2. TTaabbllee ooff CCoonntteennttss
ïDefinitions
ïApplications of Directional Drilling
ïDeflection Tools
ïMud Motors
ïTypes of Well Profile
3. DDeeffiinniittiioonnss
ïDirectional drilling is the process of directing the
wellbore along some trajectory to a predetermined
target.
ïDeviation control is the process of keeping the
wellbore contained within some prescribed limits
relative to inclination, horizontal excursion from the
vertical, or both.
4. AApppplliiccaattiioonnss
ïHistory
ïInterests in controlled directional drilling began about
1929 after new and later accurate means of measuring
hole angle was introduced during the development of
Seminole, Oklahoma field.
ïIn the early 1930âs the first controlled directional well
was drilled in Huntington Beach, California.
ïControlled directional drilling was initially used in
California for unethical purposes, that is, to
intentionally cross property lines.
5. ïIn 1933, during the development of the Signal Hill field
in Long Beach, California, several wells were drilled
under the Sunnyside Cemetery from locations across
the streets surrounding the cemetery.
ïIn 1934, it was used to kill a wild well, Madeley No.1,
near Conroe, Texas.
14. ïOther applications include:
ïTo reach multiple targets
ïHorizontal drilling
ïTo reach thin reservoirs (using horizontal and
multilateral drilling)
ïTo avoid gas or water coning problems
15. DDeefflleeccttiioonn TToooollss
ïThe wellbore can be deflected from its current
position using any of the following:
ïWhipstocks
ïJetting bit
ïBent subs with downhole motors
16. WWhhiippssttoocckkss
Advantages
âąIt provides a controlled hole
curvature
at the onset
âąCan be run at any depth in any kind
of
rock and very useful in hard rock
Dwihseardev oatnhteargs efail
âąIt is necessary to drill the pilot hole
and then trip out to change the
smaller bit to one of the wellbore
diameter.
17.
18. JJeettttiinngg bbiitt
Advantages
âąSeveral attempts can be made to initiate deflection
without
pulling out of hole
âąA full gauge hole can be drilled from the beginning
Disadvantage
âąThe technique is limited to soft-medium formations
âąSevere dog-legs can occur if the jetting is not carefully
controlled
âąOn smaller rigs there may not be enough pump capacity to
wash away the formation
19.
20. BBeenntt ssuubbss wwiitthh ddoowwnnhhoollee mmoottoorrss
ïThe bent sub is run directly above the motor and its pin is
offset at an angle of 1 â 3 degrees.
ïDeflection of the wellbore occurs when drilling is carried
out with no surface rotation to the drillstring.
ïThe drill bit is forced to follow the curve of the bent sub.
ïThe degree of curvature depends largely on the bent sub
offset angle and the OD of the motor.
ïWhen the required angles (inclination and/or azimuth)
are obtained, this BHA is tripped out to be replaced with a
rotary assembly.
21.
22. SStteeeerraabbllee mmoottoorrss
ïThe motor is designed with an in-built bent housing
below the motor section; usually the connecting rod
housing.
ïThe bent housing angle is usually 0.25 â 1.5 degrees.
ïThe use of steerable motors with the correct drill bit and
BHA reduces the number of round trips required to
produce the desired inclination/azimuth.
ïIt can be used in either :
ïOriented mode (sliding)
ïRotary mode
23. Oriented (Sliding) mode
âąThe drillstring remains
stationary (rotary table or
top-drive is locked) while the
drill bit is rotated by the
motor.
âąThe course of the well is
only changed when drilling
in sliding mode as the drill
bit will now follow the
curvature of the motor bent
housing.
Rotary mode
âąSteerable motor becomes
âlockedâ with respect to
trajectory and the hole
direction and inclination are
maintained while drilling.
26. TTuurrbbiinnee mmoottoorr
ïThe turbine motor consists of:
ïA multistage blade-type rotor and stator sections. The
number of rotor/stator sections can vary from 25 to 50.
ïA thrust bearing section and a drive shaft.
ïThe rotor blades are connected to the drive shaft and
are rotated by mud pumped under high pressure.
ïThe stator deflects the mud onto the rotor blades.
ïRotation of the rotor is transmitted to the drive shaft
and drill bit.
29. ïPower section
ïThe PDM consists of a helical steel rotor fitted inside a
spirally-shaped elastomer moulded stator.
ïMud flowing under pressure fills the cavities between
the dissimilar shapes of the rotor and stator and under
the pressure of mud, the rotor is displaced and begins
to rotate.
ïThe rotor actually moves in an elliptical shape. This
eccentric movement is converted to true circular
motion by a universal joint assembly.
30.
31. ïBy-pass valve
ïThis valve allows the drilling fluid to by-pass the mud
motor allowing the drillstring to fill during tripping in
and drain when making a connection or pulling out of
hole.
ïThe valve operates by a spring which holds a piston in
the upper position.
ïIn this position, ports in the by-pass valve are open
allowing mud to flow in or out of the drillstring.
ïAt 30% of recommended flow rate, the piston is forced
down, closing the ports and directing flow through the
mud motor.
32.
33. ïUniversal Joint:
ïA Connecting Rod assembly is attached to the lower
end of the rotor.
ïIt transmits the torque and rotational speed from the
rotor to the drive shaft and bit.
ïUniversal joints convert the eccentric motion of the
rotor into concentric motion at the drive shaft.
ïBearing and Drive Shaft Assembly
ïThe drive shaft is a rigidly-constructed hollow steel
component.
ïIt is supported within the bearing housing by radial
and axial thrust bearings
34. TTyyppeess ooff WWeellll PPrrooffiillee
ïType I
ïBuild and Hold
ïType 2
ïBuild, Hold and Drop.
ïReturns to vertical after dropping â S-shape.
ïDoes not return to vertical after dropping â Modified S-shape.
ïType 3
ïContinuous Build
35. KOP
TYPE I TYPE II TYPE III
BUILD & HOLD BUILD â HOLD & DROP CONTINUOUS BUILD
36. TTyyppee II ââ bbuuiilldd aanndd hhoolldd
ïInformation needed:
ïSurface co-ordinates
ïTarget co-ordinates
ïTVD of target
ïTVD to KOP
ïBuild-up rate
37.
38.
39.
40. TTyyppee IIII ââ bbuuiilldd,, hhoolldd aanndd ddrroopp
ïInformation needed:
ïSurface co-ordinates
ïTarget co-ordinates
ïTVD of target
ïTVD to KOP
ïTVD at end of drop-off
(usually end of
well)
ïBuild-up rate
ïDrop-off rate
ïFinal angle of
inclination through
target.
ïBecause Type II have 2 curves,
2 radii need to be calculated
and compared with the total
departure, D3.
ïThese quantities are then
used to calculate the
maximum possible
inclination angle at end of
build-up curve.
42. TTyyppee IIIIII ââ ccoonnttiinnuuoouuss bbuuiilldd
ïUsed for salt dome
drilling.
ïFor planning appraisal
wells.
ïInformation needed:
ïSurface co-ordinates
ïTarget co-ordinates
ïOne parameter
from:
ïMaximum
inclination angle
ïTVD to KOP
ïBuild-up rate
43. Design a directional well with the following
restrictions:
âą Total horizontal departure = 4,500 ft
âą True vertical depth (TVD) = 12,500 ft
âą Depth to kickoff point (KOP) = 2,500 ft
âą Rate of build of hole angle = 1.5 deg/100 ft
âą Profile type: Type I well (build and hold)
44. (i) What is the maximum hole angle
required.
(ii)What is the total measured
depth (MD)?
q
47. 47
MMeeaassuurreedd DDeepptthh ooff
WWeellll
xBuild = r1(1 - cos q
)
3,820(1- cos 26.3 )
395 ft
=
=
ïŻ
xHold 4,500 395
= -
4,105 ft
=
L sin 4,105
Hold
q =
Hold
L 9,265 ft
=