# Petroleum Engineering 406

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Petroleum Engineering 406
Lesson 21 Wellbore Trajectory Control

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

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

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

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.

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

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?

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.

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

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

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

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

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

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

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

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

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.

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.

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)

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.).

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.

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

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

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

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.

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.

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.

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

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

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

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.

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

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

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.

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.

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.

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.

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.

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.

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

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

MWD Tools

MWD Tools

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