1. Petroleum Engineering 406
Lesson 21
Wellbore Trajectory Control

2. Lesson 18 - Wellbore Trajectory Control
Bent Motor and Bent Sub
Examples
Directional Drilling Measurements
Single Shot and Multishot
Magnetic and Gyro
Steering Tools
MWD tools

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

4. Fig. 8.39: Bent sub unconstrained and constrained in a wellbore.
Nonmagnetic
Drill Collar
Orienting Sub
Hole
Bent Sub
Mud Motor
Bent Sub Angle
Bit
Fig. 8.39: Bent sub unconstrained and constrained in a wellbore.
b is not necessarily equal to the bent sub angle, but it may be close in (a) above

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:
An efficiency factor?

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.

9. Fig. 8.40: Example of three jetting stops while trying to kick off and set the wellbore lead.

10. Jetted 7’ 1745-52’ Surv 1722’: S32W 2.25o g = -122o Orient S90E
Nozzle Orientation
g = -122o
Orient S90E
Final 1799’:
S30E o

11. g = -80o
Jetted 12’ ’
Surv 1814’ S20E 3.0o
Orient N80E
Final 1877’ S36E 3.25o

12. g = -74o
Jetted 6’ ’
Surv 1877’ S36E 3.25o
Orient N70E
Final 1940’ S66E 4.75o

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)

20. Light
Housing
Center Post
Float
Fluid
Reference Mark
Main Frame
Photographic Disc
A. 0-20o
Angle-Compass Unit
B. 0-70o
Angle-Compass Unit
Fig. 8.41: Schematic diagrams of magnetic single-shot angle-compass unit (courtesy Kuster Co.).

21. 1. Pendulum
2. Circular Glass
3. Compass
4. Pressure equalization
5. Cover glass
Fig. 8.43: Pendulum suspended inclinometer and compass unit for a 0 to 17oo singe-shot unit.
Indicated inclination 5o. Direction of inclination N 45 degrees 0’ or azimuth 45 degrees.

22. Fig. 8.42: Single-shot film disks (courtesy of Kuster Co.).
A/C Units
Plumb-Bob Units
Incl. Only Units
Fig. 8.42: Single-shot film disks (courtesy of Kuster Co.).
Inclination
Direction
Tool Face Angle

23. Fig. 8.12: Pendulum assembly: a) plumb- bob angle unit b) drift arc inclinometer
Glass ring
Piston
(a)
(b)

24. Hole direction with reference to Magnetic North
Fig. 8.13: Schematic drawing of magnetic single and multi-shot instruments.
N35oW I = 5.5o

25. Fig. 8.44: Cardan suspended compass and inclinometer for a single-shot
Inclination Scale
Fig. 8.44: Cardan suspended compass and inclinometer for a single-shot
5o to 90o unit.

26. Fig. 8.45: Typical magnetic single-shot tool with landing sub.
Wire Line Socket
Rope Socket
Overshot
Swivel
Stabilizer
Stabilizer Fingers
Fig. 8.45: Typical magnetic single-shot tool with landing sub.
Protective Case
Orienting Anchor & Plug
Mule Shoe Mandrel
Bottom Hole Orienting Sub
Bottom Landing Assembly
Takes time. Rig time is costly. Temperature limitation. May have to pump down.

27. Fig. 8.46: Typical single-shot operation.
Free Falling to Bottom
Ready to be Dropped
Tool seated
Retrieve single shot
Fig. 8.46: Typical single-shot operation.

28. Fig. 8.46: Typical single-shot operation.
Timer On
3 min.
Compass Unit
Single Shot Ready to be Dropped
*Single Shot Instruments are run on slickline if there is a mule shoe sub in the hole
Single Shot Free Falling in Mud to Bottom
Fig. 8.46: Typical single-shot operation.
Non Magnetic Drill Collar
Orienting Sub Sleeve

29. Fig. 8.46: Typical single-shot operation.
3 min.
Fig. 8.46: Typical single-shot operation.
Wireline unit to retrieve single shot
10 min.
Overshot Used to Fish Single Shot
Tool seated in orienting sleeve or at stop taking picture

30. Fig. 8.47: Arrangement of the mule shoe for orienting a mud motor.
Fishing Neck
Top View
Non Magnetic Collar
Direction of Tool Face Via Bent Sub
Single Shot
Mule Shoe Orienting Sub
Orienting Sleeve Lined up with Bent Sub
Bent Sub
Mule Shoe Key Position
Mud Motor
Fig. 8.47: Arrangement of the mule shoe for orienting a mud motor.
Existing Centerline
New Centerline

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.

32. Fig. 8.48: Typical arrangement for landing a multi-shot instrument.
Non-Magnetic Drill Collar(s)
Compass Position
Fig. 8.48: Typical arrangement for landing a multi-shot instrument.
Multi-shot Instrument
Landing Plate

33. Fig. 8.49: Drop multi-shot survey instrument
Bottom Landing
Fig. 8.49: Drop multi-shot survey instrument
Rope Socket
Stabilizer with Rubber Pins
Battery Case
Battery Connector
Connector Shock Absorber
Protective Instrument Barrel
Watch Assembly
Angle Unit
Barrel Lower Ball Plug
Aluminum Spacer Bar
Bottom Shock Absorber Assembly

34. Light Switch Lever
Geneva Gear
Watch Section
Motor
Knife Switch Terminal
Geneva Drive Wheel Assembly
Winding Stem
Motor Lever Switch
Watch Switch
Film Sprocket
Supply Film Spool
Takeup Film Spool
Time Cycle Cam
Fig. 8.50: Views of the watch and camera unit of a typical multi-shot tool.

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.

37. Fig. 8.51: Use of the surface watch while running a magnetic multi-shot operation.
Synchronize with instrument watch by starting at the instant camera lights go on.

38. Time Intervals: 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. Time Intervals - cont’d
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.

40. Fig. 8.52b: Projection of one survey frame for determining inclination and direction.

41. Steering Tools Used with mud motors and bent sub
Standard Measuring Cable
Used with mud motors and bent sub
Can either pull every stand or use a side entry sub for continuous drilling
Monel DC
Probe
Mule Shoe
Bent Sub
Mud Motor

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