Errors And Failures During Oil Well Drilling Engineering Essay

actus reuss And Failures During Oil Well Drilling Engineering EssayThis paper provides a general overview of actus reuss and nonstarters during performanceing and lite trading operations in the oil industry. The overview is presented in a tabular format for quick and easy reference. The work makes a clear preeminence between phantasms and di try outs and how errors may possibly lead to drilling chastisements. A phaseification of drilling failures with their signs and symptoms as thoroughly as the possible causes of these failures is included in the overview. The overview may help during a thorough audit of failures that are encountered during a drilling operation. Developing a list of possible failures during drilling with a description of basal observatory signs and symptoms of their occurrence is the crucial first step in minimizing Non Productive Time (NPT) during drilling operations.Keywords Drilling, Error, Failure, Tripping1. IntroductionThe oil industry is unarg uably unrivaled of the most complicated industries which face so many challenges yet functions as efficiently as possible. This assertion is true because the primary object of interest to the oil engineer cum the industry is hardened thousands of feet beneath the earths surface. This is accompanied by varying conditions of temperature and pressure as well as separatewise geological factors. A combination of these factors makes the subject of understanding the process of getting at the object of interest complex to drilling engineers. The elusive nature of this understanding makes drilling operations encounter failures. These failures range from drill shaft/equipment breakdown, wellbore or formation tumble, lost circulation, kicks and blow step ups.Suffice it to say that these failures cost the industry valuable drilling time outpouring into billions of dollars annually. It is against this background that this work on drilling failures is looked into. The primary focus of thi s work therefore is to improve the drilling process, by designing a good move up to identify all possible failures, how and when they occur, and most importantly their root causes. This would be done from a taxonomic perspective. This would involve classifying failures in the industry in their inbred groups and isolating their possible causes, the key indicators to such failures as well as the errors leading to the failures.2. Reported Cases of Failures in the Oil IndustryTo put the cases of failure in the right perspective, it is necessary to first define failure and error as it applies to oil well drilling operations. Schlumberger (2012) in their oil field glossary webpage defines failure in drilling asFailure to meet the defined drilling objective.Deviation in the expected TD deepness / broaden lengthDeviation in the expected performance (penetration rates, directional, power use)Error as defined by Oxford Advanced Learners Dictionary, is a mistake especially one that causes problems or affects the outlet of something.In todays error classification carcasss, error offer mean several thingsError as the cause of failure. For usage This event was due to human error. potpourris rely on this definition when seeking the cause of operator error in, for instance, a supervisors failure to provide guidance (Shappell Wiegman, 2001.).Error as the failure itself. For example The operators decision was an error (e.g. Helmreich, 2000). Classifications rely on this definition when categorizing the kinds of manifest errors operators shadower make (e.g. decision errors, perceptual errors, skill- initiationd errors) (Shappell Wiegmann, 2001).Error as a process, or, more specifically, as a passing play from some kind of standard. This standard may consist of operating procedures. Violations, whether exceptional or routine (Shappell Wiegmann, 2001), or intentional or unintentional (Helmreich, 2000), is one example of error according to the process definition. Dep determinationing on what we use as standard, we of course come to different conclusions about what is an error.Based on the above definitions, the following are the reported cases of failures in the oil industry.The most recent case is the disconnect of Mexico oil disaster in 2010. Though the immediate and remote causes of the incident appease remains a subject of controversy, the fact remains that the incident makes the subject of failures in the oil industry a relevant one.Shokir (2004) listed the following actual failure cases that occurred in Gulf of Suez Petroleum Company (GUPCO) in Gulf of Suez area and Western Desert area. These are cases 1 to 5.Case 1This development well cut in the Western Desert Concession in the onshore Abul-Gharadig area in 1991. Egyptian drilling company Rig No.8 (EDC-8) was used to drill this well to a enumerate depth (TD) of 10,616 ft. eyepatch drilling 12.25-inch good deal from 10,503 ft to 10,616 (TD) through the Limestone of Abu Roash formati on with rotary bottom hole assembly and water system base bog down, lost 350 psi. When pulling out of hole, washout in Shock Sub was detectedCase 2This development well drilled in the Gulf Of Suez Concession in the reachshore Ramadan area in 1993. Pyramid drilling Rig (Bennevis) was used to drill this well to a total depth (TD) of 12,504 ft. While drilling 12.25-inch hole from 10,805 ft to 10,823 through the Shale and Limestone of Mheiherrat formation with rotary bottom hole assembly and water base cadaver, lost 300 psi. tweak out of hole, ready vertical crack in the top joint of heavy weight drill pipe.Case 3This development well drilled in the Gulf Of Suez Concession in the finish upshore Hilal area in 1993. Sonat Offshore drilling Rig (Mercury) was used to drill this well to a total depth (TD) of 10,267 ft. While drilling 12.25-inch hole from 8,747 ft to 8,961 through the Limestone of Rudeis formation with rotary bottom hole assembly- and water base mud, lost 600 psi. Pull out of hole, found hole in the drill pipe near the surface.Case 4This development well drilled in the Gulf Of Suez Concession in the clear upshore October area in 1995. Sonat Offshore drilling Rig (Comet) was used to drill this well to a total depth (TD) of 16,080 ft. While drilling 12.25-inch hole from 10,035 ft to 10,239 through the Anhydrite of South Gharib formation with rotary bottom hole assembly and oil base mud, lost 300 psi. Pull out of hole, found the short drill collar cleaned smooth cut 0.3 ft from the boxfish neck area.Case 5This Exploratory well drilled in the Gulf Of Suez Concession in the attainshore Badri area in 1995. Santa Fe International Rig No.124 was used to drill this well to a total depth (TD) of 12,480 ft. While drilling 12.25 inch hole from 12,417 ft to 12,480 through the Salt with Shale, Limestone and Sand Streaks of Ayun Musa formation with rotary bottom hole assembly and water base mud, had very hard back ream and very high contortion, pump pressure dropped 1200 psi. Pull out of hole found the drill string backed onward at the short drill collar.CASE 6Horbeek et.al (1995), in their work cited Shell Expros effort in 1991 to tackle drillstring failures in their operations. This they did by carrying out autopsies.The autopsies affirm what they had long been suspected fatigue particularly BHA club fatigue was the main cause of failure. Table1 briefly summarizes the autopsies carried out from 27/5/1992-1994.Failures in the BHA accounted for 79%, whilst drillpipe accounted for 21%of the total failures for this period. BHA connection fatigue alone accounted for 58% of the BHA failures and was attributed to poor inspection criteria, poor drilling practices and lack of stress relief features. Other learning points from the autopsies were mass of failures, 46%, occurred in the 12 1/4 hole section.Greater attention should be paid to rig torque gauge calibrationMWD pique logs can warn of impending drillstring failure.New drillstring c omponents were not being specified to Shell specifications.Use of stabbing guide will reduce failures associated with connection damage. forefend slip cutting drillpipe.Improved pipe identification system needed.Once a downhole pressure loss is established POOH immediately.From interviews they carried out during the autopsy process it right away became clear that a general lack of understanding of cause, effect and cost of fatigue failures existed.The failures are summarized in the Table 1.Table 1 DRILLSTRING FAILURE AUTOPSIES 1992-1994 (Horbeek et al, 1995) assignmentFAILURE outset CAUSE27/05/92 deflect off at HDISBHA connection fatigue23/07/92 curl off at crossoverBHA connection fatigue24/07/92Twist off at MWD crossoverBHA connection fatigue02/11/92Twist off at stabilizerCombination torsion/tension overload05/11/92Twist off at MWDtractile overload21/11/92 laundry at crossoverBHA connection fatigue22/11/92Cracked mud saver subOvertorque of new connection26/11/92Twist off at MWDBHA connection fatigue08/12/92Twist off at HWDPAccidental over-torque by top drive02/01/93Twist off at jarsTension/torsion overload19/02/93Twist off at consequence subBHA connection fatigue24/02/93Washout at HWDPConnection damage/bad handling12/03/93Twist off at shock subConnection fatigue19/03/93Washout at HWDPShoulder seal damage/bad handling21/03/93Washout at jarsBHA connection fatigue04/04/93Washout at crossoverBHA connection fatigue10/08/93Twist off at jar -intensifierBHA connection fatigue20/08/93Twist off at jarsInsufficient hole cleaning05/10/93Twist off at mud motorBHA connection fatigue23/10/93Twist off at hole openerpoor people hard banding application inspection08/11/93Washout at drillpipe connectionTool joint connection fatigue24/11/934 washouts from split boxes DCs and HWDPAge condition of equipment24/11/93Washout at drillpipe connectionOvertorqued connectionDATEFAILUREROOT CAUSE02/12/93Twist off at drill collarTorsion/tension overload when stuck02/12/93Twist off at jar sBHA connection failure03/01/94Washout in HDISFatigue and vibration05/01/94Washout in drillpipeFatigue and vibration09/01/94Washout in drill collarFatigue and vibration11/01/94Washout in drill collarFatigue and vibration14/02/94Washout in HWDPAge and condition11/03/94Washout in drillpipeSlip cuts09/05/943washout in drillpipeStabbing damage28/06/94Twist off NM drillpipeStress corrosion cracking23/08/94Twist off SHWDPBrittle failure23/08/94Twist off in drillpipeDrillpipe tube fatigue07/11/94Twist off NB stabilizerFatique/vibration04/12/94Drillpipe partedTensile strength exceeded04/12/94Washout in jarsFatigue3. Errors Contributing to Drilling FailureThe error leading to a drilling or blithe failure may be caused by the abnormal state of either the formation being drilled, the wellbore itself or the equipment used in the drilling or lite operation or caused by other external factors. It must be stated here that these errors may be attributed to either human, manufacturing or mechanica l errors. humanity ErrorHere are just a few generic definitions for human errorAn inappropriate or undesirable human decision or behavior that reduces, or has the authorization for reducing, effectiveness, safety, or system performanceAn action that led the task or system outside its acceptable limitsAn action whose result was not desired by a set of rules or an external observerTo put things into context, there are three primary stages of cognition (planning, storage, and execution), which consult to the three error guinea pigs (mistakes, slips, and lapses).The three human error fibres areMistakes Mistakes occur when an intended outcome is not achieved even though there was adherence to the locomote in the plan. This is usually a case in which the original plan was wrong, was followed, and resulted in an unintended outcome.Lapses. Lapses are associated with our memories (e.g., lapses of memory, senior moments, etc.). These are generally not observable events.Slips. Slips are g enerally externalized, observable actions that are not in accordance with a plan. These are often referred to as Freudian slips, in which a person may be thinking something but inadvertently says it so that someone else can hear it. Slips are most often associated with the execution phase of cognition.Manufacturing ErrorVariation caused by the manufacturing process that affects the size of the part. Manufacturing error is part of measurement value. From a design perspective the engineer or designer produces a hang on of equipment or a system with intentions to function in a certain way. When it doesnt function that way (it breaks, catches on fire, messes up its output or is befallen of some other mishap) they try to find the root cause.Typically the cause can be identified as aDesign deficiency when the mechanical, electrical or other components of the design has a problem that caused the mishapManufacturing defect when the material or assembly has an issue that causes it to fai lEnvironmental hazard when an outside factor such as the weather causes the hazardous conditionMechanical ErrorMechanical error is a deviation from correctness in computer-processed data, caused by equipment failure. This error can often be attributed to a range of different problems on both the manufacturer and the user side, as well as to the unpredictable forces of chance. When equipment malfunctions or falls short of its intended purpose, it may cause delays and lost funds. In rare cases, however, the results can be catastrophic. Serious injuries, loss of life and long-term negative repercussions can emerge from the failure of a seemingly innocuous industrial component. Such events may emphasize the importance of manufacturing standards and safety considerations, or highlight certain industrial concerns that influence the outcome of a project. These errors are link to drilling operations as shown in Table 2.Table 2 Errors during drilling swinging operationsERRORWHERE ERROR IS LOCATEDSOURCE OF ERRORPOSSIBLE CAUSE OF ERRORCONTRIBUTING FACTORS LEADING TO FAILUREAbnormal state of an EntityFormationFractured faulted formations inseparable fracture, geological fault, cavernous formation, permeable formationHuman /Mechanical ErrorsTectonically stressed formationsStressed formationAbnormal pore pressurenether compaction of shales oxidizable formationDissolving limestone, reactive shale agile formationDrilling salt fomationsUnconsolidated formation silly sediment cementationNaturally over pressured shale breachUnder compaction of shalesWellboreMaterial accumulation in the wellboreCuttings accumulation,cavings accumulationHuman/Mechanical Errors high school hydrostatic wellbore pressureHigh pore pressureLow hydrostatic wellbore pressureLow pore pressureCrooked wellboreDoglegs, keyseatEquipmentHardware errorAge of equipment, design errorsHuman Error, Mechanical Mechanical ErrorsSoftware error particular knowledge of software by drilling crew members, typo erro rsTechnical errorLack of technical know-how by drilling personnel4. General Classification of Drilling FailuresThe classification of drilling failures in this paper is broadly categorized into three namely equipment failure, wellbore failure and then formation failure. Table 3 lists these failures and their potential causes.Table 3 Summary of drilling and tripping failures, causes ErrorsFailure TypeObservationsPotential CausesErrors in the lead to failureError typeEQUIPMENT FAILUREFailure classFailure sub classDrillstem failureFailure to acquire evaluation data, high torque dragShocks vibrationsDrillstem designManufacturing errorDrill pipe washouts passage of hydrostatic pressure, Low SPPDeviated holes and doglegs, corrosive mud or gases,CO2 H2O in mudRunning drill pipe in compression, in-correct make up torque of tool jointsHuman/operator errorDrillpipe corrosionContaminants in drilling fluidsO2 in drilling fluidsHuman errorDrillpipe fatiguePipe leakageHigh cyclic loadsShallow dog legs in conjunction with high tension and slow penetration ratesH2S CO2 in mudDrillstring bucklingCompressive load in pipe exceeds a critical valueCracked pipes jerky drop in pressureOver torqued threadsSwelled or mushroomed box end shoulders,pin connection breaksWhen enough torque is not applied at the tableWhen enough torque is not applied at the tableHuman errorPipe twistTorque exceeding pipes ultimate shear strengthPipe partingUltimate tensile strength exceededGallingMetal to surface contact b/w the pin box threads, stabbingHuman errorFailure TypeObservationsPotential CausesErrors Leading to failureError typeEQUIPMENT FAILURE CONTD.Failure classFailure sub classCasing failureThermal failureHigh temperature during steam injectionSulphide stress corrosion cracking failureStress corrosion by H2O H2,high strength steelsPoor design of steelsManufacturing errorExternal corrosion failure vulnerability of casing to wet air and/or saline fluidsHuman errorHelical buckling failureaxial l oad and compressive forces exceeds the casings load carrying strengthCasing collapse failBHA hangs up when RIH, Calliper log shows collapsed casinghigh external formation pressureCentralizer failureInefficient mud displacementUnder-reamed wells, using an paradoxical unit for the jobUsing an incorrect unit for the jobHuman errorMud motor failureMud motor stallingA sudden severe increase in SPP , ROP ceasesoperating parameters exceeding the capability of the motorMotor Failure during reamingextended reaming operationsMotor Failure during trippingkey seats, ledgesMotor failure due to downhole temperaturesdownhole temperatures increase beyond 225 FFORMATION RELATED FAILURELost circulationInduced fracture LCVolume of mud in mud pit reducesHigh mud density, ,increase in annular pressureFailure TypeObservationsPotential CausesErrors Leading to failureError typeFailure classFailure sub classFORMATION RELATED FAILURE CONTDLost circulation contdNatural fracture LCVolume of mud in mud pit red ucesNatural fractures, high permeability formations, cracks,vugs, fissuresIncorrect estimation of annular pressuresHuman errorKicksHigh pore pressure kickGeo-pressured formationsOperational relate kickSwab Surge during trippingInefficient ROPFormation related Low ROPCuttings accummulationOperational related Low ROPLow WOB,Bit ballingWELLBORE FAILUREWellbore wall relatedcementuming failureStress crackingAppears as no cement on bond logsstress changes caused by casing expansionGas migrationun-cemented channel, low preponderate pressure before and during cementingCement shrinkageCement cracksExposure to air of low humidityMicro annulusInter zonal Communications,Well flightHydrostatic Pressure Reduction inside the Casing,Cement ShrinkageBorehole cavingAngular, Splintery cavingsHighly tensional/compressive stressFailure TypeObservationsPotential CausesErrors Leading to failureError typeWELBORE FAILURE CONTD.Failure classFailure sub classSolids induced pack offKeyseatingSudden overpul lCyclic overpull at tool joint intervals on trips.High tensional side forcesUnderguage holePulled bit or stabilisers are undergauge.Sudden set down weight.Circulation is unrestricted.Bit stuckPDC bit run after a roller cone bit,When drilling abrasive formationsLedges and doglegsSudden erratic overpull or set downRunning an unsuitable BHA,changes in BHA junkMissing hand tools / equipment.Circulation unrestricted.Sudden erratic torque.Inability to make hole.Poor housekeeping on the rig floor.The hole cover not installedCement blocksCement fragments.Erratic torque.Hard cement becomes unstable around the casing shoeGreen cementadd-on in pump pressure.Loss of string weight.Sudden decrease in torque.Green cement in mud returns, discoloration of mud.drill string is inadvertently run into cementBit jammingPoor hole cleaning ,fluid is too thinDifferential StickingBit ballingReduced ROP,Increased SPP, Overpull on trippingSwellable soft claysFailure TypeObservationsPotential CausesErrors Leadi ng to failureError typeWELBORE FAILURE CONTD.Failure classFailure sub classHole collapseLittle or no tense up cakeWellbore washoutsExcessive hole fill,cuttingsSwelling shale, hole erosion, insufficient mud weightReactive formationsHydrated or mushy cavings. Shakers screens blind off, clay balls form. Increase in LGS, filter cake thickness, PV, YP, MBTWhen using WBM in shales and clays in puppylike formations.When drilling with an incorrect mud specificationWhen using WBM in shales and clays in young formations.When drilling with an incorrect mud specificationUnconsolidated formationsIncrease in pump pressure.Fill on bottom.Overpull on connections.Shakers blindingLittle natural cementationMobile formationsOverpull when moving up, takes weight when running inDrilling salt formationsFractured faulted formationsHole fill on connections.Possible losses or gainsnatural fracture system in the rockTectonically stressed formationsPack-offs and bridges may occur.Cavings at the shakers (spli ntery).Increase torque and draghighly stressed formations are drilledNaturally over-pressured shale collapseCavings (splintery) at shakers.Increased torque and drag.Hole fill.An increase in ROP.Cuttings and cavings are not hydrated or mushy.under-compaction, naturally removed overburden5. ConclusionsThis work has been a modest attempt at classifying downhole failures and errors during drilling and tripping operations. Though not exhaustive, the work has been able to group failures and errors into their natural groups and then elucidated their symptoms and their potential causes. Finally, it is concluded thatFailures during tripping and drilling operations may be naturally classified into wellbore related, equipment related and formation related failuresThat errors leading to these failures may be broadly classified into errors located in the formation, errors located in the equipment or errors located in the formation or wellbore being drilledThat these errors may result from misint erpretation of test data, amiss(p) use of hardware or software, ineffective monitoring of events, under maintenance of equipmentNomenclatureBHA = Bottom Hole AssemblyBOP = Blowout PreventerCO2 = degree Celsius (IV) OxideH2O = WaterH2S = Hydrogen SulphideHWDP = Heavy Weight Drill PipeLC = Lost CirculationLGSC = Low Gravity Solids ContentMBT = Methylene Blue tryoutMWD = Measurement While DrillingO2 = OxygenPDC = Polycrystalline Diamond Compact BitPOOH = Pull out of HoleRIH = Run in HoleROP = respect of PenetrationSPP = Stand Pipe PressureTD = Total DepthWBM = Water Based MudWOB = Weight on BitYP = Yield Point quotationA work of this magnitude must have been culled from other writers work hence I wish to express my sincere gratitude to all the authors whose works were consulted in the course of writing this paper.This acknowledgement would essentially be incomplete if I fail to extend my deepest appreciation to the Almighty God-Jehovah, for without Him, there would have been no me. To others whom I have not mentioned due to space or the lack of it, I remain your debtor in gratitude.