# Petroleum Engineering 406

Oil and Offshore

Nov 8, 2013 (4 years and 6 months ago)

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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

Homework

“Applied Drilling Engineering”,

Ch. 8 (to page 390)

Fig. 8.39: Bent sub unconstrained

and constrained in a wellbore.

Nonmagnetic

Drill Collar

Hole

Orienting Sub

Bent Sub

Mud Motor

Bent Sub
Angle

Bit

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 1/2
o

bent sub in a
motor run where at 6,357’,
a

= 1
o

and
e

is S85E and at 6,382,
a
N

= 1
o

and
e
N

is S20E; the tool face is
160
o

right of
high side.

95

e

160

N
e

65

e
ft
25
L

160

1

a

1

N
a
Solution to Problem 1

Calculate
b

from Eq. 8.53:

Dogleg severity:

a
a

a
a
e

b

cos
cos
sin
sin
cos
cos
N
N
1

1
cos
1
cos
1
sin
1
sin
65
cos
cos
1

07
.
1
999824
.
0
cos
1

ft
100
28
.
4
25
100
07
.
1
L
i
o

b

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:

ft
100
0
.
6
25
100
5
.
1
o

72
.
0
0
.
6
3
.
4

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

e

predicted

=
e

measured

Let us look at some examples.

77
th

e

62
ac

e

30
ac

e

14
th

e

16
ac

e

33
th

e

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 2.25
o

Orient S90E

Final 1799’:

S30E

2.75
o

-
ㄲN
o

Nozzle Orientation

77
th

e

62
ac

e

Jetted 12’ 1850
-
62’

Surv 1814’ S20E 3.0
o

Orient N80E

Final 1877’ S36E 3.25
o

=
-
80
o

14
th

e

16
ac

e

Jetted 6’ 1925
-
31’

Surv 1877’ S36E 3.25
o

Orient N70E

Final 1940’ S66E 4.75
o

=
-
74
o

30
ac

e

33
th

e

Directional Drilling

Measurements

The trajectory

of a wellbore is determined
by the measurement of:

inclination
q, a,

I

direction
f, e,

A

measured depth

MD,

L, 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:

activate timer (activate stopwatch)

make up the tool

drop the tool

retrieve tool (wireline or drillpipe)

Fig. 8.41: Schematic diagrams of magnetic single
-
shot

angle
-
compass unit (courtesy Kuster Co.).

Light

Housing

Center Post

Float

Fluid

Reference Mark

Main Frame

Photographic
Disc

A. 0
-
20
o

Angle
-
Compass Unit

B. 0
-
70
o

Angle
-
Compass Unit

Fig. 8.43:
Pendulum
suspended
inclinometer
and
compass
unit for a 0 to
17
o
o

singe
-
shot unit.

1. Pendulum

2. Circular Glass

3. Compass

4. Pressure equalization

5. Cover glass

Indicated inclination 5
o
.
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

Inclination

Direction

Tool Face Angle

Fig. 8.12:

Pendulum
assembly: a) plumb
-
bob angle unit b) drift
arc inclinometer

Pendulum

Glass ring

Piston

(a)

(b)

Fig. 8.13:
Schematic
drawing of
magnetic
single and
multi
-
shot
instruments.

Hole direction with
reference to Magnetic North

N35
o
W
I = 5.5
o

Fig. 8.44:
Cardan suspended
compass and
inclinometer for a
single
-
shot

5
o

to 90
o

unit.

Compass

Inclination Scale

Fig. 8.45:
Typical
magnetic
single
-
shot

tool with
landing sub.

Rope Socket

Swivel

Stabilizer

Stabilizer Fingers

Wire Line Socket

Overshot

Bottom Landing Assembly

Protective Case

Mule Shoe

Mandrel

Bottom Hole
Orienting Sub

Orienting
Anchor & Plug

Takes time. Rig time is costly. Temperature limitation. May have to pump down.

Fig. 8.46: Typical single
-
shot operation.

Free Falling
to Bottom

Tool
seated

be Dropped

Retrieve
single shot

Fig. 8.46:
Typical
single
-
shot
operation.

Compass Unit

3 min.

Single Shot
Free Falling in
Mud to Bottom

Non
Magnetic
Drill Collar

Orienting Sub
Sleeve

*Single Shot
Instruments are
run on slickline if
there is a mule
shoe sub in the
hole

Single Shot
Dropped

Timer On

Fig. 8.46:
Typical
single
-
shot
operation.

3
min.

Overshot
Used to
Fish
Single
Shot

Tool seated
in orienting
sleeve or at
stop taking
picture

Wireline
unit to
retrieve
single
shot

10 min.

Fig. 8.47:
Arrangement of the
mule shoe for
orienting a mud motor.

Fishing Neck

Non Magnetic Collar

Single Shot

Mud
Motor

Top View

Existing
Centerline

New Centerline

Bent Sub

Mule Shoe
Key Position

Mule Shoe Orienting Sub

Orienting Sleeve Lined up with Bent Sub

Direction of
Tool Face Via
Bent Sub

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

Multi
-
shot Instrument

Landing Plate

Fig. 8.49:
Drop
multi
-
shot
survey
instrument

Angle Unit

Rope Socket

Bottom Landing

Battery Case

Battery
Connector

Bottom Shock Absorber

Assembly

Stabilizer with Rubber Pins

Connector
Shock
Absorber

Barrel Lower Ball Plug

Aluminum Spacer Bar

Protective Instrument Barrel

Watch
Assembly

Fig. 8.50: Views of the watch and camera

unit of a

typical multi
-
shot tool.

Watch Section

Motor

Light
Switch
Lever

Geneva
Gear

Winding

Stem

Time Cycle Cam

Watch Switch

Supply
Film Spool

Takeup Film

Spool

Film Sprocket

Motor
Lever
Switch

Geneva Drive
Wheel Assembly

Knife
Switch

Terminal

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.

Synchronize with instrument watch by
starting at the instant camera lights go on.

Fig. 8.51:
Use of the
surface
watch while
running a
magnetic
multi
-
shot
operation.

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:

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
.

Time Intervals
-

cont’d

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

Steering Tools

Used with mud
motors and bent sub

Can either pull every
stand or use a side
entry sub for
continuous drilling

Mud Motor

Bent Sub

Mule Shoe

Monel DC

Probe

Standard
Measuring
Cable

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