11

A Probabilistic Approach to Risk A Probabilistic Approach to Risk Assessment of Managed Pressure Drilling Assessment of Managed Pressure Drilling

in the Gulf of Mexicoin the Gulf of Mexico

Oliver Coker Ken Malloy

22

Managed Pressure DrillingManaged Pressure Drilling

•• Not a new conceptNot a new concept–– Slight departure from what we have historically been Slight departure from what we have historically been

taught in well control school.taught in well control school.

•• Not focused on the BHPNot focused on the BHP–– Entire pressure profile in the open section of the hole Entire pressure profile in the open section of the hole

which is not static but changes as drilling progresseswhich is not static but changes as drilling progresses

•• Not intended to maintain an overbalance over all Not intended to maintain an overbalance over all sections, but to minimize departures outside the sections, but to minimize departures outside the “pressure environment window”.“pressure environment window”.–– Pore pressure or wellbore stability pressure on the low sidePore pressure or wellbore stability pressure on the low side–– Frac or leakoff on the high side.Frac or leakoff on the high side.

33

Managed Pressure DrillingManaged Pressure Drilling

•• Maintaining in real time mud density, Maintaining in real time mud density, equivalent circulating density and casing equivalent circulating density and casing back pressure to control pressure back pressure to control pressure throughout the exposed wellbore in a throughout the exposed wellbore in a closed system.closed system.

MPD = MW + ECD + CP

44

SpindletopSpindletop

•• Technology of its DayTechnology of its Day–– Rotary DrillingRotary Drilling–– Drilling MudDrilling Mud

55

Closed Pressurized Mud SystemClosed Pressurized Mud System

•• Surface pressure control headSurface pressure control head•• RealReal--time bottom hole pressuretime bottom hole pressure•• Computer controlled circulating systemComputer controlled circulating system•• Continuous circulation with jointed pipeContinuous circulation with jointed pipe

BLOWOUTPREVENTOR

PRESSURECONTROL

HEAD PUMP

CHOKE

COMPUTERCONTROL

BHP @ bit

DRILL FLUID

66

Spindletop – A Step Change

The water which was flushed through the rotary dill pipe was failing to bring up the loose sands. Curt Hamill recognized that he had to increase the viscosity and density of the circulating fluid—but how? Hamill invented the world’s first drilling mud by driving some cattle through a shallow pond. The cattle stirred up the water enough to generate a thick mud. When the muddy water was poured down the Spindletop well bore, the hole was stabilized and the sands flushed out.

2003 EARTH SCIENTIST Magazine

77

MPD PrizesMPD Prizes••RealReal--time well controltime well control

••Reduce lost circulation and ballooningReduce lost circulation and ballooning

••Reduce risk of stuck pipeReduce risk of stuck pipe

••Drill longer ERD wells with constant BHPDrill longer ERD wells with constant BHP

••Higher ROP in deep gas wellsHigher ROP in deep gas wells

••Control shallow gas and water flowsControl shallow gas and water flows

••Safer drilling environmentSafer drilling environment

88

MPD MPD –– Size of the Prize?Size of the Prize?$10 million?$10 million?$100 $100 millionmillion??$1 billion?$1 billion?

The prize is big as you make it.

MPD is step-change technology.

MPD = MW + ECD + CP

99

What is Risk?What is Risk?• Risk is the known chance that an event will occur.

– Differentially Stuck while Drilling Well in GOM

• Risk = Probability x Severity

What is Uncertainty?• Uncertainty is the unknown chance that an event will occur.

– Don’t Know Where You Will Be Differentially Stuck while Drilling Well in GOM

1010

Risk AssessmentRisk Assessment•• Risk IdentificatiRisk Identificationon•• Risk AnalysisRisk Analysis

–– QualitativeQualitative–– QuantitativeQuantitative

Notices and meeting minutes for IADC Committees.Government Affairs; Health, Safety & Environment; Training; Maintenance; Jackup Rig; Underbalanced Operations; Well Control; Information Technology Solutions; Contracts; Rig Moving

Also: IADC Offshore Operating Division

1111

Risk AnalysisRisk Analysis ProcessProcess•• Scoring ModelsScoring Models

–– SimpleSimple–– Commensurate to the nature of expert opinion elicitationCommensurate to the nature of expert opinion elicitation

•• IADC Underbalanced Operations CommitteeIADC Underbalanced Operations Committee–– 2004 CHAIRMAN2004 CHAIRMAN

Chairman: Chairman: Mike DuBose, Rowan Drilling (UK) LTDMike DuBose, Rowan Drilling (UK) LTDEE--mail Address: mail Address: ubochairmanubochairman@@iadciadc.org.org

–– 2004 VICE CHAIRMAN 2004 VICE CHAIRMAN !! Vice Chairman: Vice Chairman: Fred Curtis, HalliburtonFred Curtis, Halliburton

–––– 2004 SUBCOMMITTEE CHAIRMEN2004 SUBCOMMITTEE CHAIRMEN

!! HSE & Training Subcommittee: HSE & Training Subcommittee: Adrian Adrian HoulbrookHoulbrook, Weatherford Int’l , Weatherford Int’l !! Standards & Nomenclature Subcommittee:Standards & Nomenclature Subcommittee: Sid Ruiz, MI Drilling Fluids Sid Ruiz, MI Drilling Fluids !! API Equipment for UBO and MPD Workgroup:API Equipment for UBO and MPD Workgroup: John John RamalhoRamalho, Shell , Shell !! NRV Task Group:NRV Task Group: Brian Grayson, Weatherford Int'l Brian Grayson, Weatherford Int'l !! Fluids Subcommittee:Fluids Subcommittee: Mike Buchanan, Weatherford Int'l Mike Buchanan, Weatherford Int'l !! Honorary ChairpersonHonorary Chairperson:: RosalvinaRosalvina GuimeransGuimerans!! Managed Pressure Drilling (MPD) Subcommittee:Managed Pressure Drilling (MPD) Subcommittee: Douglas Nunn, Douglas Nunn, GlobalSantaFeGlobalSantaFe!! Daily Report Subcommittee:Daily Report Subcommittee: Inactive Inactive

1212

Risk Analysis Risk Analysis ProcessProcess

•• Scoring Models:Scoring Models:–– Qualitative scale of 1Qualitative scale of 1--1010 for probability and for probability and

impact estimationsimpact estimations–– Impact of a risk has been considered in 3 Impact of a risk has been considered in 3

dimensions:dimensions:•• Impact on Impact on safetysafety•• Impact on cost Impact on cost •• Impact on Impact on drilling efficiencydrilling efficiency

–– Overall impact is calculated by the weighted Overall impact is calculated by the weighted average of these three scores.average of these three scores.

1313

Risk Assessment Process Element

Scoping and Screening AnalysisDefine the physical and analytical

boundaries of the assessment

Event IdentificationIdentify the events that could cause pipeline failures and lead to adverse

consequences

Frequency AnalysisEstimate how often the events might occur

Consequence AnalysisEstimate the severity of the adverse impacts should the events occur

Risk AssessmentEstimate the frequency and consequences

of potential incidents

Risk Control & Decision SupportSelect activities to reduce risk or produce equal or greater levels of safety

more efficiently

Performance Monitoring & FeedbackDetermine if the risk control decisions produce the anticipated outcomes

Risk EstimationCombine frequency and consequence estimates into relative risk values

1414

FMEA Criticality Analysis Index Codes

•• Failure Mode and Effect AnalysisFailure Mode and Effect Analysis–– SeveritySeverity–– OccurrenceOccurrence–– DetectionDetection

1515

Severity IndexSeverity Index

1No discernible effect on product or subsequent processes. No

2Customer more likely will not notice the failure. Very slight effect on product / process performance. Very slight

3Customer slightly annoyed. Slight effect on product or service performance. Slight

4Customer experiences minor nuisance. Minor effect on product orservice performance. Fault does not require attention. Minor

5Customer experiences some dissatisfaction. Moderate effect on product or service performance.Moderate

6Customer experiences discomfort. Product/process performance degraded, but operable and safe.Significant

7Customer dissatisfied. Major effect on service; rework on service

necessary. Product/service performance severely affected but functionable and safe.

Major

8Customer very dissatisfied. Extreme effect on process/service; equipment damaged. Product/service incomplete but safe. Extreme

9

Potential hazardous effect. Able to stop product/service without mishap. Safety related. Time-dependent failure. Disruption to subsequent process operations. Compliance with government regulation is in jeopardy.

Serious

10Hazardous effect. Safety related. Sudden failure. Noncompliance with government regulations. Hazardous

RankingCriteriaSeverity

1616

Occurrence IndexOccurrence Index

1Failure unlikely. History shows no failures. Unlikely

2Rare number of failures likely. Rare

3Very few failures likely. Very slight

4Few failures likely. Slight

5Occasional number of failures likely. Occasional

6Moderate number of failures likely.Medium

7Frequent high number of failures likely. Moderately High

8High number of failures likely. High

9Very high number of failures likely. Very High

10Failure almost certain. Almost Certain

RankingCriteria Occurrence

1717

Detection IndexDetection Index

1Current controls certain to detect.Certain

2Current controls will almost always will detect failure.Very High

3High likelihood current controls will detect failure. High

4Moderately high likelihood current controls will detect the failure. Moderately High

5Medium likelihood current controls will detect failure. Moderate

6Low likelihood current controls will detect failure. Low

7Very low likelihood current controls will detect failure. Very Low

8Remote likelihood current controls will detect failure. Remote

9Very remote likelihood current controls will detect failure. Very Remote

10Absolute certainty of non-detection.Almost Impossible

RankingCriteriaDetection

1818

DeliverablesDeliverables

•• Extensive Report identifying and grading the Extensive Report identifying and grading the risks involved between drilling in a conventional, risks involved between drilling in a conventional, overbalanced, openoverbalanced, open--system as we do now system as we do now compared to drilling in a balanced, closedcompared to drilling in a balanced, closed--system, managed pressure environment. system, managed pressure environment. –– Shared among the participants Shared among the participants –– Serve as a basis to modify some of the regulatory Serve as a basis to modify some of the regulatory

limits placed upon drilling operations in the Gulf of limits placed upon drilling operations in the Gulf of Mexico.Mexico.

1919

Probability Distribution FunctionProbability Distribution Function

Normal Distribution

00.00005

0.00010.00015

0.00020.00025

0.00030.00035

0.00040.00045

0 2,000 4,000 6,000 8,000 10,000

Value

Pro

babi

lity

Dis

trib

utio

n Fu

nctio

n

Normal Distribution

00.10.20.30.40.50.60.70.80.9

1

0 2,000 4,000 6,000 8,000 10,000

Value

Cum

ulat

ive

Dis

tribu

tive

Func

tion

Cumulative Distribution FunctionCumulative Distribution Function

2020

UpsideUpside

•• Anticipated long term economic benefitsAnticipated long term economic benefits–– Cost savings realized from less nonCost savings realized from less non--productive productive

trouble time associated with drilling trouble time associated with drilling operationsoperations

–– Less damage to depleted or otherwise Less damage to depleted or otherwise sensitive reservoirs, a potential reversal of sensitive reservoirs, a potential reversal of recent trends to downgrade evaluation of recent trends to downgrade evaluation of reserves. reserves.

2121

MANDATE :

To seek a fair, balanced and managed outcome by assessing an even handed comparison of risk between conventional drilling and managed pressure drilling.

VISION :

With open-minded regulatory agencies support develop an integrated, knowledgeable, open-minded, and proactive team to assist the industry in determining a future path forward.

A Probabilistic Approach to Risk A Probabilistic Approach to Risk Assessment of Managed Pressure Drilling Assessment of Managed Pressure Drilling

in the Gulf of Mexicoin the Gulf of Mexico

2222

A Probabilistic Approach to Risk A Probabilistic Approach to Risk Assessment of Managed Pressure Drilling Assessment of Managed Pressure Drilling

in the Gulf of Mexicoin the Gulf of Mexico

Oliver Coker Ken Malloy