drilling engineering - directional drilling

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Petroleum Engineering, Drilling Engineering, Directional Drilling



2. TTaabbllee ooff CCoonntteennttssDefinitionsApplications of Directional DrillingDeflection ToolsMud MotorsTypes of Well Profile 3. DDeeffiinniittiioonnssDirectional drilling is the process of directing thewellbore along some trajectory to a predeterminedtarget.Deviation control is the process of keeping thewellbore contained within some prescribed limitsrelative to inclination, horizontal excursion from thevertical, or both. 4. AApppplliiccaattiioonnssHistoryInterests in controlled directional drilling began about1929 after new and later accurate means of measuringhole angle was introduced during the development ofSeminole, Oklahoma field.In the early 1930s the first controlled directional wellwas drilled in Huntington Beach, California.Controlled directional drilling was initially used inCalifornia for unethical purposes, that is, tointentionally cross property lines. 5. In 1933, during the development of the Signal Hill fieldin Long Beach, California, several wells were drilledunder the Sunnyside Cemetery from locations acrossthe streets surrounding the cemetery.In 1934, it was used to kill a wild well, Madeley No.1,near Conroe, Texas. 6. Typical offshoredevelopment platformwith directional wells 7. Developing a field under a cityusing directionally drilled wells 8. Drilling of directionalwells where the reservoir isbeneath a major surfaceobstruction 9. Sidetrackingaround a fish 10. Using an old well to explore fornew oil by sidetracking out of thecasing and drilling directionally 11. A relief well drilled to intersect theuncontrolled well near the bottom 12. Salt dome drilling (direct the wellaway from the salt dome to avoidcasing collapse problems) 13. Fault drilling through a steeplydipping, inclined fault plane. 14. Other applications include:To reach multiple targetsHorizontal drillingTo reach thin reservoirs (using horizontal andmultilateral drilling)To avoid gas or water coning problems 15. DDeefflleeccttiioonn TToooollssThe wellbore can be deflected from its currentposition using any of the following:WhipstocksJetting bitBent subs with downhole motors 16. WWhhiippssttoocckkssAdvantagesIt provides a controlled holecurvatureat the onsetCan be run at any depth in any kindofrock and very useful in hard rockDwihseardev oatnhteargs efailIt is necessary to drill the pilot holeand then trip out to change thesmaller bit to one of the wellborediameter. 17. JJeettttiinngg bbiittAdvantagesSeveral attempts can be made to initiate deflectionwithoutpulling out of holeA full gauge hole can be drilled from the beginningDisadvantageThe technique is limited to soft-medium formationsSevere dog-legs can occur if the jetting is not carefullycontrolledOn smaller rigs there may not be enough pump capacity towash away the formation 18. BBeenntt ssuubbss wwiitthh ddoowwnnhhoollee mmoottoorrssThe bent sub is run directly above the motor and its pin isoffset at an angle of 1 3 degrees.Deflection of the wellbore occurs when drilling is carriedout with no surface rotation to the drillstring.The drill bit is forced to follow the curve of the bent sub.The degree of curvature depends largely on the bent suboffset angle and the OD of the motor.When the required angles (inclination and/or azimuth)are obtained, this BHA is tripped out to be replaced with arotary assembly. 19. SStteeeerraabbllee mmoottoorrssThe motor is designed with an in-built bent housingbelow the motor section; usually the connecting rodhousing.The bent housing angle is usually 0.25 1.5 degrees.The use of steerable motors with the correct drill bit andBHA reduces the number of round trips required toproduce the desired inclination/azimuth.It can be used in either :Oriented mode (sliding)Rotary mode 20. Oriented (Sliding) modeThe drillstring remainsstationary (rotary table ortop-drive is locked) while thedrill bit is rotated by themotor.The course of the well isonly changed when drillingin sliding mode as the drillbit will now follow thecurvature of the motor benthousing.Rotary modeSteerable motor becomeslocked with respect totrajectory and the holedirection and inclination aremaintained while drilling. 21. Bit offset:Steerable motorvs. PDM with bentsub 22. MMuudd MMoottoorrssThere are two types of mud motors:TurbinesPositive displacement motors (PDM) 23. TTuurrbbiinnee mmoottoorrThe turbine motor consists of:A multistage blade-type rotor and stator sections. Thenumber of rotor/stator sections can vary from 25 to 50.A thrust bearing section and a drive shaft.The rotor blades are connected to the drive shaft andare rotated by mud pumped under high pressure.The stator deflects the mud onto the rotor blades.Rotation of the rotor is transmitted to the drive shaftand drill bit. 24. Positive ddiissppllaacceemmeenntt mmoottoorrss ((PPDDMM))A PDM consists of:Power section (rotor and stator)By-pass valveUniversal jointBearing assembly 25. Power sectionThe PDM consists of a helical steel rotor fitted inside aspirally-shaped elastomer moulded stator.Mud flowing under pressure fills the cavities betweenthe dissimilar shapes of the rotor and stator and underthe pressure of mud, the rotor is displaced and beginsto rotate.The rotor actually moves in an elliptical shape. Thiseccentric movement is converted to true circularmotion by a universal joint assembly. 26. By-pass valveThis valve allows the drilling fluid to by-pass the mudmotor allowing the drillstring to fill during tripping inand drain when making a connection or pulling out ofhole.The valve operates by a spring which holds a piston inthe upper position.In this position, ports in the by-pass valve are openallowing mud to flow in or out of the drillstring.At 30% of recommended flow rate, the piston is forceddown, closing the ports and directing flow through themud motor. 27. Universal Joint:A Connecting Rod assembly is attached to the lowerend of the rotor.It transmits the torque and rotational speed from therotor to the drive shaft and bit.Universal joints convert the eccentric motion of therotor into concentric motion at the drive shaft.Bearing and Drive Shaft AssemblyThe drive shaft is a rigidly-constructed hollow steelcomponent.It is supported within the bearing housing by radialand axial thrust bearings 28. TTyyppeess ooff WWeellll PPrrooffiilleeType IBuild and HoldType 2Build, Hold and Drop.Returns to vertical after dropping S-shape.Does not return to vertical after dropping Modified S-shape.Type 3Continuous Build 29. KOPTYPE I TYPE II TYPE IIIBUILD & HOLD BUILD HOLD & DROP CONTINUOUS BUILD 30. TTyyppee II bbuuiilldd aanndd hhoollddInformation needed:Surface co-ordinatesTarget co-ordinatesTVD of targetTVD to KOPBuild-up rate 31. TTyyppee IIII bbuuiilldd,, hhoolldd aanndd ddrrooppInformation needed:Surface co-ordinatesTarget co-ordinatesTVD of targetTVD to KOPTVD at end of drop-off(usually end ofwell)Build-up rateDrop-off rateFinal angle ofinclination throughtarget.Because Type II have 2 curves,2 radii need to be calculatedand compared with the totaldeparture, D3.These quantities are thenused to calculate themaximum possibleinclination angle at end ofbuild-up curve. 32. D3 > (R1 + R2) D3 < (R1 + R2) 33. TTyyppee IIIIII ccoonnttiinnuuoouuss bbuuiillddUsed for salt domedrilling.For planning appraisalwells.Information needed:Surface co-ordinatesTarget co-ordinatesOne parameterfrom:Maximuminclination angleTVD to KOPBuild-up rate 34. Design a directional well with the followingrestrictions: Total horizontal departure = 4,500 ft True vertical depth (TVD) = 12,500 ft Depth to kickoff point (KOP) = 2,500 ft Rate of build of hole angle = 1.5 deg/100 ft Profile type: Type I well (build and hold) 35. (i) What is the maximum hole anglerequired.(ii)What is the total measureddepth (MD)?q 36. MMaaxxiimmuummIInncclliinnaattiioonnAAnnggllee3,820 ftr 18,000 1 ==1.5pr2 = 0( )D4 D112,500 2,500= -10,000 ft=-x4 = 4,500 ft 37. 46 2tan D D x (D D ) 2(r r )x- - + - - +2 22 tan 10,000 4,500 10,000 2(3,820)4,500 - + --=2(3,820) 4,500-126.3 qmax = + -q = -1 2 41 2 424 121 4 1 4max 2(r r ) x 38. 47MMeeaassuurreedd DDeepptthh ooffWWeellllxBuild = r1(1 - cos q)3,820(1- cos 26.3 )395 ft==xHold 4,500 395 = -4,105 ft=L sin 4,105Hold q =HoldL 9,265 ft = 39. 48MD = D1 +r1qrad +LHold26.3 3,820 2,500 + = + p MD = 13,518 ft9,265180