WO2006045144A1

WO2006045144A1 - Platform and a method of locating an object in a borehole

Info

Publication number: WO2006045144A1
Application number: PCT/AU2005/001654
Authority: WO
Inventors: Geoffrey Robbins
Original assignee: Sanleo Holdings Pty Ltd; Soothjet Pty Ltd
Priority date: 2004-10-27
Filing date: 2005-10-25
Publication date: 2006-05-04

Abstract

A device (70) to be lowered into a borehole (40) to engage the sidewall (42) thereof so that a support member (71) of the device may support an objection thereon. The member has attached to it a first line (74) via which the member is lowered and a second (78) via which the member is manipulated to move angularly from a longitudinally downward orientation toward a horizontal orientation, at which the periphery of the member engages the side wall so that the object may be supported thereon.

Description

Platform and a Method of Locating an Object in a Borehole

Technical Field

The present invention relates to boreholes. More particularly, the invention relates to a platform for use inside a borehole and to a method of locating an object in a borehole.

Background of the Invention

In open cast mining operations, overburden usually has to be removed from an area above an ore body. To achieve this in a cost effective manner, a number of boreholes, each having a diameter of from about 75 mm to more than 300 mm, usually either 270 mm or 311 mm in diameter, are drilled into the overburden, which is then blasted loose, whereafter the overburden is removed by suitable machinery. The same technique is also used in other fields of blasting where large amounts of material must be removed or loosened up first, by means of explosives, before it is removed.

After drilling of the boreholes as aforementioned, a primary explosive and a secondary explosive material such as a mixture of ammonium nitrate and fuel oil (AKFO) or some other suitable low cost explosives are lowered into each borehole, to a desired depth. The depth is usually determined by careful analysis of exploration data of the location of the ore body.

A suitable platform for explosives to be used in the above manner can be provided by using an inflatable borehole plug such as the one that is described in UK patent No. 2262757.

The secondary explosive is usually provided in a free flowing applied form, or in a pumpable slurry or emulsion forms, so that it may be easily disposed down the borehole. When a required number of boreholes has been drilled and charged with secondary explosive, the working area is blasted.

A detonator is usually provided in the primary explosive inside each hole and the detonators are in turn connected to a firing system adapted to fire the detonators, preferably in a desired sequence, which is usually predetermined.

Inflatable borehole plugs are suitable for bore holes where no water is present. In addition, they are difficult or impossible to retrieve and/or relocate.

There accordingly exists a need for an inexpensive, but cost effective device for supporting objects such as explosives in a borehole where the borehole is full of water. There is also a need for a support in a borehole that can be retrieved and/or repositioned. Object of the Invention

It is an object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages.

It is another object of the present invention to address at least one of the aforementioned needs.

Summary of the Invention

There is disclosed herein a device to be lowered into a borehole, the borehole having a longitudinal side wall and a diameter, the device being operable to engage the side wall to support an object in the borehole by the object resting on the device, said device having: a support member having a periphery to engage the side wall, a longitudinal length that is to be larger than the diameter, and a transverse width less than the diameter; a flexible line attached to the support member so that when the support member is suspended therefrom the support member is oriented so that the longitudinal length is downwardly extending; and wherein said support member is manipulable to move angularly from a longitudinally downward orientation, to a position at which said longitudinal length is displaced angularly from the downward orientation toward a horizontal orientation at which said periphery engages the side wall so that the object may be supported thereon. Preferably, said support member has a centre of gravity, and said line is attached to said support member at a position displaced from the centre of gravity toward said periphery.

Preferably, said support member includes at least one spike to engage said side wall to aid in manipulation of the support member to move the support member angularly to engage the side wall.

Preferably, said periphery includes projections to aid in engagement with said side wall.

Preferably, said_. support member includes a first portion pivotally attached to a second portion, with said flexible line being attached to said first portion; and wherein said device includes a second line attached to said second portion, with the lines being manipulated to cause angularly displacement between the two portions to move the periphery into engagement with the side wall. Preferably, the two portions are moved angularly apart to cause the periphery to engage the side wall.

Preferably, said device includes a third flexible line to cause angular movement between the two portions. Preferably, said portions are moved angularly together to cause the periphery to engage the side wall.

Preferably, said device further includes a weight attached to said support member to aid in orienting said support member with said longitudinal length extending downwardly. Preferably, said support member is formed of sheet material.

There is further disclosed herein a method of locating a support member in a borehole so that the support member may support an object to rest thereon, said method including the steps of: providing the above device; lowering the device into the borehole; and manipulating said support member to cause said periphery to engage said side wall.

Brief Description of the Drawings

A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein:

Figure 1 is a plan view of one embodiment of a device in accordance of the invention;

Figure 2 is an elevational view of the device of Figure 1;

Figure 3 is a plan view of another embodiment in accordance with the invention; Figure 4 is an elevational view of the device of Figure 3;

Figure 5 is a diagrammatic representation of part of a borehole showing the location of a device in accordance with the invention;

Figure 6 is a plan view of another embodiment in accordance with the invention;

Figure 7 is an elevational view of the device of Figure 6; Figure 8 is an elevational view of yet another embodiment in accordance with the invention;

Figure 9 is a schematic side elevation of a modification of the device of Figure 8 being inserted in a borehole; Figures 10 and 11 are schematic sectioned side elevations of the device of Figure 9 being manipulated to engage the borehole;

Figure 12 is a schematic side elevation of a modification of the device of Figure 1 being engaged with a borehole; 5 Figure 13 is a schematic top plan view of the device of Figure 1 ; and

Figure 14 is a plurality of schematic plan views of alternative configurations of the device of Figure 13.

Detailed Description of the Preferred Embodiments

Referring to Figures 1 and 2, there is shown a device 10 in accordance with one

I₀ embodiment of the invention. The device 10 comprises a support member 12 which is a disc of compressed fibre cement (or other suitable sheet material) having a generally elliptical shape periphery, with rounded projections 12.1, 12.2, 12.3, 12.4, 12.5 at either end. The support member 12 has a first centre line or line of symmetry 14 extending (through the centre of gravity 13 of the member 12) from a first end 16 to a second end is 18, and a second centre line or line of symmetry 20 extending from a first short side 22 to a second short side 24. The support member 12 is substantially symmetrical about the first and second lines of symmetry 14, 20.

A pair of holes 24.1, 24.2 are provided adjacent the first end 16, with the holes 24.1, 24.2 spaced equally from the first line of symmetry 14. A string 26 extends through 0 the holes 24.1, 24.2 and is fastened to the device 10. When device 10 is lowered down a borehole, the weight of the device 10 is carried by the string 26 in such a way that the line of symmetry 14 is substantially parallel to the string 26.

Referring to Figures 3 and 4, there is shown another embodiment 310 of the device in accordance with the invention. In Figures 3 and 4, like reference numerals refer ₅ to like parts.

The device 310 comprises a support member 312 which is a disc of compressed fibre cement (or other suitable sheet material) having a generally elliptical shape, with rounded projections 312.1, 312.2, 312.3, 312.4, 312.5 at either end. The support member 312 has a first centre line or line of symmetry 314 extending from a first end 316 to a 0 second end 318, and a second centre line or line of symmetry 320 extending from a first short side 322 to a second short side 324. The support member 312 is substantially symmetrical about the first and second lines of symmetry 314, 320 and has a centre of gravity 313. A pair of holes 324.1, 324.2 are provided adjacent the first end 316, with the holes 324.1, 324.2 spaced equally from the first line of symmetry 314. A string 326 extends through the holes 324.1, 324.2 and is fastened to the device 310. When device

310 is lowered down a borehole, the weight of the device 310 is carried by the string 326 in such a way that the line of symmetry 314 is substantially parallel to the string 326.

The device 310 shown in Figures 3 and 4 is accordingly generally the same as the device 10 shown in Figures 1 and 2, except that the device 310 also comprises a pair of spikes 330, 332, and a transversely extending deflection plate 334. Each of the spikes 330, 332 has a free end 330.1, 332.1 which is sharpened so that it can more easily bite into the side of the borehole; and an opposite end 330.2, 332.2 which is hingedly connected to an underside of the support member 312. The string 326 extends around the underside of the prongs 330, 332.

The deflection plate 334 extends transversely across the support member 312, and is hingedly connected to it. A further hole 334 is provided in the support member 312, conveniently adjacent the end 318, and a second string 336 may be fastened to the support member 312. The function of the further hole 334 and the second string 336 is to enable the device 310 to be relocated upwards in the borehole in the event that the device 312 has been lowered deeper than where it is required to be located into the borehole. When upwards tension is applied to the string 336, the device can be pulled up for retrieval from the borehole or for relocation at a higher elevation.

In Figure 5, there is shown a borehole 50 provided with a short length of casing 52 at its top end. A device 10 is shown located in the borehole 50, where it can support a load of explosives (not shown). One end of the string 26 is attached to the end 16 of the device, whilst the other end is attached at a fixed anchorage point 54 at the top of the borehole 50, after it has passed over a pulley 56. The anchorage point 54 is a steel member welded to the casing 52.

In use, the device 10, 310, is lowered down the borehole 50 to a level where it is required to form a platform for supporting an object or a load. The device 10, 310, is preferably lowered down the borehole 50 with its first end 16, 316 inserted first, so that the opposite or second end 18, 318 is above the first end 16, 316.

When the desired depth is reached, the string 26 is pulled upwards, causing the projections 12.1 to 12.5 (312.1 to 312.5) of the end 18 (318) to bite into the side of the borehole. By pulling the string 26 more, the projections 12.1 to 12.5 (312.1 to 312.5) of the first end 16 (316), are caused to bite into the side wall of the borehole in a region substantially opposite the region in which the projections 12.1 to 12.5 (312.1 to 312.5) of the first end 16 are located. Tension is maintained on the string 26. Thereafter, a weight such as explosives, may be lowered down the borehole or dropped down the borehole 50 until the weight comes to rest on the support member 12, 312.

In the case of the embodiment shown in Figures 3 and 4, the deflection plate 334 deflects the explosives to the end 18, preventing it from becoming disengaged from the side wall of the borehole.

Referring to Figures 6 and 7, there is shown another embodiment of the device 610 in accordance with the invention. In Figures 6 and 7, like reference numerals refer to like parts.

The device 610 comprises a support member 612 which is a disc of compressed fibre cement (or other suitable sheet material) having a periphery of generally elliptical shape, with rounded projections 612.1, 612.2, 612.3, 612.4, 612.5 at either end. The support member 612 has a first centre line or line of symmetry 614 extending from a first end (portion) 616 to a second end 618 (portion), and a second centre line or line of symmetry 620 extending from a first short side 622 to a second short side 624. The support member 612 is substantially symmetrical about the first and second lines of symmetry 614, 620. The support member 612 is divided into two halves 612.1, 612.2 hingedly connected to each other along the centre line 620.

The ends 616 and 618 pivot about a transverse axis from a position in which the ends 616 and 618 are abutting, to a configuration in which they are pivoted so as to angularly part to cause the periphery 615 to engage the longitudinal side wall of the borehole.

A first pair of holes 624.1, 624.2 are provided adjacent the first end 616, with the holes 624.1, 624.2 spaced equally from the first line of symmetry 314. A first string 626 extends through the holes 624.1, 624.2 and is fastened to the support member 612. A second pair of holes 624.3, 624.4 are provided adjacent the second end 618, with the holes 624.3, 624.4 also spaced equally from the first line of symmetry 614. A second string 627 extends through the holes 624.3, 624.4 and is fastened to the support member 612. A third pair of holes 624.5, 624.6 are provided on either side of the second line of symmetry 620. A third string 629 extends through the holes 624.5, 624.6 and is also fastened to the support member 612.

When the device 610 is to be lowered down a borehole, the weight of the device 310 is carried by the third string 629. When it has to be located, the first and second strings 626, 627 are pulled whilst the tension on the third string 629 is relaxed. In' this way, the ends 616, 618 of the support member 612 are pushed outwards to engage with the side wall of the borehole50. When the support member 612 is loaded with a weight, the projections 612.1, 612.2, 612.3, 612.4, 612.5of the ends 616 618 push harder into the side wall of the borehole. The length of the support member is preferably selected such that the centre line or line of symmetry 620 of the support member 612 will in use always be at least slightly higher than the ends 616, 618, thus forming a bridge between oppositely located points in the sidewall of the borehole, with the ends 616, 618 never pivot through a plane extending through the ends 616, 618. When upwards tension is applied to the third string 629, the device can be pulled up for retrieval from the borehole 50 or for relocation at a higher elevation, where it can be relocated in the same manner as before.

Referring to Figure 8, there is shown a device .810 in accordance with another embodiment of the invention. As in previous figures, like reference numerals refer to like parts.

The device 810 comprises a first support member 812.1 and a second support member 812.2, both of which are discs of compressed fibre cement (or other suitable sheet material) having a generally elliptical shape. The length of each of the support members 812.1 and 812.2 exceeds the diameter of a borehole in which the device 810 is to be used, whilst the width of each of the support members 812.1 and 812.2 is less than the diameter of the borehole.

The support members 812.1 and 812.2 have first ends 816, 1, 816.2 and second ends 818.1, 818.2. The support members 812.1 812.2 are substantially symmetrical about first and second lines of symmetry (not shown). They are fastened to each other by suitable means, for example two strips of plastics material 859, which extend through holes 851, 853 provided through the support members 812.1 and 812.2 near their second ends 818.1, 818.2, in such a way that the support members 812.1 and 812.2 are able to pivot from one position (not shown) in which the support member 812.1 is located immediately above and parallel to the support member 812.2 (a "closed position"), to another position in which the support member 812.1 forms an angle with the support member 812.2 (an "open position").

A hole 860 is provided adjacent the first end 816.1 of the first support member 812.1. A pair of holes 824.1, 824.2 are provided adjacent the first end 816.2 of the second support member 812.2.

A first string 826 extends through the hole 860 as well as through the holes 824.1, 824.2 and is fastened to the first support member 812.1. The other end of the first string 826 may be held by a person when the device 810 is lowered down a borehole. A second string 861 is fastened to a suitable tag 863 which in turn is tied to the first support member 812.1, using a hole 863 extending through the first support member 812.1, near its end 816.1.

In use, the device 810 is lowered down a borehole, with the support members 812.1 and 812.2 in the open position. The device 810 is then suspended from the string 861.

When a desired depth is reached, the first string 826 is pulled, causing the support members 812.1 and 812.2 to be pivoted to their closed position. This causes the support members 812.1 and 812.2 to become jammed in the borehole.

The second string 861 may then be removed, by severing its attachment to support members 812.1, whilst maintaining a tension of the first string 826, so as to keep the device 810 jammed in the borehole. If the tension is not maintained on the first string

826, the device 810 may be recovered from the borehole for possible reuse or relocation within the borehole.

In Figure 9 there is schematically depicted a borehole 40, the borehole 40 having a generally central longitudinal axis 41 and a generally cylindrical side wall 42. Located in the borehole in engagement with the side wall 42 is a device 43 that is to support an object in the borehole 40. The device 43 includes a support member 44 including a first portion 45 and a second portion 46, the portions 45 and 46 being formed of sheet material

(such as compressed fibre cement or laminated ply). The portions 45 and 46 are pivotally attached by means of flexible hinges 47 so as to be movable angularly relative to each other about a pivot axis 48. Typically the axis 48 would be generally horizontal and normal to the longitudinal axis 41. The portions 45 and 46 each have a periphery 49 that engages the side wall 8. Preferably each periphery 49 has a plurality of projections 50 that aid in gripping the side wall 42.

Suspended from the portion 46 is a weight 51.

5 As best seen in Figures 10 and 11, the device 43 is lowered down the borehole

40 by means of a flexible line 52. The line 52 is detachably secured to the portion 45 by means of a strap 53 that breaks when sufficient pressure is applied thereto so as to release the line 52.

The device 40 further includes a second line 54. The line 54 extends through a Q first aperture 55 in the member 45, and passes through a pair of apertures 56 in the member 46 and is ultimately secured to the member 45 by being looped through the apertures 55 and 57. m that regard, the line 54 is slidable through the apertures 55 and

56.

Initially the device 40 is lowered into the borehole 40 as illustrated in Figure 10. s The weight 51 elongates the device 40 so that it fits down the borehole 40, that is, with the longitudinal length of each member 45 and 46 extending downwardly.

When the device 40 is directly located (as seen in Figure 11) the line 54 is tensioned so that the members 45 and 46 move angularly toward each other to thereby bring the peripheries 49 into engagement with the side wall 42. Accordingly the device Q 40 is then anchored to the side wall 42. Continued pressure applied to the line 52 will cause the strap 53 to break and release the line 52. The line 54 is anchored by means of a stake 58.

In Figure 12 there is schematically depicted a support device 70. In this embodiment the device 70 consists of a support member 71 that is formed of sheet 5 material as previously discussed. The support member 71 has a periphery 72 with a plurality of projections 73 that aid in engaging the side wall 42. In this embodiment a first flexible line 74 is attached to a strap 75 to aid in lowering the member 71. The strap 75 is attached to adjacent the periphery 72 and is spaced from the centre of gravity 77 of the member 71. Attached to the member 71 is a flexible line 78, at a position spaced from Q the strap 75, and preferably located between the strap 75 and the centre of gravity 77. Initially the member 71 is lowered into the borehole 40 by means of the flexible line 74 while attached to the strap 75. Accordingly with the member 71 suspended by the lines 74, the longitudinal axis 79 of the member 71 is generally downwardly extending. Accordingly the longitudinal length of the member 71 extends generally downwardly. Upon a desired location being reached, the flexible line 78 is tensioned to cause the member 71 to move angularly so as to extend generally transverse of the borehole 40, that is to reposition itself so that the projections 73 engage the side wall 42. Thereafter the line 74 is further tensioned to cause the strap 75 to break and thereby release the line 74. In the embodiment of Figure 12 the strap 75, attachment point 90 for the line 78, and centre of gravity 91 are located on the longitudinal axis 79. As best seen in Figure 13, the member 71 has a longitudinal length 92 that is greater than the diameter of the borehole 40, and a transverse with 93 that is less than the diameter of the borehole 40. Preferably the axis 79 passes through the centre of the member 71. In Figure 14 there is schematically depicted a variety of different shapes applicable to the member 71, 45, 46, 812.1, 812.2, 612, 312, 12. In each instance the member 71 has a longitudinal length greater than the diameter of the borehole 40 and a transverse width less than the borehole 40.

Claims

CLAIMS:

1. A device to be lowered into a borehole, the borehole having a longitudinal side wall and a diameter, the device being operable to engage the side wall to support an object in the borehole by the object resting on the device, said device having:

5 a support member having a periphery to engage the side wall, a longitudinal length that is to be larger than the diameter, and a transverse width less than the diameter; a flexible line attached to the support member so that when the support member is suspended therefrom the support member is oriented so that the longitudinal length is downwardly extending; and wherein o said support member is manipulable to move angularly from a longitudinally downward orientation, to a position at which said longitudinal length is displaced angularly from the downward orientation toward a horizontal orientation at which said periphery engages the side wall so that the object may be supported thereon.

2. The device of claim 1, wherein said support member has a centre of s gravity, and said lines attached to said support member at a position displaced from the centre of gravity toward said periphery.

3. The device of claim 1 or 2, wherein said support member includes at least one spike to engage said side wall to aid in manipulation of the support member to move the support member angularly to engage with the side wall. 0

4. The device of claim 1, 2 or 3, wherein said periphery includes projections to aid in engagement with said side wall.

5. The device of claim 1, wherein said support member includes a first portion pivotally attached to a second portion, with said flexible line being attached to said first portion; and wherein said device includes a second line attached to said second 5 portion, with the lines being manipulated to cause angularly displacement between the two portions to move the periphery into engagement with the side wall.

6. The device of claim 5, wherein the two portions are moved angularly apart to cause the periphery to engage the side wall.

7. The device of claim 5, wherein said portions are moved angularly o together to cause the periphery to engage the side wall.

8. The device of claim 7 further including a third line, the third line being manipulated to cause the angular movement between the two portions.

9. The device of anyone of claims 1 to 8, further including a weight attached to said support member to aid in orienting said support member with said longitudinal length extending downwardly.

10. The device of anyone of claims 1 to 9, wherein said support member is formed of sheet material.

11. A method of locating a support member in a borehole so that the support member may support an object to rest thereon, said method including the steps of: providing the above device; lowering the device into the borehole; and manipulating said support member to cause said periphery to engage said side wall.

12. A device to aid in supporting an object in a borehole, the device being substantially as hereinbefore described with reference to Fig. 1, Fig. 2, Fig. 6, Fig. 8 and Fig. 12.