Section 4 - Directional Drilling for drilling

Section 4 - Directional Drilling.ppt

1. Introduction to Directional Drilling
What is it?
Why do it?
How is it done?
What you need to know?

2. What is Directional Drilling?
•Directional wells are
deviated from Vertical
(Straight)
•Directional wells are drilled
with intention to control :
–inclination (angle)
–azimuth (direction).
•Think 3-D when Directional

3. Why Drill Directional?
•On Land:
–Surface constraint
due to land owner,
natural event, etc.
–Relief well in
blowout situation
–Horizontal

4. Why Drill Directional?
•Offshore:
–Save Cost on Platforms
–Relief well in blowout
situation
–Horizontal
–Extended Reach
–Multi-Lateral

5. Well Profile Terminology
Vertical Section
Tangent
Drop Section
EOH
EOB
KOP
Build Section
RKB
TVD
RKB = Rotary Kelly Bushing
KOP = Kick-off Point
EOB = End of Build
EOH = End of Hold
TVD = True Vertical Depth
TD = Well Depth
TD

6. Directional Profiles & Terminology
•Build and Hold
•S-Type
•Horizontal
Kick Off Point
Build Section
Tangent Section
Drop Section
Horizontal Section
Build Section

7. Vertical View
•View of 3-D well
path from side
•Vertical Section - is
projection of actual
well path onto plane
of Vertical View
–VS to target (+)
–VS away (-)
•TVD & MD

8. Vertical View
TVD
Vertical Section

9. Plan View
•View of 3-D well
path from top
•Coordinates from
original surface
location
–N(+) / S(-)
–E(+) / W(-)

10. Plan View
East
North

11. Direction - Oilfield
•Hole Direction
•Uses Quadrants
•Expressed in
degrees from
North or South
45
75
E
N
W
S
N45E
S75W

12. Direction - Azimuth
•Hole Direction
•Reference from
North
•Expressed in
degrees (0-
360) from North
45
255
E
N
W
S
45
255

13. Survey Corrections
•Magnetic North
–Magnetic surveys are influenced by earth’s
mass of magnetic materials  varies w/ time
•True (Geographic) North
–North Pole  where Santa lives
•Declination is the angular difference
between Magnetic North and True North
–West (-), if MN is west of TN
–East (+), if MN is east of TN

14. Survey Corrections
•Mapping Grid
The angle from
True North to
Grid North is
called the
convergance
•Drilling Grid
Local reference
Grid north
differs from
true north

15. Survey Calculation Methods
•Tangential - Never use this!!!
•Average Angle - Trigonometry to calculate by
hand held calculator - simple but accurate,
don’t need program.
•Radius of Curvature - More accurate, need
programmable calc or PC.
•Minimum Curvature - Use this, most accurate!
Need programmable calc or PC.

16. Typical Rotary Configurations
30 – 90 ft
9 – 27 m
30 ft
9 m
Dropping Pendulum
30 – 90 ft
9 – 27 m
30 ft
9 m
as close as
possible
Building Fulcrum
30 - 60 ft
9 - 18 m
30 ft
9 m
5-20 ft
1.5 – 6 m
Holding Packed hole

17. Directional Drilling Practices
Kick Off & Rotary Drill:
Orient and kick off with steering tool, bent sub and motor (right).
Come out of hole and go in with a rotary assembly (below) to
continue drilling. Bit walk is a common occurrence.

18. Evolution of Directional Technology
1960 1970 1980 1985 1990 1995 2000
PDM
+
bent sub
Wireline
steering
tool
MWD
2-D
Adjustable
stabilizer
Steerable
motor
RST
Push the bit
RST
Point the bit

19. Changes in Directional Drilling Practices
Mid 1990’s1970’s Late 1980’s
Singleshot or
Steering Tool
1990’s

20. Directional Drilling Practices
Steerable Motor Systems:
Orient with MWD, kick off with steerable motor with
bent housing or adjustable kick-off sub, and establish
desired inclination and direction in sliding mode (drill
string is not rotated). Rotate the drill string to continue
drilling and monitoring directional data received at
surface from the MWD tool. Go into sliding mode to
make corrections or trajectory changes in 2-D or 3-D.
Operation involves alternate sliding and rotating.
Advanced tools for near bit measurements, better
trajectory control with adjustable gauge stabilizers,
formation logging, and Pressure While Drilling (PWD)
can be added to the bottom hole assembly.
Motor torque can be a limiting factor, especially with
PDC bits.

21. Kick-off in Open Hole
hole bottom
The bit, motor and stabilizers form 3 contact points
for a defined circular path
3-point geometry applies

22. PackStock Whipstock
orienting stinger
packer key for orientation
drill collar
orienting sub
UBHO
starter mill
shear pin
whipstock
slips
window
hinge
casing collar
Kick-off in Cased Hole

23. Dog Leg Severity - DLS
DLS is the rate of change in hole
angle over a course length (MD)
Long radius: 2-6 / 100’
Med radius: 6-35 / 100’
Short radius: >35 / 100’
2D profiles are in one plane
3D and ‘designer’ profiles involve
change in inclination and direction,
and DLS accounts for the
combined change
General rule: DLS ()
= Mech Risk ()
90
0
Radius = 5730/DLS

24. Dog-Legs & Problems
Hi Hang Wt = Keyseat ~ Stuck
Many DL’s = Hi Drag ~ Can’t Slide ~ Stop Drlg
Drag = Linear Function
Drag = Exponential Function
Hi Drag ~ Stuck
Pipe
Keyseat

25. Positive Displacement Motors
•Power Section - uses rotor and stator to convert fluid
power into mechanical power to rotate the bit
•Transfer Section - usually uses U-Joints or CV-Joints to
convert spirograph motion of rotor to true rotary motion
•Bearing Section - transfer radial and axial force from
motor to bit

26. The differential pressure causes drilling fluid to enter the cavities at
the top of the motor. As it moves through the motor, the fluid
pushes on the rotor causing it to rotate.
How the Positive Displacement Mud Motor Works

27. Motor Lobe Configurations

28. Stabilizers, bend and bit provides 3
contact points
Behavior is sensitive of WOB
Sliding and rotating are possible
Bend might be adjusted on site
More tortuous hole
Steerable Motor Assembly

29. Rotary Steerable Systems
Rotary steerable systems are the latest
generation of directional drilling tools. They do
not depend on a downhole motor for bit rotation
for steering the tool. The entire drill string is
rotated and available torque is limited only by
the torsional strength of the drill string. Steering
functions are performed by an intricate system
of adjustable parts that can be programmed
from the surface.

30. The Rotary Steerable Concept
Desire to rotate the drillstring 100% of the time
Improves weight transfer and ROP
Improves hole cleaning by constant agitation of
cuttings
Desire to orient the bit and drill directional well
“Push” the bit technology
“Point” the bit technology
Goal: DECOUPLE THE METHOD OF BIT
DEFLECTION FROM THE DRILLSTRING

31. Adjustable Gauge Stabilizers

32. 3-D Visualization of Development Wells

33. “Designer” Well
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 ERD Wells with significant
azimuth change(s)
 Highly engineered well plan
required

34. Extended Reach Well – 3D Profile