Abstract:
A system for removing desired subsurface materials. A drilling system has a sonic drill head assembly capable of rotating a drill string and transmitting oscillating forces to the drill string. A material removal system comprises an outer tube attachable to the drill string. An inner tube has an outer diameter sized so that that at least a portion of the inner tube is positionable in an inner volume of the outer tube with an annular void defined between the outer tube and the inner tube. A distal end of the inner tube defines at least one opening such that an interior conduit of the inner tube is in fluid communication with the annular void outside of the distal end of the inner tube. Pressurized fluid can be urged from the annular void through the opening to the interior conduit, entraining the desired subsurface materials therein for removal to a discharge tank.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 61/674,356, filed on Jul. 22, 2012, and U.S. Provisional Patent Application Ser. No. 61/674,809, filed on Jul. 23, 2012 the entire disclosures of which are incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     This application relates generally to systems and methods for removing materials below the surface of the earth. More specifically, this application relates to systems and methods for removing subsurface materials without excavating the overburden using “open pit”, “floating dredge” or other conventional excavation methods. 
     BACKGROUND TECHNOLOGY 
     Core drilling allows sampling of subterranean materials from various depths to be obtained for many purposes. For example, drilling a core sample and testing the retrieved core helps determine what materials are present or are likely to be present in a given formation. For instance, a retrieved core sample can indicate the presence of petroleum, precious metals, sand, and other desirable materials. Accordingly, core samples can be used to determine the desirability of further exploration and/or mining in a given area. 
     In sonic core drilling processes, variable frequency vibration is created by an oscillator. The vibration is then mechanically transferred to the drill string of the core barrel and/or casing. The vibration is transmitted in an axial direction down through the drill string to an open-faced drill bit. As a result, the drill string may be rotated and/or mechanically pushed as it is vibrated into the subsurface formation. 
     Often, sonic core drilling processes are used to retrieve a sample of material from a desired depth below the surface of the earth. Although there are several ways to collect core samples, core barrel systems are often used for core sample retrieval. Core barrel systems include an outer tube with a coring drill bit secured to one end. The opposite end of the outer tube is often attached to a drill string that extends vertically to a sonic drill head that is often located above the surface of the earth. The core barrel systems also may include an inner polycarbonate tube located within the outer core barrel. As the drill bit cuts formations in the earth, the inner tube can be filled with a core sample. Once a desired amount of a core sample has been cut, the inner tube, core barrel, and core sample can be brought up through the drill string and retrieved at the surface. 
     The sonic drill head may include high-speed, rotating counterbalances that produce resonant energy waves and a corresponding high-speed vibration to be transmitted through the drill string to the core barrel. As a result, the sonic drill head can vertically vibrate the core barrel. In addition, the drill head can rotate and/or push the core barrel into the subsurface formation to obtain a core sample. Once the core sample is obtained, the core barrel (containing the core sample) is retrieved by removing the entire drill string out of the borehole that has been drilled. Once retracted to the surface, the core sample may then be removed from the core barrel. 
     In a sonic wireline drilling process, the core barrel and the casing are advanced together into the formation. The casing again has an open-faced drill bit and is advanced into the formation. However, the core barrel (inner tube) does not contain a drill bit or connect to a drill string. Instead, the core barrel mechanically latches inside of and at the bottom of the casing and advances into the formation along with the casing. When the core sample is obtained, a drill operator can retrieve the core barrel using a wireline system. Thereafter, the drill operator can remove the core sample from the core barrel at the surface, and then drop the core barrel back into the casing using the wire line system. As a result, the wireline system eliminates the time needed to trip the drill rods and drill string in and out of a borehole for retrieval of the core sample. 
     Conventionally, upon detecting the presence of subterranean desirable materials, such as precious metals, sand and the like, an open pit mine is dug. In open pit mining, a large pit is dug and the overburden material positioned over the desirable materials is removed and hauled to a different location. However, forming an open pit mine is very time-consuming and expensive. Often an extensive dewatering system is required. There is also a large carbon footprint as millions of tons of overburden material removed from the open pit are trucked away. Further, there can be large capital costs in excavation equipment and infrastructure such as roads in order to form the open pit. Moreover, in some instances the open pit can be refilled, increasing cost as the removed overburden material is returned to the pit. 
     Thus, there is a need in the art for systems and methods for removing desirable subsurface materials without the need to dig an open pit mine to remove the overburden waste material. The present invention fulfills these needs and provides further related advantages as described herein 
     The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced. 
     SUMMARY 
     The invention relates to systems and methods for removing a desired subsurface material. In one aspect, the systems and methods for removing a desired subsurface material comprise removing subsurface materials without excavating the overburden waste material other than that excavated when forming a conventional exploratory borehole. 
     The system for removing desired subsurface materials comprises a drilling system and a material removal system. In one aspect, the drilling system comprises a drill head assembly capable of rotating a drill string and transmitting oscillating forces to the drill string. In use, the drill head assembly can cause a drill bit attached to the drill string to form a borehole extending into a surface. The drill string can line the borehole forming an outer casing. 
     The material removal system comprises a sonic air lift tooling system (“S3RP”) and a discharge tank. In one aspect, the sonic air lift tooling system comprises an outer tube having an outer diameter and defining an inner volume. The outer tube annulus can be in fluid communication with a source of pressurized fluid, such as air, and the like. 
     The sonic air lift tooling system can further comprise an inner tube. In one aspect, the inner tube has an outer diameter sized so that that at least a portion of the inner tube can be positioned in the inner volume of the outer tube. In another aspect, the outer diameter of the inner tube can be sized so that an annular void is defined between the outer tube and the outer diameter of the inner tube. In a further aspect, a distal end of the inner tube can define at least one opening such that an interior conduit of the inner tube is in fluid communication with the annular void outside of the distal end of the inner tube. A proximal end of the inner tube can be in fluid communication with a discharge tank such that the interior conduit of the inner tube is in fluid communication with the discharge tank. 
     In use, the pressurized fluid, such as compressed air, and the like can be injected through the outlet tube inlet and into the annular void between the outer tube and the inner tube. The pressurized fluid can be urged towards the distal end of the inner tube. Upon reaching the distal end of the inner tube, in one aspect, the pressurized fluid can pass from the annular void through the opening to the interior conduit of the inner tube. Because the desired subsurface material can be a flowing material, such as, for example and without limitation, sand, the desired subsurface material can become entrained in the fluid in the interior conduit of the tube. In the interior conduit of the tube, the fluid and the desired subsurface material entrained therein can be “lifted” or otherwise urged to the discharge tank. 
     In other aspects, varying combinations of pressurized fluids and flow directions can be utilized. However, in each aspect, the desired material can be removed from below the surface using the same borehole that was formed during exploratory drilling without the need for additional overburden material removal. 
     For purposes of summarizing, some aspects, advantages and features of a few of the embodiments of the invention have been described in this summary. Some embodiments of the invention may include some or all of these summarized aspects, advantages and features. However, not necessarily all of (or any of) these summarized aspects, advantages or features will be embodied in any particular embodiment of the invention. Thus, none of these summarized aspects, advantages and features are essential. Some of these summarized aspects, advantages and features and other aspects, advantages and features may become more fully apparent from the following detailed description and the appended claims. 
    
    
     
       DETAILED DESCRIPTION OF THE DRAWINGS 
       The appended drawings contain figures of preferred embodiments to further clarify the above and other aspects, advantages and features. It will be appreciated that these drawings depict only preferred embodiments of the invention and are not intended to limit its scope. These preferred embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  is an elevational view of a drilling system, according to one example. 
         FIG. 2A  is a side elevational view of a sonic air lift tooling system of a system for sonic subsurface material removal, according to one aspect. 
         FIG. 2B  is a cross-sectional view of the sonic air lift tooling system of  FIG. 2A  taken along line B-B of  FIG. 2A . 
         FIG. 2C  is a perspective view of the sonic air lift tooling system of  FIG. 2A . 
         FIG. 3  is a schematic diagram illustrating a system and method for sonic subsurface material removal, according to one aspect. 
         FIG. 4  is schematic diagram illustrating a system and method for sonic subsurface material removal, according to one aspect. 
         FIG. 5  is an elevational view of an exemplary system and method for sonic subsurface material removal, according to one aspect. 
         FIG. 6  is an elevational view of a second exemplary system and method for sonic subsurface material removal, according to one aspect. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present invention can be understood more readily by reference to the following detailed description, examples, drawings, and claims, and their previous and following description. However, before the present devices, systems, and/or methods are disclosed and described, it is to be understood that this invention is not limited to the specific devices, systems, and/or methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. 
     The following description of the invention is provided as an enabling teaching of the invention in its best, currently known embodiment. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects of the invention described herein, while still obtaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be obtained by selecting some of the features of the present invention without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not in limitation thereof. 
     As used throughout, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a pipe” can include two or more such pipes unless the context indicates otherwise. 
     Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. 
     As used herein, the terms “optional” or “optionally” mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. 
     In one aspect, the system for sonic subsurface material removal can comprise a drilling system  100  and a material removal system  200 . 
       FIG. 1  illustrates a drilling system  100  for drilling into the surface  105  of the earth that comprises a drill head assembly  110 . The drill head assembly can be coupled to a mast  120  that in turn is coupled to a drill rig  130 . The drill head assembly  110  is configured to have a drill rod  140  coupled thereto to form a drill string  150 . As can be appreciated, any number of drill rods can be added so that the drill string is the desired length. In turn, the drill string  150  can be coupled to a drill bit  160  configured to interface with the material to be drilled, such as a formation  170 . 
     In at least one example, the drill head assembly  110  is configured to rotate the drill string  150 . In particular, the rotational rate of the drill string  150  can be varied as desired during the drilling process. Further, the drill head assembly  110  can be configured to translate relative to the mast  120  to apply an axial force to the drill head assembly  110  to urge the drill bit  160  into the formation  170  during a drilling process. The drill head assembly  110  can also generate oscillating forces that are transmitted to the drill rod  140 . These forces are then transmitted from the drill rod  140  through the drill string  150  to the drill bit  160 . 
     Upon insertion of a drill rod  140  into a borehole  180 , the drill rod can form an outer casing  190 . As a result, a drill operator can use the outer casing to maintain the borehole. Once an outer casing is in place, the drill operator can trip a core barrel and its corresponding drill string into the borehole through an interior volume  195  of the outer casing and advance the core barrel ahead of the casing to retrieve a core sample. In another aspect, in a wireline drilling processes, a drill operator can simultaneously advance the casing and the core barrel together through a formation. Using a wireline process, the drill operator can trip the inner core barrel in and out of the drill string to obtain core samples from the core barrel. 
     In one aspect, the material removal system  200  of the system for sonic subsurface material removal comprises at least one of a sonic air lift tooling system  210 , and a discharge tank  230 . 
     With reference to  FIGS. 2A ,  2 B and  2 C, the sonic air lift tooling system  210  can, in one aspect, comprise an outer tube  235  and an inner tube  240 . The outer tube can be sized such that at least a portion of the outer tube can be coupled to the outer casing  190  in the borehole. For example, at least a portion of the outer tube  235  can have an outer diameter  245  of about 4 inches, about 5 inches, about 6 inches, about 7 inches, about 8 inches, or greater than about 8 inches. In another aspect, a distal end  250  of the outer tube can be threaded to engage complementary threads on a portion of the outer casing. In a further aspect, an internal diameter of the outer tube  235  can be substantially the same as an internal diameter of the outer casing, and/or the external diameter of the outer tube can be substantially the same as the external diameter of the outer casing. In one aspect, a proximal end  255  of the outer tube  235  can be configured to couple to a discharge head  260 . 
     In another aspect, an outer tube inlet  265  can be defined in a portion of the outer tube  235  of the sonic air lift tooling system  210 . In this aspect, the outer tube inlet can be a boss configured to place an inner volume  270  of the outer tube in fluid communication with a source of pressurized fluid, such as air, and the like. 
     The inner tube  240  of the sonic air lift tooling system  210  can be sized such that at least a portion of the inner tube can be positioned in the inner volume  270  of the outer tube  235 . For example, at least a portion of the inner tube can have an outer diameter  275  of less than about 4 inches, about 4 inches, about 5 inches, about 6 inches, about 7 inches, or greater than about 7 inches. In one aspect, the outer diameter of the inner tube  240  can be sized so that, when the inner tube is positioned in the inner volume  270  of the outer tube  235 , an annular void  277  is defined between the outer tube and the inner tube  240 . In another aspect, a proximal end  280  of the inner tube can be configured to couple to the discharge head  260  such that an interior conduit  285  of the inner tube is in fluid communication with an inner conduit  290  of the discharge head. 
     A distal end  295  of the inner tube  240  can be open such that a fluid can enter or exit the interior conduit of the inner tube. In one aspect, the distal end of the inner tube can define a plurality of holes  300 . In this aspect, at least one hole of the plurality of holes can be angled from the center of the inner tube upwardly towards the outer diameter  275  of the inner tube  240 . That is, the longitudinal axis L H  of the at least one hole can be at an acute angle relative to the longitudinal axis L I  of the inner tube. For example, an angle formed between the longitudinal axis L I  of the inner tube and the longitudinal axis L H  of the at least one hole  300  can be about 10 degrees, about 20 degrees, about 30 degrees, about 40 degrees, about 45 degrees, about 50 degrees, about 60 degrees, about 70 degrees, about 80 degrees, or about 90 degrees. In still another aspect, each hole of the plurality of holes can have a hole diameter of less than 0.25 inches, about 0.25 inches, about 0.50 inches, about 0.75 inches, about 1.0 inches, or greater than about 1 inch. 
     A central portion  305  of the inner tube  240  can connect the distal end  295  of the inner tube to the proximal end  280  of the inner tube. As can be appreciated, the central portion can have a length configured so that the proximal end of the inner tube  240  is positioned above the surface  105  of the formation  170  and the distal end of the inner tube is positioned in the borehole  180  at a desired depth, described more fully below. For example, the central portion  305  of the inner tube can comprise a plurality of inner tube sections that can be coupled together at the surface to form an inner tube having the desired length. 
     In one aspect, the discharge head  260  can be sized and configured so that material removed from the borehole  180  through the sonic air lift tooling system  210  can be redirected to the discharge tank  230 . For example, material removed from the borehole can be urged through the interior conduit  285  of the inner tube, through the inner conduit  290  of the discharge head and to the discharge tank. In one aspect, at least a portion of the discharge head can have a diameter of about 3 inches, about 4 inches, about 5 inches, about 6 inches, about 7 inches, or greater than about 7 inches. It is contemplated that a variety of flanges, gaskets, fasteners, adapters and the like can be provided to couple portions of the sonic air lift tooling system and/or the discharge head together as necessary. 
     The discharge tank  230 , illustrated in  FIGS. 5 and 6 , can be a tank configured to hold a liquid, such as water. In one aspect, the discharge tank can comprise a recirculation baffle plate  232 . The recirculation baffle plate can allow water to flow over the plate while restricting the flow of solids, such as a desired material  340 , from passing over the plate. Thus, the recirculation baffle plate  232  can at least partially separate the desired material from water or other fluid it can become mixed with. In another aspect, the discharge tank can further comprise a recirculation line  234 . In this aspect, the recirculation line can place the discharge tank in fluid communication with the outer tube inlet  265  of the sonic air lift tooling system  210  so that water from the discharge tank can be selectively directed to the inner volume  270  of the outer tube  235 . Optionally, the discharge tank can further comprise at least one of a cyclone  231  and a backhoe  233 , as known in the art, configured to further separate and/or remove the desired material from the fluid in the discharge tank. It is of course contemplated that the discharge tank  230  can further comprise at least one overflow drain, flow meter, valve and the like as necessary to process water discharged from and/or injected into the material removal system  200 . 
     Referring now to  FIGS. 3 and 4 , in order to remove subsurface materials using sonic drilling techniques, a borehole  180  can be formed as in conventional sonic drilling. For example, a target drilling zone can be identified through obtaining sonic samples of geological formations  170 . In one aspect, the outer casing  190  and/or the core barrel can be advanced through any overburden material  335  and the desired material  340  until a lower layer  345  of the desired material is reached. As can be appreciated, sonic technology allows for the installation of the outer casing to the lower layer of the desired geological formation without the use of drilling fluids or disturbance to the target geological formation around the borehole (i.e., the area around the borehole can remain substantially intact until the mining process commences). Further, sonic drilling technology can accurately identify the bottom of the desired geological formation so that the outer casing  190  can be properly positioned. 
     Upon locating the lower layer  345  of the desired material  340 , a portion of the outer casing  190  can be retracted from the borehole  180 . In one aspect, the outer casing can be retracted from the borehole a predetermined distance, such 1 foot, 2 feet, 3 feet and the like. In another aspect, the outer casing  190  can be retracted from the borehole until a distal end  320  of the outer casing is positioned a predetermined distance from the lower layer  345  and/or an upper layer  350  of the desired material. For example, the distal end of the outer casing can be positioned just below the upper layer of the desired material. In still another aspect, the distal end  320  of the outer casing can be positioned at any location between the upper and lower layers of the desired material. If the desired material  340  is a flowing material, such as, for example and without limitation, quartz or sand containing ore, upon retraction of the outer casing  190  the predetermined distance, the desired material can at least partially flow into the open borehole  180 . 
     After the desired material has been located using the sonic drilling system  100 , at least a portion of the sonic drilling system can be removed and replaced with the material removal system  200 . Thus, at least a portion of the material removal system can be inserted into the same borehole  180  that was drilled to identify the location of the desired material  340 . ( FIG. 4  illustrates separate boreholes for clarity). 
     In one aspect, the outer tube  235  of the sonic air lift tooling system  210  can be coupled to an upper portion  355  of the outer casing  190 . After placing the distal end  320  of the outer casing in the predetermined position relative to the lower layer  345  and/or the upper layer  350  of the desired material  340 , the desired material can be removed from the borehole  180  using a plurality of removal methods, such as, for example and without limitation, a direct reverse lift method  420 , and a flooded reverse lift method  430 , illustrated in  FIGS. 5-6  respectively. 
     As illustrated in  FIG. 5 , the direct reverse lift method  420  comprises injecting a pressurized fluid, such as air, water and the like through the outer tube inlet  265  of the outer tube  235 . For example, a compressor  405  can urge pressurized air from above the surface  105  of the formation  170  through the annular void  277  defined between the outer tube/outer casing  190  and the inner tube  240  so that the pressurized fluid travels around the distal end  295  of the inner tube. Upon reaching the distal end of the inner tube, at least a portion of the pressurized fluid can pass through at least one hole  300  of the plurality of holes of the inner tube. As the distal end  320  of the outer casing  190  is typically below the water line  407  (i.e., at least portions of the borehole  180  and the interior conduit  285  of the inner tube  240  are filled with ground water), the pressurized fluid can bubble up through the ground water towards the surface. In one aspect, portions of the desired material  340 , such as for example and without limitation, sand, can become entrained in the pressurized fluid as it bubbles up through the interior conduit  285  of the inner tube and can be carried towards the surface  105 . Upon reaching the proximal end  280  of the inner tube, the portions of the desired material can be urged through the discharge head  260  to the discharge tank  230  for collection. 
     The flooded reverse lift method  430  comprises injecting a pressurized first fluid, such as air and the like through the outer tube inlet  265  of the outer tube  235 . For example, a compressor  405  can urge pressurized air from above the surface  105  of the formation  170  through the annular void  277  defined between the outer tube/outer casing  190  and the inner tube  240 . A second fluid, for example and without limitation, water, can also be injected into the outer casing so that the annular void defined between the inner tube and the outer casing is at least partially filled with a combination of the first and second fluids. In one aspect, water injected into the outer tube  235  can be water recycled from the discharge tank  230 . The pressurized first fluid can travel down the annular void towards the distal end  295  of the inner tube. Upon reaching the distal end of the inner tube, at least a portion of the first pressurized fluid can pass through at least one hole  300  of the plurality of holes of the inner tube. As the distal end of the inner tube  240  is below the water line  407  (i.e., at least portions of the borehole  180  and the interior conduit  285  of the inner tube can be filled with ground water and/or the second fluid), the pressurized first fluid can bubble up through the water in the inner tube towards the surface  105 . In one aspect, portions of the desired material  340 , such as for example and without limitation, sand, can become entrained in the first fluid as it bubbles up through the interior conduit  285  of the inner tube and can be carried towards the surface. Upon reaching the proximal end  280  of the inner tube, the portions of the desired material can be urged through the discharge head  260  to the discharge tank  230  for collection. 
     Regardless of the lifting method used, if at any time the desired material  340  is no longer being brought to the surface  105  at a desired rate, in one aspect, the distal end  320  of the outer casing  190  can be adjusted to a different predetermined from the lower layer  345  and/or an upper layer  350  of the desired material. For example, if a low level of desired material is being extracted from the borehole  180 , the outer casing can be lowered so that the distal end of the outer casing is adjusted to a different predetermined distance from the lower layer of the desired material  340 . 
     The methods and systems described above require no particular component or function. Thus, any described component or function—despite its advantages—is optional. Also, some or all of the described components and functions described above may be used in connection with any number of other suitable components and functions. 
     Although several embodiments of the invention have been disclosed in the foregoing specification, it is understood by those skilled in the art that many modifications and other embodiments of the invention will come to mind to which the invention pertains, having the benefit of the teaching presented in the foregoing description and associated drawings. It is thus understood that the invention is not limited to the specific embodiments disclosed hereinabove, and that many modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although specific terms are employed herein, as well as in the claims which follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described invention, nor the claims which follow.