Method and apparatus for hydraulic steering of downhole rotary drilling systems

Abstract: A method for hydraulically controlling the direction of a drill bit or bottom hole assembly containing a drill contains lateral orifices which can be selectively opened and closed to move a portion of drilling fluid from the drill string out into a narrow gap between the lateral orifices and a lateral bore hole face or wall, which produces a lateral hydraulic force to thereby push the drill bit or bottom hole assembly in an opposite direction of the fluid flow through the lateral orifices. The apparatus for accomplishing this hydraulic steering can provide for the movement of the tip of the orifice into close proximity with the bore hole face to thereby increase the lateral hydraulic force created. This method can also be adapted to push-the-bit bore hole pads to minimize their contact with the bore hole while increasing the lateral force obtained by their engagement. (end of abstract)

Method and apparatus for hydraulic steering of downhole rotary drilling systems description/claims

Brief Patent Description

Full Patent Description

Patent Application Claims

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a directional rotary drilling method and apparatus; specifically, to a method and apparatus for moving a drill bit in a desired path by selectively adjusting a portion of drilling fluid flow through orifices located adjacent a drill bit body to apply a lateral hydraulic force and minimize contact with a bore hole with mechanical guides.

2. Related Art

All methods known to applicant use some manner of mechanical contact with the well bore to achieve the desired steering of the drilling tool, or as in the case of point-the-bit methods, the steering is achieved by offsetting the angle of the drill bit axis relative to the rest of the drill tool. Fluid pressure necessary to cause fluid flow through changing flow geometries (orifices, bends, narrow passages, conduits, etc.) commonly described as pressure loss is typically considered a negative effect of changing flow conditions because it often requires alternative design requirements. That same changing fluid flow conditions is used in the described method and apparatus to create a pressure differential between the two sides of the drilling tool and thereby achieve a desired lateral force on the drilling tool useable for steering the tool in the given direction. There have been attempts to use changing directional fluid flows that are different than this invention and not intended to use the hydraulic pressure difference around the drilling tool for steering the tool in the preferred direction. See U.S. Pat. No. 4,836,301 as an example of these types of fluid directing systems, which uses changing direction of drilling fluid flow inside the drilling tool to generate a hydrodynamic force to tilt the drill bit axis in a given direction using a point-the-bit steering method and system.

SUMMARY OF THE INVENTION

A method for hydraulic steering of a drill bit is described which provides the steps of setting an angular direction from a longitudinal axis of a bottom hole assembly providing the drill bit; and, opening one or more lateral orifices at a selected interval to divert drilling fluid from the drill bit to provide motive hydraulic force in an angular direction opposite the angular direction required for forward progress of the drill bit toward the set direction. The method can further comprise adjusting a gap between a distal tip of the orifices and a universal joint sleeve to increase a force applicable to move the bottom hole assembly in an opposite direction.

This method can further provide for determining a direction for forward progress of a drill bit and directing the flow of drilling fluid from the orifices toward a lateral face of a well bore in a manner currently practiced in directional drilling programs.

Where the point-the-bit directional drilling apparatus is used, this method can include determining a direction for forward progress of a drill bit and directing the flow of drilling fluid from the orifices to a universal joint sleeve connected to a drill bit to move the drill bit in set direction. Since the lateral hydraulic force exerted by the drilling fluid flow through the lateral orifices is a function of the distance from the distal tip of the orifice to the opposing well bore face, this method can also provide the steps of adjusting a gap between a distal tip of the orifices and a well bore face to increase a hydraulic force applicable to move the bottom hole assembly in an opposite direction, or diverting a portion of drilling fluid through a lateral pad of a rotary steerable drill bit system to direct additional force against a lateral bore hole wall.

A directional drilling bottom hole assembly used to practice the method of this invention is a bottom hole assembly having one or more lateral orifices circumferentially spaced around said bottom hole assembly, and activation valves to selectively open and close said lateral orifices to provide lateral hydraulic force on said directional drilling bottom hole assembly. The directional drilling bottom hole assembly can further provide in the bottom hole assembly a drill bit and a control unit for sensing and controlling drilling fluid flow through the lateral orifices which control the movement of the assembly while drilling. This may be controlled either from the surface by the collection and transmission of data or using auto-steering techniques to control the direction based upon sensor input.

The directional drilling bottom hole assembly can be entirely located in a control unit located adjacent a drilling motor. Alternatively, the directional drilling bottom hole assembly can be adapted to a standard push-the-bit drilling assembly by providing orifices in each control pad to selectively and lateral forcefully move drilling fluid against the borehole thereby minimizing wear on the pads to achieve directional control.

The method can additionally further comprise diverting a portion of drilling fluid through a lateral pad of a rotary steerable drill bit system to direct additional force against a lateral bore hole wall or diverting a portion of drilling fluid through one or more lateral orifices to direct the drill bit and the entire drilling BHA straight ahead along the longitudinal axis of the drilling BHA. This method can further be accomplished by using a control module/unit to measure and process drilling parameters, direction and orientation of the BHA, and using that information to control opening and closing of said lateral orifices to achieve the desired drilling direction.

The present invention also encompasses a directional drilling bottom hole assembly comprising: a bottom hole assembly; one or more lateral orifices circumferentially spaced around said bottom hole assembly; and, activation valves to selectively open and close said lateral orifices to provide lateral hydraulic force on said directional drilling bottom hole assembly. This embodiment can also be realized wherein the bottom hole assembly comprises a drill bit and a control unit or wherein the bottom hole assembly comprises a control unit located adjacent a drilling motor or wherein the lateral orifices are located in the drill bit body.

The apparatus of this embodiment can also provide the lateral orifices either located in the hole gauge section of the drill bit assembly, or in a separate BHA section between the drill bit an the control unit or in a section that is integral part of a control unit. Additionally, this apparatus can provide the lateral orifices inside a universal joint sleeve connected to a drill bit in a point-the-bit drilling assembly thereby permitting the hydraulic pressure to move the sleeve in the desired direction. The directional drilling bottom hole assembly can be accomplished wherein the bottom hole assembly comprises a push-the-bit drilling assembly and wherein the lateral orifices are in a control pad or wherein the bottom hole assembly comprises a mechanism for adjusting a gap between a distal tip of the lateral orifices and a well bore face or a universal joint sleeve to increase a force applicable to move the bottom hole assembly in an opposite direction.

The directional bottom hole assembly apparatus of this invention can also provide the bottom hole assembly which provides a mechanism for diverting a portion of drilling fluid through lateral orifices to direct the drill bit and the entire drilling BHA straight ahead along the longitudinal axis of the drilling BHA. Finally, the bottom hole assembly of this invention can comprise a control module/unit to measure and process drilling parameters, direction and orientation of the BHA, and uses that information to control opening and closing of said lateral orifices to achieve the desired drilling direction.

Possible benefits/advantages of the proposed drilling tool steering method and apparatus are:

- Simpler tool design—elimination of many parts, subassemblies and manufacturing processes, such as clamp plate subassemblies, kickers, pads, pistons, toroidal bore, hardfacing, nuts and bolts and other parts currently needed to achieve the push-the-bit force used for steering drilling tools.
- Elimination or minimization of wear of outer bias or steering unit parts due to fluid-only contact with the abrasive borehole.
- Substantial reduction of shock loads on the drilling bottom-hole assembly (BHA), because the fluid used to produce the lateral hydraulic force would absorb much of shock loading thereby increasing BHA reliability.
- Substantially lower cost of new bias or steering units because of fewer parts and manufacturing processes.