The present invention relates to the field of motors, and specifically to using a pressurized fluid to drive a rotary, indexing motor for a drill assembly.
Down-the-hole (DTH) drills are used for oil drilling, geothermal drilling, and other deep earth penetration applications. For nearly any drilling method, rotational energy must be transferred downhole in order to promote rock reduction. The drill bit may be rotated by an electric motor or fluid/hydraulic system. The rotating action can be produced either at the surface or near the drill bit. In additional to rotational cutting, drills may also be pressurized or mechanically actuated to force the drill bit to hammer against the rock/earth. Prior art rotation systems and methods are complex, require large form factors to create sufficient torque, and require a high degree of maintenance.
The most common method of downhole energy transfer is rigid drill pipe. The drill pipe is rotated from the surface, with 30 ft drilling joints added for tripping (moving in and out of the hole). For this type of system, the entire drill string rotates. Typically a rotary table system or a top drive is used to drive the drill string. Although it is well suited for vertical drilling, it has limited applications in directional drilling because the drill string curvature and thrust loads generate additional torque that the surface based motor must overcome and drill pipe survive.
Downhole techniques used to generate rotation such as positive displacement motors (PDMs) are limited in their temperature range due to the use of elastomers. Energy resources like geothermal and deep oil and gas wells lie in hot (160° C.-300° C.), and often hard rock. The high-temperatures limit the use of PDM's in those environments.
What is needed is a drill rotation system and method that overcomes the limitations of the prior art.
Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts.
According to an embodiment of the disclosure, a motor assembly is disclosed that includes an engagement mechanism that provides improved peak torque to an output shaft in a compact form factor. The motor includes a vane motor coupled to a drive section. The drive section includes cam lobes releasably coupled to an output shaft.
According to another embodiment of the disclosure, a motor assembly is disclosed that includes a casing, a vane motor disposed within the casing, a drive section coupled to the vane motor; and an output shaft coupled to the drive section. The drive section includes a drive hammer coupled to the vane motor that engages the output shaft to provide rotation thereto.
According to another embodiment of the disclosure, a drill assembly is disclosed that includes a motor assembly a drill bit assembly coupled to the output shaft of the motor assembly. The motor assembly includes a casing, a vane motor disposed within the casing, a drive section coupled to the vane motor; and an output shaft coupled to the drive section. The drive section includes a drive hammer coupled to the vane motor that engages the output shaft to provide rotation thereto.
An advantage of the disclosed motor assembly is improved peak torque to an output shaft in a compact form factor.
Another advantage of the disclosed motor assembly is that the motor assembly is capable of generating rotation during drilling in extreme conditions such as high-temperature. This is due to the fact that it does not require elastomeric components, unlike conventional drilling motors.
Another advantage of the disclosed motor assembly is that the power delivery does not require a gear set to transmit power. The design allows high torque generation in a compact package.
Another advantage of the disclosed motor assembly is the compact packaging can allow directional control using down-the-hole hammer (DTHH).
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
The input end cap 20 is coupled to the outer casing 18 via threads 26. In another embodiment, the input end cap 20 may be welded, brazed or fastened to the outer casing 18. The input end cap 20 includes an internal fluid passage 28 having an inlet 30 and an outlet 32 for receiving and exiting a fluid, respectively.
The motor body 210 includes a motor shaft 211 and a vane section 212. The motor shaft 211 includes a first end 213 for centrally positioning the motor body 210 in the second bearing plate 250, which allows the motor body 210 to freely rotate adjacent the second bearing plate 250. The motor shaft 211 also includes a second end 214 for centrally positioning the motor body in the first bearing plate 240 and for coupling the vane motor 12 to the drive section 14 (see
The vane section 212 includes vane section body 218 attached to the motor shaft 211. The vane body section 218 may be attached to the motor shaft 211 by welding, brazing or other suitable joining method. In another embodiment, the vane body section 218 may be integral to the shaft 211. The vane section 212 further includes vanes 217 attached to the vane section body 218. The areas between the vanes 217 are referred to as chambers 217A. As is appreciated by one of ordinary skill in the art, the vane section body 218 is eccentric with respect to the housing 220. In this manner, the vanes 217 are mounted to the vane body section 218 at offset depths in the vane section body 218 as shown in
The motor body 210 is disposed or fits within the housing 220 in such a manner that the motor body 210 may freely rotate within the housing 220. The housing 220 includes a cavity 221 and has a first end 222 and a second end 224. The cavity 221 is configured to circumferentially surround the vane section 212.
The first bearing plate 240 is attached to the first end 224 of the housing 220 by screw fasteners (not shown). In another embodiment, the first bearing plate 240 may be attached to the housing 220 by welding, brazing, fasteners or other joining method. The first bearing plate 240 includes a bearing 242 and a passage 244 for receiving the motor shaft 211 and allowing the motor shaft 211 to rotate, respectively.
The second bearing plate 250 is attached to the second end 224 of the housing 220 by screw fasteners (not shown). In another embodiment, the second bearing plate 250 may be attached to the housing 220 by welding, brazing, fasteners or other joining method. The second bearing plate 250 includes a bearing 252 and a passage 254 for receiving the motor shaft 211 and allowing the motor shaft 211 to rotate. The second bearing plate 250 also includes channels 258 for distributing a fluid provided by the air distributor 230 to the motor body 210.
The air distributor 230 is attached to the second bearing plate 250 by screw fasteners (not shown). In another embodiment, the air distributor 230 may be attached to the housing 220 by welding, brazing, fasteners or other joining method. The air distributor 230 includes an inlet 232 for receiving a fluid from the fluid passage 28 of the input end cap 20 (see
In such a manner, fluid may flow from the passage 234 of the air distributor 230 to the second bearing plate passage 254, or fluid may flow from the passage 234 into the channels 236 and then into channels 258 of the second bearing plate 250. The amount of fluid that flows through the second bearing plate passage 254 is controlled by orifice 245.
Orifice 245 is disposed within the first end 213 of the motor shaft 211. In another embodiment, the orifice 245 may be disposed within the motor shaft 211, the passage 254 of the second bearing 250, or both. The orifice 245 includes a passage 246 that allows a predetermined amount of fluid to pass through the orifice 245 from the passage 254 of the second bearing to the through passage 216 of the shaft 211. In another embodiment, the orifice 245 may have no passage 246 and functions as a plug to prevent any fluid from entering the through passage 216.
During operation, fluid enters the inlet 30 of inlet section 20, passes through fluid passage 28 and exits the outlet 32 into the inlet 232 of the passage 234 of the air distributor 230. The fluid then enters the channels 236 of the air distributor 230 to be distributed to the channels 258 of the second bearing plate 250 to be directed to the chambers 217A of the motor body 210 or passes through the orifice 245 to enter the through passage 216 of the motor shaft 211, or both. As the fluid travels through the chambers 217A, the vane motor 12 rotates due to pressure differences in the chambers 217A. As discussed above, the vane body section 218 is mounted with an eccentricity EV with respect to the housing 220. The eccentricity creates a variable volume between neighboring chambers 217A. The differential pressure between neighboring chambers 217A results in a non-zero net force. The seal between the vanes 217 and the housing 220 is created by either spring forces or air pressure.
The fluid may be a gas or liquid. In an embodiment, the fluid may be a pressurized gas such as, but not limited to air, nitrogen, or drilling foam. In an embodiment, the pressurized gas may be at a pressure between about 200 psi to about 500 psi. In another embodiment, the fluid may be a pressurized liquid, such as, but not limited to water, hydraulic fluid, or oil.
As can be seen in
Referring again to
As can be further seen in
The rotation of the output shaft 630 by the vane motor 12 will now be described by referring to
An analysis of the energy transfer during rotation is as follows. The rotational hammer is used to generate rotation in the output shaft through the transfer of angular momentum. The rotating hammer is driven to a specified angular velocity before impacting the output shaft. Upon impact, energy is transferred from the rotating hammer to the output shaft, resulting in rotational advancement.
Analysis of the rotating hammer system begins with the vane motor. Given an input pressure P1 and outlet pressure P2, the moment delivered by the motor is given by Equation (1). In the equation, CM is a geometric parameter, LV is the length of the motor, ZV is the number of vanes.
The geometric parameter CM is given by
where am=RR/HV, φV is the angle between vanes, and ω1 is the angle at the end of the charging process.
If the moment is known, then the equation of motion for the rotational hammer is given by Equation (3). In the equation, I1 is the mass moment of inertia of the body, and Mimpact is the torque rebound due to impact. The equation shows that the applied moment from the vane motor is resisted by the impact between the rotational hammer and the output shaft.
I1{umlaut over (θ)}1=MM−Mimpact(t) (3)
The impact moment Mimpact is estimated from the angular impulse imparted to the output shaft. Treating the rotating hammer and the output shaft as a system, the conservation of momentum for the system is given by Equation (4).
I1ω1+I2ω2=I1ω1′+I2ω2′ (4)
The relationship between the rotational speeds before and after impact is given by the coefficient of restitution e.
Looking at the components individually, the moment impulse imparted on the output shaft to cause rotation is given by
I2ω2+MimpactΔt=I2ω2′ (6)
The equation of motion for the output shaft takes a similar form. Assuming the impact moment accelerates the output shaft from rest, then the equation of motion is given by
I2{umlaut over (θ)}2=Mimpact(t)−MWOB (7)
The estimated torque load from the weight on output shaft is given by
where μ is the coefficient of friction, d is the output shaft diameter, WOB is the weight on the output shaft, and Carea is the ratio of the button area (the button area being the surface area of the cutting inserts contacting the cutting surface) to the output shaft face.
An analysis of the applied force between the hammer and output shaft at the position shown in
Referring again to
The bearing/shaft section 16 is held in place in the casing 18 by output end cap 22. Output end cap 22 is assembled to the casing 18 by threads 22A. In another embodiment, the output end cap 22 may be welded, brazed or fastened to the casing 18.
The coupler 24 is attached to the output shaft 30 by threads 25. In another embodiment, the coupler 24 may be welded, brazed or fastened to the output shaft 30. The coupler 24 includes an internal fluid passage 26 having an inlet 26A and an outlet 26B. The inlet 26A is in fluid connectivity with the passage 633 of the outlet shaft 630 so as to receive fluid therefrom and discharge fluid via the outlet 26B. The coupler 24 may be attached to a shaft, drill bit, or other extension for providing rotation to a tool or device.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
This application claims benefit of U.S. Provisional Patent Application No. 61/785,431, “AIR DRIVEN DOWNHOLE DRILLING MOTOR”, filed Mar. 14, 2013, which is incorporated by reference herein in its entirety.
The United States Government has rights in this invention pursuant to Contract No. DE-AC04-94AL85000 between the United States Department of Energy and Sandia Corporation, for the operation of the Sandia National Laboratories.
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4287956 | Mauer | Sep 1981 | A |
6561777 | Grupping | May 2003 | B2 |
7331404 | Pusateri | Feb 2008 | B2 |
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Entry |
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PCT/US2014/019012 International Search Report and Written Opinion dated Jun. 20, 2014. |
Number | Date | Country | |
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61785431 | Mar 2013 | US |