Petroleum Engineering 406

1. Petroleum Engineering 406 Lesson 21 Wellbore Trajectory Control

3. Homework READ: �Applied Drilling Engineering�, Ch. 8 (to page 390)

5. Problem 1 Determine the effective bent sub response for a 1 1/2o bent sub in a motor run where at 6,357�, a = 1o and e is S85E and at 6,382, aN = 1o and eN is S20E; the tool face is 160o right of high side.

6. Solution to Problem 1 Calculate b from Eq. 8.53: Dogleg severity:

7. Solution to Problem 1 - cont�d If the mud motor length is 25 ft from the bit face to the bent sub, the maximum angle change that could be reached if there are no restrictions is: The lower rate of build implies that the formation resisted the maximum rate of build by a factor of:

8. b = Bent Sub Angle? Since the value of b for any given run may differ from the bent sub angle, it should not surprise us if De predicted = De measured Let us look at some examples.

13. Directional Drilling Measurements The trajectory of a wellbore is determined by the measurement of: inclination q, a, I direction f, e, A measured depth DMD, DL, L

14. Directional Drilling Measurements - cont�d A tool-face measurement is required to orient: a whipstock the large nozzle on a jetting bit a bent sub or bent housing

15. Directional Drilling Measurements - cont�d Tools available single-shot magnetic or gyroscopic multi-shot magnetic or gyroscopic magnetometers, accelerometers, MWD tools

16. Magnetic Single-Shot Instrument Records inclination direction tool face position on sensitized paper or photographic film Inclination may be determined by a float on a liquid a pendulum

17. Magnetic Single-Shot Instrument Unit may be triggered by: clock timer. inertial timer (after stop). Unit may be dropped (pumped down) and later retrieved by wireline or the drillpipe.

18. Magnetic Single-Shot Instrument Single-shot instruments are used: to monitor progress of directional-control well. to monitor progress of deviation-control well. to help orient tool face for trajectory change.

19. Magnetic Single-Shot Instrument - cont�d Procedure: load film into instrument activate timer (activate stopwatch) make up the tool drop the tool retrieve tool (wireline or drillpipe)

31. Magnetic Multishot Instruments Are capable of taking numerous survey records in one run. May be dropped down the drillpipe or run on wireline in open hole. The unit contains a watch that is spring wound and uses the power of the spring to operate a timer cam.

35. Magnetic Multishot - cont�d The multishot tool is usually dropped down the drillpipe and landed in the nonmagnetic drill collar. During the trip out, a survey is taken every 90 ft, i.e. every stand.

36. Magnetic Multishot - cont�d More closely spaced stations could be obtained by stopping the pipe more often, and waiting for a picture. A stopwatch at the surface is synchronized with the instrument watch.

38. A. 10 seconds - Lights are on, exposing film B. 15 seconds - Delay before moving. This is an allowance for instrument watch lag during survey.

39. C. 20 seconds - Instrument is idle allowing movement of drill string without affecting picture. Most moves require sufficient time for taking one or more shots while moving D. 15 seconds - Minimum time for plumb bob and compass to settle for good picture, plus allowance for instrument gain during survey.

41. Steering Tools Used with mud motors and bent sub Can either pull every stand or use a side entry sub for continuous drilling

42. MWD Tools

43. MWD Tools

44. Gyroscopic Tools Non-magnetic drill collars used to prevent magnetic interference from drillstring Gyros used if magnetic interference is from non drillstring source