PISTON CONVERTER FOR DOWNHOLE DRILLING TOOL

Abstract

A steerable drilling tool in accordance to an embodiment includes a steering actuator having an axially moveable piston connected to a steering pad by a linkage to convert axial movement of the piston into a radial movement of the steering pad.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 62/158,836, filed May 8, 2015, which is incorporated herein by reference in its entirety.

BACKGROUND

This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.

Oil and gas reservoirs may be accessed by drilling wellbores to enable production of hydrocarbon fluid, e.g. oil and/or gas, to a surface location. In many environments, directional drilling techniques have been employed to gain better access to the desired reservoirs by forming deviated wellbores as opposed to traditional vertical wellbores. However, forming deviated wellbore sections can be difficult and requires directional control over the orientation of the drill bit used to drill the deviated wellbore.

Rotary steerable drilling systems have been used to drill deviated wellbore sections while enabling control over the drilling directions. Such drilling systems often are classified as push-the-bit systems or point-the-bit systems and allow an operator to change the orientation of the drill bit and thus the direction of the wellbore.

SUMMARY

A steerable drilling tool in accordance to an embodiment includes a steering actuator having an axially moveable piston connected to a steering pad by a linkage to convert the axial movement of the piston into a radial movement of the steering pad.

A method includes deploying a bottom hole assembly (BHA) on a drill string in a wellbore, the BHA including a drill bit and a steering actuator having an axially moveable piston connected to a steering pad by a linkage, axially moving the piston in response to the application of a hydraulic pressure, radially extending the steering pad in response to the axially moving the piston and steering the drill bit in response to radially extending the steering pad.

A drilling system includes a BHA deployed in a wellbore on a drill string, the BHA including a drill bit and a steering actuator having an axially moveable piston connected to a steering pad by a linkage to convert the axial movement of the piston into a radial movement of the steering pad.

This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with standard practice in the industry, various features may not be drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a schematic view of an example of a drill string incorporating a steerable drilling system and piston converter according to one or more aspects of the disclosure.

FIG. 2 illustrates an example of a steerable drilling tool incorporating a steering actuator piston converter according to one or more aspects of the disclosure.

FIG. 3 illustrates a point or hybrid type of steerable drilling tool incorporating an axial piston and piston converter according to one or more aspects of the disclosure.

FIG. 4 illustrates a push type steerable drilling tool incorporating an axial piston and piston converter according to one or more aspects of the disclosure.

FIG. 5 illustrates a prior art radial piston type of steering actuator.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

As used herein, the terms connect, connection, connected, in connection with, and connecting may be used to mean in direct connection with or in connection with via one or more elements. Similarly, the terms couple, coupling, coupled, coupled together, and coupled with may be used to mean directly coupled together or coupled together via one or more elements. Terms such as up, down, top and bottom and other like terms indicating relative positions to a given point or element are may be utilized to more clearly describe some elements. Commonly, these terms relate to a reference point such as the surface from which drilling operations are initiated.

FIG. 1 illustrates a drilling system 20 in which piston converters 10 for steerable systems can be incorporated. System 20 includes a bottom hole assembly (BHA) 22 which is part of a drill string 24 used to form a directionally drilled wellbore 26. The illustrated bottom hole assembly 22 of drilling system 20 includes a steerable drilling assembly 28, e.g. a rotary steerable system, which controls the drilling orientation of a drill bit 30. The steerable drilling assembly 28 in FIG. 1 is illustrated as a hybrid type system including steerable system components 32, 34 which pivot with respect to each other to enable the desired directional drilling of wellbore 26. Steering actuators 36 may be mounted between components 32 and 34 to control the pivoting of component 34 with respect to component 32 by providing the desired lateral forces for steering the steerable drilling assembly 28 when forming the desired, deviated wellbore 26. The steerable system components 32, 34 may be coupled together by a pivot joint 38, such as a universal joint. The illustrated steerable drilling system is a non-limiting example of a steerable drilling system in which embodiments of this disclosure can be incorporated.

The depicted steering actuators 36 incorporate a piston converter, generally denoted by the numeral 10, operationally connecting an axially aligned piston 12 to a radially moveable pad 14. The axial movement of piston 12 is transferred to the radial movement of pad 14. A control system generally identified with the numeral 40 selectively directs drilling fluid to the steering actuators 36 to extend the pads 14 radially or laterally relative to the bottom hole assembly (e.g., too, drill string) and into contact with the outer steerable component 34 (e.g., sleeve) or into contact with the wellbore wall to steer the drill bit 30. The control system 40 may include for example control electronics 42 and one or more valves 44 (e.g., spider valve, bistable valve, etc.). The steering actuator can be provided in various forms. Non-limiting examples of steerable systems in which the piston convert can be utilized are disclosed in U.S. Pat. Nos. 8,590,636, 8,701,795, 8,708,064, 8,763,725 and 9,057,223, the teachings of which are incorporated herein by reference.

Depending on the environment and the operational parameters of the drilling job, drilling system 20 may comprise a variety of other features. For example, drill string 24 may include drill collars 46 which, in turn, may be designed to incorporate desired drilling modules, such as logging-while-drilling and/or measurement-while-drilling modules 48. In some applications, stabilizers may be used along the drill string to stabilize the drill string with respect to the surrounding wellbore wall. Various surface systems also may form a part of the drilling system 20. In the example illustrated, a drilling rig 50 is positioned above the wellbore 26 and a drilling mud system 52 is used in cooperation with the drilling rig. For example, the drilling mud system 52 may be positioned to deliver drilling fluid 54 from a drilling fluid tank 56. The drilling fluid 54 is pumped (pump 53) through appropriate tubing 58 and delivered down through drilling rig 50, into drill string 24, and down through drill bit 30. In many applications, the return flow of drilling fluid flows back up to the surface through an annulus 60 between the drill string 24 and the surrounding wellbore wall (see arrows 62 showing flow down through drill string 24 and up through annulus 60). The drilling system 20 also may comprise a surface control system 64 which may be used to communicate with steerable drilling assembly 28. In some embodiments, the surface control system 64 communicates with a downhole steering control system within steerable drilling assembly 28.

FIG. 2 schematically illustrates a non-liming example of a steerable drilling assembly 28 incorporating a steering actuator 36 and piston converter 10 in accordance to an embodiment. With additional reference to FIG. 1, the illustrated steerable drilling assembly 28 is in the form of a rotary steerable system which utilizes the steering actuators 36 to control the relative angular orientation between steering components 32 and 34. The steering components 32 and 34 are pivotally coupled to each other via pivot joint 38 which, in this particular example, is in the form of a universal joint. Downhole drilling tools generally utilized the pumping pressure (pump 53), of the drilling fluid 54 to control the steering actuator 36. The drilling fluid is directed for example by the downhole steering control system 40, through a control valve 44 to the piston 14 of the steering actuator 36 to drive the piston 12 axially relative to the axis 66 which in turn radially extends the pad 14 outward relative to the longitudinal axis 66 of the tool (e.g., BHA). In accordance to embodiments, the piston converter 10 is a mechanical link. In the example of FIG. 2, the pad 14 extends radially outward to apply a steering force and pivot the steering components 32, 34 relative to one another. In some steerable tools the pads are extended radially from the drilling tool to contact and apply the steering force to the wall of borehole.

FIGS. 3 and 4 are schematic illustrations of steerable drilling tools 28 incorporating steering actuators 36 utilizing a piston converter 10 in accordance to one or more aspects of the disclosure. The piston 12 is moveably disposed in a longitudinally extending cylinder 68, i.e., along the longitudinal axis 66 of the tool, as opposed to being oriented in the radial direction. Piston converter 10 is a mechanical linkage that transfers the axial movement of the piston 14 into a radial movement of the pad 14.

The piston cylinder 68 is oriented in the axial direction with the piston 12 movement and the piston push in the axial direction in response to the application of hydraulic fluid 54, e.g. drilling mud. The piston cylinder 68 is longer and the movement of piston 12 is longer than that permitted in a radial piston arrangement, see e.g., U.S. Pat. No. 8,590,636. The longer axial movement allows for more lifting movement of the rocker assembly 70 (see, FIG. 4) and the pad 14. During operation the pad (e.g., the top surface) or other components wear and/or become washed out requiring that the pad assembly move further radially than prior to the wear. The axial piston facilitates the additional radial movement without compromising the piston seal 72, e.g. the piston seal pushed out of the pressure chamber. The circular shaped seal 72 (e.g., O-ring) circumferentially encircling the axially moving piston 12 is a reliable seal. FIG. 3 illustrates the piston converter arranged in a point-type or hybrid-type steerable tool and FIG. 4 illustrates the piston converter arranged steering actuator in a push-the-bit steerable drilling tool.

FIG. 5 illustrates an example of a prior art steering actuator able drilling tool and prior art radial piston assembly. A further description of a prior art radial piston assembly is disclosed in U.S. Pat. No. 8,590,636, the teachings of which are incorporated herein by reference. Hydraulic pressure, e.g., the drilling mud 54, acts on the actuator piston 12 causing it to move radially relative to the longitudinal axis 66 of the steerable drilling tool as it pivots about the hinge pin 74. Because of the space restriction in the radial direction, the opening angle 76 of the hinged piston may be limited to around six degrees. Space is restricted, or limited, in the radial direction according to the drilling tool size. During drilling operations the piston rocker top surface 70 and other components may wear, permitting the piston to open greater than the original limit. When this happens, the dynamic piston seal 78 may pop out of the metal pocket and the sealing mechanism may be damaged. This could result in washout of the piston and reduction in the steering performance of the drilling tool.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the disclosure. Those skilled in the art should appreciate that they may readily use the disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. For example, features shown in individual embodiments referred to above may be used together in combinations other than those which have been shown and described specifically. Accordingly, any such modification is intended to be included within the scope of this disclosure. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not just structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke means-plus-function for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.

Claims

1. A steerable drilling tool, comprising a steering actuator having an axially moveable piston connected to a steering pad by a linkage to convert axial movement of the piston into a radial movement of the steering pad.

2. The tool of claim 1, wherein the steering pad comprises a rocker assembly.

3. The tool of claim 1, comprising a seal circumferentially encircling the axially moveable piston.

4. The tool of claim 1, wherein the steering pad comprises a rocker assembly and further comprising a seal circumferentially encircling the axially moveable piston.

5. The tool of claim 1, further comprising a pair of steering components pivotally mounted to each other via a pivot joint and extending axially along a tool axis; and

the steering actuator disposed with one of the pair of steering components such that axial movement of the piston moves the steering pad radially relative to the tool axis thereby pivoting the steering components relative to one another.

6. The tool of claim 5, wherein the steering pad comprises a rocker assembly.

7. The tool of claim 5, comprising a seal circumferentially encircling the axially moveable piston.

8. The tool of claim 5, wherein the steering pad comprises a rocker assembly and further comprising a seal circumferentially encircling the axially moveable piston.

9. A method, comprising:

deploying a bottom hole assembly (BHA) on a drill string in a wellbore, the BHA comprising a drill bit and a steering actuator comprising an axially moveable piston connected to a steering pad by a linkage;

axially moving the piston in response to the application of a hydraulic pressure;

radially extending the steering pad in response to the axially moving the piston; and

steering the drill bit in response to radially extending the steering pad.

10. The method of claim 9, wherein the steering pad comprises a rocker assembly.

11. The method of claim 9, comprising a seal circumferentially encircling the axially moveable piston.

12. The method of claim 9, wherein the steering pad comprises a rocker assembly and further comprising a seal circumferentially encircling the axially moveable piston.

13. The method of claim 9, wherein the radially extending the steering pad comprises contacting the wellbore with the steering pad.

14. The method of claim 9, wherein the radially extending the steering pad comprises pivoting a first and a second steering component relative to one another.

15. The method of claim 14, comprising a seal circumferentially encircling the axially moveable piston.

16. A drilling system, comprising a bottom hole assembly (BHA) deployed in a wellbore on a drill string, the BHA comprising a drill bit and a steering actuator having an axially moveable piston connected to a steering pad by a linkage to convert axial movement of the piston into a radial movement of the steering pad.

17. The system of claim 16, comprising a seal circumferentially encircling the axially moveable piston.

18. The system of claim 16, wherein the steering pad comprises a rocker assembly and further comprising a seal circumferentially encircling the axially moveable piston.

19. The system of claim 16, wherein the BHA comprises a pair of steering components pivotally mounted to each other via a pivot joint and extending axially along a tool axis, whereby the steering components are pivoted relative to one another in response to radially extending the steering pad.

20. The system of claim 19, comprising a seal circumferentially encircling the axially moveable piston.