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DIRECTIONAL WELL DRILLI
PART 2
By: Titus N. Ofei
Petroleum Engineering Department
Universiti Teknologi PETRONAS, Malaysia
2015
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DEFLECTION TOOLS FOR KICK
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LEARNING OBJECTIVES (CO1)
At the end of the lecture, students should be able to:
List the main deflection tools for kick-off.
Describe how controlled deflection is achieved for each deflection tool.
State the advantages and limitations of each deflection tool.
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WELL KICK-OFF
In kicking off a well, or making a controlled trajectory chang
deflection tool or method must be used to force the bit in the d
direction.
All deflection methods depend on manipulating the drillpipe
and downward motion) to cause a departure of the bit in eith
direction plane (azimuth), or the inclination plane, or both.
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1. WHIPSTOCK (DOWNHOL
A whipstock is a wedge-shaped casting,
generally of steel with a slightly tapered
concave groove on one side that holds and
guides the whipstock drilling assembly.
A whipstock is used to drill past an
obstruction or deflect the bit out of the main
hole where the casing has been milled.
Open Hole
Whipstock
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KICK-OFF PROCEDURE: WH
1. Run liner hanger packer.
2. Determine the orientation using a gyro
or MWD run.
3. Run retrievable whipstock and mill
window (1 trip system)
4. Drill lateral and retrieve whipstock
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ADVANTAGES/LIMITATIONS OF W
1. Angle and orientation is built-in
for correct kick-off where there
is no angle
2. Start a deviated hole to
sidetrack in conditions unsuitable
for running a downhole drive
(mud motor or turbine)
1. Possible slipping of
whipstock when ge
with the pipe
2. Requires multi trips
retrieve
3. More hardwares in
Advantages Limitations
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2. JETTING
A jetting tool consists of two or three cone
bit with three jet nozzles, two small andone large.
The large nozzle is oriented to the desired
direction where mud is pumped to wash
the formation without drillstring rotation.
They are used to deviate a wellbore in
soft, highly drillable and homogeneous
formations.
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KICK-OFF PROCEDURE: J
1. Orient the large bit nozzle to the
desired formation.
2. Jet to wash a pocket of the formation.
3. Reciprocate the drillstring up and down
to wash out a large jet eye.
4. Continue building the angle with rotary
BHA
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ADVANTAGES/LIMITATIONS OF
1. Simple and cheap
2. Sometimes, its the only way to
build angle in soft formations
3. Orientation is fairly easy
4. Same assembly can be used to
build and rotate
1. Severe doglegs can o
short sections of the h
2. Below 2000-ft TVD, th
normally becomes too
efficient jetting
3. Can only be used at s
Advantages Limitations
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3. PDM WITH BENT SUB - PR
A PDM with bent sub is driven by drilling fluid
pumped down the drillstring to produce rotarypower in the downhole motor.
The drilling fluid is transmitted to the drillbit,
thus eliminating the need to rotate the drillstring.
The bent sub is used to impart a constant
deflection to the tool.
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ADVANTAGES/LIMITATIONS OF PDM WITH
1. They drill smooth curves2. They can be used in most formations
3. Dogleg severity is more predictable
4. Compatible with steering tools and
mud pulse guidance system
1. Motors are expensiv2. Cannot rotate the dr
3. Hole cleaning proble
4. Must be tripped to a
Advantages Limitations
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4. STEERABLE PDM
The most common type of steerable
motor is the single bent-housing design.It permits drilling of a full gauge hole at
the kick-off point, thus eliminating costly
follow-up trips to ream the hole to full
gauge.
Orientation is also more accurate since
the motor penetrates along a smooth
gradual curve in build-up and drop-off
portions.
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Advantages/limitations of steerable PDM
1. They drill smooth curves2. They can be used in most formations
3. Dogleg severity is more predictable
4. Drills faster and compatible with
steering tools and mud pulseguidance system
5. Same configuration can build curves
and rotate the drillstring in tangents
and laterals
1. Motors are expens
2. Temperature limite
3. Chemicals and gas
adverse effects on
stator
Advantages Limitations
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5. ROTARY STEERABLE SYS
This allows for continuous steering while
rotating the drillstring.
Two main types exist:
a) Push-the-bit: applies side force to increase
side cutting action of the bit.b) Point-the-bit: offsets the drilling trajectory
similar to bent sub housing but allowing
continuous rotation.
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ADVANTAGES/LIMITATIONS
1. Steadier deviation control2. Smoother in-gauge hole
3. Better hole cleaning, minimizing
wiper trips
4. Long reach drilling5. Higher overall ROP
6. Continuous acquisition of
azimuthal formation data
1. Expensive
Advantages Limitations
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SUMMARY
Now, you should be able to:
List the main deflection tools for kick-off.
Describe how controlled deflection is achieved for each deflect
State the advantages and limitations of each deflection tool.
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END OF PRESENTATION
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