Wells – Processes – Perforating – weakening – bending or separating pipe at an...
Reexamination Certificate
2001-10-30
2003-06-24
Dang, Hoang (Department: 3672)
Wells
Processes
Perforating, weakening, bending or separating pipe at an...
C166S055100, C166S055800
Reexamination Certificate
active
06581690
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an active downhole cutting tool guide device for use in a hole with sides between which a hole-cutting tool provided with said device may be disposed.
There is a need for guiding of downhole cutting tools for various purposes including inter alia lateral hole cutting, directional drilling, as well as to stabilise an existing cutting tool advance direction against unwanted deviation therefrom. Existing solutions to such problems are generally cumbersome to use and/or unsuitable for use with coiled tubing.
There is a need for cutting windows in oil/gas well casings used to line the sides of well holes. Well casing is however normally very tough, thick walled steel pipe which is placed inside a borehole of a well as a lining to secure the borehole and prevent the walls thereof from collapsing. Casing—sometimes referred to as casing tubing—may be seamless, spiral welded or seam welded and may, for example, be fabricated from various API grades of steel such as H40, J55, N80 or P110. Sizes typically vary from around 4 inches (101.6 mm) OD to 30 inches (762 mm)OD, while weights typically range from around 11 lb/ft to 200 lb/ft (16.4 kg/m to 298 kg/m approximately) depending on diameter, thickness and grade. It has also been known to employ glass fibre reinforced plastic casing.
It is known that the cutting of windows in oil well casing, as required for side tracking, is a complicated process, normally requiring the use of a large number of tools not directly related to the cutting of the window itself, such as whipstocks, packers etc. The normal procedure is the setting of a cement plug on top of a packer above which a so-called “whipstock” is placed. The whipstock basically consists of a hard metal wedge which guides a window milling drill bit gradually into the casing thus cutting a slot in the casing. As the slope of the whipstock is of a low value the pinching action on the drill bit is very severe therefore requiring extremely high torque and yet a low rate of progress is achieved due to the high friction losses of the drill bit against the whipstock which have to be subtracted from the total energy available for the cutting of the window. Furthermore once the window has been cut the whipstock and packer require to be retrieved which is often a difficult and tedious process. To date the duration of an average window milling job is three to four days and often much longer.
There is also a need for stabilising drilling tools used to clear well holes which have become obstructed to a greater or lesser degree as a result of deposits on the sides thereof, and/or as a result of deformation of a well hole casing as a result of movement of the surrounding strata. Conventional near bit stabilisers are essentially passive devices, typically comprising a heavy duty ring with four angularly distributed wings which more or less closely approach the hole sides thereby limiting the amount of deviation of the cutting tool possible. With such stabilisers though the resistance to deviation remains substantially constant throughout use of the device, i.e., during travel of the cutting tool along clear sections of the hole when ease of travel is desired and stabilisation is not required, as well as during cutting through obstructions, so that in practice the degree of stabilisation available when it is required is substantially insufficient for proper stabilisation.
There is a further need for improved and less cumbersome methods of steering drilling tools for the purposes of directional drilling. Conventional directional drilling is typically effected by means of the use of so-called bent subs as illustrated schematically in FIG.
1
. The drilling apparatus
1
shown has an indexer
2
for angular orientation of the drill bit
3
and drive system
4
therefor. In more detail the drive system comprises motor
5
, typically a Moineau motor, a bent sub
7
, and a bearing pack
8
which is connected to the drill bit
3
. For straight ahead drilling the whole drill string comprising jointed tubing
9
from which the drilling apparatus
1
is supported is rotated at around 30 rpm so that the bent sub
7
rotates and the drill bit
3
orbits around the drill string axis while the motor
5
rotates at around 700 rpm to drive the drill bit
3
so that the drill bit
3
in effect follows a helical path. When it is desired to kick-off or change direction from the existing drill string axis, the rotation of the drill string is stopped in an arbitrary position and the indexer
2
operated to orientate the bent sub
7
in the desired angular direction. The motor
5
then drives the drill bit
3
while the drill string and bent sub
7
remain stationary, so that the drill bit
3
drills off at an angle determined by the bent sub
7
. Once the required new drilling direction has been established, then the slow rotation of the whole drill string is resumed to provide straight ahead drilling in the new direction. Thus it may be seen that not only is the construction of the apparatus required for directional drilling relatively complex and cumbersome, but operation thereof is also awkward and inflexible.
OBJECTS OF THE INVENTION
It is an object of the present invention to obviate or mitigate at least some of the aforementioned problems and disadvantages in the prior art.
It is a further object of the present invention to provide a cutting tool guide device which may be used with coiled tubing with its inherently shorter positioning and retrieval times against the use of jointed oil field tubing.
It is another object of the invention to provide a cutting tool guide device suitable for down-hole use in a hole with sides between which a hole-cutting tool provided with said device may be disposed, whereby in use of the device at least one of the angle, the orientation and the lateral offset of a hole-cutting tool relative to the longitudinal axis of the hole in which said tool is disposed, may be controlled.
SUMMARY OF THE INVENTION
The present invention provides in one aspect an active downhole cutting tool guide device for use in a hole with sides between which a hole-cutting tool mounted on a drill string and provided with said device may be disposed, said device comprising at least one elongate longitudinally extending hole-side engagement member mounted on a body disposable, in use of the device, in-line with the drill string, so as to be movable relative to said body between a retracted position and a radially outwardly displaced position for hole-side engagement, each said at least one engagement member having pressurised-fluid operable actuator means formed and arranged for driving said hole-side engagement member between said retracted and hole-side engagement positions, said device including pressurised fluid supply means formed and arranged for controlling the supply of pressurised fluid, in use of the device, to said actuator means for operation thereof, whereby in use of the device a said hole-cutting tool may be directed relative to the central longitudinal axis of the hole in which said tool is disposed.
In use of the guide device of the invention, operation of the actuator means forces one (or more) said engagement member(s) into engagement with the hole-side. Where a resulting differential force is exerted at different sides of the hole, the drill string will tend to be displaced away from the central longitudinal axis of the hole so that the cutting tool can be driven laterally through the hole side and/or its forward cutting direction steered away at an angle from the previous forward cutting direction. Where an equal force is exerted by each of the engagement members (where two or more symmetrically angularly distributed ones are provided) on the hole sides around the drill string, then the drill string is positively directed so that the existing forward cutting direction of the cutting tool is stabilised.
Thus by means of the present invention guiding of cutting tools in a variety of downhole situations may be achieved in a particularly
Stewart Kenneth Roderick
Van Drentham-Susman Hector F. A.
Casperson John R
Dang Hoang
Rotech Holdings Limited
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