The present invention relates, generally, to a drilling apparatus and method for drilling a well. More particularly, but not by way of limitation, the present invention relates to a non-reactive torque device that contains an inner bit and a counter-rotating outer bit and a related method of use. Embodiments of the present invention will significantly reduce the reactive torque generated during the drilling phase of a well bore.
In the search for oil and gas, operators have utilized various types of devices to drill wells. Operators are continually searching for ways to drill the wells faster and more economically. Traditionally, a specifically designed drill string was used to drill wells. The drill string would have attached thereto a drill bit. To drill the well, the driller would cause the drill string to rotate, which would in turn cause the bit to rotate, and thus, drill the well. Over the years, various types of drill strings have been developed in order to enable drilling directional, or inclined, well bores.
Further, different types of bottom hole assemblies have also been developed to facilitate drilling these wells. A typical directional drill string may contain a bottom hole assembly which includes: a bit, a bent sub, a drilling motor, and one or more measurement-while-drilling surveying and logging tools. When using this type of bottom hole assembly, the drill string ideally is held stationary with respect to down hole rotation. The drilling motor causes rotation of the bit via circulation of drilling fluid through the drilling motor, as is well understood by those of ordinary skill in the art. With the drill string held stationary with respect to rotation, the well is drilled in the desired, controlled direction of the bend in the bent sub.
A common problem encountered when using this type of drilling assembly is the torque generated by the bit. Torque from the bit torque generates an equal and opposite reactive torque that is transferred from the motor into the bottom hole assembly and drill string, causing it to counter-rotate relative to the bit. Further, the reactive torque, and hence the drill sting counter-rotation, varies due to drilling conditions, such as the weight applied to the bit, properties of the rock being drilled, and hole condition, all of which 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 drilled changes with the changes in 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 the desired direction. These numerous adjustments cost valuable rig time and reduce the efficiency of the drilling operation. 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 the bit to increase drilling rates and enable drilling of 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 express reference.
As those of ordinary skill in the art will appreciate, daily rig costs are substantial. In many cases, 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 provides significant cost savings. Prior art tools have not enabled 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.
The 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. However, embodiments of the non-reactive torque drilling device herein described, drilling with an attached casing string is possible. Numerous advantages and features flow from embodiments of the present invention.
Therefore, there is a need for a drilling apparatus that will allow the drilling of a well with a casing string attached thereto. There is also a need for a non-reactive drilling tool with dual bits, that enables a casing string to be left within the well after cessation of drilling operations. The casing string can be cemented in place, and other remedial well work can then be performed, such as perforating the casing to produce hydrocarbons from a subterranean reservoir.
An apparatus for drilling a well bore with a down hole motor is disclosed. The down hole motor contains a power shaft for imparting rotational movement. In one preferred embodiment of the invention, the apparatus includes a driver operatively connected to the power shaft, with the driver having a cylindrical body, wherein an outer portion of the cylindrical body contains a plurality of cogs. The apparatus further contains a first bit having a first end, wherein the first end is connected to the driver so that rotational movement of the driver is imparted to the first bit. A sleeve disposed about a portion of the power shaft, with the sleeve having a plurality of pinions placed therein, such as through use of openings for containing the pinions using pins disposed there through, the sleeve having a radial shoulder for attaching the plurality of pins. A housing is included, with a second bit is formed on a first end. The second bit can be offset relative to the first bit such that the first bit extends farther into a well than the second bit. The housing has an internal portion that contains internal cogs, which engage the pinions within the sleeve so that as the driver rotates in a first direction, rotation is imparted to the pinions which in turn imparts a counter rotation to the second bit.
In one preferred embodiment, the driver contains an outer radial surface that is disposed within the sleeve, the outer radial surface containing an outer coating material for preventing wear with the sleeve during rotation. The apparatus can further include thrust bearing means, operatively positioned within the housing, for transferring the axial and lateral loads of the apparatus during drilling. The thrust bearing means generally include a thrust mandrel disposed between the housing and the driver, and a plurality of roller bearings operatively associated with the thrust mandrel. A trim spacer may also be included, disposed within the housing and abutting the thrust mandrel, for engagement with the thrust mandrel. In various embodiments of the invention, the first bit can be offset relative to the second bit, such that the first bit extends farther into a well bore relative to the second bit.
In one embodiment, the sleeve is attached to a coiled tubing string. In another embodiment, the downhole motor and planetary bit driver is attached to a work string. And, in the most preferred embodiment, the sleeve is attached to a casing string.
A method of drilling a well with a motor having a power shaft is also disclosed. The method comprises providing a drilling apparatus, as described previously, having a first bit connected to a driver, a sleeve about a portion of the power shaft having pinions disposed therein, and a housing having a second bit formed thereon, with internal cogs for engaging the pinions
The method further comprises providing a string concentrically placed within the well, which can include a casing string in various embodiments of the invention, the string being operatively connected to the sleeve. The power shaft is rotated, such as through use of a fluid flow down an internal portion of the string and drilling apparatus, which causes rotation of the first bit in a first direction, thereby drilling the well with the first bit. Rotation of the first bit also includes rotation of the cogs on the driver, which engage and rotate the pinions, which in turn engage and rotate the internal cogs on the housing, thereby causing rotation of the second bit in a counter direction opposite the first bit.
The method can further include terminating the drilling of the well with the first bit and the second bit, such as by terminating fluid flow down the string and drilling apparatus. The internal portion of the drilling apparatus, including the first bit, can be retrieved from the well. If a casing string is used with drilling apparatus, the casing string can then be cemented in place within the well, and perforated to enable communication with a subterranean reservoir.
In yet another preferred embodiment, a device for boring a well is disclosed. In this most preferred embodiment, the device is attached to a motor and wherein the motor has a power shaft for imparting rotational movement. The apparatus comprising a driver mandrel operatively connected to the power shaft, with the driver mandrel containing a cylindrical body. Also included is a first bit member having a first end and a second end, and wherein the first end is connected to the driver mandrel so that rotational movement of the driver mandrel is imparted to the first bit member, and wherein the first bit member has an inner bore. A sleeve is disposed about a portion of the power shaft, and wherein the sleeve has a radial shoulder. In this preferred embodiment, a casing string is attached to the sleeve, and wherein the casing string is designed to be permanently placed within the well once the boring is completed, and wherein the inner bore of the casing string is in fluid communication with the inner bore of the first bit. The device further includes a housing disposed about the driver mandrel, a second bit member attached to the housing, and a planetary gear anchored to the radial shoulder and disposed between the driver mandrel and the housing, and wherein the planetary gear is adapted for imparting rotation from the driver mandrel to the housing in a counter radial direction.
The device may further comprise thrust bearing means, operatively placed between the housing and the driver mandrel, for transferring the axial and lateral loads generated during boring. The thrust bearing means comprises a thrust mandrel and a plurality of ball bearings operatively associated with the thrust mandrel. A bearing assembly may also be included, wherein the bearing assembly having a first end and a second end, with the second end of the motor housing being rotatably associated with the first end of the bearing assembly so that rotation of the first bit member and the second bit member is facilitated. Additionally, the first bit includes a first set of cutter teeth positioned to drill the well in the first rotational direction and the second bit includes a second set of cutter teeth positioned to drill the well in the counter rotational direction. Also, in the most preferred embodiment, the first bit member is offset relative to the second bit member so that the first bit member extends further into the well relative to the second bit member.
An advantage of the present invention is the ability to drill with non-reactive torque utilizing a first bit and a second concentric bit. Another advantage of the present invention is that wells can be drilled and completed faster. Another advantage is that the work string used with the dual bit is a casing string. Yet another advantage is that a casing string can be left in the hole after the intended total depth of the well is reached.
Still yet another advantage is that after drilling the well, the well can be cemented. By cementing the well quicker than prior art methods, the well will experience less skin damage to potential hydrocarbon bearing reservoirs. Another advantage is that operators will realize significant cost savings due to significantly faster completion times. Another feature is that the drilling apparatus can utilize coiled tubing string as a work string, and wherein drilling is possible utilizing the coiled tubing string due to the non-reactive torque produced by the disclosed drilling apparatus.
A feature of the present invention includes the ability to drill-in with a casing string without the need to pull the entire length of casing string from the well. Yet another feature is that the casing string can be cemented into the well. Yet another feature is the option to perforate the casing string to produce hydrocarbon reservoir. Another feature is that the drill-in casing string can employ the same thread connection means used on commercially available casing strings. In other words, commercially available thread means can be used with the drill-in casing. Yet another feature is the pinions are mounted about pins, and are mounted on a radial shoulder of the sleeve. Therefore, the pinions are capable of rotation. Still yet another feature is that the down hole motors used with the disclosed system are commercially available.
Referring now to
Referring now to
The power shaft 4 is connected to the down hole motor 84 (also referred to as a mud motor). Down hole motors are commercially available from Robbins and Meyers Inc. under the name positive displacement motors. As seen in
Referring now to
Referring now to
As those of ordinary skill in the art will appreciate, many times a well progresses in a series of hole sections which are drilled in progressively smaller hole sizes. Casings are run to consolidate the current progress, to protect some zones from contamination as the well progresses (such as freshwater sources) and to give the well the ability to hold higher pressures.
Referring now to
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.
The present application is a continuation application, claiming priority to the U.S. patent application having Ser. No. 11/713,942, filed Mar. 5, 2007, and to the U.S. patent application having Ser. No. 11/904,136, filed Sep. 26, 2007, both of which are incorporated herein by reference in their entirety.
Number | Date | Country | |
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Parent | 11904136 | Sep 2007 | US |
Child | 12584100 | US | |
Parent | 11713942 | Mar 2007 | US |
Child | 11904136 | US |