GB2422387A - Steerable Drilling System - Google Patents
Steerable Drilling System Download PDFInfo
- Publication number
- GB2422387A GB2422387A GB0501142A GB0501142A GB2422387A GB 2422387 A GB2422387 A GB 2422387A GB 0501142 A GB0501142 A GB 0501142A GB 0501142 A GB0501142 A GB 0501142A GB 2422387 A GB2422387 A GB 2422387A
- Authority
- GB
- United Kingdom
- Prior art keywords
- piston
- bias
- pad
- unit
- drilling system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000005553 drilling Methods 0.000 title claims abstract description 22
- 239000012530 fluid Substances 0.000 description 14
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/10—Wear protectors; Centralising devices, e.g. stabilisers
- E21B17/1014—Flexible or expansible centering means, e.g. with pistons pressing against the wall of the well
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
- E21B7/06—Deflecting the direction of boreholes
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
- E21B7/06—Deflecting the direction of boreholes
- E21B7/061—Deflecting the direction of boreholes the tool shaft advancing relative to a guide, e.g. a curved tube or a whipstock
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J1/00—Pistons; Trunk pistons; Plungers
Landscapes
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Chemical & Material Sciences (AREA)
- Earth Drilling (AREA)
Abstract
A bias unit for use in a steerable drilling system comprising at least one bias pad (20,fig. 1) which, due to hydraulic pressure, pivots to steer the drill (10,fig. 1) bit towards its target area. As the pad applies pressure to the wall of the well, the drill bit is turned in the desired direction. Pressure is applied to the pad via a piston 36 of non-circular cross-sectional shape, such as an elliptical or obround shape. Additionally the piston 36 may slide within a bore 30 of curved or part toroidal form and may form part of the bias pad.
Description
Steerable Drilling System This invention relates to a steerable drilling
system for use in the formation of subterranean boreholes, for example for subsequent use in the extraction of hydrocarbons.
The invention relates, in particular, to a bias unit for use in such a drilling system.
A known form of steerable drilling system includes a bias unit having a plurality of bias pads pivotally mounted thereon. Each bias pad is moveable between a retracted position and a radially extended position. In the extended position, the bias pad is forced into engagement with the surface ofthe borehole being formed, thereby applying a sideways acting bias load to the bias unit. The bias load applied to the bias unit is transmitted to a drill bit connected to the bias unit so as to urge the drill bit away from the axis of the part of the borehole in which the drill bit is located or otherwise alter the orientation of the drill bit, and thereby, over time, cause the formation of a curve in the borehole.
By appropriate control of the bias unit to control which of the bias pads are in their extended positions at any given time, steering of the drill bit to cause the borehole to follow a desired path can be achieved.
The bias pads are typically moved to their extended positions by pistons, the pistons being of generally circular cross-sectional shape and of diameter limited by, for example, the design of the remainder of the bias unit. The pistons are driven, in use, by drilling fluid or mud supplied under pressure to the bias unit.
It has been found that, in some conditions and applications, the magnitude ofthe bias load achievable with such arrangements is less than desired. In some applications, although an acceptable bias load magnitude may be achievable, this may require the supply pressure of the drilling fluid or mud to be higher than is desirable. Even where an acceptable bias load magnitude can be achieved at an acceptable supply pressure, it may be desirable to achieve a reduction in supply pressure to reduce the forces applied to the piston seals and thereby achieve an increase in seal working life.
It is an object of the invention to provide a bias unit in which the disadvantages set out above are reduced, and to provide a steerable drilling system including such a bias unit.
According to the present invention there is provided a bias unit comprising at least one bias pad moveable, by a piston, between retracted and extended positions, wherein the piston is of non-circular crosssectional shape.
Conveniently, the piston is of cross-sectional shape having a major axis and a minor axis. The bias pad is conveniently pivotally moveable about a pivot axis, and the piston is preferably arranged such that the major axis lies parallel or substantially parallel to the pivot axis. Such an arrangement is advantageous in that it allows an increase in the crosssectional area of the piston to be achieved without requiring, for example, an increase in the diameter of the bias unit. As a result, the bias load achievable, for a given drilling fluid pressure, is increased.
The piston maybe of obround cross-sectional shape.
The piston is preferably slidable within a bore of curved or parttoroidal form.
The piston may be attached to or form part of the bias pad. I lowever, arrangements are possible in which this is not the case.
For cJarity, references herein to the cross-sectional shape of the piston are to the cross-sectional shape of that part or those parts of the piston which form the effective surface area upon which fluid under pressure acts, in use.
The invention also relates to a steerable drilling system incorporating such a bias unit, the drilling system including a drill bit the position and/or orientation of which is adjustable by the bias unit in use.
The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view of part of a steerable drilling system; Figures 2, 3 and 4 are views of p arts of the bias unit of the steerable drilling system of Figure 1; and Figure 5 is a sectional view through the parts shown in Figures 2, 3 and 4 when assembled.
The drilling system illustrated, diagrammatically, in Figure 1 comprises a drill bit 10 arranged to be rotated about its axis by, for example, a fluid powered motor 12. As illustrated, the motor 12 is carried by part of a bias unit 14. Operation of the bias unit 14 is controlled by a control unit 16 which controls the operation of a valve arrangement located within a valve housing 18.
Although only a few components of the downhole steerable drilling system are illustrated in Figure 1, it will be appreciated that a number of additional components may be provided. For example, stabiliser units may be provided to hold certain parts of the downhole assembly in a chosen position or orientation. Further, a range of sensor devices could be provided, if desired.
The bias unit 14 comprises a housing upon which is pivotally mounted a series of bias pads 20. Each bias pad 20 is pivotally movable between a retracted position and a radially extended position, movement of each pad from the retracted position to the radially extended position being achieved by means of a piston arrangement 22 associated with the respective bias pad 20. Although Figure 1 only illustrates the provision of two bias pads, it will be appreciated that three or more such pads will typically be provided.
Referring next to Figure 2 there is shown a clamp plate 24 which forms part of the outer periphery of the housing of the bias unit 14. The clamp plate 24 includes knuckles 26 adapted to receive a pivot pin 28 (see Figure 5) to allow the pivotal connection of an associated one of the bias pads 20 thereto. The clamp plate 24 further includes a bore 30 which, as shown in Figure 5, is curved in cross-section so as to be ofpart- toroidal form, the centre of curvature of the part-toroidal bore 30 being the pivot axis 32.
As shown in Figure 3, the bias pad 20 is also shaped to include knuckles 34 adapted to receive parts of the pivot pin 28 to establish the pivotal connection between the pad 20 and the clamp plate 24. The pad 20 further includes a projection defining a piston 36 which, in use, is received within the bore 30 to form the piston arrangement 22.. The piston 36 carries a seal member 38 so as to form a seal between the piston 36 and the wall defining the bore 30. The pad 20 and piston 36 further define a flowpath 40 whereby fluid supplied to the toroidal bore 30 can escape therefrom, the flowpath 40 being defined, in part, by an orifice formed in a flow restrictor plate 42 located within the piston 36 and arranged so as to ensure that the rate at which fluid can escape from the toroidal bore 30 is restricted to a predetermined rate.
In use, in order to move a pad 20 to its extended position, drilling fluid under pressure is supplied to the appropriate bore 30 to apply a force to the associated piston 36.
Subsequently, the supply of fluid under pressure is broken. Fluid escapes from the bore 30 along the flowpath 40 at a restricted rate, thereby allowing the fluid pressure within the bore to fall and the engagement between the pad 20 and the wall of the borehole urges the pad back toward its retracted position.
The supply of fluid under pressure to the bore 30 is controlled by the control unit 16 and valves located within the valve housing 18. Typically, in use, the bias unit 14 rotates and so, in order to maintain a bias load in a substantially constant direction over a period of time, the bias pads must be moved to their extended positions in turn at a speed related to the speed of rotation of the bias unit.
As illustrated, the piston 36 and the toroidal bore 30 are not of circular cross- section, but rather have a cross-section taking the form of a pair of semi-circles separated by a region of rectangular or square cross-section, and thus is of obround or obround-like cross-sectional shape. This is apparent from Figure 2 and from the shape of the seal shown in Figure 4 which conforms to the shape of the toroidal bore 30. The obround cross- sectional shape of the seal 38, piston upon which the seal 38 is mounted, and bore 30 thus defines a major axis 44 and a minor axis 46. The major axis lies parallel to the pivot axis 32.
As a result, the overall effective cross-sectional area of the piston can be increased, compared to conventional arrangements without requiring an increase in the width of the clamp plate 24, thereby avoiding requiring an increase in the diameter of the bias unit 14.
By increasing the effective cross-sectional area of the piston in this way, an increase in the magnitude of the bias load achievable using the bias unit 14 for a predetermined fluid pressure can be attained. Depending upon the application in which the bias unit 14 is used, the magnitude of the bias load achievable may be increased, or alternatively, the bias unit 14 may be operated at a reduced drilling fluid pressure. A further benefit, where a reduced operating pressure is used, is that the seal 38 may be of increased useful working life. As a result, servicing and maintenance of the bias unit 14 may be required at less frequent intervals.
Although the description hercinbefore is ofan arrangement in which the piston is of obround shape, it will be appreciated that the invention is also applicable to other arrangements. For example, the piston could be of elliptical cross-sectional shape. A number of other modifications and alterations are possible within the scope of the invention.
Further, the invention may be used in steerable drilling systems of a range of other types, for example steerable drilling systems in which the bias unit is separated from the drill bit by a significant distance, a stahiliser and universal joint being located between the bias unit and the drill bit, or one of a range of other steering techniques.
Claims (8)
1. A bias unit comprising at least one bias pad moveable, by a piston, between retracted and extended positions, wherein the piston is of noncircular effective cross-sectional shape.
2. A unit according to Claim I, wherein the piston is of effective crosssectional shape having a major axis and a minor axis.
3. A unit according to Claim 2, wherein the bias pad is pivotally moveable about a pivot axis, and the piston is arranged such that the major axis lies substantially parallel to the pivot axis. I.'. * I I...
*
4. A unit according to any of Claims I to 3, wherein the piston is of obround effective cross-sectional shape. * * S.'.
I'S''.
I I
5. A unit according to any ofthe preceding claims, wherein the piston is slidable within a bore of curved or part-toroidal form.
6. A unit according to any of the preceding claims, wherein the piston is attached to or forms part of the bias pad.
7. A bias unit substantially as hereinbefore described with reference to the accompanying drawings.
8. A steerable drilling system incorporating a bias unit as claimed is any one of the preceding claims, the drilling system including a drill bit the position and/or orientation ot which is adjustable by the bias unit in use. * S. * I III. * S S.'. * S
S S I'S.
I,.... * a
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0501142A GB2422387A (en) | 2005-01-20 | 2005-01-20 | Steerable Drilling System |
US11/329,970 US20060157283A1 (en) | 2005-01-20 | 2006-01-10 | Steerable drilling system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0501142A GB2422387A (en) | 2005-01-20 | 2005-01-20 | Steerable Drilling System |
Publications (2)
Publication Number | Publication Date |
---|---|
GB0501142D0 GB0501142D0 (en) | 2005-02-23 |
GB2422387A true GB2422387A (en) | 2006-07-26 |
Family
ID=34224867
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB0501142A Withdrawn GB2422387A (en) | 2005-01-20 | 2005-01-20 | Steerable Drilling System |
Country Status (2)
Country | Link |
---|---|
US (1) | US20060157283A1 (en) |
GB (1) | GB2422387A (en) |
Families Citing this family (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8960329B2 (en) * | 2008-07-11 | 2015-02-24 | Schlumberger Technology Corporation | Steerable piloted drill bit, drill system, and method of drilling curved boreholes |
US8157024B2 (en) | 2008-12-04 | 2012-04-17 | Schlumberger Technology Corporation | Ball piston steering devices and methods of use |
US20110156357A1 (en) * | 2009-12-28 | 2011-06-30 | Nissin Kogyo Co., Ltd. | Dynamic seal member |
US8614273B2 (en) * | 2009-12-28 | 2013-12-24 | Nissin Kogyo Co., Ltd. | Seal member |
US8403332B2 (en) * | 2009-12-28 | 2013-03-26 | Nissan Kogyo Co., Ltd | Seal member |
US9085941B2 (en) | 2012-02-10 | 2015-07-21 | David R. Hall | Downhole tool piston assembly |
JP6615444B2 (en) | 2013-10-17 | 2019-12-04 | 日信工業株式会社 | Method for producing rubber composition and rubber composition |
US9869140B2 (en) * | 2014-07-07 | 2018-01-16 | Schlumberger Technology Corporation | Steering system for drill string |
US9874069B2 (en) | 2015-05-26 | 2018-01-23 | Schlumberger Technology Corporation | Seal assembly |
US10378292B2 (en) | 2015-11-03 | 2019-08-13 | Nabors Lux 2 Sarl | Device to resist rotational forces while drilling a borehole |
GB2581926B (en) * | 2017-12-29 | 2022-05-11 | Halliburton Energy Services Inc | Steering pad overextension prevention for rotary steerable system |
WO2020113311A1 (en) * | 2018-12-05 | 2020-06-11 | Halliburton Energy Services, Inc. | Steering pad apparatus and related methods |
CA3145578C (en) | 2019-09-25 | 2023-10-03 | Halliburton Energy Services, Inc. | Steering actuation mechanism |
US11753871B2 (en) * | 2021-02-24 | 2023-09-12 | Halliburton Energy Services, Inc. | Rotary steerable system for wellbore drilling |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2277260A1 (en) * | 1974-07-02 | 1976-01-30 | Festo Maschf Stoll G | Hydraulic power cylinder - has two diameters set at 45 degrees with unequal lengths |
US4416339A (en) * | 1982-01-21 | 1983-11-22 | Baker Royce E | Bit guidance device and method |
US4463814A (en) * | 1982-11-26 | 1984-08-07 | Advanced Drilling Corporation | Down-hole drilling apparatus |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3326305A (en) * | 1964-09-10 | 1967-06-20 | Drilco Oil Tools Inc | Drill bit control apparatus |
US4185704A (en) * | 1978-05-03 | 1980-01-29 | Maurer Engineering Inc. | Directional drilling apparatus |
US6116355A (en) * | 1994-06-04 | 2000-09-12 | Camco Drilling Group Limited Of Hycalog | Choke device |
US7004263B2 (en) * | 2001-05-09 | 2006-02-28 | Schlumberger Technology Corporation | Directional casing drilling |
US6761232B2 (en) * | 2002-11-11 | 2004-07-13 | Pathfinder Energy Services, Inc. | Sprung member and actuator for downhole tools |
US7204325B2 (en) * | 2005-02-18 | 2007-04-17 | Pathfinder Energy Services, Inc. | Spring mechanism for downhole steering tool blades |
-
2005
- 2005-01-20 GB GB0501142A patent/GB2422387A/en not_active Withdrawn
-
2006
- 2006-01-10 US US11/329,970 patent/US20060157283A1/en not_active Abandoned
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2277260A1 (en) * | 1974-07-02 | 1976-01-30 | Festo Maschf Stoll G | Hydraulic power cylinder - has two diameters set at 45 degrees with unequal lengths |
US4416339A (en) * | 1982-01-21 | 1983-11-22 | Baker Royce E | Bit guidance device and method |
US4463814A (en) * | 1982-11-26 | 1984-08-07 | Advanced Drilling Corporation | Down-hole drilling apparatus |
Also Published As
Publication number | Publication date |
---|---|
US20060157283A1 (en) | 2006-07-20 |
GB0501142D0 (en) | 2005-02-23 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |