SPE DISTINGUISHED LECTURER SERIES is funded principally through a grant of the through a grant of the SPE FOUNDATION The Society gratefully acknowledges those companies that support the program by allowing their professionals to participate as Lecturers. And special thanks to The American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) for their contribution to the program.
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SPE DISTINGUISHED LECTURER · PDF fileSPE DISTINGUISHED LECTURER SERIES ... BP EXPLORATION Wellbore Quality Characterization ... 0 < WQS ≤ 2 stuck pipe or stuck casing
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IntroductionIntroductionDefinitionDefinitionDefinitionDefinitionMeasuring wellbore qualityMeasuring wellbore qualityM i llb litM i llb litManaging wellbore qualityManaging wellbore qualityField case studiesField case studiesConclusionsConclusions
IntroductionIntroduction
"Wellbore quality" common oilfield concept "Wellbore quality" common oilfield concept Often associated with directional drillingOften associated with directional drillingggOften linked with performance improvementsOften linked with performance improvementsDiverse interpretations for each disciplineDiverse interpretations for each disciplinep pp pNo unique definition existsNo unique definition existsNo proven method of measurement existNo proven method of measurement existNo proven method of measurement existNo proven method of measurement existContext: Context: Drilling and CompletionsDrilling and Completions
Straight wellboreStraight wellbore –– minimal tortuosity and minimal tortuosity and minimal hole spiralling (microminimal hole spiralling (micro--tortuosity)tortuosity)Round gauge holeRound gauge hole –– minimal wellbore breakminimal wellbore break--out,out,no washno wash--outs and hole not undergaugeouts and hole not undergaugeSmooth wellboreSmooth wellbore –– minimal ledgingminimal ledgingClean holeClean hole –– minimal residual cuttings bed minimal residual cuttings bed Integrity Integrity –– no leakage, no formation damageno leakage, no formation damageFit for purposeFit for purpose –– casing or logs will run to depthcasing or logs will run to depth
Wellpath selectionWellpath selectionTortuosity (planned versus actual)Tortuosity (planned versus actual)Tortuosity (planned versus actual)Tortuosity (planned versus actual)
Hole spiralling exists in most wells Hole spiralling exists in most wells Pitch, amplitude, drift, gauge Pitch, amplitude, drift, gauge –– key parameterskey parametersNegatively impacts drilling and completion operationsNegatively impacts drilling and completion operationsUsually can be detected from logsUsually can be detected from logsEff t d i h i t l / ERD llEff t d i h i t l / ERD llEffects more pronounced in horizontal / ERD wellsEffects more pronounced in horizontal / ERD wellsLong gauge bits Long gauge bits –– tend to help reduce spirallingtend to help reduce spiralling
Implicit MethodsImplicit MethodsRequire a methodology / philosophyRequire a methodology / philosophyRequire a methodology / philosophyRequire a methodology / philosophyIdentify appropriate response variableIdentify appropriate response variableInformation to characterize responsesInformation to characterize responsesInformation to characterize responses Information to characterize responses Analysis and interpretationAnalysis and interpretationScoring / ranking processScoring / ranking processScoring / ranking processScoring / ranking process
Head Trauma Injury AssessmentHead Trauma Injury Assessment
ScenarioScenarioScenarioScenarioPatient arrives at Emergency RoomPatient arrives at Emergency RoomApparent Head InjuryApparent Head InjuryApparent Head InjuryApparent Head InjuryImmediate assessment of brain function neededImmediate assessment of brain function neededNo immediate visual assessment possible No immediate visual assessment possible pp–– no useful explicit measureno useful explicit measureHow does the physician carry out the evaluation?How does the physician carry out the evaluation?Responses to stimuli are carried out Responses to stimuli are carried out –– implicit measuresimplicit measures
Head Trauma Injury AssessmentHead Trauma Injury Assessment
Three responsesThree responsesdetermine determine overall severityoverall severityoverall severityoverall severityof head traumaof head trauma
3 3 ≤≤ GCS GCS ≤≤ 8 Severe Brain Injury8 Severe Brain InjuryGCS = Glasgow Coma Scale
The Wellbore Quality Scorecard (WQS)The Wellbore Quality Scorecard (WQS)
MethodologyMethodologyTechnique based on head trauma assessmentTechnique based on head trauma assessmentWellbore quality inferred from response variablesWellbore quality inferred from response variables–– drilling, trippingdrilling, tripping--out and casing runningout and casing running
Primary response variables are T&D parametersPrimary response variables are T&D parametersSurface logging data used to characterize responsesSurface logging data used to characterize responsesTrend analysis principal evaluation toolTrend analysis principal evaluation toolTrend analysis principal evaluation toolTrend analysis principal evaluation toolExtent and intensity of data variations evaluatedExtent and intensity of data variations evaluated
Example – Torque Trend DataExample – Torque Trend Data
35Narrow
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Narrow bandwidthVery low open hole friction factor
indicative of good drilling practicesalso OBM used so good lubricityhole quality considered excellent
WQS is recorded as a response mnemonicWQS is recorded as a response mnemonicWQS is recorded as a response mnemonicWQS is recorded as a response mnemonic–– D4T5C5D4T5C5 (Drilling 4; Tripping(Drilling 4; Tripping--out 5; Casing Running 5)out 5; Casing Running 5)
WQS = sum of each response scoreWQS = sum of each response scoreWQS sum of each response scoreWQS sum of each response score
Horizontal Well Offshore NorwayHorizontal Well Offshore Norway WQSWQS
Drilling Response (max 5 points)Drilling Response (max 5 points)Persistent erratic torque response observed. Observation is indicative of vibration problems Persistent erratic torque response observed. Observation is indicative of vibration problems typically seen in the chalk reservoir. Vibrations are considered a transient problem and should typically seen in the chalk reservoir. Vibrations are considered a transient problem and should not significantly impact overall wellbore quality. not significantly impact overall wellbore quality.
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g y p q yg y p q yAverage rotary friction factors of 0.20/0.15 are typical of fieldAverage rotary friction factors of 0.20/0.15 are typical of field--wide torque behaviour.wide torque behaviour.
Final TripFinal Trip--out Of Hole Response (max 7 points)out Of Hole Response (max 7 points)Elevated drag levels in excess of 50klbs are observed from 4,300 to 4,600m and from 5,200 to Elevated drag levels in excess of 50klbs are observed from 4,300 to 4,600m and from 5,200 to 5,400m indicating a possible hole cleaning problem. Overpulls also occur at chalk / shale 5,400m indicating a possible hole cleaning problem. Overpulls also occur at chalk / shale
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, g p g p p, g p g p ptransition zones. A form of sliptransition zones. A form of slip--stick axial drag is also present when trippingstick axial drag is also present when tripping--out through the out through the open hole section. open hole section. Average pickAverage pick--up friction factors of 0.15/0.20 are typical of fieldup friction factors of 0.15/0.20 are typical of field--wide experience.wide experience.
Liner Running Response (max 8 points)Liner Running Response (max 8 points) 33Liner running in open hole is far from smooth; significant axial slipLiner running in open hole is far from smooth; significant axial slip--stick events observed which stick events observed which increase in intensity with depth. String has to be worked significantly over last 600m. String increase in intensity with depth. String has to be worked significantly over last 600m. String also had to be torqued to overcome tight spots / ledges. also had to be torqued to overcome tight spots / ledges. SlackSlack--off friction factors of 0.12/0.45 are in line with fieldoff friction factors of 0.12/0.45 are in line with field--wide experience.wide experience.
WQS (D3T2C3)WQS (D3T2C3)A score of 8 corresponds to a medium quality wellbore.A score of 8 corresponds to a medium quality wellbore.
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Cost vs Wellbore Quality RelationshipCost vs. Wellbore Quality Relationship
LearningsLearningsA low WQS does not always equate to poor performanceA low WQS does not always equate to poor performanceA l WQS b d t d f diffi lt f d illiA l WQS b d t d f diffi lt f d illiA low WQS can be due to degree of difficulty of drilling A low WQS can be due to degree of difficulty of drilling and casing running in that fieldand casing running in that fieldPoorly designed casing run can result in failurePoorly designed casing run can result in failurey g gy g gImplications of scoring wellbore quality need to be Implications of scoring wellbore quality need to be understood by operators / service companiesunderstood by operators / service companiesWellbore Quality has to be managed at field levelWellbore Quality has to be managed at field levelWellbore Quality has to be managed at field levelWellbore Quality has to be managed at field levelNeed to understand Cost vs. Wellbore Quality relationshipNeed to understand Cost vs. Wellbore Quality relationship
Tripping / Casing Running PracticesTripping / Casing Running PracticesSurge and Swab Pressure CyclesSurge and Swab Pressure CyclesSurge and Swab Pressure Cycles Surge and Swab Pressure Cycles –– can result in rock fatiguecan result in rock fatigue
Emerging TechnologiesEmerging TechnologiesContinuous Circulation SystemContinuous Circulation SystemContinuous Circulation System Continuous Circulation System –– reduces swab and surge cycles in wellreduces swab and surge cycles in well