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Petroleum Engineering 406 Lesson 18 Directional Drilling

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Title: Petroleum Engineering 406 Lesson 18 Directional Drilling


1
Petroleum Engineering 406Lesson 18
Directional Drilling
2
Lesson 10 - Directional Drilling
  • When is it used?
  • Type I Wells (build and hold)
  • Type II Wells (build, hold and drop)
  • Type III Wells (build)
  • Directional Well Planning Design
  • Survey Calculation Methods

3
Homework
  • READ. Applied Drilling Engineering Ch. 8, pp.
    351-363
  • REF. API Bulletin D20, Directional Drilling
    Survey Calculation Methods and Terminology

4
What is Directional Drilling?
  • Directional Drilling is the process of directing
    a wellbore along some trajectory to a
    predetermined target.
  • Basically it refers to drilling in a non-vertical
    direction. Even vertical hole sometimes require
    directional drilling techniques.

Examples Slanted holes, high angle holes (far
from vertical), and Horizontal holes.
5
Non-Vertical Wellbore
q, a or I
Inclination Angle
Inclination Plane Y
Z Axis (True Vertical Depth)
North
Direction Angle
f, e or A
Direction Plane X
6
Lease Boundary
Surface Location for Well No. 1
Surface Location for Well No. 2
Bottom Hole Location for Well 2
Houses
Oil-Water Contact
Figure 8.2 - Plan view of a typical oil and gas
structure under a lake showing how directional
wells could be used to develop it. Best
locations? Drill from lake?
7
Top View
NOTE All the wells are directional
5 - 50 wells per platform
Figure 8.3 - Typical offshore development
platform with directional wells.
8
Drilling Rig Inside Building
Figure 8.4 - Developing a field under a city
using directionally drilled wells.
9
Why not drill from top of mountain?
Maximum lateral displ.?
Fig. 8.5 - Drilling of directional wells where
the reservoir is beneath a major surface
obstruction.
10
Fish Lost in Hole and Unable to Recover
Cement Plug
Sidetracked Hole Around Fish
Figure 8.6 - Sidetracking around a fish.
11
Figure 8.7 - Using an old well to explore for new
oil by sidetracking out of the casing and
drilling directionally.
Oil Producing Well Ready to Abandon
Sidetracked Out of Casing
Possible New Oil
Old Oil Reservoir
12
Horizontal Departure to Target
Type II
Build-hold and Drop (S Type)
Build and Hold Type
Build-hold Drop and/or Hold (Modified S Type)
Type I
Continuous Build
Type III
Figure 8.8 - Major types of wellbore
trajectories.
13
Figure 8.10 - Geometry of the build section.
Build Section
Build Radius
14
  • Build Section

15
Start of Buildup
End of Build
Type II
Drop Off
Target
Build-hold-and drop for the case where
16
Kickoff
End of Build
Type II
Maximum Inclination Angle
Build-hold-and drop for the case where
Drop Off
Target
17
Projected Trajectory
Projected Trajectory with Left Turn to Hit Targets
Target 1
Target 2
Target 3
  • Fig. 8-14. Directional well used to intersect
    multiple targets

18
N18E
S23E A 157o
  • Fig. 8-15. Directional quadrants and
  • compass measurements

N55W A 305o
S20W
19
Projected Well Path
Lead Angle
Surface Location for Well No. 2
Target at a TVD 9,659
Lake
Figure 8-16 Plan View
20
Example 1 Design of Directional Well
  • Design a directional well with the following
    restrictions
  • Total horizontal departure 4,500 ft
  • True vertical depth (TVD) 12,500 ft
  • Depth to kickoff point (KOP) 2,500 ft
  • Rate of build of hole angle 1.5 deg/100 ft

21
Example 1 Design of Directional Well
  • This is a Type I well (build and hold)
  • (i) Determine the maximum hole angle
    (inclination) required.
  • (ii) What is the total measured depth of the
    hole (MD)?

22
Type I Build-and-Hold
2500
Imax
TVD1
12,500
10,000
HD1
Imax
4,500
23
0
Uniform 130 Increase in Drift per 100 ft of
hole drilled
10,000 Vert. Depth
Try Imax 27o ??
4,500 Horizontal Deviation
24
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25
Solution
  • Type I Well 1.5 deg/100

2500
Available depth 12,500-2,500 10,000
Imax
TVD1
10,000
From Chart, Try 27o
Imax
Imax
HD1
26
Build Section
From chart of 1.5 deg/100, with Imax 27o In
the BUILD Section
  • MD1 1,800 (27/1.5)
  • TVD1 1,734
  • HD1 416
  • Remaining vertical height
  • 10,000 - 1,734 8,266

Imax
TVD1
8,266
Imax
HD1
27
Solution
  • Horizontally
  • 416 8,266 tan 27o 4,628
  • We need 4,500 only
  • Next try Imax 25 30 min

Imax
8,266
MD2 1,700 (25.5/1.5) TVD2 1,644 HD2
372
28
Solution
  • Remaining vertical depth 10,000-1644
  • 8,356 ft.
  • ? Horizontal deviation 3728,356 tan 25.5
  • 4,358 ft. ?4500
  • Approx. maximum angle 26
  • What is the size of target?

29
MD MDvert MDbuild MDhold
30
Type II Pattern
  • Given KOP 2,000 feet
  • TVD 10,000 feet
  • Horiz. Depart. 2,258 feet
  • Build Rate 20 per 100 feet
  • Drop Rate 10 30 per 100 feet
  • The first part of the calculation is the same
    as previously described.

31
Procedure - Find
  • a) The usable depth (8,000 feet)
  • b) Maximum angle at completion of buildup
    (180)
  • c) Measured depth and vertical depth at
    completion of build up (M.D.900 ft. and TVD
    886)
  • d) Measured depth, horizontal departure and TVD
    for 1 /100 ft from chart.

32
Solve
  • For the distances corresponding to the sides of
    the triangle in the middle.
  • Add up the results.
  • If not close enough, try a different value for
    the maximum inclination angle, Imax

33
Example 1 Design of Directional Well
  • (i) Determine the maximum hole angle required.
  • (ii) What is the total measured depth (MD)?
  • (MD well depth measured along the wellbore,
  • not the vertical depth)

34
(i) Maximum Inclination Angle
35
(i) Maximum Inclination Angle
36
(ii) Measured Depth of Well
37
(ii) Measured Depth of Well
38
We may plan a 2-D well, but we always get a 3D
well (not all in one plane)
Horizontal
View
N
Vertical
View
39
MD, a1, e1
DMD
b dogleg angle
a2, e2
  • Fig. 8-22. A curve representing a wellbore
    between survey stations A1 and A2

40
Directional Drilling
  • 1. Drill the vertical (upper) section of the
    hole.
  • 2. Select the proper tools for kicking off to a
    non-vertical direction
  • 3. Build angle gradually

41
Directional Tools
  • (i) Whipstock
  • (ii) Jet Bits
  • (iii) Downhole motor and bent sub

42
Whipstocks
Standard retreivable Circulating Permanent
Casing
43
Setting a Whipstock
  • Small bit used to start
  • Apply weight to
  • set chisel point
  • shear pin
  • Drill 12-20
  • Remove whipstock
  • Enlarge hole

44
Jetting Bit
  • Fast and economical
  • For soft formation
  • One large - two small nozzles
  • Orient large nozzle
  • Spud periodically
  • No rotation at first

Small Jets
45
Jetting
  • Wash out pocket
  • Return to normal drilling
  • Survey
  • Repeat for more angle if needed

46
Mud Motors
Drillpipe
Non-magnetic Drill Collar
Bent Sub
Mud Motor
Rotating Sub
47
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48
Increasing Inclination
  • Limber assembly
  • Near bit stabilizer
  • Weight on bit forces DC to bend to low side of
    hole.
  • Bit face kicks up

49
Hold Inclination
  • Packed hole assembly
  • Stiff assembly
  • Control bit weight and RPM

50
Decrease Inclination
  • Pendulum effect
  • Gravity pulls bit downward
  • No near bit stabilizer

51
Packed Hole Assemblies
Drillpipe
String Stabilizer
String Stabilizer
String Stabilizer
NB Stab
MonelDC
Steel DC
Steel DC
HW DP
52
Vertical Calculation
Horizontal Calculation
53
3D View
Dog Leg Angle
54
Deflecting Wellbore Trajectory
0
270
90
180
55
Bottom Hole Location
56
Survey Calculation Methods
  • 1. Tangential Method
  • Backward Station Method
  • Terminal Angle Method
  • Assumption Hole will maintain constant
    inclination and azimuth angles between survey
    points

57
A
IA
IB
B
Poor accuracy!!
IB
58
Average Angle Method Angle Averaging Method
  • Assumption Borehole is parallel to the simple
    average drift and bearing angles between any two
    stations.
  • Known Location of A, Distance AB,
  • Angles

59
A
  • (i) Simple enough for field use
  • (ii) Much more accurate than
  • Tangential Method

IA
IB
IAVG
B
IAVG
60
A
  • Average Angle Method
  • Vertical Plane

IA
IB
IAVG
B
IAVG
61
  • Average Angle Method
  • Horizontal Plane

N
AB
B
AAVG
DN
AA
DE
E
A
62
  • Change in position towards the east
  • Change in position towards the north

Change in depth
Where L is the measured distance between the two
stations A B.
63
Example
  • The coordinates of a point in a wellbore are
  • x 1000 ft (easting)
  • y 2000 ft (northing)
  • z 3000 ft (depth)
  • At this point (station) a wellbore survey shows
    that the inclination is 15 degrees from vertical,
    and the direction is 45 degrees east of north.
    The measured distance between this station and
    the next is 300 ft.

64
Example
  • The coordinates of point 1 are
  • x1 1000 ft (easting)
  • y1 2000 ft (northing) I1 15o
  • z1 3000 ft (depth) A1 45o
  • L12 300 ft
  • At point 2, I2 25o and A2 65o
  • Find x2 , y2 and z2

65
Solution
  • H12 L12 sin Iavg 300 sin 20 103 ft
  • DE H12 sin Aavg 103 sin 55 84 ft
  • DN H12 cos Aavg 103 cos 55 59 ft
  • DZ L12 cos Iavg 300 cos 20 282 ft

66
Solution - contd
  • DE 84 ft
  • DN 59 ft
  • DZ 282 ft
  • x2 x1 DE 1,000 84 ft 1,084 ft
  • y2 y1 DN 2,000 59 ft 2,059 ft
  • z2 z1 DZ 3,000 282 ft 3,282 ft
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