CHAPTER # 8

forestsaintregisOil and Offshore

Nov 8, 2013 (4 years and 5 days ago)

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1

CHAPTER # 8

Directional Drilling and
Deviation Control

DRILLING ENGINEERING

2

Definition

Directional Drilling:



The process of directing the wellbore along some
trajectory to a predetermined target.


Deviation Control:



The process of keeping the wellbore contained within
some prescribed limits, relative to inclination angle,
horizontal excursion from the vertical or both.


X
-
Y Plane


X


Plane = direction plane


Y


Plane = inclination plane

3

Angles



X
-
Y = Plane X


angle = direction angle


Y
-
Z = Plane Y


angle = inclination angle


Purpose of Directional Drilling



Res. Under lake (economics, environmental reasons)


Offshore drilling.


Res. beneath population centers.


Res. beneath natural obstruction (mountains) Or
severe topographical features.


Sidetracking out of an existing wellbore to bypass an
obstruction (fish) or explore additional producing
horizons in adjacent sectors.


Relief well to plug a blow out.


4

Inclination and direction planes as a wellbore proceeds in
the depth plane.

5

Plan view of a typical oil and gas structure under a lake

6

Typical offshore development platform with directional
wells

7

Developing a field under a city using directionally drilled
wells

8

Drilling of directional wells where the reservoir is
beneath a major surface obstruction

9

Sidetracking around a fish

10

Using an old well to explore for new oil by sidetracking
out of the casing and drilling occasionally

11

7.1

Planning The Directional Well
Trajectory

Trajectory



Well path that will intersect given target
.



First design propose the various types of paths that
can be drilled economically.



Second includes effects of geology on the bottomhole
assemblies (BHA) and other factors that could
influence the final wellbore trajectory.


12

Types of Trajectories


Build and hold trajectory penetrates target at max.
build
-
up angle.



Build
-
hole and drop (s
-
shape) penetrate angle vertically



Build
-
hold drop and/or hold (modified s
-
shape)
penetrates target at angle less than max. inclination
angle in the hold section.



Continuous build trajectory inclination angle is
increasing.




q
1
<
q
3
<
q
2
<
q
4

13


X
3

= horizontal departure


g
1

= radius of curvature


D
3

= TVD true vertical depth


D
1

= kick off point TVD


q = rate of inclination angle build up



14

Geometry of build
-
and
-
hold type well

15

7.2

Build and Hold Trajectory



Circumference =
2p
r


S=r
q


q i
n radians max. inclination angle


1 radian = 180

o
/
p

㴠㔷⸲㤵㜸

o


1
o

=
p
⼱㠰⁲慤楡湳


q = degrees per unit length =
q


†

†
㴠楮捬楮慴楯渠慮杬攠扵楬搠異b牡re



q = 1
o
/100ft





r = S /
q


r = radius of curvature


16



S =
g q


q
length
rees
S



deg
1
q
g









rees
length
q
deg
1
g















p
g
180
deg
1
rees
length
q










p
g
p
g
1
1
180
1
180
q
or
q
(8.1)

17


q
=
W
-

T



To find angle T look at triangle OBA


1
3
3
1
tan
D
D
X
AO
BA
T
-
-


g
1
3
3
1
arctan
D
D
X
T
-
-

g
To find angle
W
捯湳摥d瑲t慮杬攠佂O


BO
CO
Sin

W
(8.2)

(8.3a)

(8.3b)

(8.4)

18



CO =
g
1


2
2
)
(
)
(
BA
OA
BO


2
3
1
2
1
3
)
(
)
(
X
D
D
BO
-

-

g
2
1
3
2
3
1
1
)
(
)
(
D
D
X
Sin
-

-

W
g
g








-

-

W
2
1
3
2
3
1
1
)
(
)
(
arcsin
D
D
X
g
g
q
=
W
-

T


(8.5)

19









-
-
-








-

-

1
3
3
1
2
1
3
2
3
1
1
arctan
)
(
)
(
arcsin
D
D
X
D
D
X
g
g
g
q
Length of the arc section DC (buildup section)


(8.6)

180
1
p
q
r
DC

q
DC
q
r
q
p


1
180
1
(8.7)

20

Length of CB (Trajectory Path)


Straight at constant inclination angle can be
determined from BCO

W



W
tan
tan
1
1
r
CB
CB
r
CB
CO
Total measured depth D
M
for TVD of D
3

is

W



tan
1
1
r
q
D
D
m
q
(8.8)

21

Horizontal departure at end of build up

)
cos
1
(
cos
1
1
1
2
2
q
q
-

-




r
r
r
X
OC
D
consider
EC
X
(8.9)

True Vertical depth at end of build up section

q
sin
1
1
2
r
D
D
-

(8.12)

22

Geometry for the build section

23

Measure depth and Horizontal departure before reaching
maximum angle along any part of build up.

Consider
q

楮i敲e敤楡e攠楮捬楮慴楯渠慮杬攠
q


X
N
=Horizontal Departure at C

D
N
=Vertical depth

Consider

䑏D


)
cos
1
(
cos
sin
1
1
1
1
1
1
q
q
q
-

-

-

r
X
r
r
X
r
D
D
N
N
N
(8.11)

(8.10)

24

New measured depth for any part of the build up

q
D
D
MN
q




1
New measured depth at TVD of (D
*
< D
3
)(D
2
<D
*
< D
3
)









-
-




q
q
q
cos
sin
1
1
1
r
D
D
q
D
D
MP

(8.13)

(8.16)

Horizontal Departure X
*

(X
2
<X
*
< X
3
)

q
q
q
tan
)
sin
(
)
cos
1
(
1
1
r
D
D
r
X
-
-

-



(8.18)

25

For r
1

< X
3









-
-

-
-
-
-
-

)
(
sin
)
(
)
(
180
1
3
1
3
1
3
1
1
3
1
3
r
X
D
D
arcTan
D
D
r
arcCos
r
X
D
D
arcTan
q
(8.20)

26

Build
-
hold
-
and
-
drop and hold (modified
-
S)

27

Directional quadrants and compass measurements

28

Vertical calculation

29

Horizontal calculation

30

Three
-
dimensional view of a wellbore showing components that
comprise the X, Y and Z parts of the trajectory

31

Techniques for making a positive direction change

32

7.3

Directional Drilling Tools


Stabilizing Tools


The Stiff Hook
-
Up


The Pendulum Hook
-
Up


Angle Building Hook
-
Ups


The Lock
-
in Hook
-
Ups


Angle Losing Hook
-
Ups

33

Directional drilling applications

34

Stabilizing tool

35

The use of stabilizers in directional drilling

36

Other Application of Stabilizing Tools


Key seat Guide


Avoidance of Pressure Differential Sticking


Whip stock


Knuckle Joint

37

Whip stocks

38

Knuckle joint

39

40

Using a section mill to prepare for a kick
-
off

41

Jetting bit

42

Jetting a trajectory change

43

Fig 8.95: A typical positive
-
displacement mud motor
(PDM)