Petroleum Engineering 406 Lesson 18 Directional Drilling

1. Petroleum Engineering 406Lesson 18 Directional Drilling

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.

14. Build Section:

17. Fig. 8-14. Directional well used to intersect multiple targets

18. Fig. 8-15. Directional quadrants and compass measurements

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)?

25. Solution Type I Well 1.5 deg/100�

26. Build Section MD1 = 1,800� (27/1.5) TVD1 = 1,734� HD1 = 416� Remaining vertical height = 10,000 - 1,734 = 8,266�

27. Solution Horizontally: 416 + 8,266 tan 27o = 4,628 We need 4,500� only: Next try Imax = 25� 30 min

28. 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?

29. MD = MDvert + MDbuild + MDhold

30. 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.

31. 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.

32. 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

33. 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)

34. (i) Maximum Inclination Angle

35. (i) Maximum Inclination Angle

36. (ii) Measured Depth of Well

37. (ii) Measured Depth of Well

38. We may plan a 2-D well, but we always get a 3D well (not all in one plane)

39. Fig. 8-22. A curve representing a wellbore between survey stations A1 and A2

40. 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

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

42. Whipstocks

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

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

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

46. Mud Motors

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

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

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

51. Packed Hole Assemblies

54. Deflecting Wellbore Trajectory

55. Bottom Hole Location

56. Survey Calculation Methods 1. Tangential Method = Backward Station Method = Terminal Angle Method Assumption: Hole will maintain constant inclination and azimuth angles between survey points

58. Average Angle Method = Angle Averaging Method Assumption: Borehole is parallel to the simple average drift and bearing angles between any two stations. Known: Location of A, Distance AB, Angles

59. (i) Simple enough for field use (ii) Much more accurate than �Tangential� Method

60. Average Angle Method Vertical Plane:

61. Average Angle Method Horizontal Plane:

62. Change in position towards the east: Change in position towards the north:

63. Example The coordinates of a point in a wellbore are: x = 1000 ft (easting) y = 2000 ft (northing) z = 3000 ft (depth) At this point (station) a wellbore survey shows that the inclination is 15 degrees from vertical, and the direction is 45 degrees east of north. The measured distance between this station and the next is 300 ft�.

64. Example The coordinates of point 1 are: x1 = 1000 ft (easting) y1 = 2000 ft (northing) I1 = 15o z1 = 3000 ft (depth) A1 = 45o L12 = 300 ft At point 2, I2 = 25o and A2 = 65o Find x2 , y2 and z2

65. Solution H12 = L12 sin Iavg = 300 sin 20 = 103 ft DE = H12 sin Aavg = 103 sin 55 = 84 ft DN = H12 cos Aavg = 103 cos 55 = 59 ft DZ = L12 cos Iavg = 300 cos 20 = 282 ft

66. Solution - cont�d DE = 84 ft DN = 59 ft DZ = 282 ft x2 = x1 + DE = 1,000 + 84 ft = 1,084 ft y2 = y1 + DN = 2,000 + 59 ft = 2,059 ft z2 = z1 + DZ = 3,000 + 282 ft = 3,282 ft