Petroleum Engineering 406

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Nov 8, 2013 (3 years and 9 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

READ:

“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:


load film into instrument


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

Ready to
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
Ready to be
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