedaysbeforethetemporary

abandonment.

Duringallwellactivities,includingtemporaryabandonment,crew

membersmonitorvarioussensorsontherigthatshowfluidvolumesandwell

pressures.37 Thesesensorsproviderealtimedatatothecrew,whichmonitors

andanalyzesthedataonelectronicdisplaystoidentifypotentialkicks,among

otherthings. Earlykickdetectioniscriticaltomaintainingwellcontrol.

OnApril20,thecrewconductedteststoevaluatetheintegrityofthe

productioncasingcementjob. ThetestswerebasedonMMSapproved

procedures

that

a

BP

drilling

engineer

had

sent

to

the

rig

that

morning.38

The

crewfirstconductedapositivepressuretesttoevaluatewhetherthewellcasing

couldsustainpressureexertedonitfromtheinsideofthewellandreceived

favorableresults.39 Onthesameafternoon,thecrewcirculatedmudupfromthe

33Additivesareusedtotailorthecementtotheneedsofawell. Forexample,aweighting

materialmightbeaddedtoacementslurrywhenahigherdensitycementisneeded.34Apositivepressuretestisconductedbypumpingfluidintothewellaftersealingtheblind

shearrams. Therigcrewmonitorsthewelltodeterminewhetherpressuresinthewellremain

static.35

A

negative

pressure

test

seeks

to

create

conditions

that

simulate

what

will

occur

when

the

well

isabandoned. Therigcrewdisplacesdrillingmudwithotherfluids,resultinginthewellbore

beingunderbalancedagainsttheformationpressures. Therigcrewthenmonitorspressuresand

flowtodeterminetheintegrityofthebarrierbeingtested.36BPHZNMBI00129108. EachofthesestepsisdiscussedindetailinSectionIofthefindings

andconclusionsinthisReport.37Fluidincludesanyfluid(mud,spacer,seawater)comingoutofthewelloracrosstherig.38BPHZNMBI00021237.39BPHZNMBI00136947.


27/217

22

well,andpumpedtherecoveredmudontotheDamonBankston,avesselworking

alongsidetheDeepwaterHorizonatMacondo. Becauseofthemovementofthe

mud,itwasdifficultforthecrewtotrackfluidvolumesinthewellboreandin

themudpitsontherig.40

Next,crewmembersturnedtoconductingnegativepressuretestsonthe

well,whichwouldgivethecrewinformationaboutwhethertheproduction

casingcementjobwascapableofkeepinghydrocarbonsoutofthewellbore. The

crewrantwoseparatenegativetestsusingdifferentproceduresforeachtest.

Justpriorto8:00p.m.onApril20,theBPwellsiteleaderondutyontherig,

DonaldVidrine,andTransoceancrewmembersconcludedthatthesecond

negativetestshowedthatthefinalcementjobwassuccessful.41 Vidrinealso

calledMarkHafle,aBPengineerinHouston,around8:50p.m.todiscussthe

surfaceplug. Duringthiscall,Vidrinedescribedtheresultsofthenegativetests.

HaflequestionedVidrineabouttheresultsofthenegativetest,buthechosenottoinvestigatefurtherbyaccessingandreviewingtheavailablerealtimedata.

Instead,HaflechosetorelyuponVidrinesassurancethattherigcrewhad

successfullyperformedanegativetest.42

DuringtheeveningofApril20,theDeepwaterHorizoncrewcontinued

withthetemporaryabandonmentprocedurebyopeningtheBOPandpumping

seawaterdownthedrillpipetodisplacemudandaspacerfromtheriser.43

Duringthesewellactivities,thewellexperiencedsignificantchangesinpressure.

Personnelresponsible

for

monitoring

the

condition

of

the

well,

however,

did

not

recognizethesechangesassignsofakick. Thecrewmembersshutdownthe

wellaround9:15p.m.toperformasheentestonthespacerthattheyplannedto

sendoverboardasitwasdisplacedfromthewell.44 Thedecisiontosendthe

displacedspaceroverboardrenderedSperrySunpersonnelunabletomeasure

returnsononeoftherigsflowmeters. Duetotheplacementoftheflowmeters,

40BPHZNMBI00021238.41TestimonyofJimmyHarrell,JointInvestigationHearing,May27,2010,at9091;Testimonyof

MilesEzell,JointInvestigationHearing,May28,2010,at279282.42

BP

HZN

BLY00125470.

43Spacerreferstomaterialthatrigcrewspumpintoawelltoseparatethedrillingmudfrom

seawater. Displacementofmudandspacerarepartofthetemporaryabandonmentprocedures

discussedindetailinSectionIVofthefindingsandconclusions.44SperrySunrigdata,April20,2010. Thecrewperformedasheentesttoconfirmthatallofthe

oilbasedmudhadbeendisplacedfromtheriser. Asheentestisintendedtoindicatethe

presenceoffreeoilwhendrillingfluid,drilledcuttings,deckdrainage,welltreatmentfluids,

completionandworkoverfluids,producedwaterorsandorexcesscementslurryaredischarged

intooffshorewaters.


28/217

23

theSperrySuncrewcouldonlymeasurereturnssenttothemudpitsandcould

notmeasureflowvolumessentoverboard.45

F.

TheBlowout

OnApril20,2010,ataround9:40p.m.,powerfulpressuresfromthewell

causedmudtoflowupfromthewell. Mudspilledontherigfloorasthewell

begantoblowout. Thecrewrespondedtothesituationbydivertingtheflowto

themudgasseparator,partofthedivertersystemtowhichthecrewcoulddirect

fluidscomingupfromthewell.46 Atthistime,crewmemberslikelyrealizedthat

theyhadlostcontrolofthewellandattemptedtoregaincontrolofthewellby

activatingtheBOPstacksupperannularpreventerandtheuppervariablebore

ram.47

Themudgasseparator,towhichthecrewhaddivertedflowfromthewell,wasquicklyoverwhelmedandfailed,causingagasplumetofilltherig

floor. Thegasquicklyignited,causingthefirstexplosionontherigat9:49p.m.

Approximatelytensecondslater,asecondlargerexplosionoccurredandthefire

onboardtherigspreadrapidly. Shortlyafterthesecondexplosion,theriglost

powerandexperiencedatotalblackout.

Atapproximately9:56p.m.,therigssubseaengineerattemptedto

activatetheBOPstacksemergencydisconnectsystemfromtheBOPpanelonthe

rigsbridge.

The

emergency

disconnect

system

is

designed

to

activate

the

BOP

stacksblindshearramanddisconnecttherigslowermarineriserpackage

(LMRP)fromthewell. TheBOPpanelapparentlyindicatedthatthe

emergencydisconnectsystemwasactivated,buttherigremainedconnectedto

thewellandhydrocarbonscontinuedtoflowuncontrolledfromthewell.48

Aboutfourminutesaftertheattempttoactivatetheemergencydisconnect

system,personnelontheDeepwaterHorizonsbridgemanuallysoundedthe

generalalarmandmadeamustercallforpersonneltogatheratdesignated

45

Testimony

of

Joseph

Keith,

Joint

Investigation

Hearing,

December

7,

2010,

at

135.

46Themudgasseparator,andtherigcrewsdecisiontouseittohandletheinfluxof

hydrocarbonsfromthewell,isdiscussedindetailinSectionVDofthefindingsandconclusions.47DNV,ForensicExaminationofDeepwaterHorizonBlowoutPreventer,March20,2001,(DNV

Report)at4. AsdiscussedinlaterinthisReport,theupperannularpreventerandtheupper

variableboreramaretwoBOPstackcomponentsthatareusedbyrigcrewsinwellcontrol

events. Neithercomponent,however,isdesignedtoshearthedrillpipeandcompletelysealthe

welltheblindshearramontheBOPstackisdesignedtoperformthesefunctions.48TestimonyofChrisPleasant,JointInvestigationHearing,May28,2010,at123.


29/217

24

lifeboatstations. Personnel,includingcrewmembers,contractorsandvisiting

executivesfromBPandTransocean,evacuatedtherigontwolifeboatsandalife

raft. Atleastsixpeoplejumpedfromtherigintothewater.

At10:00p.m.,theDamonBankston,whichpriortotheexplosionshadbeen

directedbytheDeepwaterHorizontomove500metersawayfromtherig,

receiveddistresscallsfromtheDeepwaterHorizonandprepareditsfastrecovery

craftforlaunchandrescueofthosewhohadabandonedtherig. TheDamon

Bankstonretrievedsixpeoplefromthewaterandrecoveredanother108people

fromthetwolifeboatsandliferaft. Uncontrollablefirescontinuedtoblazeon

theDeepwaterHorizon,andtherigsankonthemorningofApril22.

Elevenmendiedasaresultoftheblowoutandsixteenotherswere

injured. EstimatesarethattheMacondowellspilledclosetofivemillionbarrels

ofoilintotheGulfofMexicoduring87daysbetweentheblowoutandwhenthewellwassuccessfullycappedonJuly15,2010. Aftermonthsofadditional

interventionwork,thewellwaspermanentlysealedonSeptember19,2010.


30/217

25

II. WellDesign

Welldesignisafundamentalandimportantphaseofoffshoredrilling

operations. Operatorsmustconsidersitespecificfactors,includingflows,

pressurizedformation

flows,

reservoir

natural

gas

and

oil

type,

reservoir

lithology(formationcharacteristics),reservoirstructure,andtheanticipated

volumeofhydrocarbonstodeterminethebestwaytodrilltothetargetreservoir

andtoconfigurecasingtoallowproductionfromthewell. Duringthedesign

process,engineersuseallavailabledatatodetermineplannedtotaldepth

(sometimesreferredtoasTD)ofthewell,casingpointselections,required

casingspecifications,casingpressureratings,cementslurrydesign,mudweight,

andriskfactorsparticulartothewell.49

Developmentwellsaretypicallydesignedanddrilledbasedinparton

datafromnearbywells,referredtoasoffsetwelldata. Inthecaseofexploratory

wells,suchasMacondo,operatorshavelimitedoffsetwelldataavailable,

makingitmoredifficulttoanticipatewellconditionspriortothespudofthe

well. Asaresult,designprocessesinexploratorywellsaresubjecttochange.

Operatorstypicallydealwithwelldesignchangesduringdrillingoperations

throughdocumentedmanagementofchangeprocesses,whichareintendedto

aidpersonnelinsystematicallyidentifyingandmitigatingtherisksassociated

withthechanges.

TheBP

well

engineering

team

and

the

BP

subsurface

team

were

involved

indevelopingtheMacondowelldesign. Theteamsreferredtovarious

documentsandmanualswhiledesigningtheMacondowell,includingBPs

internalcasingdesignmanual,drillingwelloperationspolicy(DWOP),

advancedguidelinesfordeepwaterdrillingandotherguidance.50

A.

CostoftheMacondoWell

BPexceededitsoriginalcostestimatesfordrillingtheMacondowell. To

obtainadditionalfundsandcontinuedparticipationfromitspartnersinthe

Macondoproject,BPsubmittedtoAnadarkoE&PCompanyLPandAnadarko

PetroleumCorporation(collectivelyAnadarko)andMOEXseveral

49Casingpointisthedepthatwhichdrillingaparticularwellborediameterwillendsothat

casingofagivensizecanberunandcemented.50BPHZNMBI000010362.


31/217

26

AuthorizationsforExpenditures(AFEs),whichincludedwrittendescriptions

oftheprojectandcostestimatesforproposedwellactivitiesandoperations.51

UndertheiroperatingagreementwithBP,AnadarkoandMOEXcould

choosetoparticipateintheactivitiesandoperationsdescribedintheAFEand

therebycommittothefundingnecessarytocontinuetheoperation;theycould

proposeanalternativeoperatingplan;ortheycouldendtheirparticipationinthe

Macondoproject.52

BPsubmittedtoAnadarkoandMOEXaninitialAFEfortheMacondo

wellinAugust2009,estimatingthatthetotalcostsofthewellwouldbeabout

$96.1million. BothAnadarkoandMOEXapprovedtheoperationand

expenditures.53 BPsoughtitsfirstsupplementalAFEforapprovalofan

additional$27.9millioninJanuary2010,whichthepartnersacceptedinFebruary

2010.54 InMarch2010,BPsoughtauthorizationforanadditional$27million,explainingthatithadexceededthefirstsupplementalAFEduetounexpected

lostcirculationandwellcontrolevents.55 AnadarkoandMOEXapprovedthe

expenditureandofferednoalternativeoperatingplan.56

OnApril14,afterBPhaddrilledtotheMacondowellsrevisedtarget

depth,itsoughtafinalAFEfor$3.5milliontofundsettingtheproductioncasing

inconnectionwiththetemporaryabandonmentofthewell. Anadarkoand

MOEXapprovedtheAFEanddidnotproposeanyalternativeoperatingplan.57

Intotal,

the

companies

allocated

$154.5

million

to

drilling

the

Macondo

exploratorywell,anamountwellinexcessoftheoriginalestimatedcostof

$96.16millionandthenottoexceedcostof$139.5million.

UndertheiroperatingagreementwithBP,AnadarkoandMOEXhad

accessto,andinfactreviewed,dataandfilesrelatedtotheMacondowellthatBP

madeavailabletothemthroughsharedwebsites. ThePanelfoundnoevidence,

otherthanreviewingthisinformationandapprovingtheAFEs,indicatingthat

51BPHZNMBI000173275.52BPHZNMBI00173275.53BPHZNMBI00192546,BPHZNMBI00192549.54BPHZNMBI00192552,BPHZNMBI00192553.55BPHZNMBI00192557.56BPHZNMBI00192558.57BPHZNMBI00192559,BPHZNMBI00192561.


32/217

27

AnadarkoorMOEXweredirectlyinvolvedindecisionsrelatedtothedesignor

drillingoftheMacondowell.58

B.

DrillingMargin

Drillingengineersmustdesignawelltomanageporepressureand

fracturegradientsatdifferentwelldepths. Porepressureisthepressureexerted

byfluidsintheporespaceoftheformationbeingdrilled. Fracturepressureis

thepointatwhichpressureexertedbythedrillingfluidinthewellwouldcause

thesurroundingformationtofracture. Thefracturegradientplot,expressedasa

calculatedequivalentmudweight,isacurvethatshowsthewellsestimated

fracturegradientbydepth. Duringwelldesign,engineerstypicallyusea

graphicalrepresentationoftheestimatedporepressure,mudweight,and

fracturegradient,whichtogetherdefinetheappropriatedrillingmargins.

Drillingengineersconductaleakofftesttodeterminethestrengthor

fracturepressureoftheopenformation. Thistestisusuallyconducted

immediatelyafterdrillingpastthecementedcasingshoeinthewell.59 During

thetest,thewellisshutinandfluidispumpedintothewellboretogradually

increasethepressurethattheformationexperiences. Atacertainpressure,fluid

pumpedintothewellwillentertheformation,orleakoff,bymovingthrough

permeablepathsintherockorbycreatingaspacebyfracturingtherock. Ifthe

pressureisincreasedbeyondtheformationfracturepoint,fracturingofthe

formationcan

occur.

The

results

of

the

leak

off

test

dictate

the

maximum

pressureormudweightthatmaybeappliedtothewellduringdrilling

operationsbeforetheformationcanbeexpectedtotakefluid.

BOEMREregulationsrequirethat[w]hiledrilling,youmustmaintainthe

safedrillingmarginidentifiedintheapprovedAPD[ApplicationforPermitto

Drill]. Whenyoucannotmaintainthissafedrillingmargin,youmustsuspend

drillingoperationsandremedythesituation.60 Safedrillingmargincanbe

maintainedbyensuringthatthemudweightremainsbetweenthekick

toleranceorkickmargin,whichistypically0.5poundspergallon(ppg)

58DataobtainedfromHalliburtonshowedthatrepresentativesofAnadarkoandMOEX

periodicallyreviewedinformationrelatedtotheMacondowellduringdrilling.59Thecasingshoeisashortsteelcollarthatistypicallyattachedtothebottomofthecasing

string. Ithelpstoestablishproperpositioningofthecasingstringinthewellbore.6030CFR250.427(b). BOEMREregulationsdonotspecifywhatasafedrillingmarginis.

Theremaybeinstanceswhereasafedrillingmargincanbemaintainedoutsidethekickor

swabmargins.
http://www.glossary.oilfield.slb.com/Display.cfm?Term=formationhttp://www.glossary.oilfield.slb.com/Display.cfm?Term=formation


33/217

28

belowthefracturegradient,andtheswabmargin,whichistypically0.2ppg

abovetheporepressure. Inshort,themudmustbeheavyenoughtocontrolthe

porepressureandensurethattheformationfluids(includinghydrocarbons)do

notenterthewellbore,whilenotsoheavythatitfracturestheformation.61

BOEMREregulationsrequireoperatorstoprovidevariousdatatothe

Agencydemonstratingthattheoperatorismaintainingasafemargin. For

example,operatorsmustshow,inasinglegraphicplot,porepressures,mud

weightsandfracturegradientsforthefullextentofthewell.62 Theplotteddata

reflectsforecasteddatabasedon3Dseismicandoffsetwelldata.63 When

operatorsencounterunexpectedpressuresthatdifferfromtheirforecasts,

applicableregulationsrequiretheoperatortoreviseitscasingdesignandapply

totheAgencyforapprovalofthemodification.64

ThefinalestimatedMacondowellporepressure,mudweight,andfracturegradientplotsubmittedtoMMSonMarch26isshownatFigure1. The

verticalaxisofFigure1showsthedepthofthewell. Thehorizontalaxisshows

themudweight. TheredlinedepictsBPsplannedmudweight,whichwas

designedtobebetweenthekickmarginandtheswabmarginidentifiedin

Figure1.

61Maintainingmudweightinthisrangeisanindustryacceptedpracticebutisnotspecifically

requiredbyBOEMREregulations.6230CFR250.413and414.63Offsetwelldataaredataobtainedfromwellsthataredrilledinanareaclosetothetarget

well.6430CFR250.427(b).


34/217

29

Figure1MacondoWellPorePressureFractureGradientPlot65

AsseeninFigure2,theformationintegritytestatthe97/8inchlinershoe

locatedat17,168feetyieldedresultsof15.98ppg(asidentifiedintheIADCdaily

reports,whicharecompletedbytherigcrewtodocumentdailyoperations)and

16.22ppg(identifiedinBPsDailyOperationReport). ThePanelfoundthatthis

integritytestmayhavecreateduncertaintybecause(1)itwas1.0ppghigherthan

anticipatedand(2)therewasapossibilitythatthetestresultsdidnotreflecta

truetestoftheformationbelowthe97/8inchlinershoe. Althoughthisfracture

gradienttestwasquestionable,BPchosenottoretestthefracturegradientatthe

shoeanddecidedtodrillahead. AfterdrillingtheM57Csandinterval,BP

65API608174116901,March26APD(RevisedBypass)fortheMacondoWell.


35/217

30

conductedaGeotapsurveytodeterminethesandporepressure. Thesandpore

pressurewasdeterminedtobe14.15ppg. BPalsoconvertedthisporepressure

toanestimatedfracturegradientof15.0ppg. Theopenholesectiondrilled

utilizedasurfacemudweightrangeof14.114.5ppg,whichallowedforasafe

drillingmargintobemaintainedbetweenporepressureandfracturegradient.

Throughoutthisinterval,however,BPencounteredmultipleproblems

associatedwithbothlostreturnsandregressingporepressures(1.9ppg

difference)between17,001and18,066feet. BPlostapproximately4,000barrels

(bbls)ofmudintheproductionopenholeinterval. BPutilizedlosscirculation

materialinthisintervaltoattempttocontroltheselosses.

Figure2 DrillingmargindatafromIADCreportsandBPDailyReports

BPcontinueddrillinguntilitconcludedithadrunoutofdrillingmargin

betweenmudweightandformationporepressure. RobertBodek,BPGeological

Operations

Coordinator,

emailed

Michael

Bierne,

another

BP

employee,

on

April

13,2010,andexplainedthereasonswhyBPconcludedthatithadrunoutof

drillingmarginat18,360feet. Hesaidthattheteamdecidedtostopdrilling

becauseithadbecomeawellintegrityandsafetyissue.66 Theemailalsostates:

Wehadonemajorproblemhowever:thesandthatwetooktheinitial

GeoTappressureinwasmeasuredat14.15ppg. Theabsoluteminimum

surfacemudweightwecouldusetocovertheporepressureinthissand

was14.0ppg. Thiswouldgiveusapproximatelya14.2ppgESDoverthe

aforementionedsand. Ifweweretodrillaheadwitha14.0surfacemud

weight/14.2ESD,ourequivalentcirculatingdensity(ECD)wouldbeapproximately14.414.5ppg. Wehadalreadyexperiencedstaticlosses

witha14.5ppgESD! Itappearedasifwehadminimal,ifany,drilling

margin... Drillingaheadanyfurtherwouldunnecessarilyjeopardizethe

wellbore. Havinga14.15ppgexposedsand,andtakinglossesina12.6

66BPHZNMBI00126338.

Date Depth MW Losses PP Remarks Hydrocarbon Zones

2-Apr 17,007 - 17,321 14.3 17,168 FIT 16.22 PPG 17,684 - 17,693 M-57C 14.1 PPG

3-Apr 17,321 - 17,835 14.5 233 bbls 17,723 - GeoTap 14.15 ppg (PP) 17,786 - 17,791 M-56A 13.1 PPG

3-Apr 17,835 - 17,909 14.34-Apr 17,909 - 18,195 14.3 12.58 @ 18,089 Schematic - 12.6 ppg at 18,066 18,061 - 18,223 M-56E 12.6 PPG

4-Apr 18,215 - 18,250 14.4 639 bbls

Lost full returns

5-Apr 18,260 14.0 1263 - Total

6-Apr 14.0 1586 - Total

7-Apr 14.0

8-Apr 14.0

9-Apr 18,360 14.0 called TD

Open Hole Interval below 9 7/8-in Liner @ 17,168 - FIT 15.98 PP 13.9


36/217

31

ppgreservoirinthesameholesectionhadforcedourhand. Wehad

simplyrunoutofdrillingmargin.

C.

CasingProgram

Casingprogramsdescribethenumberandsizesofthecasingstringstobe

setinthewellboreandarebaseduponporepressureandfracturegradientplots.

Casingprogramsaredesignedbasedonanumberoffactors,includingburstand

collapsepressures,67tensilestrength,68drillbitsize,anticipatedhydrocarbon

flow,andhydrocarbontype. BPoriginallydesignedtheMacondowellto

includesevencasingstringstoreachthetargetwelldepth. However,basedon

theactualconditionsencounteredduringdrilling,BPusedninecasingstringsto

reachtotaldepth.

Conditionsencounteredduringdrillingcandrivechangesincasingprograms. Forexample,circulationlosseventsoccurredintheopenholesection

oftheMacondowell. Lostcirculationisthelossofdrillingfluids(suchas

drillingmudandspacer)intotheformation. Thislossofdrillingfluidis

observedduringthecirculationofdrillingfluids. Whenlessfluidisreturnedup

thewellannulusthanwaspumpedintothewellthroughthedrillstring,this

meansalossofdrillingfluidlostreturnshasoccurred. Theselostreturns

wereafactorinBPsdecisiontolimitthewelltotaldepthto18,360feet(shortof

the20,200feetoriginallyplanned)andalsoledBPtorevisethewellscasing

designprogram

to

account

for

mud

weight

and

fracture

gradient

drilling

margin

issues. Specifically,BPmodifieditscasingprogramseveraltimesbecauseof:(1)

awellcontroleventinMarch2010thatresultedinthedrillpipebecomingstuck;

(2)changesinporepressureestimates;and(3)wellballooning.69 AfterBP

reviseditscasingprogram,itsubmittedarevisedApplicationforPermittoDrill

toMMSforapproval.70

67Burstpressureisthetheoreticalinternalpressuredifferentialatwhichajointofcasingwillfail.

Collapsepressureisthepressureatwhichatubeorvesselwillcatastrophicallydeformasaresult

of

differential

pressure

between

the

outside

and

the

inside

of

the

tube

or

vessel.

Schlumberger

OilfieldGlossary.68Tensilestrengthistheforceperunitcrosssectionalarearequiredtopullasubstanceapart.

SchlumbergerOilfieldGlossary.69Ballooning,inwhichtheformationabsorbsdrillingmudwhiletherigspumpsareactivated

andthenreleasesthemudbackintothewellwhenthepumpsarenotactive,canbe

misinterpretedasakick.70MMSapproved:BPsApplicationforPermittoBypass,whichaddedanadditionalcasing

string,onMarch15,2010;BPsRevisedApplicationforPermittoBypass,whichaddedaliner,on


37/217

32

D. MudProgramandType

Drillingmudprovideshydrostaticpressure pressureexertedbyafluid

atequilibriumduetotheforceofgravity topreventformationfluidsfrom

enteringthewellbore.Drillingmudalsokeepsthedrillbitcoolandcleanduring

drilling,carriesdrilledcuttingsoutofthewellandsuspendsthedrillcuttings

wheneverdrillingispaused.

Operatorshavemultipleoptionsforthetypeofmudtouseduringthe

drillingofawell,includingoilbasedmud,syntheticoilbasedmudandwater

basedmud. Dependingonreservoirconditions,operatorsassesswhichmud

typeismostappropriateforthespecificwellbeingdrilled.

FortheMacondowell,BPchoseasyntheticoilbasedinvertmudsystem,asysteminwhichsyntheticoilinthemudremainsinacontinuousfluidphasein

thelowerholesectionsofthewell. BPchosethissystemforseveralreasons:(1)

toenhancetheabilitytomaintainconsistentfluidpropertiesindependentofthe

temperatureandpressureconditionsofthewell;(2)toimproveholecleaning

andminimizebaritesag,controlofpressurespikes,andgaininggelstrengths;71

and(3)todealwithotherproblemsthatresultwhenbalancingequivalent

circulatingdensity(ECD).72 Inselectingthesyntheticoilbasedmud,BPalso

soughttoreducefluidlossinordertominimizeformationdamagewhile

maintaininga

higher

drilling

efficiency.

Syntheticoilbasedmud,suchasthetypeBPusedintheMacondowell,

hasmanypositivefeaturesasdescribedabove. However,thistypeofmudalso

presentsrisksrelatingtoitseffectonthecrewsabilitytoaccuratelydetect

naturalgasinflux(kicks)intothewell. Arecentstudyofdrillingfluidmixtures

andwellcontrolfoundthatdrillersmighthaveahardertimedetectingkicks

March26,2010;andBPsRevisedApplicationforPermittoBypass,whichincludedaproduction

casing,onApril15,2010.71

Society

of

Professional

Engineers,

SPE

116013

PA

Studyof

the

PVT

Properties

of

GasSynthetic

DrillingFluidMixturesAppliedtoWellControl(2009). Baritesagisthesettlingofbariteparticles

(orotherweightingmaterials),whichcanresultinfluctuationsindrillingfluiddensity. When

thisoccursindrillingmud,themudlosesitsintegrityandcanonlybeatemporarybarrierinthe

well. Gaining,orprogressive,gelstrengthstypicallyrequirehigherpumppressurestobreak

circulation.72ECDisthetotaleffectivepressurethatacolumnofdrillingmudexertsonaformationasthe

mudiscirculatedthroughthedrillstringandbackupthewellbore,accountingforfrictional

forcesthroughoutthecirculatorysystem.


38/217

33

whenusingsyntheticoilbasedmud. Thestudystatedthatanimportantaspect

thatshouldbeaddressedwhendrillingwithasyntheticfluidisthepeculiarities

concernedwithwellcontrol. Becauseofthesolubilityofformationgasinoil

basedfluids,itcouldbecompletelydissolvedinthemudatbottomhole

temperatureandpressureconditions,makingkickdetectionverydifficult.73

ThePanelfoundnoevidencethatBPandMISWACOdiscussedwhether

theuseofsyntheticoilbasedmudwouldaffecttherigcrewsabilitytodetect

kicksduringdrillingoperationsatMacondo. Evenso,thePanelfoundno

evidencethatthespecificmudprogramusedbyBPandMISWACOwasacause

oftheblowout.

E. MudLosses

Throughout

the

drilling

of

the

Macondo

well,

BP

experienced

multiple

incidentswheremudwaslostintotheformation. Whilethelossofmudduring

drillingoperationsisnotuncommon,itisakeyindicatortodrillingengineers

thattheymustmonitorthewellcloselytoensurethatwellandformation

integrityarebeingmaintainedproperly. Abnormalpressurezonesidentifiedas

aresultofmudlosseventsoftenleaddrillingengineerstochangethewelldesign

andcasingsettingpoints.

BPdrilledtheMacondowelltoameasureddepthof18,360feet. Thecrew

seta97/8inchlinerinplaceat17,168feetmeasureddepthpriortodrillingthe

productionsection,whichwasthefinalsectionofthewell. Thelastsectionwasdifficulttodrillduetoadecreaseinthefracturegradientatthebottomofthe

wellbore. ThisconditionrequiredBPtocarefullyselectthecorrectmudweight

necessarytomaintainoverbalancerelativetotheformationwhileavoidingfluid

lossestothewell.

AccordingtoIADCdailyreports,thewellexperiencedmudlossesof

approximately3,000bblsacrossthehydrocarbonzonesofinterestduringthe

drillingoftheproductioncasingopenholesection. Thecrewcontrolledthese

losseswith

the

addition

of

lost

circulation

material

(LCM)

pills

and

a

relatively

smallquantity(lessthan200bbls)ofaspecialblendofdrillingfluid,whichhelp

retardthelossofmudintofracturesandhighlypermeableformations. Fromthe

timetheDeepwaterHorizonmovedontolocationatMacondo,atotalof

73Id.


39/217

34

approximately15,500bblsofdrillingfluidswerelostduringdrilling,running

casingandcementingoperations.74

F.

WellBallooning

Wellballooningisacommonphenomenoninwhichtheformation

absorbsdrillingmudwhiletherigspumpsareactivatedandthenreleasesthe

mudbackintothewellwhenthepumpsarenotactive. Wellballooningis

significantbecauseitcanmimicakick. Rigcrewscanthereforemisscriticalkick

indicatorsiftheymistakenlybelievethatballooningisoccurringinthewell.

MudloggingdatafortheMacondowelldemonstratedthattheproduction

casingzonestartedballooningbetween17,530feetand17,761feet. Thedaily

IADCreportsalsoshowthatthewellflowedbackduringflowchecksfollowing

mudlossatthosedepths.

G.

PlannedandActualTotalDepth

Indesigningawell,engineerscalculateaplannedtotaldepthofthewell.

BPsFebruary2009ExplorationPlanestimatedthewelldepthatapproximately

20,200feettrueverticaldepth. Duetoanarroweddrillingmargin,BPultimately

Federal Government Issues Report on Causes of BP Oil Spill

Documents

Transcript of Federal Government Issues Report on Causes of BP Oil Spill