阅读说明：本技术 用于采矿的方法和系统 (Method and system for mining ) 是由 S·D·巴特 A·R·克拉姆 J·德莫拉尤尼奥尔 于 2019-11-29 设计创作，主要内容包括：一种用于开采矿石的窄矿脉矿床的方法,所述窄矿脉矿床具有上盘和下盘,所述方法包括：沿着上盘和上盘之间的大致中心的路径,将导向孔钻凿到所述窄矿脉矿床中至矿脉内的一深度；使用更大直径的钻井组件跟随所述导向孔以将矿石破碎成钻屑；将钻屑循环到井口；以及收集钻屑进行加工以回收其中的矿石。(A method for mining a narrow vein deposit of ore, the narrow vein deposit having an upper tray and a lower tray, the method comprising: drilling a pilot hole into the narrow vein deposit to a depth within the vein along a substantially central path between the upper plate and the upper plate; following the pilot hole using a larger diameter drilling assembly to break up the ore into drill cuttings; recycling the drill cuttings to the wellhead; and collecting the drill cuttings for processing to recover ore therein.)

1. A method for mining a narrow vein deposit of ore, the narrow vein deposit having an upper tray and a lower tray, the method comprising: drilling a pilot bore having a pilot bore diameter into the narrow vein deposit to a depth within the vein along a substantially central path between the upper and lower discs; following the pilot hole using an open-hole drilling assembly of larger diameter than the pilot hole to break up the mineral surrounding the pilot hole into drill cuttings; circulating the drill cuttings up the liquid stream to a wellhead; and collecting the drill cuttings for processing to recover ore therein.

2. The method of claim 1, wherein drilling the pilot hole comprises surveying the narrow vein deposit from the pilot hole to determine a position of the pilot hole relative to the upper and lower discs, and directing a pilot hole drilling assembly to continue drilling substantially centrally between the upper and lower discs.

3. The method of claim 2, wherein surveying comprises non-destructively imaging a narrow vein deposit around the pilot hole.

4. The method of any of claims 1-3, wherein following the pilot hole comprises pushing a spike on a front end of the open-hole drilling assembly through the pilot hole, the spike comprising an outer diameter about equal to or less than a diameter of the pilot hole.

5. The method of any of claims 1-4, wherein the pilot hole remains open while following the advancement of the pilot hole.

6. The method of any of claims 1-5, wherein drilling the pilot bore is accompanied by circulating liquid down through a pilot bore drilling assembly and up through an annulus, and circulating while operating the open-hole drilling assembly comprises reverse pumping liquid down through the annulus and up through the open-hole drilling assembly.

7. The method of claim 6, wherein water-based liquid is recycled in operating the open-hole drilling assembly.

8. The method of claim 7, further comprising injecting compressed gas at the open-hole drilling assembly to facilitate the water-based liquid return.

9. The method of any of claims 1-8, further comprising increasing the pressure of the fluid above the open-hole drilling assembly when operation of the open-hole drilling assembly is initiated near the surface.

10. The method of any of claims 1-9, wherein a diameter of the open-hole drilling assembly is selected to substantially match a distance between the upper and lower discs, and further comprising reaming to drill a diameter larger than the diameter during operation of the open-hole drilling assembly.

11. A mining system for mining narrow vein deposits of ore, the system comprising:

a drilling machine;

a pilot hole drilling assembly comprising: a drill bit for drilling a pilot hole in ore; a downhole survey tool for positioning an upper and lower disc of the narrow vein deposit relative to the pilot hole; and an orientation assembly for guiding the drill bit along a path between an upper disc and a lower disc;

a hole cutter assembly comprising: an end portion configured to follow the guide hole; and a hole cutter drill configured to drill a borehole having a diameter larger than the pilot hole to break ore into drill cuttings; and

a fluid circulation subsystem moves fluid through the well to circulate the cuttings from the borehole to the wellhead.

12. The system of claim 11, wherein the downhole survey tool is configured to extend through an opening in the pilot hole drill bit.

13. The system of claim 12, wherein the downhole survey tool is a non-destructive imaging tool.

14. The system of any of claims 11-13, wherein the end of the hole cutter assembly is a spike having an outer diameter that: the outer diameter is about equal to or less than the pilot hole diameter.

15. The system of any of claims 11-14, wherein the fluid circulation subsystem is configured to circulate forward through the pilot hole drill bit and reverse through the open-hole drilling assembly.

16. The system of claim 15, wherein the fluid circulation subsystem comprises a conduit for injecting compressed air at the open-hole drilling assembly.

17. The system according to any one of claims 11-16, wherein a diameter of the hole cutter drill is selected to substantially match a distance between an upper and lower disc of the narrow vein deposit, and the hole cutter drill includes an expandable reamer operable to drill a diameter larger than the diameter.

18. The system of any of claims 11-17, further comprising a surface casing having an inner diameter sufficient to accommodate passage of both the hole cutter bit and the pilot hole drilling assembly.

19. The system of claim 18, further comprising a cartridge having a diameter smaller than the inner diameter and large enough to receive an outer diameter of the pilot hole drilling assembly, and the cartridge is mounted substantially coaxially within the casing when the pilot hole drilling assembly is in operation.

Technical Field

The present invention relates to a method and system for mining, in particular for mining narrow vein deposits.

Background

Mining narrow vein deposits is challenging. It is believed that the thickness of the narrow vein between the upper and lower trays is below 3 meters. In some deposits, there is a vein of precious ore, such as gold, which is not only narrow but also steeply inclined. These deposits were set aside because there was no efficient method to mine the deposits. Both strip and underground methods of excavation are economically infeasible for mining steeply dipping seams and, in fact, these methods often result in net losses. The environmental impact of these methods is also unattractive.

That said, it is estimated that there are 340 ten thousand ounces of gold resources in these narrow steeply dipping veins in finland province, canada.

Disclosure of Invention

According to a broad aspect of the present invention, there is provided a method of mining a narrow vein deposit of ore, the narrow vein deposit having an upper tray and a lower tray, the method comprising: drilling a pilot hole into the narrow vein deposit to a depth within the vein along a substantially central path between the upper disc and the upper disc; following the pilot hole using a larger diameter drilling assembly to break up the ore around the pilot hole into drill cuttings; circulating the drill cuttings up the fluid stream to the wellhead; the drill cuttings are collected for processing to recover the ore therein.

According to another broad aspect of the invention, there is provided a mining system for mining narrow vein deposits of ore, the system comprising: a drill rig, a pilot hole drilling assembly, a hole cutter assembly, and a fluid circulation subsystem, wherein the pilot hole drilling assembly comprises: a drill bit for drilling a pilot hole in ore; a downhole survey tool for positioning the upper and lower discs of the narrow vein deposit relative to the pilot hole; and a directional assembly for guiding a drill bit along a path between the upper and lower discs, the hole cutter assembly comprising: an end portion configured to follow the guide hole; and a hole cutter drill configured to drill a borehole having a diameter greater than the pilot hole to break the ore into cuttings, the fluid circulation subsystem moving fluid through the well to circulate the cuttings from the wellbore to the wellhead.

It is understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments and its several details of design and implementation are capable of modification in various other respects, all as encompassed by the present claims. Accordingly, the detailed description and examples are to be regarded as illustrative in nature and not as restrictive.

Drawings

For a better understanding of the invention, the drawings are as follows:

fig. 1A to 1G are a series of schematic views showing steps in a mining method and illustrating a possible mining system and aspects thereof;

FIGS. 2A and 2B are perspective views of a drilling rig useful with the present invention;

FIGS. 3A and 3B are perspective cutaway views through a flexible drill string joint useful in the present invention and cross-sectional views along line I-I, respectively;

FIGS. 4A, 4B and 4C are an enlarged installation view, a perspective partial view and an overall installation rig view of another casing embodiment, respectively, of one casing embodiment in an upper pressurization system and a reamer assembly that may be used in the present invention;

FIG. 5 is a perspective view of a hole-forming drill tip useful in the present invention;

fig. 6A and 6B are enlarged views of a cartridge for handling near-surface fluids in pilot hole drilling operations.

Detailed Description

The detailed description and examples set forth below are intended as descriptions of various embodiments of the invention and are not intended to represent the only embodiments contemplated by the inventors. The detailed description includes specific details for the purpose of providing a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details.

The thickness between the upper and lower disks of the narrow vein deposit is typically less than 3 meters (typically about 1-2 meters). The narrow vein may be steeply inclined, for example from 45 to 90 ° or most often from 60 to 85 ° to the horizontal. They may be accessed from an access location, such as on or near the surface of the earth, or in an underground location (e.g., in a mine).

The mining method comprises the following steps: drilling a pilot bore downwardly into the narrow vein deposit from the entry location and along a substantially central path between the upper disc and the upper disc to a depth within the vein; breaking up the ore into drill cuttings using a larger diameter drilling assembly following the pilot hole; circulating the drill cuttings up to the entry location with drilling fluid circulation; the drill cuttings are collected for processing to recover the ore therein.

From a sustainable mining perspective, the method provides one or more advantages over conventional methods, such as:

enhanced safety-an entry location may be selected as close as possible to the upper end of the vein, for example at or near the surface of the earth where the vein is exposed and extends downwardly therefrom or in a mine. This method eliminates the risks associated with collapse, as all operations can be performed from a defined access location above the vein. Since many of the veins of interest are accessible from the surface, exposure of workers to underground mining can be completely avoided. The entire mining operation can be performed from the surface without reason for having workers underground.

Minimize environmental footprint-this method has minimal surface area requirements during mining and the bore hole can be easily recovered. Also, the method may include bore backfilling as part of the mining cycle, which may reduce surface tailings storage requirements.

Improved mining and energy efficiency-without blasting, the method can be highly selective with minimal dilution. Since the ore is recovered as drill cuttings, the usual crushing step is essentially eliminated. Most devices can be powered by electricity. Overall, this means a reduction in energy consumption and less emissions per unit of ore produced.

With reference to fig. 1A to 1G, the new mining method aims at mining stranded, narrow and possibly steeply dipping veins which are too small or isolated to be economically mined using conventional methods. An example of such a vein v is shown in fig. 1A. Such a vein v has a strike length of, for example, typically 100-300 metres and a thickness T of less than 3 metres between its upper and lower discs 2, 4, for example typically about 1-2 metres. The thickness T may vary with the depth and strike length of the vein.

The narrow vein deposit v may be steeply inclined, for example at an angle of from 45 to 90, or most often 60 to 85, to the horizontal. The vein may have a dip angle that varies along its depth, e.g., at an angle α 1 near the upper end, becoming α 2 at deeper depths.

The vein may be accessed from an access location above the vein (e.g., on or near the surface s). While an access location on the surface is preferred, the mining method may also be performed from exposed vein deposits in the mine intersecting the vein.

The mining method is a two-stage method, which can be summarized as well-drilling mining.

In a first stage (fig. 1B and 1C), the site is prepared, if necessary, for example by removing any covering ob to access the upper end of the vein. Thereafter, a pilot hole 6 is drilled downwardly from the access location to the depth of the vein v between the upper and lower discs 2, 4 using a drilling assembly comprising a pilot bit 10 on a drill string 12. The directional drilling tool 14 and method and the downhole survey tool 16 and method may be used to maintain pilot holes within the vein along the vein depth and to map the vein. Non-destructive survey methods may be used to determine the vein trajectory and the distance from the pilot hole to the upper and lower discs. Thus, the pilot bit 10 can drill downward while remaining substantially centered between the upper and lower discs, without drilling sideways past the edge of the deposit into the upper and lower layers of waste rock. At the same time, the vein may be characterized, including, for example, its inclination and thickness.

The non-destructive survey may include near borehole imaging techniques. The surveying and imaging may be performed at least periodically. Thus, at times a downhole survey may be conducted while drilling the pilot hole. In one embodiment, an imaging and surveying tool (such as a cable survey and/or geophysical tool) measures the borehole trajectory and the location and geometry of the vein near the borehole and around the drill tip. The pilot hole trajectory is then changed as necessary to follow the inclination and remain within the vein, e.g., approximately centered between the upper and lower disk contacting portions.

The survey tools may be mounted on the drilling assembly, or they may be run into the pilot hole from time to time. In one embodiment, the drilling is occasionally stopped and the survey tool 16 is advanced to assess the location of the vein and pilot hole. This includes pulling up the drill string 12 and the drill tip 10 and accessing it with the survey tool, or pulling up only a portion of the drilling assembly (e.g., all or part of the pilot drill tip 10) so that the survey tool 16 can be run through the drill string, such as on a cable, and operated in the pilot hole. In one embodiment, when the borehole 6 is drilled to survey depth, a portion of the pilot bit, such as a cable core or bit plug 10a, is removed to open a passage through the drill string 12 at the distal end of the drill string, the drill string is pulled up a short distance from the bottom hole 6a, and at least a portion of the survey tool 16 is extended into the pilot hole to measure well trajectory and distance including, for example, vein imaging (fig. 1C). Thereafter, the tool 16 may be removed, the pilot bit restored and the path maneuvered, if necessary, to maintain the inclination along the deposit and midway between the upper and lower discs. In this manner, the pilot hole is drilled to a total depth within the vein.

When the pilot hole is drilled to the desired overall depth, the pilot hole drilling assembly and drill string may be pulled out of the hole. The hole may remain bare, said hole being cannulated.

In the second stage, open hole drilling (possibly with accompanying reaming) is used to extract the vein by following the pilot hole, as shown in figure 1D. The method includes moving the aperture assembly 18 along the pilot hole 6 and centered on the pilot hole 6. The opening assembly comprises a drill string 20 with an opening drill tip 22 having a front end 24 configured to follow the pilot hole. Because the pilot hole 6 has drilled into the vein v and may be approximately centered between the upper and lower discs 2, 4, the open-hole drill bit drills an enlarged borehole 26 of diameter D centered on the pilot hole. Based on survey information obtained during pilot hole drilling regarding vein thickness, the opening can be extended to the limits of the vein to extract the vein to approximately its full thickness without drilling too much waste rock w. The trephine drilling diameter may be selected based on survey/imaging information previously mapped as the pilot hole is drilled. The second stage mining continues while the open hole drill string is allowed to bend to follow the trajectory of the pilot hole. This second stage may include one or more drills and optionally reams to open the hole to a larger diameter along a selected length. The diameter of the borehole may be 1-3 meters, which may be accomplished in a limited number of (e.g., one) drills by selecting a drilling assembly having a diameter of 1-3 meters.

The ore is recovered as drill cuttings which are circulated as the circulating fluid flows up to the wellhead. The cuttings may be circulated upwardly (arrow F) with liquid from the pilot hole. However, due to the relative size of the holes, the ore cuttings will mostly come from the open pores. The cycle may be forward or reverse. The forward direction is down the drill string and up the annulus between the drill string and the borehole wall, while the reverse direction is down the annulus and up the drill string. While drilling, the drilling process can be reversed to reverse circulation (arrow R). The hydraulic pressure of the circulating fluid supports the borehole wall, thus eliminating the need for casing or additional bore supports or liners. However, if severe instability in the vein is found, the upper plate may be pre-supported by means of cables and bolts installed prior to opening the hole. The borehole does not require dewatering because circulation of fluids and lifting of cuttings is possible even in the presence of geological water.

When the cuttings reach the surface, they are then separated from the circulating fluid and the ore is recovered from the cuttings.

Once the hole 26 is fully produced, the drilling assembly 18 is pulled out of the borehole. Thereafter, the borehole may be filled with backfill, for example (fig. 1E). The backfill may include the waste tailings and optionally a carrier or binder, such as cement. Thus, the method may comprise filling the hole or pumping the tailings and binder into the hole. This provides an environmental benefit as the tailings do not need to be stored at the surface and the geology is stabilized. Furthermore, when the backfill is reinforced with an adhesive, it allows the drilling mining operation to be performed directly alongside the filled borehole.

The mining of the vein continues by moving and mining more boreholes along the run of the vein, including drilling pilot holes 6a at multiple locations, and then tapping 26 a. In one approach, time is allowed for backfill 28 to solidify before mining adjacent boreholes so that new boreholes may be mined directly into, and possibly partially overlapping, the solidified backfill in completed boreholes 26 to ensure maximum ore recovery. A method of allowing continued mining while backfill cures in a first borehole includes mining and filling the first borehole 26 (referred to as the main borehole) and then mining and filling the other main boreholes 6a, 26a (fig. 1F) spaced from the first borehole so that the open borehole 26a (so that the undrilled portion of the vein remains between the boreholes 26, 26a and the borehole 26a is not in communication) is out of contact with or overlaps the first borehole 26. It is possible to plan to extract the remainder of the vein from the further pilot holes 6b, 6 c. For example, after time has allowed the backfill in the holes 26, 26a to solidify, the secondary borehole 6b may be drilled and opened alongside the first main borehole to recover the undrilled portion of the vein between the two main boreholes 26, 26 a. Fig. 1G shows the two main boreholes 26, 26a backfilled for the first time and the secondary pilot hole 6b therebetween drilled and ready to open. The further proposed or drilled pilot holes 6c, 6d will extract the rest of the vein. The openings may be arranged for a plurality of primary pilot holes before the secondary pilot holes between the leading primary pilot holes begin to proceed. Alternatively, the mining plan may alternate primary and secondary pilot holes. Pilot hole drilling may be independent of tapping, or the entire pilot hole and tapping may be completed before moving to the next location along the vein. Because the pilot holes can be precisely located, the vein can be efficiently mined by opening holes to the vein thickness, controlling any overlap between mined holes, or drilling into the debris and backfilling the completed holes.

The method may require field preparation prior to the first stage. For example, the earth's surface may be cleaned to expose the vein, or drilling operations may drill down through the surface material to access the vein.

This method allows selective opening of holes substantially only in the vein and minimizes or at least provides control over how much waste rock is drilled out. Thus, the drill cuttings processed for ore recovery are almost free of contamination from the waste rock of the upper and lower trays or backfill from the backfill of the adjacent mining backfill holes. This facilitates the handling of drill cuttings for ore recovery.

Each enlarged borehole drilled may generally span the thickness of the vein, e.g., 1-3 meters, and may be drilled to a substantial depth, e.g., 250 meters or more, along the vein, which may be about 200 meters deep in an inclined vein. For a hole drilled in an ore-containing vein of specific gravity 2.8 tonnes per cubic meter, 2 metres in diameter and 250 metres in length, the hole can therefore produce approximately 2200 tonnes of ore.

A mining system for mining narrow vein deposits may include: a drill rig, a pilot hole drilling assembly, a hole cutter assembly, and a circulation subsystem, wherein the pilot hole drilling assembly comprises: a drill bit for drilling a pilot hole in ore; a downhole tool for positioning the upper and lower discs of the narrow vein deposit relative to the drill bit; and a directional assembly for guiding a drill bit along a path between the upper and lower discs, the hole cutter assembly comprising: an end portion configured to follow the guide hole; and a hole cutter drill configured to drill a borehole having a diameter greater than the pilot hole to break the ore into drill cuttings, the circulation subsystem circulating the drill cuttings from the borehole to the wellhead for collection and processing to recover the ore.

Of course, the drill rig conducts drilling fluid, steers the drill string and tool, applies Weight On Bit (WOB), and applies torque or at least reaction torque in the drill string. In this system, it is desirable that a single drill machine can handle all drilling, both pilot and enlarged boreholes. It is desirable that a drilling rig handle both near surface operations and operations that go to full depth, all of which are necessary to mine a full bore hole through the vein. Thus, for example, the drilling rig should be able to handle drilling equipment for pilot holes and second stage large diameter holes. This means, for example, that the handling diameter ranges from 10 cm for pilot holes to 3 m for drilling operations. Considering that the parent rock strength of a typical gold mine is about 70-200 mpa and that the process involves large variance in pore size, the drilling rig must be able to apply 10 to 450kN WOB. The drilling rig may also be configured for slant drilling in order to drill into slant deposits. The drilling machine may also need to be operated with forward and reverse circulation, wherein the cuttings flow up from the inside of the drill string to the surface.

Considering that the method may require drilling a plurality of spaced apart boreholes into the vein and the remote location of some vein deposits, the drills should be moved relative to each other. The drilling rig may be movable, for example, by a crane, attached skid, or a transport chassis such as a trailer or attached tractor transport.

In one embodiment, a pile top drilling rig may be useful. Pile top drilling rigs work on top of casing, typically for construction such as driving a pile. A pile tip drilling rig comprising: a bottom plate mounted on top of the sleeve; a table and a clamp located on the base plate and within the sleeve; and an upper structure above the base plate, the upper structure comprising: an arched mast having a side structure and an upper portion; a top drive with powered rotation supported in the upper portion of the mast; and a pressurizing cylinder in each side structure. A suction tube is in driving communication with the top. Such rigs are relatively small and can be transported to remote locations. Although it is normally used for large diameter drilling, the drilling rig in this embodiment is configured for handling the apparatus for drilling holes having a size in the range of 15 cm to 3 m from the same rotary table. Further, such a drilling rig may be configured to use forward (forward) or reverse circulation drilling. The drilling rig may use both liquid and gaseous drilling fluids.

However, pile top rigs may require some adjustment to be most effective for this mining method operation. For example, it may be difficult to place casing with a drilling rig installed because mining sometimes requires early drilling into bedrock. Thus, the system and method may be configured to perform additional drilling steps at the surface in order to achieve casing placement. In particular, a typical pile top drilling rig requires a casing length of about 16 meters to generate sufficient head to lift the cuttings. In this embodiment, the bedrock may be very close to the surface, and thus it may be difficult or impossible to reach a depth of 16 meters. Thus, the system uses a shorter or variable length casing, possibly in combination with a pressurization cycle, to allow pile top drive to operate without 16 meters of casing. Adjustments may also be necessary to place the open hole drill string completely below the rig floor prior to normal drilling operations. Furthermore, the drill rig floor and/or top drive may need to be adjusted to handle different sized tubulars, such as drill pipe and larger space pipe in one drill string. Alternatively or additionally, the drilling rig may benefit from a drilling rig to surface anchoring system to enhance rotational torque and thrust capability.

Fig. 2A and 2B show two pile-top drilling rigs configured for drilling into narrow veins. While both drills are movable due to their compact size, the drill of fig. 2A is more easily moved.

The mobile drilling rig of fig. 2A includes a pile-top drilling rig structure 110 mounted on a transport undercarriage 112, for example on a rail-type, also known as carter-type or crawler-type undercarriage. The transport chassis ensures rig mobility between drilling sites and operational flexibility for drilling operations. The transport chassis can be driven on uneven and loose road surfaces. In this embodiment, the sleeve 114 is supported on the chassis. The pile-top drilling machine is fixed to the upper end of the casing by a casing connection device. The mobile platform may also include an anchoring system 115 for securing the drilling rig to the ground. The anchoring system may be sized to support the reaction forces during drilling operations. In one embodiment, the drilling rig is anchored to the ground by grouting steel bars firmly anchored into the bedrock. The anchoring system is configured to resist drilling reaction forces while avoiding interference with drilling operations.

The drilling rig may comprise a base platform for storing equipment, for example a setting on a chassis.

Although not shown, the mobile drilling rig may be configured for tilt operations, where, for example, in the undercarriage, the casing 114 and the upper structure 118 of the drilling rig, such as by using a hydraulic tilt system, are actually tilted about the drilling axis (defined between the top drive 118a and the floor clamp 118 b). For example, the chassis may include an actuator that tilts the sleeve 114 and the upper structure 118. In one embodiment, there is an undercarriage system, e.g. based on hydraulic actuation, which drives the bushings and the upper structure backwards or forwards with respect to the direction of travel, which is parallel to the long axis of the rails. These functions allow the drill rig to be tilted to drill a hole matching the surface vein inclination angle.

The drilling rig may also be configured with a floor 116 and a leveling system for the floor, for example also by means of hydraulic actuators. Thus, the floor is allowed to remain horizontal, e.g. substantially horizontal, even if the undercarriage, the superstructure and/or the bushings are tilted. This facilitates the work of workers on the floor.

The drilling rig may also be provided with a height adjustment assembly for the drilling rig deck, including height adjustable, e.g. telescopic legs 117, telescopic sleeves 114 and a system to drive the height adjustment movement. This allows for variations in the height of the rig deck and casing. The drilling operation proceeds from the rig deck down through the casing and then into the surface (e.g., the vein) where production is to take place. Initially the casing 114 is placed on the surface. In particular, similar to the system of FIG. 2B, the lower flange of the casing is installed at the surface with an O-ring seal therebetween to seal the interface and provide a fluid seal within the casing. The lower flange may be configured to float on the casing so that the angle for the casing to be oriented may be adjusted to substantially match the angle of inclination, with the lower surface of the flange oriented parallel to the ground.

For example, when the rig deck 116 needs to be taller, such as at an early stage of drilling, the telescoping members 114a in the casing allow the casing length to be longer, and then the casing can be shortened by telescopically axially folding a length of casing into a second large diameter casing section. In the initial opening phase, the casing may need to be higher as the hole is shallower to provide the required drilling pressure at the bottom of the hole. As the hole depth increases, the telescoping tube and drill rig can be lowered to reduce the height of the drill rig. The telescoping member may include a telescoping interface and a pressure-retaining sliding seal between two casing sections. The casing with flange may be on the bottom and a vertical displacement assembly (e.g., hydraulic system) may be at the telescoping interface to allow adjustment of the casing flange while lowering the height of the casing and drilling rig (during installation).

In such mining operations, the casing may seal against the surface of the vein, or extend a short distance into the vein, to allow a liquid seal between the casing and the bore. This allows the hole to be expanded using open hole unlined drilling.

Fig. 2B shows the pile-top drilling rig 110 secured and mounted on the bedplate 120. When installed at one location, the cost of disassembling, moving (e.g., using a crane), and reinstalling the drilling rig at a new location along the vein may be an acceptable alternative, taking into account the cost of the movable undercarriage. The base is made of concrete and provides a strong, horizontal base on which the casing 114' of the drilling machine can be mounted. The base is positioned above the entry point of the vein v, for example the cleared area of rock directly above the exposed vein. If desired, the plinth may extend along the length of the vein more than the space required to install the drill rig in one operation, so that there is room to move the drill rig down and drill the next borehole without having to build another plinth. A flange connection 122 may be employed between the sleeve and the base. A gasket 123 may be used between the flange and the base to improve drilling fluid retention in the above ground casing. The bolts used to secure the casing flange to the base are sized to support axial and torsional stresses during drilling operations. In one embodiment, the flanged pipe is anchored to the bedrock using grout bolts/rebar that pass through the flange and penetrate the concrete slab and the underlying bedrock b.

The casing may be mounted on a slope corresponding to the initial inclination of the vein so that the drilling axis generally follows the vein. Thus, the flange 122 of the sleeve may be configured to be angled rather than orthogonal with respect to the long axis of the sleeve. The flange helps to hold the casing at an inclination, and in particular the angle of the flange relative to the long axis of the casing determines the angle at which the casing will extend upwardly from the base and thus the angle of the drilling axis relative to the vein. The rig floor 116 may be fixed in a horizontal, horizontal orientation, while the above-the-rig structure 118, such as the pipe handling equipment and top drive, above the floor may be on an incline and axially aligned with the long axis of the casing.

In addition to casing, the drill rig may also include a support post 124 to support the drill floor. The struts are rigidly connected to the casing 114' and the superstructure 118 by bolting or welding, acting to accommodate equipment weight, rotational torque, and thrust forces due to rig pull-up during drilling operations.

The pilot hole drilling assembly functions in a first stage of the method to create a borehole through the vein having a pilot hole size. The pilot hole follows the inclination of the vein and drills along a trajectory within the vein, for example, approximately in the center between the upper and lower discs. The pilot hole drilling assembly comprises:

a drill bit 10 for drilling a pilot hole in ore, the drill bit being any drill tip, and a connector configured to advance a drilling assembly through an ore body, such as a gold deposit. In one embodiment, the drill bit may be configured to drill by a combination of rotation and percussion. The drill bit is also configured to process a drilling fluid of interest, such as air, mud, or a combination in one example. In one embodiment, for example, a hydraulic turbine or pneumatic rotary percussion drill bit is employed. Pilot hole drill bits may be configured to drill holes of 10 to 45 centimeters or more likely 22 to 38 centimeters. The drill bit 10 may be removable up through the drill string while the drill string remains downhole, or it may include a removable core barrel or nozzle plug 10a to allow access to the borehole to be opened from the distal end of the drill string.

The downhole survey tool 16 for positioning the upper and lower disks of the narrow vein deposit relative to the drill bit is a non-destructive survey tool, such as a downhole imaging tool. Survey tools are configured for near borehole Imaging and may include, for example, geophysical tools that are incorporated on the drill bit or conveyed through the drill string or wireline and employ techniques such as ground penetrating radar, high frequency acoustic, ultrasonic, X-ray, Magnetic Resonance Imaging (MRI), and the like.

In one embodiment, a near borehole imaging tool is used during the pilot hole drilling phase. At different depth intervals while drilling the pilot hole, a survey is conducted using an imaging tool. If the imaging tool is not incorporated into a pilot hole drilling assembly, surveying may include using the downhole imaging and surveying tool to enter the borehole through a wireline and/or through an attachment at the end of a drill string.

One possible downhole imaging and surveying tool has two main components: i) the first component is a geophysical imaging system which provides high resolution images of the near-wellbore region to identify the distance of the borehole from the point of contact of the upper and lower walls of the vein, information about the continuity of the vein in the transverse direction along the run of the vein, and information about the continuity of the drill bit of the drill tip; ii) the second component is a guidance information system comprising a combination of accelerometers, magnetometers and north-seeking gyroscopes, providing information about the inclination and azimuth of the borehole trajectory and the toolface angle of the imaging tool.

The downhole imaging and survey tool information is used to determine whether the borehole trajectory deviates from a path within the vein (e.g., approximately midway between the upper and lower wall vein contacts), whether the trajectory deviates from the dip angle of the vein, whether the vein changes thickness or direction, or some combination of these. If the borehole deviates from the desired trajectory, a trajectory adjustment is planned using the downhole steering tool with near wellbore information.

The geophysical imaging system for the survey tool may be a ground penetrating radar. However, other embodiments using high resolution acoustic, ultrasound, XRF, or Magnetic Resonance Imaging (MRI) are also possible.

The pilot hole drilling assembly further comprises a directional assembly 14 for guiding the drill bit along a path between the upper and lower discs. The orientation assembly is configured to steer the drill string such that it can drill a pilot hole path within the vein, e.g., substantially centered between the upper and lower discs. The orienting assembly may include wedges, whipstocks, flex joints, automatic kickers, or other orienting tools. Care may be taken to ensure that the directional assembly works with the drill string, drill bit and fluid used.

The pilot bore drilling assembly drill string may also include drill collars, stabilizers, centralizers, logging instruments, and the like.

While the rig may be used for first and second stage drilling, during the first stage, drilling a pilot hole, the system may require a jumper 112a to connect American Petroleum Institute (API) drill pipe in a pile-top rig. The jumper is the interface between the top drive of the pile top rig and the API standard drill string. It allows forward circulation of drilling fluid. The lower end of the jumper is the API pin connection. The jumper may include connections between top-driven liquid injection points. In particular, if the pilot hole is drilled using a rotary percussion drill tool, compressed air with or without foam is used and is circulated forward down the drill string and up the annulus. The proposed jumper allows switching from forward compressed air circulation for pilot hole drilling to gas lift assisted reverse circulation for open hole drilling.

After a length of pilot hole has been drilled, the hole cutter assembly is activated in a second stage of the method to enlarge the hole diameter along the pilot hole. This will therefore recover more ore in the vein. The hole opener may be passed one or more times to enlarge the hole to approximately the thickness of the vein. The process may include reaming so that thicker regions of the vein may be mined using the hole opener. Referring to fig. 1D, 5A and 5B, a useful hole cutter assembly includes:

A. a lower pilot end 24 configured to follow the pilot hole-the hole cutter assembly is intended to follow the pilot hole. Thus, the opening produces an enlarged radius in the vein that is approximately equal to and exceeds the radius of the pilot hole. The guide end is configured to find and hold the hole cutter centered on and following the guide hole. The guide end 24 may be, for example, a spike, otherwise known as a nose cone (bullnose), which is an elongated extension sized to fit into and be pushed along the guide hole. The pilot end 24 may have an outer diameter just smaller than the pilot hole and may include a bearing surface to increase the wear resistance of the pilot end 24 as it moves along the pilot hole. The leading end 24 may be configured to rotate as this may facilitate penetration. Although it is not generally necessary, if the pilot end is rotated, its lower end may have a bit.

B. The hole cutter drill 22 is connected directly or indirectly to the upper end of the pilot end 24. The hole cutter drill is configured to drill a borehole within and along the deposit. The hole cutter drill includes a cutting face 28, the cutting face 28 including a cutter 28a and a stabilizer surface 29. The drill hole has a larger diameter than the pilot hole and the drill is used to break up the ore around the pilot hole into drill cuttings. As the pilot end 24 is pushed along the pilot hole, the cutting face 28 engages and cuts into the rock surrounding the pilot hole. Each of the hole cutter drills 22 is sized to be at least larger than the diameter of the pilot hole. The diameter of at least one (the last if more than one) of the hole cutter drills is selected to produce the final diameter in the vein. The purpose of the trepanning process is to drill substantially all of the ore through the thickness of the vein without significantly drilling into the waste rock on either side of the vein. Thus, the final hole cutter drill may, for example, have a maximum diameter of: for example about the same as +/-10% thickness of the vein from the upper tray to the lower tray, which is up to 3 meters and typically about 1-2 meters. If the diameter of the hole is to be enlarged in multiple runs, there may be multiple hole opener drills used one after the other. However, in one embodiment, the hole is opened to a selected full diameter by a single hole opener drill.

To ensure that as much of the vein is mined as possible, the hole cutter drill may include a reamer mechanism 30, the reamer mechanism 30 allowing at least some of the cutters 28a to expand to a larger diameter while the bit remains downhole. Thus, if the thickness of the vein is greater along the depth, for example, as determined by surveying and imaging during pilot hole drilling, the hole cutter drill may be extended to a greater diameter along that particular depth. This allows the hole to be reamed and a larger diameter to be mined along a particular length of the hole. For example, reaming may increase the hole diameter by up to 30% of the normal diameter of a hole cutter drill. Thus, while it is preferred to drill a minimum diameter hole for penetration and to avoid drilling of waste rock, where the vein has a greater thickness along a particular length, the hole may be mined along that particular length closer to the contact of the upper and lower discs. If desired, the hole cutter drill may be retracted to the original hole diameter after the reaming process. This allows as much ore as possible to be recovered from the vein in one opening operation.

Drilling parameters affect the drill cuttings particle size distribution, which affects the ore grinding and comminution requirements in ore processing and separation processes and equipment. For example, in conventional ore processing, a large amount of energy is consumed in breaking down the ore to a fragment size suitable for ore extraction. Herein, drilling parameters such as the size of the drill tip may be selected to break ore as it is mined, for example, to break ore to a size more suitable for ore extraction as pilot holes and larger diameter holes are drilled. Thus, the drill tip size may be selected to break the vein to an average cut size of less than 5 cm diameter or possibly less than 1 cm or less than 5 mm. Cuttings of this size can be easily removed by circulation of the liquid and easily disposed of at the surface.

In one embodiment, the hole cutter drill may be a reverse circulation type drill bit including a fluid inlet 32 adjacent to, for example, the cutter 28a on the cutting face.

C. The hole cutter assembly also includes a drill string 33. The drill string is connected to the upper end 22' of the hole cutter drill 22 and axial movement of the drill string toward and away from the surface also moves the hole cutter bit and guide end 24. Likewise, the rotational movement of the drill string also rotates the hole cutter assembly, including the hole cutter bit 22 and pilot end 24, to drill out the ore that contacts the bit cutters 28 a.

The drill string employs pipe joints 34 that are capable of transmitting torque to the hole opener bit and delivering drilling fluid and/or recovering drill cuttings. In one embodiment, the drill string comprises large diameter drill pipes (e.g., 15 to 45 centimeters or more likely 22 to 38 centimeters) that are joined by bolting flange ends of the drill pipes together. The bolted flange connection enables the drill string and the drill tip to be rotated in both directions as required to prevent jamming of the drill string to clear accumulated cuttings and the like. The bolted flange connection (possibly with an O-ring at the interface) also provides a good seal against leakage of drilling fluid and cuttings during the recovery cycle.

The above described drill string has been found to work well in the system. However, if the use of these large diameter, flange-to-flange connected pipes makes the drill string too stiff to bend properly to follow the different directions of the pilot bore along the vein, the drill string can be adjusted to increase its flexibility. For example, it may be reconfigured to have a degree of flexibility, for example up to 5 degrees of curvature. In one embodiment, as shown in fig. 3A and 3B, a flexible drill string joint is employed that includes an elastomeric ring 40 with a steel liner 42 sandwiched between flanged ends 44a, 44B of at least some (e.g., every second or third) drill string joints 34. The elastomeric ring 40 is located between the flange 44a of the first pipe and the flange 44b of the second pipe so that the two flanges are spaced apart and not in contact. The steel liner is a cylinder with an inside Diameter approximately the same as the inside Diameter (Inner Diameter, ID) of the pipe to which it is attached. The steel liner is abutted between the pipe ends to transmit compressive forces through the drill string and to limit axial loads to prevent extrusion of the elastomeric ring into the inner diameter.

The flanges are then bolted together around bolts 48 using rigid elastomeric washers 46 (e.g., belleville washers). This flexible connection allows the joint to flex without breaking the bolts or compromising the seal between the flanges. By this flexible connection, the drilling machine can still transmit high rotational torque between drill string components, but the drill string can bend, so the large diameter hole cutter can easily follow the directional pilot hole, and the drill string can bend along a varying trajectory.

In one embodiment, the drill string is configured for operation with reverse circulation of liquid, and may have multiple conduits for downward circulation of air to improve upward circulation of conveyed drill cuttings, for example. The drill pipe may have a plurality of walls, for example configured as double walls or with external conduits for such air injection. Referring also to fig. 3A and 3B, the drill string may include one or more external conduits 50 extending along the main drill pipe to convey compressed air down the drill string. Each conduit extends downwardly to a port through the drill tip. The port discharges at an injection point located on the hole cutter drill bit. A discharge port is on the surface of the drill bit near the drill bit circulation inlet for delivering drill cuttings through the inlet 32 to the string inner diameter ID. Each conduit 50 may be secured at the flanges 44a, 44 b. In one embodiment, each conduit is formed from a plurality of pipe sections 50a, 50b, each of which is mounted between upper and lower flanges of a drill pipe, with the upper ends of the pipe sections terminating and sealing in the upper flanges and the lower ends of the pipe sections terminating and sealing in the lower flanges. Communication between the aligned pipe sections at the joint is via the flange and the aperture through the annular ring 40. Thus, although the pipe sections form a continuous conduit along a plurality of pipes, the same degrees of freedom remain along the conduit as are provided at the drill string connections.

The conduit conveys compressed air downward to allow for an increase in bottom hole pressure during a hole cutter drilling operation. This type of drill pipe (with conduits for injecting compressed air) may be used when there is insufficient bottom hole pressure to support cuttings transport, during a reverse circulation hole cutter drilling operation, such as when the hole cutter is near the surface. The compressed air mixes with the water in the hole at the drill tip and promotes lift. The hole may be filled and refilled with water to replace the water that rises out with the cuttings.

The drill string may also include stabilizers and other drilling tools. Stabilizers may be installed every 2 to 4 pipe joints. The stabilizer may have a diameter that is the same as the diameter of the hole cutter bit. The circulation subsystem circulates drilling fluid through the well, for example, to lift drill cuttings from the borehole to the wellhead for collection and processing to recover ore.

The type of drilling fluid selected may depend on the type of drilling well. For example, the drilling fluid may be water-based, foamed, or gaseous. It is possible that one type of liquid is used for pilot hole drilling and another type of liquid is used for opening the hole. In one embodiment, compressed air is used for pilot hole drilling, possibly with foam compressed air at greater depths. For the open pores, water may optionally be used with an air lift assist, as described above with respect to conduit 50.

The circulation system may include pumps, conduits, valves and means for changing the direction of circulation (reverse or forward) of the drilling fluid at the drilling rig. The device allows the direction of circulation of the drilling fluid to be changed and can be operated using a variety of fluid types, such as water, compressed air and foam. The apparatus may include a valve block and a mixer that can produce a foam having selected characteristics. In one embodiment, the direction of circulation is switched when reconfiguring from pilot hole drilling to open hole drilling.

Drill cuttings from both pilot hole drilling and open hole drilling are valuable because they contain ore. Thus, there is a rock debris collection system that collects rock debris in both stages. Thus, the system includes a collection path that can be used for both forward and reverse cycles. Depending on the direction of circulation, there may be returns from the drill string or from the annulus. Thus, returns containing cuttings may be conveyed by the top drive 118a and discharged through the discharge line 118c or through the ports 60 in the casing for annular communication.

As described above, the casing 114, which spans the distance between the drilling deck 116 and the surface, houses drilling operations and equipment for pilot and enlarged hole drilling. The casing 114 thus has an inner diameter large enough to allow the apertured assembly to pass therethrough and thus may be at least 1 meter and may be about 3 meters in diameter. There are some considerations in operating through the cannula.

As noted above, in some situations, such as when drilling near the surface (i.e., when the bottom hole assembly has just begun drilling or is near the surface), there may not be sufficient casing height and head volume to provide sufficient drilling pressure. In such embodiments, the bore pressure above the drill tip may be increased to provide a more suitable hydrostatic pressure.

For example, when drilling a pilot hole, the drill string has a diameter many times smaller than the diameter of the casing 114. Thus, when drilling a pilot hole, a cuttings collection apparatus and adapter for the smaller diameter drill pipe 12 may be employed that is configured to stabilize the smaller diameter drill string within the larger diameter casing and allow drilling fluid and cuttings to flow out during the pilot hole drilling operation. As shown in fig. 6A and 6B, the apparatus includes a housing 61 having a diameter greater than the outer diameter of the drill string 12, but much smaller than the casing 114. The housing provides a liquid-tight conduit through which the drill string 12 may be run and operated. The casing extends along the length of the casing 114 to span between the drill deck and the clamp 118b and the surface (e.g., the exposed vein v in which the pilot hole is to be drilled). The housing 61 forms an annular space between its inner wall 61' and the drill string to accommodate circulation of fluid. Thus, during forward circulation, which is typically used with a pilot hole drilling assembly, drilling fluid and cuttings may flow out of the annulus and prevent the cuttings from descending down the pilot hole. Further, the device includes i) a stuffing box 62, which isolates the hole from atmospheric pressure; ii) a centralizer 64 on the cartridge for stabilizing and securing the device within the casing 114; iii) a port 61a through which drilling fluid and cuttings may exit the casing; and iv) a resilient seal 63 mounted between the bottom end of the housing 61 and the ground. The elastomeric seal 63 prevents leakage of drilling fluid between the housing 61 and the surface. In a pilot hole drilling operation, the assembly comprising the cartridge 61 is secured substantially coaxially within the casing 114 by the centralizer 64, and the return line is connected at port 61 a. The drill string 12 may be accessed through the stuffing box 62 and operated within the casing 61. Normal pilot hole drilling operations may begin from the casing 61 to the vein v. Below the seal 63, a pilot hole is drilled. The positive fluid circulation may exit the bore through the housing 61 and exit through the port 61 a. The space between the cartridge 61 and the sleeve 114 remains open but is not in fluid communication with the interior of the cartridge 61. When the pilot hole is completed, the assembly including the cartridge 61 and centralizer 64 is removed from the casing 114. This opens the casing for drilling activities using the hole cutter assembly 18.

It has been noted above that when drilling near the surface, measures may be taken to ensure a sufficient hydrostatic head. This is especially noted during the opening of the holes. As described above, in some embodiments, the casing 114 and drilling rig may be raised to achieve a casing string height of approximately 16 meters above the bit face. Referring to fig. 4A-4C, a sufficient drilling fluid pressure P in the upper annulus may be achieved by pressurizing the annulus above the hole cutter bit 18¹Possibly with a forward cycle. To pressurize the annulus, a means of forming an annular seal between the open hole drill string 33 and the inner surface of the casing 114 may be used so that the pressure therebelow may be increased. The upper pressure device is mounted on the drill string 33 andis positioned in the sleeve 114. The apparatus includes a flange 70 having an annular seal 72 which together form a rotary seal assembly which spans the annular region between the casing and the drill pipe. The flange may rotate with the drill string while maintaining a pressure seal by pushing the seal 72 against the casing wall. For example, fig. 4C shows the drill tip 22 ready to dig an enlarged borehole through the bed 120 and into the bedrock or vein as the pilot end 24 enters the pilot bore 6. Although the length of casing as shown is not sufficient to provide sufficient hydrostatic head for drilling operations, the pressure below the flange 70 and seal 72 may be increased to this pressure P¹. The sleeve above the flange 70 is open to the atmosphere.

As drilling progresses, the flange 70 moves downwardly in the casing 114. A port such as port 60 maintains fluid communication between the casing and the annular region (between the drill string 33 and the casing 114) and is a port that: annular pressure is maintained through the port. Therefore, the rotary seal assembly must remain above the port. Thus, eventually the drill string 33 and flange are pulled out of the hole and more pipe joints are added to the drill string between the flange 70 and the drill tip 22. When the hole cutter reaches a depth where the fluid column is sufficient to support drilling operations, the rotating flange assembly may be pulled out of the hole and the hole may be opened without pressurizing the upper annulus. The opening is produced without a casing liner and the seal 123 prevents leakage. At this point, if the circulation is forward, the circulation may be reversed to return through the inner diameter of the drill string 33.

During the opening of the hole, the drill cuttings are collected at the wellhead and processed to recover the ore. Whether the cuttings are from a pilot hole or an open hole, the return flow is a mixture of cuttings and the fluid used. The drill cuttings may be separated from the liquid by passive sedimentation or active phase separation. Sedimentation may be carried out in a settling chamber or tank or pond. The active treatment may be performed by a cyclone or a screen (e.g. a vibrating screen). The rate of separation or size of the debris may dictate the selection.

Once separated, the drill cuttings are processed to recover the ore. Because the vein is broken by mining through the drilling process, the need for crushing and grinding may be minimized and possibly eliminated.

The foregoing description and examples have been set forth to provide those skilled in the art with a better understanding of the invention. The invention is not limited by the description and examples, but is to be construed broadly based on the appended claims.