This invention relates to the field of directional drilling tools. The prior art includes several methods for steering a tool string. A bent sub system is generally depicted in
A push-the-bit system is generally depicted in
Variations of these systems are disclosed in the following prior art documents. U.S. Pat. No. 5,529,133 to Eddison, which is hereby incorporated by reference for all that it contains, discloses a steerable rotary drilling tool that includes a drill bit mounted on the lower end of a housing by a drive shaft having an articulative coupling that allows the bit's rotation axis to be inclined relative to the rotation axis of the housing, an eccentric weight in the housing that maintains the bit axis pointed in only one direction in space as the bit is turned by the housing, and a clutch system that allows such direction to be changed downhole. A measuring-while-drilling tool is included to allow the progress of the drilling to be monitored at the surface, and to allow changing the bit axis or toolface by a selected amount.
U.S. Pat. No. 5,078,650 to Foote which is herein incorporated by reference for all that it contains discloses a universal joint arrangement that includes a first adapter having two projecting support formations; a drive plate having a first pair of matching depressions or pockets is seated with these depressions on the projecting support formations of the first adapter and the drive plate has a second pair of pockets for the projecting support formations of a respective second adapter.
U.S. Pat. No. 7,188,685 to Downton which is herein incorporated by reference for all that it contains discloses a bottom hole assembly that is rotatably adapted for drilling directional boreholes into an earthen formation. It has an upper stabilizer mounted to a collar, and a rotary steerable system. The rotary steerable system has an upper section connected to the collar, a steering section, and a drill bit arranged for drilling the borehole attached to the steering section. The steering section is joined at a swivel with the upper section. The steering section is actively tilted about the swivel. A lower stabilizer is mounted upon the steering section such that the swivel is intermediate the drill bit and the lower stabilizer.
In one aspect of the invention a tool string steerable system has a drill bit body with a working face. An indenter protrudes from the working face, and the indenter is rotational fixed to a tool string component above the drill bit body. The indenter is rotationally isolated from the drill bit body.
The drill bit body may be attached to a downhole motor housed within the tool string, and the indenter may be rigidly attached to the motor. In some embodiments, the motor may be a hydraulic motor, an electric motor, a positive displacement motor, or a combination thereof Embodiments with a positive displacement motor may comprise a central stator and an outer rotor that moves around the central stator. A rotary bearing may be disposed between an inner surface of the tool string's bore wall and the outer surface of the outer rotor. At least one end of the outer rotor may comprise a thrust bearing. In some embodiments, the outer rotor is rotationally fixed to the drill bit body. A collar may be disposed within at least a portion of the tool string and rigidly connected at a first end to the drill bit body and to the outer rotor at a second end.
A drive shaft connected to the indenter may run through the motor. A universal joint or a constant velocity joint may be used to keep the indenter centered despite the nutating motion caused by the positive displacement motor.
The indenter may comprise an asymmetric distal end. In some embodiments, the distal end comprises a planar region that forms an angle of 35 to 55 degrees with the drill bit's axis of rotation. The indenter may be coaxial with the drill bit's rotational axis.
In some embodiments, the drill bit body may be rigidly attached to a turbine. Also, the system may include an orientation package that determines the indenter's orientation relative to the drill bit body.
In another aspect of the invention a tool string steerable system has a drill bit body with a working face and a shank. The drill bit body is rotationally isolated from the tool string. An indenter protrudes from the working face, and the indenter is rotational fixed to a tool string. The indenter is rotationally isolated from the drill bit body.
a is a cross sectional diagram of an embodiment of a bent sub steering system.
The drive shaft may be connected to the indenter's proximal end 211. Thrust and rotary bearings 212 are disposed within the bore 204 to help stabilize the indenter. A portion of the collar 203 is connected to the outer rotor at one end 213 and threaded to the drill bit at the other end 214.
When a straight trajectory is desired, the tool string is rotated, preferably by a kelly at the surface or by a top hole drive. Rotating the tool string rotates the indenter, so the asymmetric distal end can not urge the drill bit in any particular direction.
The indenter is preferably made of a cemented metal carbide with adequate hardness and toughness for harsh drilling environments. In some embodiments, the indenter's distal end is enhanced with sintered polycrystalline diamond, cubic boron nitride, or another suitable material harder than carbide. Asymmetries of the indenter's distal end that may be compatible with the present invention are disclosed in U.S. Pat. Nos. 7,506,701 and 7,360,610 and U.S. Patent Publication Nos. 2007/0272443, 20080142264, 2009/0133936, which are all incorporated by reference for all that they contain. In some embodiments, the distal end comprises a planar region 304 that forms a 35 to 55 degrees angle with the drill bit's rotational axis 303.
The present figure discloses a rotary drag bit with conventional cylindrically shaped diamond enhanced cutters 305. In some embodiments, the cutters may be chisel or conical shape. Percussion bits, roller cone bits, horizontal drill bits, and water well bits may be adapted to include the steering system.
The indenter may off load some weight-on-bit (WOB) and contribute to breaking the formation in compression. The distal end's build rate may be affected by the formations' hardness, the amount of WOB loaded to the indenter, and the amount of WOB loaded to the bit's working face. In some embodiments, the indenter is capable of moving vertically with respect to the working face to adjust the amount of WOB loaded to the indenter. In some embodiments, a hammering mechanism may also be adapted to induce a vibration through the indenter to degrade the formation or induce an acoustic signal into the formation.
The drive shaft's rigid connection to the tool string's bore wall may include threading, welding, bonding, or keying them together. Fluid bypass ports 404 are preferably incorporated in the connection so drilling mud can pass through.
In some embodiments, no joints (constant velocity or universal) are necessary because the central stator is sufficiently rigidly connected to the downhole pipe and all of the movement takes place in the rotor. In some embodiments, the central stator moves laterally from the action of the positive displacement motor, but remains rotational fixed to the tool string.
In some embodiments, a gyroscope, magnetometer for sensing the earth's magnetic field, and/or accelerometers may be used to determine the relative orientations of the drill bit body and the indenter.
Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.
This Patent Application is a continuation-in-part of U.S. patent application Ser. No. 12/362,661 which is a continuation-in-part of U.S. patent application Ser. No. 11/837,321, which is a continuation-in-part of U.S. patent application Ser. No. 11/750,700, which is a continuation in-part of U.S. patent application Ser. No. 11/737,034, which is a continuation in-part of U.S. patent application Ser. No. 11/686,638 which is a continuation-in-part of U.S. patent application Ser. No. 11/680,997 which is a continuation-in-part of U.S. patent application Ser. No. 11/673,872 which is a continuation-in-part of U.S. patent application Ser. No. 11/611,310, which is a continuation-in-part of U.S. patent application Ser. No. 11/278,935 which is a continuation-in-part of U.S. patent application Ser. No. 11/277,294 which is a continuation-in-part of U.S. patent application Ser. No. 11/277,380 which is a continuation-in-part of U.S. patent application Ser. No. 11/306,976 which is a continuation-in-part of U.S. patent application Ser. No. 11/306,307 which is a continuation-in-part of U.S. patent application Ser. No. 11/306,022 which is a continuation-in-part of U.S. patent application Ser. No. 11/164,391. All of these applications are herein incorporated by reference in their entirety and their priorities claimed.
Number | Date | Country | |
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Parent | 12362661 | Jan 2009 | US |
Child | 12491149 | US | |
Parent | 11837321 | Aug 2007 | US |
Child | 12362661 | US | |
Parent | 11750700 | May 2007 | US |
Child | 11837321 | US | |
Parent | 11737034 | Apr 2007 | US |
Child | 11750700 | US | |
Parent | 11686638 | Mar 2007 | US |
Child | 11737034 | US | |
Parent | 11680997 | Mar 2007 | US |
Child | 11686638 | US | |
Parent | 11673872 | Feb 2007 | US |
Child | 11680997 | US | |
Parent | 11611310 | Dec 2006 | US |
Child | 11673872 | US | |
Parent | 11278935 | Apr 2006 | US |
Child | 11611310 | US | |
Parent | 11277294 | Mar 2006 | US |
Child | 11278935 | US |