The present invention relates to a coil tubing system including a rig and, more particularly, to using coil tubing and a drilling bottom-hole assembly (BHA) during mining exploration applications, and to using threaded tubulars and a coring bottomhole assembly during coring operations with the same rig.
In typical mining operations, an earth borehole apparatus is used to drill a borehole and then obtain a core sample from a desired subsurface locations. Analysis of a core sample provides information as to the composition of the subsurface formation and helps geologists determine whether further mining activity is warranted. Apparatus for conducting coring operations, as well as core sampling tools, e.g., core barrels, are well known to those skilled in the art.
In the drilling of a conventional earth and/or hard rock borehole prior to coring, successive lengths of the casing are connected to a suitable bottom-hole assembly, such as a reverse circulation air hammer or a drill bit. In a typical coring operation, the apparatus comprises a mast, a powered drill head or drive unit with a chuck mounted on the mast for longitudinal movement therealong, and threaded tubular pipe similar to surface casing used in oil and gas well drilling, or a rod string.
Typically, a borehole used in the mining exploration coring operations will be up to about 3,000 meters deep, and can be vertical or at an angle up to about 45°. Drilling below a cased surface borehole may be conducted with various types of drilling methods, such as diamond bits or percussion reverse circulation air hammer bits. The cuttings are commonly returned to the surface using an aqueous medium. The fluid is pumped down the drill string and returned up the annulus between the borehole and the drill string. The cuttings and chip samples may be analyzed to determine the general composition of the subsurface formation at any given depth. In the past, coring activities have been conducted after drilling with a string of rods, or with casing pipes extending to the desired depth to determine the precise composition of the cored sample.
One of the drawbacks of these conventional methods of drilling is that it requires the making and breaking of successive length of threaded drill pipe, which is jointed. This operation is time consuming and labor intensive, as well as posing safety concerns. The use of so-called down the hole (DTH) percussive drilling assemblies, particularly so-called water hammers, has found wide-spread acceptance in the mining field for percussive drilling of a bore hole in hard rock condition.
Relevant patents include U.S. Pat. Nos. 4,694,911, 5,476,421, 5,647,445, 5,803,118, 6,125,952, 7,073,610, 7,240,744, 7,617,886, and 7,748,478. Other publications of interest include a description of products and services of Coil Tubing Technology Holding Inc., Products & Services, Operational Strategy by Scientific Prospectus: Integrated Ocean Drilling Program Expedition 313, Steerable Percussion Air Drilling System by Huy Bui, et al., Percussion Drilling in Oil Industry: Review and Rock Failure Modelling by Gang Han, et al., Water Driven Down-the-Hole Well Drilling Equipment for Hard Rock by Bo Nordell, et al., U.S. Publications 2004/0140131 and WO 2008/068546.
The disadvantages of the prior art are overcome by the present invention, an improved system for drilling and coring a mining exploration well is hereinafter disclosed.
It is therefore the logic of the present invention to provide a system for drilling earth and/or hard rock boreholes, then for coring during mining exploration activities.
Another object of the present invention is to provide a method for drilling an earth and/or hard rock type borehole, and then core sampling in mining exploration applications.
In one aspect, the present invention provides a drilling system comprising a rig with a mast, a coil tubing injector attached to the mast for selective movement into an out of alignment with the mast, and a drilling BHA comprising a percussive drilling component, e.g., water hammer, a shock sub assembly and a down-hole fluid motor. The same drilling rig may be used for coring conducted with threaded tubulars, with a drilling head chuck or drive unit carried by the mast for longitudinal movement along the mast while rotating the tubular string, and a coring BHA including a core sampler.
These and further features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.
Referring first to
Extending from the top and attached to coil tubing injector 22 is a segmented guide arch shown generally as 24, having a first section 26 and a second section 28. The guide arch 24 may be moved from its substantially horizontal transportation position, wherein injector 22 and guide arch 24 rest on a suitable support or bed 24 for transit, to the vertical position, as shown in
Sections 26 and 28 of guide arch 24 are connected by a hydraulic/piston cylinder arrangement 25, so that when injector 22 is in its operative position, i.e., pivoted so as to be in line with mast 16, section 26 is pivoted by means of hydraulic piston cylinder 25, so that a smooth curve is formed whereupon coil tubing from reel 16 can be passed through guide arch 24 and into injector 22.
The drilling BHA of the present invention is generally comprised of drill collars, one or more stabilizers, a shock absorber sub, a downhole fluid motor or mud motor, a water hammer and a connection to connect to the coil tubing. One such assembly is shown in
Drilling is conveniently carried out using, for example, a DTH water hammer 30 manufactured and marketed by Wassara. Water hammers of the type under consideration are generally powered by high water pressure which in this case is pumped through coil tubing 40 using pumping equipment mounted on the bed 12 of truck T. The high pressure water or other incompressible fluid provides both the driving force for the hammer and rotation of the rotor of the fluid motor 34 for delivering a known revolution range needed for adequate drilling performance, as well as returning the cuttings to the surface for possible analysis.
Because it is necessary for the efficiency of drilling to rotate the water hammer 30 so as to present a constantly changing face for impact, down-hole fluid motor 34 is employed to rotate the portion of the BHA below motor 34. Mud motor 34 in conjunction with steering capabilities also ensures that the borehole stays on a desired track.
Because coil tubing is used, there is no necessity to stop the drilling operation for the purpose of adding additional joints of drill pipe as would be conventionally done. Furthermore, when it is necessary to replace the bit mounted on the water hammer, it is unnecessary to break out successive joints of threaded tubular rods since the coil 40 can simply be reeled back upon the reel 16 to retrieve the drilling BHA and replace the bit.
In a typical coring operation, the drilling head/chuck 20 and mast 16 in the
A suitable coring bottomhole assembly 50 as shown in
The present invention is particularly suitable for conducting coring activities for mining operations which require a core sample to return to the surface for analysis. The present invention can also be used for other applications in which a well is drilled and a core sample obtained.
A drill rig as disclosed herein includes an injector which is movable from a position in line with the mast for conducting coil tubing operations, e.g., when drilling the well, but the injector may be spaced laterally from the mast for conducting coring operations which require threaded tubulars. In a preferred embodiment as disclosed herein, the injector will be tilted into and out of alignment with the mast by one or more hydraulic cylinders in a manner similar to the disclosure in WO 2008/068546. In other applications, the injector may be moved laterally relative to the mast from an in line to an out of line position. In the out of line position, the injector is thus sufficiently spaced from the mast so as not to interfere with the movement of threaded tubulars. Moreover, this feature allows the drive unit which moves along the mast and rotates the threaded tubulars to be positioned below the injector, so that when the rig is moving coil tubing with the injector, the coil tubing passes through the drive unit.
The present system presents a huge improvement toward a safer environment for the drill workers as well as a cost effective improvement to the mining exploration drilling practice.
Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.
This application claims the priority of U.S. Provisional Application No. 61/301,116 filed on Feb. 3, 2010.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2011/023605 | 2/3/2011 | WO | 00 | 11/16/2012 |
Publishing Document | Publishing Date | Country | Kind |
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WO2011/097380 | 8/11/2011 | WO | A |
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Number | Date | Country | |
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20130056276 A1 | Mar 2013 | US |
Number | Date | Country | |
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61301116 | Feb 2010 | US |