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Petroleum Engineering 406 Lesson 18 Directional Drilling

Petroleum Engineering 406 Lesson 18 Directional Drilling. Lesson 10 - Directional Drilling. When is it used? Type I Wells (build and hold) Type II Wells (build, hold and drop) Type III Wells (build) Directional Well Planning & Design Survey Calculation Methods. Homework:.

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Petroleum Engineering 406 Lesson 18 Directional Drilling

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  1. Petroleum Engineering 406Lesson 18 Directional Drilling

  2. Lesson 10 - Directional Drilling When is it used? Type I Wells (build and hold) Type II Wells (build, hold and drop) Type III Wells (build) Directional Well Planning &Design Survey Calculation Methods

  3. Homework: READ.“Applied Drilling Engineering” Ch. 8, pp. 351-363 REF. API Bulletin D20, “Directional Drilling Survey Calculation Methods and Terminology”

  4. What is Directional Drilling? Directional Drilling is the process of directing a wellbore along some trajectory to a predetermined target. Basically it refers to drilling in a non-vertical direction. Even “vertical” hole sometimes require directional drilling techniques. Examples: Slanted holes, high angle holes (far from vertical), and Horizontal holes.

  5. Non-Vertical Wellbore q, a or I Inclination Angle Inclination Plane Y Z Axis (True Vertical Depth) North Direction Angle f, e or A Direction Plane X

  6. Lease Boundary Surface Location for Well No. 1 Surface Location for Well No. 2 Bottom Hole Location for Well 2 Houses Oil-Water Contact Figure 8.2 - Plan view of a typical oil and gas structure under a lake showing how directional wells could be used to develop it. Best locations? Drill from lake?

  7. Top View NOTE: All the wells are directional 5 - 50 wells per platform Figure 8.3 - Typical offshore development platform with directional wells.

  8. Drilling Rig Inside Building Figure 8.4 - Developing a field under a city using directionally drilledwells.

  9. Why not drill from top of mountain? Maximum lateral displ.? Fig. 8.5 - Drilling of directional wells where the reservoir is beneath a major surface obstruction.

  10. Fish Lost in Hole and Unable to Recover Cement Plug Sidetracked Hole Around Fish Figure 8.6 - Sidetracking around a fish.

  11. Figure 8.7 - Using an old well to explore for new oil by sidetracking out of the casing and drilling directionally. Oil Producing Well Ready to Abandon Sidetracked Out of Casing Possible New Oil Old Oil Reservoir

  12. Horizontal Departure to Target Type II Build-hold and Drop (“S Type”) Build and Hold Type Type I Build-hold Drop and/or Hold (Modified “S” Type) Continuous Build Type III Figure 8.8 - Major types of wellbore trajectories.

  13. Figure 8.10 - Geometry of the build section. Build Section Build Radius:

  14. Build Section:

  15. Start of Buildup End of Build Type II Drop Off Target Build-hold-and drop for the case where:

  16. Kickoff End of Build Type II Maximum Inclination Angle Build-hold-and drop for the case where: Drop Off Target

  17. Projected Trajectory Projected Trajectory with Left Turn to Hit Targets Target 1 Target 2 Fig. 8-14. Directional well used to intersect multiple targets Target 3

  18. N18E S23E A = 157o Fig. 8-15. Directional quadrants and compass measurements N55W A = 305o S20W

  19. Projected Well Path Lead Angle Surface Location for Well No. 2 Target at a TVD 9,659 Lake Figure 8-16: Plan View

  20. Example 1: Design of Directional Well Design a directional well with the following restrictions: 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

  21. Example 1: Design of Directional Well This is a Type I well (build and hold) (i) Determine the maximum hole angle (inclination) required. (ii) What is the total measured depth of the hole (MD)?

  22. Type I: Build-and-Hold 2500’ Imax TVD1 12,500’ 10,000’ HD1 Imax 4,500’

  23. 0’ Uniform 1’30” Increase in Drift per 100 ft of hole drilled 10,000’ Vert. Depth Try Imax = 27o ?? 4,500’ Horizontal Deviation

  24. Solution 2500’ Available depth = 12,500-2,500 = 10,000’ Imax Type I Well1.5 deg/100’ TVD1 10,000’ From Chart, Try = 27o Imax Imax HD1

  25. Build Section From chart of1.5 deg/100’, with Imax = 27o In the BUILD Section: Imax MD1 = 1,800’ (27/1.5) TVD1 = 1,734’ HD1 = 416’ Remaining vertical height = 10,000 - 1,734 = 8,266’ TVD1 8,266’ Imax HD1

  26. Solution Horizontally: 416 + 8,266 tan 27o = 4,628 We need 4,500’ only: Next try Imax = 25’ 30 min Imax 8,266’ MD2 = 1,700’ (25.5/1.5) TVD2 = 1,644’ HD2 = 372’

  27. Solution: Remaining vertical depth = 10,000-1644 = 8,356 ft.  Horizontal deviation = 372+8,356 tan 25.5 = 4,358 ft. { 4500 } Approx. maximum angle = 26 What is the size of target?

  28. MD = MDvert + MDbuild + MDhold

  29. Type II Pattern Given: KOP = 2,000 feet TVD = 10,000 feet Horiz. Depart. = 2,258 feet Build Rate = 20 per 100 feet Drop Rate = 10 30’ per 100 feet The first part of the calculation is the same as previously described.

  30. Procedure - Find: • a) The usable depth (8,000 feet) • b) Maximum angle at completion of buildup (180) • c) Measured depth and vertical depth at completion of build up (M.D.=900 ft. and TVD = 886) • d) Measured depth, horizontal departure and TVD for 1 /100 ft from chart.

  31. Solve: • For the distances corresponding to the sides of the triangle in the middle. • Add up the results. • If not close enough, try a different value for the maximum inclination angle, Imax

  32. Example 1: Design of Directional Well (i) Determine the maximum hole angle required. (ii) What is the total measured depth (MD)? (MD = well depth measured along the wellbore, not the vertical depth)

  33. (i) Maximum Inclination Angle

  34. (i) Maximum Inclination Angle

  35. (ii) Measured Depth of Well

  36. (ii) Measured Depth of Well

  37. We may plan a 2-D well, but we always get a 3D well (not all in one plane) Horizontal View N Vertical View

  38. MD,a1, e1 DMD b = dogleg angle Fig. 8-22. A curve representing a wellbore between survey stations A1 and A2 a2, e2

  39. Directional Drilling • 1. Drill the vertical (upper) section of the hole. • 2. Select the proper tools for kicking off to a non-vertical direction • 3. Build angle gradually

  40. Directional Tools • (i) Whipstock • (ii) Jet Bits • (iii) Downhole motor and bent sub

  41. Whipstocks Standard retreivable Circulating Permanent Casing

  42. Setting a Whipstock • Small bit used to start • Apply weight to: • set chisel point & • shear pin • Drill 12’-20’ • Remove whipstock • Enlarge hole

  43. Jetting Bit • Fast and economical • For soft formation • One large - two small nozzles • Orient large nozzle • Spud periodically • No rotation at first Small Jets

  44. Jetting • Wash out pocket • Return to normal drilling • Survey • Repeat for more angle if needed

  45. Mud Motors Drillpipe Non-magnetic Drill Collar Bent Sub Mud Motor Rotating Sub

  46. Increasing Inclination • Limber assembly • Near bit stabilizer • Weight on bit forces DC to bend to low side of hole. • Bit face kicks up

  47. Hold Inclination • Packed hole assembly • Stiff assembly • Control bit weight and RPM

  48. Decrease Inclination • Pendulum effect • Gravity pulls bit downward • No near bit stabilizer

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