406 Lesson 21

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Petroleum Engineering 406

Lesson 21

Wellbore Trajectory Control

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Lesson 18 - Wellbore Trajectory Control

Bent Motor and Bent Sub

Examples

Directional Drilling Measurements

Single Shot and Multishot

Magnetic and GyroSteering Tools

MWD tools

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Homework

READ: ³Applied Drilling Engineering´,

Ch. 8 (to page 390)

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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

F is not necessarily equal to the bent sub angle, but it may be close in (a) above

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Problem 1

Determine the effective bent sub

response for a 1 1/2o bent sub in a

motor run where at 6,357¶, E = 1o and

I is S85E and at 6,382, E2 = 1o and I2is S20E; the tool face is 160o right of

high side.

Q95!I

Q160!

N I

Q65!(I

ft25L !

Q160

!KQ1!E

Q1! N

E

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Solution to Problem 1

Calculate F from Eq. 8.53:

Dogleg severity:

? AEEEE( F coscossinsincoscos

NN

1

? AQQQQQ 1cos1cos1sin1sin65coscos 1 !

Q07.1999824.0cos

1 !!

ft10028.4

25

10007.1

L

i o!! F!H

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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 theformation resisted the maximum rate of

build by a factor of:

ft255 o

!!H

72.00.6

3.4!

Q

Q

An efficiency factor?

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F=

Bent Sub Angle?

Since the value of F for any given run

may differ from the bent sub angle, itshould not surprise us if

(I predicted = (I measured

Let us look at some examples.

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Q

77th

!I(

Q62

ac!I(

Q30

ac!I

Q14

th!I(

Q16

ac!I(

Q33

th!I(

Fig. 8.40: Example of three jetting stops while trying to

kick off and set the wellbore lead.

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Jetted 7¶ 1745-52¶

Surv 1722¶: S32W 2.25o

Orient S90E

Final 1799¶:

S30E 2.75o

K = -122o

Nozzle Orientation

Q

t !I(Q

62ac

!I(

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Jetted 12¶ 1850-62¶

Surv 1814¶ S20E 3.0o

Orient N80E

Final 1877¶ S36E 3.25o

K=

-80

o

Q14

th!I(

Q16

ac!I(

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Jetted 6¶ 1925-31¶

Surv 1877¶ S36E 3.25o

Orient N70E

Final 1940¶ S66E 4.75o

K = -74o

Q30

ac!I(

Q33

th!I(

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Directional Drilling

Measurements

The trajectory of a wellbore is determined

by the measurement of:

inclination UE I

direction JI A

measured depth (MD, (L, L

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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

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Measurements - cont¶d

Tools availablesingle-shot magnetic or gyroscopic

multi-shot magnetic or gyroscopic

magnetometers, accelerometers,MWD tools

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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

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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.

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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)

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Fig. 8.43:

Pendulumsuspended

inclinometer

and

compassunit for a 0 to

17oo singe-

shot unit.

1. Pendulum

2. Circular Glass

3. Compass

4. Pressure equalization

5. Cover glass

Indicated inclination 5o.

Direction of inclination

N 45 degrees 0¶ or

azimuth 45 degrees.

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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

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Fig. 8.12:

Pendulumassembly: a) plumb-

bob angle unit b) drift

arc inclinometer

Pendulum

Glass ring

Piston

(a) (b)

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Fig. 8.13:

Schematicdrawing of

magnetic

single and

multi-shotinstruments.

Hole direction with

reference to Magnetic North

N35oWI = 5.5

o

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Fig. 8.44:

Cardan suspendedcompass and

inclinometer for a

single-shot

5o

to 90o

unit.

Compass

Inclination Scale

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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.

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Fig. 8.46: Typical single-shot operation.

Free Falling

to BottomTool

seated

Ready to

be Dropped

Retrieve

single shot

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Fig. 8.46:Typical

single-shot

operation.

CompassU

nit

3 min.

Single ShotFree 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

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Fig. 8.46:

Typical

single-shotoperation.

3

min.

Overshot

Used to

Fish

SingleShot

Tool seatedin orienting

sleeve or at

stop taking

picture

Wireline

unit toretrieve

single

shot

10 min.

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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

CenterlineNew 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

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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.

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Fig. 8.48:

Typical

arrangement

for landing a

multi-shot

instrument.

Non-Magnetic Drill Collar(s)

Compass Position

Multi-shot Instrument

Landing Plate

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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 SpoolTakeup Film

Spool

F

ilm Sprocket

Motor

Lever

Switch

Geneva Drive

Wheel Assembly

Knife

Switch

Terminal

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Magnetic Multishot - cont¶d

The multishot tool is usually dropped down

the drillpipe and landed in the nonmagneticdrill collar.

During the trip out, a survey is taken every

90 ft, i.e. every stand.

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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 synchronizedwith the instrument watch.

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Synchronize with instrument watch by

starting at the instant camera lights go on.

Fig. 8.51:

Use of thesurface

watch while

running a

magneticmulti-shot

operation.

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A. 10 seconds -

Lights are on, exposing film

B. 15 seconds - Delay before moving.

This is an allowance for instrumentwatch lag during survey.

Time Intervals:

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C. 20 seconds - Instrument is

idle allowing movement of drill string

without affecting picture. Most movesrequire 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

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Fig. 8.52b:

Projection of

one survey

frame for

determining

inclination and

direction.

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Steering Tools

Used with mud

motors and bent subCan 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

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MWD Tools

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MWD Tools

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Gyroscopic ToolsNon-magnetic drill

collars used to prevent

magnetic interferencefrom drillstring

Gyros used if magnetic

interference is from

non drillstring source

Documents

406 Lesson 21