Petroleum Engineering 406

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
Homework

• READ Applied Drilling Engineering,
• Ch. 8 (to page 390)

4
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 - contd

• 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
Nozzle Orientation
g -122o
Orient S90E Final 1799 S30E 2.75o
11
g -80o
Jetted 12 1850-62 Surv 1814 S20E 3.0o
Orient N80E Final 1877 S36E 3.25o
12
g -74o
Jetted 6 1925-31 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 - contd

• 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 - contd

• 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 - contd

• 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
B. 0-70o Angle-Compass Unit
A. 0-20o 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
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
Pendulum
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
Compass
Inclination Scale
Fig. 8.44 Cardan suspended compass and
inclinometer for a single-shot 5o to
90o unit.
26
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
Free Falling to Bottom
Tool seated
Ready to be Dropped
Retrieve single shot
Fig. 8.46 Typical single-shot operation.
28
Timer On
3 min.
Single Shot Ready to be Dropped
Compass Unit
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
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
Fishing Neck
Top View
Non Magnetic Collar
Single Shot
Direction of Tool Face Via Bent Sub
Mule Shoe Orienting Sub
Orienting Sleeve Lined up with Bent Sub
Bent Sub
Mud Motor
Mule Shoe Key Position
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
Non-Magnetic Drill Collar(s)
Fig. 8.48 Typical arrangement for landing a
multi-shot instrument.
Compass Position
Multi-shot Instrument
Landing Plate
33
Fig. 8.49 Drop multi-shot survey instrument
Bottom Landing
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
Geneva Drive Wheel Assembly
Knife Switch Terminal
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 - contd

• 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 - contd

• 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 - contd

• 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
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