Drilling apparatus and system for drilling wells
A device for boring a well is provided, the device being attached to a motor having a power shaft for imparting rotational movement responsive to a fluid flow. The device includes a driver operatively connected to the power shaft, the driver having a tubular body with an internal bore for accommodating fluid flow, a first bit connected to the driver at a first end so that rotational movement of the driver is imparted to the first bit, and an inner bore. A second bit is attached to housing about the first bit. A nozzle communicating the internal portion of the tubular body with an outer portion thereof, the nozzle being oriented to deliver a portion of the fluid flow to the second bit.
The present application is a continuation application, claiming priority to the U.S. patent application having Ser. No. 11/904,136, filed Sep. 26, 2007, which claims priority to the U.S. patent application having Ser. No. 11/713,942, filed Mar. 5, 2007, now U.S. Pat. No. 7,607,496. The present application also claims priority to the U.S. patent application having Ser. No. 12/584,100, filed Aug. 31, 2009. The above-referenced patents and patent applications are incorporated herein by reference, in their entirety.
BACKGROUND OF THE INVENTIONConventionally, in the search for oil and gas, operators have utilized a specifically designed drill string to drill wells, the drill string being attached to a drill bit. To drill the well, the drill string is rotated, which in turn causes the bit to rotate, forming a hole in the earth, thus drilling the well. Various types of drill strings have been developed to drill directional, or inclined, well bores.
Different types of bottom hole assemblies have also been developed to drill wells. A typical drilling string for use drilling directional well bores may contain a bottom hole assembly having a bit, a bent sub, a drilling motor, and one or more measurement-while-drilling surveying and logging tools. When using a conventional bottom hole assembly, the drill string ideally is retained in a stationary orientation with respect to down hole rotation. The drilling motor generates rotation of the bit via circulation of the drilling fluid through the drilling motor, as known in the art. With the drill string retained in a stationary orientation with respect to the rotation, the well is drilled in the desired, controlled direction of the bend in the bent sub.
A common problem when using this type of drilling assembly is the torque generated by the bit. The torque from the bit generates an equal and opposite reactive torque that is transferred from the motor into the bottom hole assembly and drill string, causing counter-rotation relative to the bit. Further, the reactive torque, and hence the drill sting counter-rotation, can vary due to drilling conditions, such as the weight applied to the bit, properties of the rock being drilled, and the hole condition, which all vary independently of each other. As the bent sub is part of the bottom hole assembly being counter-rotated, the direction in which the well is being drilled changes responsive to changes in the reactive torque.
As a result, the directional driller is required to make numerous surface adjustments of the drill string, and hence the bent sub, to maintain drilling in a desired direction. These numerous adjustments reduce the efficiency of the drilling operation and require substantial time and cost. By eliminating, or greatly reducing, the reactive torque in the bottom hole assembly and drill string, drilling can proceed unabated in the desired direction, saving valuable rig time. Other benefits of eliminating, or reducing, reactive torque include the ability to use more powerful motors and more weight on bit to increase drilling rates, and the ability to drill a smoother, less tortuous borehole for running logging tools and setting casing. A non-reactive bit apparatus and method were disclosed in U.S. Pat. No. 5,845,721 entitled “Drilling Device And Method Of Drilling Wells”, which is incorporated herein by reference.
After a well is drilled, the well is prepared for running and cementing a casing string into the well. Hence, any time saved cleaning, running and cementing the casing can result in significant cost savings. Conventional tools have not allowed an operator to effectively drill with a casing string forming a part of the work string due to structural limitations of the casing string and the casing string thread connections. Generally, casing strings and casing string connections are not structurally designed to handle the stress and strain applied by the numerous torquing requirements for a drill string. Use of a non-reactive torque drilling device can enable drilling with an attached casing string.
Therefore, a need exists for a drilling device that will allow the drilling of a well with a casing string attached thereto, with the casing string able to be left within the well after cessation of drilling operations such that additional remedial operations, such as perforation of the casing, can be performed. There is also a need for a non-reactive drilling tool with dual bits.
SUMMARY OF THE INVENTIONEmbodiments of the invention relate, generally, to devices for boring a well that include a motor with a power shaft for imparting rotational movement responsive to fluid flow. A driver can be operatively connected to the power shaft, the driver having a tubular body with an internal bore for accommodating the fluid flow. A first bit is attached to the driver such that rotational movement of the driver is imparted to the first bit. A second bit is attached to or otherwise formed on a housing disposed about the driver. A nozzle communicates fluid between the internal bore of the tubular body to an outer portion of the tubular body, the nozzle being oriented to deliver at least a portion of the fluid flow to the second bit. Directing of the fluid flow directly to the second bit can maximize the removal of cuttings. Additionally, the upward flow direction of the nozzles can provide a Venturi affect that reduces bottomhole pressure below the nozzles, which can improve hydraulic performance and drilling performance of the bits.
In an embodiment of the invention, the nozzles can be provided in a cross-over sub, or similar element, between the drive shaft and the first bit. In a further embodiment of the invention, a flow directing skirt can be provided to the cross-over sub and/or to the housing of the driver to direct fluid flow toward the second bit, the junk slot area, and into the annulus, which can further facilitate removal of cuttings generated by the first bit and cleaning of the second bit. In another further embodiment of the invention, the nozzles can include three or more nozzles angled in an upward direction, such as at an approximate 45 degree angle, oriented to provide fluid to the cutters of the second bit.
Referring now to
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The power shaft 4 is shown connected to a down hole motor 84, which can include a mud motor, such as a positive displacement motor available from Robbins and Meyers Inc. As seen in
Referring now to
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Under many circumstances, a well is drilled in a series of sections, which are provided with progressively smaller hole sizes. Casings are run to consolidate the current progress, to protect some zones from contamination and to provide the well with the ability to hold higher pressures.
Referring now to
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Disposed within the first passage is a first nozzle 144, and disposed within the second passage is a second nozzle 146. The nozzles 144, 146 are shown oriented relative to the axial center line 148, in an upward direction, such as an approximate forty-five (45) degree angle of inclination. In various embodiments of the invention, the angle of inclination can range from 30 degrees to 75 degrees in an upward direction. While
Referring now to
In an embodiment of the invention, the nozzles can be machined for threaded placement into the cross-over sub 64 to allow different sizes of nozzles to be used. The nozzles can be supplied with drilling fluid flow from inside the cross-over sub 64. Because the inner bit 70 is drilling only part of the bore hole, a larger quantity of drilling fluid is pumped through the drill string than the quantity is required to adequately clean the inner bit. The nozzles which provide flow “A” on the inner bit can be sized and positioned such that the inner bit will receive the required flow to be effectively cleaned during the drilling. The remainder of the flow (i.e. flow “B”) can ext from the nozzles exiting the cross-over sub 64.
In an embodiment of the invention, the flow skirt 150 can be provided as an integral part of the cross-over sub 64 that extends about the circumference of the cross-over sub 64. The flow skirt 150 can direct drilling fluid flow toward the cutters of the outer bit 58 and into the annulus 162. The flow being directed can be continuous flow from the inner bit and from the nozzles, while the continuous flow from the nozzle will strike the bit face intermittently due to the counter rotation. The flow skirt 150 can also prevent drilling fluid and cuttings from becoming lodged in the bearing area between the cross-over sub 64 and the outer bit 58. Additionally, the flow skirt 150 can be used as simply a deflector sleeve without the use of the nozzles, to deflect fluid flow from the bearing area.
In an embodiment of the invention, the upward direction of the nozzles can provide a Venturi effect that will reduce the bottom-hole pressure below the nozzles. The resulting reduction of bottom-hole pressure can improve both the hydraulic performance and drilling performance of the inner bit 70.
Changes and modifications in the specifically described embodiments can be carried out without departing from the scope of the invention which is intended to be limited only by the scope of the appended claims and any equivalents thereof.
Claims
1. A device for boring a well, the device comprising:
- a driver comprising a first end and a second end, wherein the first end of the driver is operatively connected to a power shaft of a motor for receiving rotational force;
- a first bit attached to the second end of the driver;
- a second bit attached to the driver at a point between the first end and the second end;
- at least one fluid passage comprising a nozzle, wherein said at least one fluid passage communicates between an internal bore of the driver and an exterior of the driver, wherein said at least one fluid passage is disposed between the first bit and the second bit, and wherein said at least one fluid passage, the nozzle, or combinations thereof are angled toward the second bit such that fluid passing through the nozzle flows in an uphole direction to contact the second bit.
2. The device of claim 1, further comprising at least one bearing assembly operatively disposed between the driver and a housing disposed about the driver for transferring axial and lateral loads generated during drilling.
3. The device of claim 2, wherein said at least one bearing assembly comprises a thrust mandrel and a plurality of ball bearings operatively associated with the thrust mandrel.
4. The device of claim 2, wherein said at least one bearing assembly comprises a first end and a second end, and wherein an end of the housing is rotatably associated with the first end of said at least one bearing assembly for facilitating rotation of the first bit and the second bit.
5. The device of claim 1, wherein the first bit comprises a first set of cutter teeth positioned to drill a well in a first rotational direction, and wherein the second bit comprises a second set of cutter teeth positioned to drill the well in a counter rotational direction opposite the first rotational direction.
6. The device of claim 1, wherein the first bit is offset relative to the second bit such that the first bit extends farther into a well relative to the second bit.
7. The device of claim 1, further comprising a casing string disposed in communication with the driver, wherein the casing string is in fluid communication with the first bit.
8. The device of claim 1, further comprising a flow skirt disposed between said at least one fluid passage and the second bit for further directing fluid flow to the second bit.
9. The device of claim 8, wherein the flow skirt comprises a ring member having an angled surface that extends to a radially flat surface.
10. A device for boring a well, the device comprising:
- a driver comprising a first end and a second end, wherein the first end of the driver is operatively connected to a power shaft of a motor for receiving rotational force;
- a first bit attached to the second end of the driver;
- a second bit attached to the driver at a point between the first end and the second end;
- at least one fluid passage comprising a nozzle, wherein said at least one fluid passage communicates between an internal bore of the driver and an exterior of the driver, and wherein said at least one fluid passage is disposed between the first bit and the second bit; and
- a flow skirt disposed between said at least one fluid passage and the second bit for directing fluid flow from said at least one fluid passage to the second bit.
11. The device of claim 10, wherein the flow skirt comprises a ring member having an angled surface that extends to a radially flat surface.
12. The device of claim 10, wherein said at least one fluid passage, the nozzle, or combinations thereof are angled toward the second bit such that fluid passing through the nozzle flows in an uphole direction to contact the second bit
13. The device of claim 10, further comprising at least one bearing assembly operatively disposed between the driver and a housing disposed about the driver for transferring axial and lateral loads generated during drilling.
14. The device of claim 13, wherein said at least one bearing assembly comprises a thrust mandrel and a plurality of ball bearings operatively associated with the thrust mandrel.
15. The device of claim 13, wherein said at least one bearing assembly comprises a first end and a second end, and wherein an end of the housing is rotatably associated with the first end of said at least one bearing assembly for facilitating rotation of the first bit and the second bit.
16. The device of claim 10, wherein the first bit comprises a first set of cutter teeth positioned to drill a well in a first rotational direction, and wherein the second bit comprises a second set of cutter teeth positioned to drill the well in a counter rotational direction opposite the first rotational direction.
17. The device of claim 10, wherein the first bit is offset relative to the second bit such that the first bit extends farther into a well relative to the second bit.
18. The device of claim 10, further comprising a casing string disposed in communication with the driver, wherein the casing string is in fluid communication with the first bit.
19. A method for boring a well, the method comprising the steps of:
- rotating a first bit in a first direction to thereby cause the first bit to bore into a formation, wherein rotation of the first bit produces a first torque;
- rotating a second bit in a second direction opposite the first direction to cause the second bit to bore into the formation, wherein rotation of the second bit produces a second torque equal and opposite the first torque, thereby minimizing effects of the first torque; and
- flowing drilling fluid in an uphole direction to contact the second bit.
20. The method of claim 19, wherein the step of rotating the first bit in the first direction comprises rotating a drive member of a motor in operative communication with the first bit.
21. The method of claim 20, wherein the step of rotating the second bit in the second direction comprises transferring rotational force from the drive member to at least one associated gear or pinion to change the direction of the rotational force, and transferring the rotational force from said at least one associated gear or pinion to the second bit.
22. The method of claim 20, wherein the step of flowing drilling fluid in the uphole direction to contact the second bit comprises providing the drilling fluid through at least one fluid passage disposed between the first bit and the second bit, wherein said at least one fluid passage is angled in the uphole direction.
23. The method of claim 20, wherein the step of flowing drilling fluid in the uphole direction to contact the second bit comprises contacting the drilling fluid with a flow skirt disposed between the first bit and the second bit, wherein the flow skirt comprises an angled surface for directing the drilling fluid to the second bit.
Type: Application
Filed: Jan 19, 2010
Publication Date: May 27, 2010
Inventor: Robert Charles Southard (Houston, TX)
Application Number: 12/657,330
International Classification: E21B 4/02 (20060101); E21B 7/00 (20060101); E21B 7/28 (20060101); E21B 10/26 (20060101);