INTEGRATED INSPECTION AND MAINTENANCE RAISE BORING METHOD AND AN ASSOCIATED DRILL STRING ARRANGEMENT

Abstract

A raise boring method is disclosed including the steps of cutting a raise with a raise boring arrangement comprising a surface-mounted drilling unit from which a hollow drill string, comprising a plurality of hollow drill pipes fitted together, extends downwardly through a pre-drilled pilot hole, with a reamer head to cut the raise being fitted to the end of the drill string; stopping the cutting process; lowering a cable through the hollow drill string towards the bottom of the raise; fitting an inspection device at the bottom of the raise to the cable extending through the hollow drill string, the inspection device comprising a controller to receive data obtained by the inspection device; operating the inspection device so as to inspect the side wall below where the reamer head is cutting; communicating the data obtained by the inspection device to an inspection station; and determining whether maintenance is required on the side wall.

Description

FIELD OF THE INVENTION

This invention relates to a raise boring method, and in particular to an integrated inspection and maintenance method for use during raise boring, and to an associated drill string for use in such a method.

BACKGROUND OF THE INVENTION

There are numerous raise boring methods. Conventional raise boring begins with the drilling of a pilot hole vertically down, typically using a directional drilling system. It is drilled using a drilling unit at the surface from which a hollow drill string, comprising a plurality of drill pipes fitted together, extends downwardly. A roller bit to drill the pilot hole is fitted to the lowermost drill pipe of the drill string, with the pipes having a standard thread for high-torque applications.

The cuttings of the drilled pilot hole are typically removed from the pilot hole with the aid of water flushing introduced through the center of the drill string. When the pilot hole breaks through into a lower level, the roller bit is removed and replaced with a reamer head comprising a plurality of cutters. The reamer head is rotated and pulled back towards the surface-mounted drilling unit so as to cut a larger hole, or raise, through the ground and rock. The cuttings fall by gravity into a chamber at the bottom of the hole, typically in an uncontrolled manner, where they are removed using a loader.

Raises up to 6 m in diameter and up to 1000 m in length, although not uncommon, present certain difficulties. For example, during the drilling of the raise, ground and rock from a side wall below where the reamer head is cutting may give way resulting in side wall cavities, thus causing instability in the drilled raise and resulting in a hazardous and possibly life-threatening structure. Typically, these unwanted side wall cavities do not get detected until only after the entire raise has been fully drilled. Only thereafter would it be possible to send a reinforcing device down into the hole to patch up these side wall cavities. However, this approach has numerous shortcomings, such as safety issues during the subsequent reinforcing of the side wall, as a result of the precarious structure of the drilled raise. In addition, these side wall cavities tend to get bigger over time, thereby further increasing the dangers associated with the reinforcement of the side wall. The enlarged side wall cavities also require more reinforcement than would have been required had these cavities been detected sooner i.e. during the drilling process. The use of additional reinforcement and the associated additional time spent represent inefficiencies that are undesirable, particularly during a mining operation.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a raise boring method and, in particular, to an integrated inspection and maintenance method for use during raise boring that can address the shortcomings described above.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a raise boring method comprising:

• • cutting a raise with a raise boring arrangement comprising a surface-mounted drilling unit from which a hollow drill string, comprising a plurality of hollow drill pipes fitted together, extends downwardly through a pre-drilled pilot hole, with a reamer head to cut the raise being fitted to the end of the drill string;
  • stopping the cutting process;
  • lowering a cable through the hollow drill string towards the bottom of the raise;
  • fitting an inspection device at the bottom of the raise to the cable extending through the hollow drill string, the inspection device comprising a controller to receive data obtained by the inspection device;
  • operating the inspection device so as to inspect the side wall below where the reamer head is cutting;
  • communicating the data obtained by the inspection device to an inspection station; and
  • determining whether maintenance is required on the side wall, and if maintenance is required, the method further comprises:
    • removing the inspection device from the cable;
    • fitting a maintenance device at the bottom of the raise to the cable; and
    • operating the maintenance device so as to perform the required maintenance on the side wall.

In an embodiment, after the maintenance performed by the maintenance device, the method comprises removing the maintenance device from the cable and then either refitting the inspection device to the cable to inspect the maintenance work or, after raising the cable back up through the drill string, allowing the raise boring arrangement to continue cutting.

In an embodiment, the step of operating the inspection device so as to inspect the side wall comprises raising and lowering the cable and/or rotating the inspection device, or at least an inspection component of the inspection device, through 360°, so as to inspect the entire side wall.

According to a second aspect of the invention there is provided a hollow drill string arrangement that can be secured to a raise boring arrangement for cutting a raise, the raise boring arrangement comprising a surface-mounted drilling unit from which the hollow drill string extends downwardly through a pre-drilled pilot hole, with a reamer head to cut the raise being fitted to the end of the drill string, the drill string arrangement comprising:

• • a plurality of hollow drill pipes fitted together;
  • a cable that can extend through the plurality of hollow drill pipes, the cable being connectable to either an inspection device for inspecting the side wall below where the reamer head is cutting or a maintenance device for performing any required maintenance on the side wall.

In an embodiment, the cable is a simple hoisting cable to mechanically connect the inspection and maintenance devices to an actuating device on the ground to raise and lower the devices as required.

In an alternative embodiment, the cable is an integral data and hoisting cable to not only mechanically connect the inspection and maintenance devices to an actuating device on the ground to raise and lower the devices as required, but also to allow data communication between the devices and an inspection station.

In this latter embodiment, the integral data and hoisting cable comprises:

• • a support cable to support the device;
  • a data network cable to facilitate communications between the shaft device and the inspection station; and
  • a power conducting cable to conduct electrical power to the device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic side view of a raise boring assembly, in which the integrated inspection and maintenance method of the present invention can be implemented;

FIG. 2 shows a schematic side view of the integrated inspection and maintenance method of the present invention, in which an inspection device has been fitted to a cable extending through a hollow drill string;

FIG. 3 shows a schematic side view of the integrated inspection and maintenance method of the present invention, in which a maintenance device has been fitted to a cable extending through a hollow drill string;

FIG. 4 shows a detailed view of the arrangement shown in FIG. 3;

FIG. 5 shows a schematic side view of the maintenance device being lowered once the required maintenance has been performed; and

FIG. 6 shows a flow chart representing a raise boring method according to a further embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the attached figures, a raise boring arrangement 10 comprises a surface-mounted drilling unit 12 from which a hollow drill string 14, comprising a plurality of hollow drill pipes 16 fitted together, extends downwardly through a pre-drilled pilot hole 18. A reamer head 20 to cut the raise 22 is fitted to the end of the drill string 14.

Thus, as shown in FIG. 1, the raise boring arrangement 10 is shown cutting the raise 22, as is well known in the art. However, FIG. 1 further shows an inspection device 24 supported on a cradle 26, for example, and a maintenance device 28, ready for use but substantially out of the way during the cutting process. The inspection device 24 is used to inspect the side wall 30 below where the reamer head 20 is cutting, and the maintenance device 28 is subsequently used to perform any required maintenance on the side wall 30. These aspects will be explained in more detail further on in the specification.

Significantly, a cable 32 can extend through the hollow drill string, as best shown in FIGS. 2, 4 and 5. The cable is connectable to both the inspection device 24 and the maintenance device 28.

In one version, the cable 32 is a simple hoisting cable to mechanically connect the inspection and maintenance devices 24, 28 to an actuating device 36 on the ground to raise and lower the devices 24, 28 as required.

Alternatively, the cable 32 is an integral data and hoisting cable to not only mechanically connect the inspection and maintenance devices 24, 28 to the actuating device 36 on the ground to raise and lower the devices 24, 28 as required, but also to allow data communication between the devices 24, 28 and an inspection station (not shown). In this latter embodiment, the integral data and hoisting cable comprises a support cable to support the devices 24, 28, a data network cable to facilitate communications between the devices 24, 28 and the inspection station, and a power conducting cable to conduct electrical power to the devices 24, 28.

In use, the cutting process shown in FIG. 1 is stopped. This may either take place at regular, predetermined time intervals or based on some either trigger event.

The cable 32 is then lowered through the hollow drill string, typically by a winch 36 or by any other arrangement, towards the bottom of the raise 22. The inspection device 24 is then fitted to the end of the cable 32 and then raised using the winch 36 to the region in the raise 22 that is to be inspected. As best shown in FIG. 2, the inspection device 24 is then operated so as to inspect the side wall 30 below where the reamer head 20 is cutting, to locate, for example, the cavity 40 in the side wall 30.

The inspection device 24 may comprise a controller to receive data obtained by the inspection device 24, with this data then being communicated to an inspection station typically positioned on the ground (although not shown). The inspection device 24 is typically fitted with a camera 42 to compile video data of the side wall 30 defining the cut raise 22 and a light to illuminate the area being inspected.

In an embodiment, an actuating arrangement is provided to rotate the inspection device and/or the camera through 360°, as indicated by circular arrow 44 in FIG. 2, so as to inspect the entire side wall 30 of the raise 22. The actuating arrangement may either be on the inspection device itself or on the ground.

Personnel at the inspection station then have to determine whether maintenance is required on the side wall. If maintenance is required, the cable 32 is lowered using the winch 36 to the bottom of the raise 22. Thereafter, the inspection device 24 is removed from the cable 32 to enable a maintenance device 28 to be fitted to the end of the cable 32 and then raised to the region requiring maintenance. As best shown in FIGS. 3 and 4, the maintenance device 28 is then operated so as to perform the required maintenance on the side wall 30. In the illustrated example, the maintenance device 28 includes a cement lining application member 46 for spraying or dispersing a cement lining so as to fill the cavity 40 in the side wall 30. Clearly, other maintenance devices may be used, such as bolters and mesh applicators.

In the illustrated example, the maintenance device 28 comprises a support frame 48 to which the end of the cable 32 is connected, and a carrier arm 50 for supporting the cement lining application member 46. The maintenance device 28 typically also comprises a controller, a video camera and a light to transmit data regarding the maintenance being performed to the inspection station. The controller thus accumulates and transmits data to the inspection station, and it also receives operating instructions from the inspection station for controlling at least the carrier arm 50. The carrier arm 50 is typically rotatably mounted to the support frame 48 to facilitate maintenance on a wide area of the side wall 30.

As shown in FIG. 5, after the required maintenance has been performed by the maintenance device 28, the cable 32 is lowered back down to the bottom of the raise 22 to enable the maintenance device 28 to be removed from the cable 32. Thereafter, either the inspection device 24 is refitted to the cable 32 to inspect the maintenance work, or, after raising the cable 32 back up through the drill string 14, the raise boring arrangement 10 is simply allowed to continue cutting.

Turning now to FIG. 6, a raise boring method 60 comprises cutting a raise with a raise boring arrangement, as indicated by block 62. As described above, the raise boring arrangement comprise a surface-mounted drilling unit from which a hollow drill string, comprising a plurality of hollow drill pipes fitted together, extends downwardly through a pre-drilled pilot hole, with a reamer head to cut the raise being fitted to the end of the drill string. Thereafter, the method comprises stopping the cutting process, as indicated by block 64, and then fitting an inspection device to a cable extending through the hollow drill string, as indicated by block 66. As described above, the inspection device comprises a controller to receive data obtained by the inspection device.

The method continues by operating the inspection device so as to inspect the side wall below where the reamer head is cutting, as indicated by block 68, communicating the data obtained by the inspection device to an inspection station, as indicated by block 70, and determining whether maintenance is required on the side wall, as indicated by decision block 72.

If maintenance is required, the method continues by removing the inspection device from the cable, as indicated by block 74, fitting a maintenance device to the cable, as indicated by block 76, and operating the maintenance device so as to perform the required maintenance on the side wall, as indicated by block 78.

If, however, no maintenance is required, the method concludes by simply removing the inspection device from the cable, raising the cable and continuing cutting, as indicated by block 80.

The present invention thus provides an efficient and cost-effective integrated inspection and maintenance raise boring method, and an associated hollow drill string arrangement.

Claims

1. A raise boring method comprising:

cutting a raise with a raise boring arrangement comprising a surface-mounted drilling unit from which a hollow drill string, comprising a plurality of hollow drill pipes fitted together, extends downwardly through a pre-drilled pilot hole, with a reamer head to cut the raise being fitted to the end of the drill string;

stopping the cutting process;

lowering a cable through the hollow drill string towards the bottom of the raise;

fitting an inspection device at the bottom of the raise to the cable extending through the hollow drill string, the inspection device comprising a controller to receive data obtained by the inspection device;

operating the inspection device so as to inspect the side wall below where the reamer head is cutting;

communicating the data obtained by the inspection device to an inspection station; and

determining whether maintenance is required on the side wall, and if maintenance is required, the method further comprises: removing the inspection device from the cable; fitting a maintenance device at the bottom of the raise to the cable; and operating the maintenance device so as to perform the required maintenance on the side wall.

2. The raise boring method of claim 1, wherein, after the maintenance performed by the maintenance device, the method comprises removing the maintenance device from the cable and then either refitting the inspection device to the cable to inspect the maintenance work or, after raising the cable back up through the drill string, allowing the raise boring arrangement to continue cutting.

3. The raise boring method of either claim 1 or claim 2, wherein the step of operating the inspection device so as to inspect the side wall comprises raising and lowering the cable and/or rotating the inspection device, or at least an inspection component of the inspection device, through 360°, so as to inspect the entire side wall.

4. A hollow drill string arrangement that can be secured to a raise boring arrangement for cutting a raise, the raise boring arrangement comprising a surface-mounted drilling unit from which the hollow drill string extends downwardly through a pre-drilled pilot hole, with a reamer head to cut the raise being fitted to the end of the drill string, the drill string arrangement comprising:

a plurality of hollow drill pipes fitted together; and

a cable that can extend through the plurality of hollow drill pipes, the cable being connectable to either an inspection device for inspecting the side wall below where the reamer head is cutting or a maintenance device for performing any required maintenance on the side wall.

5. The hollow drill string arrangement of claim 4, wherein the cable is a hoisting cable to mechanically connect the inspection and maintenance devices to an actuating device on the ground to raise and lower the devices as required.

6. The hollow drill string arrangement of claim 4, wherein the cable is an integral data and hoisting cable to not only mechanically connect the inspection and maintenance devices to an actuating device on the ground to raise and lower the devices as required, but also to allow data communication between the devices and an inspection station.

7. The hollow drill string arrangement of claim 6, wherein the integral data and hoisting cable comprises:

a support cable to support the device;

a data network cable to facilitate communications between the shaft device and the inspection station; and

a power conducting cable to conduct electrical power to the device.