Title of Invention	"DEVICE FOR SEALING INSIDE AN UPWARD DRILLED BOREHOLE FOR HIGH PRESSURE WATER INJECTION IN UNDERGROUND MINES"
Abstract	Device for sealing inside an upward drilled borehole for high pressure water injection in underground mines which comprises an externally threaded injection pipe (1) , characterized in that the said pipe(1) having an end flange (2) welded onto the said injection pipe (1) at the injection end top, the said injection pipe being provided at the flange end with a plurality of externally mounted expandable flexible rings (3) of circular cross section, the said rings (3) being held in position by a steel gasket (4) and a peripherally slotted locking nut (5) fitted to the said pipe (1), the said externally threaded injection pipe(1) being provided at the bottom end portion with an internally threaded retreating tapered nut (11) having a sealing ring (10) and a concentric flange (6) being provided with at least four threaded ground studs (8) and nuts (9).

Title of Invention

"DEVICE FOR SEALING INSIDE AN UPWARD DRILLED BOREHOLE FOR HIGH PRESSURE WATER INJECTION IN UNDERGROUND MINES"

Abstract

Device for sealing inside an upward drilled borehole for high pressure water injection in underground mines which comprises an externally threaded injection pipe (1) , characterized in that the said pipe(1) having an end flange (2) welded onto the said injection pipe (1) at the injection end top, the said injection pipe being provided at the flange end with a plurality of externally mounted expandable flexible rings (3) of circular cross section, the said rings (3) being held in position by a steel gasket (4) and a peripherally slotted locking nut (5) fitted to the said pipe (1), the said externally threaded injection pipe(1) being provided at the bottom end portion with an internally threaded retreating tapered nut (11) having a sealing ring (10) and a concentric flange (6) being provided with at least four threaded ground studs (8) and nuts (9).

Full Text	This invention relates to a device for sealing inside an upward drilled borehole for high pressure water injection in underground mines. This device is useful for sealing inside an upward drilled borehole in overlying strata for water injection urder high-pressure in an underground mine. The successful extraction of coal from underground either by Bord and Pillar or by Longwall method depends on the systematic caving of overlying roof rocks. It is necessary to induce caving of hard roof encountered in the active caving zone by water injection under high pressure. Boreholes are drilled in the goaf area upward in the roof. Water is injected in these boreholes under high pressure, which eliminates the problem of delayed caving and ensures regular caving of roof rocks behind the supports. This reduces the load on supports and improves the stability of immediate roof in the working area. Sealing of the hole has to be done deep inside the borehole for injection of water under high pressure, which is useful for softening and hydrofracturing of the hard rock bed lying above the coal seam. The sealing arrangement should be recoverable so that it can be used for injection in next borehole. The present known process of sealing is by grouting the injection pipe with quick setting cement capsules and thus sealing the mouth of the hole. In this case, the pipe can not be recovered and sealing can not be done deep inside the borehole. Sealing near the mouth of the hole provides an easy path for the water to come out in the developed galleries and injection pressure cannot be maintained. Sealing at a higher depth is advantageous and will be useful for softening/ hydrofracturing of strong rock beds lying above. At present to the best of our knowledge, there is no mechanical device available for sealing the borehole and injecting water at high pressure at the same time; reusable and easily withdrawable. The objective of the present invention is to provide a device for sealing an upward drilled borehole for high pressure water injection in underground mines and the present invention overcomes the drawbacks mentioned above. The other objectives of the present invention are to provide a device wherein the sealing arrangement is reusable and easily withdrawable. The device of the present invention for sealing inside an upward drilled borehole for high pressure water injection in underground mines consists essentially of a plurality of expandable flexible rings fitted on an externally threaded injection pipe in such a manner so as to effect lateral expansion of the said rings on application of vertical pressure by mechanical means. After effectively sealing the borehole water may be injected at high pressure to weaken the rock mass to induce and ensure systematic controlled caving of mine roof rocks behind the strategically placed supports. This eliminates the problem of delayed and uncontrolled mine roof caving. The device of the present invention is easily removable and reusable. The device of the present invention is depicted and described in the drawings accompanying this specification. Figure 1 shows the schematic diagram of an injection pipe and the sealing arrangement inside an upward drilled borehole for water injection under high pressure in an underground mine. The various parts are injection pipe (1), end flange (2), flexible rings(3), steel gasket (4), locking nut (5), flange (6), rubber gasket (7), threaded grout studs (8), nuts (9), sealing ring (10) and tapered nut (11). The injection pipe (1) is used for injecting water at a high pressure from a high-pressure pump deep inside an upward drilled -borehole. The flexible rings (3) expands and seals the borehole when it is squeezed between the end flange (2) and the steel gasket (4) by screwing the locking nut (5) over the externally threaded portion of the injection pipe (1). This injection pipe is held in position at mouth of the injection borehole by the concentric flange (6) and the internally threaded retreating tapered nut (11) with a sealing ring (10) that seals at the mouth of the injection borehole. The concentric flange (6) having a sealing Flange (6) with a sealing gasket (7), the said concentric flange (6) being provided with at least four threaded grout studs (8) and nuts (9). In an embodiment of the present invention, the expandable flexible rings used are of material such as neoprene rubber and of size 1-2 mm smaller than the diameter of the borehole to be sealed. In another embodiment of the present invention, the peripherally slotted nut (5) is provided with a setting / lightening tool for installing the above device in borehole, which consists of a setting pipe (12) having a plurality of rectangular steel protrusions (13), matching the locking nut slots, on one end and handle (14) welded to the said setting pipe (12) on the other end. Installation of the device of the present invention for sealing an upward drilled borehole for high pressure water injection may be carried out as follows: A number of expandable flexible rings (3) are fitted onto the injection pipe (1) between the top end flange (2) and the steel gasket (4) and held by the locking nut (5) over the externally threaded portion of the injection pipe. The injection pipe along with the flexible rings is inserted in the injection borehole to be sealed and the flexible rings are positioned at the horizon to be sealed deep inside the borehole. The clearance between the inner diameter of the borehole to be sealed and the flexible rings Is kept within 1-2 mm. The setting-tightening tool (12,13,14) is then inserted over the injection pipe (1) in the injection borehole. The steel rectangular protrusions (13) at the end of the setting pipe (12) get engaged with the matching rectangular grooves of the locking nut (5). The handle (14) provided on the setting pipe (12) is rotated to tighten the locking nut (5) until the expandable flexible rings (3) gets sufficiently squeezed and expand to seal the injection borehole. Two nuts are temporarily fitted face to face at the externally threaded portion of the injection pipe at the outer end. The inner nut is held by a spanner to prevent rotation of the injection. Pipe during tightening of the locking nut by the setting pipe. Thereafter the temporary nuts and the setting pipe are taken out. The retreating tapered nut (11) with sealing ring (10) is then fitted on the externally threaded portion of the injection pipe (1) at its bottom outer end. The concentric flange (6) with sealing Gasket (7) is held on the mouth of the borehole with at least 4 threaded grout studs (8) and nuts (9). Figure 2 shows the cross-section of locking nut (5) with four peripheral rectangular slots. Figure 3 shows the schematic diagram of the setting tool, which will be necessary for installation and withdrawal of the sealing arrangement. The setting tool comprises of setting pipe (12), matching steel protrusions (13) and handle (14). During installation, the steel protrusions (13) gets engaged with the matching slots of the locking nut (5). The setting pipe (12) is rotated by the handle (14) to screw the locking nut (5). Figure 4 shows the cross-section of the four rectangular steel protrusions (13) on the outer periphery at one end of the setting pipe. These protrusions match the peripheral rectangular slots of locking nut (5). Figure 5 shows the cross-sectional view of the handle (14), welded to the setting pipe (12), which enables rotational movement to screw the locking nut for pressing the steel gasket and expandable flexible rings. Figure 6 shows the sectional view of the concentric flange (6). Figure 7 (a) and (b) shows the internally threaded retreating tapered nut (11). Accordingly, the present invention provides device for sealing inside an upward drilled borehole for high pressure water injection in underground mines which comprises an externally threaded injection pipe (1) , characterized in that the said pipe(l) having an end flange (2) welded onto the said injection pipe (1) at the injection end top, the said injection pipe being provided at the flange end with a plurality of externally mounted expandable flexible rings (3) of circular cross section, the said rings (3) being held in position by a steel gasket (4) and a peripherally slotted locking nut (5) fitted to the said pipe (1), the said externally threaded injection pipe(l) being provided at the bottom end portion with an internally threaded retreating tapered nut (11) having a sealing ring (10) and a concentric flange (6) being provided with at least four threaded ground studs (8) and nuts (9). gasket (7) is held over the retreating tapered nut (5) at the mouth of the injection borehole to be sealed with atleast 4 threaded grout studs (8) and tightened by the nuts (9). The tapered retreating nut (5) is then rotated counter clockwise so that sealing ring (10) gets tightened on the inner-matching groove of the flange(6). One end of a flexible high-pressure hose with matching connectors is fitted to the outer end of the injection pipe and the other end of the flexible pipe connected to the delivery of a high-pressure pump. Water from the high-pressure pump goes through the injection pipe and pressurizes the borehole above the horizon of sealing inside the injection borehole. Water is injected in these boreholes under high pressure. This weakens the rock mass and eliminates the problem of delayed caving and ensures regular caving of roof rocks behind the supports. Withdrawal of the device of the present invention for re-use is carried out as follows : The nuts (9) on the studs (8) are unscrewed to release the concentric flange (6). The retreating tapered nut (5) is unscrewed and taken out. The setting tool (12,13,14) is used to unscrew the locking nut (5) and the sealing device is thus loosened and taken out of the hole for reuse in the next borehole for water injection. The total sealing arrangement can be withdrawn except for the studs (8), which are grouted on the mine roof. The novelty of the device of the present invention is that it seals a borehole for high pressure water injection and thereafter is, easily withdrawable for reuse, which is convenient, less time taking and cost effective. No specialised training is required for its user. The inventive step resides in the incorporation of a plurality of expandable flexible rings which get expanded diametrically when compressed between the top end flange and steel gasket by tightening the locking nut. This not only enables sealing of an injection borehole for water injection under high pressure above the sealing horizon of the injection borehole, but also easy removal and reuse of the device. The main advantages of the present invention are: - 1) The device effectively seals a borehole for injecting water at a high pressure inside a drilled hole. 2) The sealing of the hole can be done deep inside the overlying stratum and not near the mouth of the hole. This prevents any unwanted effect of water injection in the immediate roof rock. 3) It can be easily withdrawn from the hole and can be easily reinstalled in another hole. Allows multiple use. 4) It is very handy and economic. 5) Needs no specialized training for user. 6) The total system is bolted to the grouted studs at the mouth. This provides improved safety for workmen in high-pressure workings. We Claim: 1. Device for sealing inside an upward drilled borehole for high pressure water injection in underground mines which comprises an externally threaded injection pipe (1), characterized in that the said pipe(l) having an end flange (2) welded onto the said injection pipe (1) at the injection end top, the said injection pipe being provided at the flange end with a plurality of externally mounted expandable flexible rings (3) of circular cross section, the said rings (3) being held in position by a steel gasket (4) and a peripherally slotted locking nut (5) fitted to the said pipe (1), the said externally threaded injection pipe(l) being provided at the bottom end portion with an internally threaded retreating tapered nut (11) having a sealing ring (10) and a concentric flange (6) being provided with at least four threaded ground studs (8) and nuts (9). 2. Device for sealing as claimed in claim 1 wherein the expandable flexible rings used are of material such as neoprene rubber and of size 1 -2 mm smaller than the diameter of the borehole to be sealed. 3. Device for sealing as claimed in claim 1 wherein the peripherally slotted locking nut (5) is provided with a setting/tightening tool which consists of a setting pipe (12) having a plurality of rectangular steel protrusions (13), matching the locking nut slots, on one end and handle (14) welded to the said setting pipe (12) on the other end. 4. Device for sealing inside an upward drilled borehole for high-pressure water injection in underground mines substantially as herein described with reference to the drawings accompanying this specification.

Full Text

This invention relates to a device for sealing inside an upward drilled borehole for high pressure water injection in underground mines. This device is useful for sealing inside an upward drilled borehole in overlying strata for water injection urder high-pressure in an underground mine.
The successful extraction of coal from underground either by Bord and Pillar or by Longwall method depends on the systematic caving of overlying roof rocks. It is necessary to induce caving of hard roof encountered in the active caving zone by water injection under high pressure. Boreholes are drilled in the goaf area upward in the roof. Water is injected in these boreholes under high pressure, which eliminates the problem of delayed caving and ensures regular caving of roof rocks behind the supports. This reduces the load on supports and improves the stability of immediate roof in the working area. Sealing of the hole has to be done deep inside the borehole for injection of water under high pressure, which is useful for softening and hydrofracturing of the hard rock bed lying above the coal seam. The sealing arrangement should be recoverable so that it can be used for injection in next borehole.
The present known process of sealing is by grouting the injection pipe with quick setting cement capsules and thus sealing the mouth of the hole. In this case, the pipe can not be recovered and sealing can not be done deep inside the borehole. Sealing near the mouth of the hole provides an easy path for the water to come out in the developed galleries and injection pressure cannot be maintained. Sealing at a higher depth is advantageous and will be useful for softening/ hydrofracturing of strong rock beds lying above.
At present to the best of our knowledge, there is no mechanical device available for sealing the borehole and injecting water at high pressure at the same time; reusable and easily withdrawable.
The objective of the present invention is to provide a device for sealing an upward drilled borehole for high pressure water injection in underground mines and the present invention overcomes the drawbacks mentioned above. The other
objectives of the present invention are to provide a device wherein the sealing arrangement is reusable and easily withdrawable.
The device of the present invention for sealing inside an upward drilled borehole for high pressure water injection in underground mines consists essentially of a plurality of expandable flexible rings fitted on an externally threaded injection pipe in such a manner so as to effect lateral expansion of the said rings on application of vertical pressure by mechanical means. After effectively sealing the borehole water may be injected at high pressure to weaken the rock mass to induce and ensure systematic controlled caving of mine roof rocks behind the strategically placed supports. This eliminates the problem of delayed and uncontrolled mine roof caving. The device of the present invention is easily removable and reusable.
The device of the present invention is depicted and described in the drawings accompanying this specification.
Figure 1 shows the schematic diagram of an injection pipe and the sealing arrangement inside an upward drilled borehole for water injection under high pressure in an underground mine. The various parts are injection pipe (1), end flange (2), flexible rings(3), steel gasket (4), locking nut (5), flange (6), rubber gasket (7), threaded grout studs (8), nuts (9), sealing ring (10) and tapered nut (11).
The injection pipe (1) is used for injecting water at a high pressure from a high-pressure pump deep inside an upward drilled -borehole. The flexible rings (3) expands and seals the borehole when it is squeezed between the end flange (2) and the steel gasket (4) by screwing the locking nut (5) over the externally threaded portion of the injection pipe (1). This injection pipe is held in position at mouth of the injection borehole by the concentric flange (6) and the internally threaded retreating tapered nut (11) with a sealing ring (10) that seals at the mouth of the injection borehole. The concentric flange (6) having a sealing
Flange (6) with a sealing gasket (7), the said concentric flange (6) being provided with at least four threaded grout studs (8) and nuts (9).
In an embodiment of the present invention, the expandable flexible rings used are of material such as neoprene rubber and of size 1-2 mm smaller than the diameter of the borehole to be sealed.
In another embodiment of the present invention, the peripherally slotted nut (5) is provided with a setting / lightening tool for installing the above device in borehole, which consists of a setting pipe (12) having a plurality of rectangular steel protrusions (13), matching the locking nut slots, on one end and handle (14) welded to the said setting pipe (12) on the other end.
Installation of the device of the present invention for sealing an upward drilled borehole for high pressure water injection may be carried out as follows:
A number of expandable flexible rings (3) are fitted onto the injection pipe (1) between the top end flange (2) and the steel gasket (4) and held by the locking nut (5) over the externally threaded portion of the injection pipe. The injection pipe along with the flexible rings is inserted in the injection borehole to be sealed and the flexible rings are positioned at the horizon to be sealed deep inside the borehole. The clearance between the inner diameter of the borehole to be sealed and the flexible rings Is kept within 1-2 mm.
The setting-tightening tool (12,13,14) is then inserted over the injection pipe (1) in the injection borehole. The steel rectangular protrusions (13) at the end of the setting pipe (12) get engaged with the matching rectangular grooves of the locking nut (5). The handle (14) provided on the setting pipe (12) is rotated to tighten the locking nut (5) until the expandable flexible rings (3) gets sufficiently squeezed and expand to seal the injection borehole. Two nuts are temporarily fitted face to face at the externally threaded portion of the injection pipe at the outer end. The inner nut is held by a spanner to prevent rotation of the injection. Pipe during tightening of the locking nut by the setting pipe. Thereafter the temporary nuts and the setting pipe are taken out. The retreating tapered nut (11) with sealing ring (10) is then fitted on the externally threaded portion of the injection pipe (1) at its bottom outer end. The concentric flange (6) with sealing
Gasket (7) is held on the mouth of the borehole with at least 4 threaded grout studs (8) and nuts (9). Figure 2 shows the cross-section of locking nut (5) with four peripheral rectangular slots.
Figure 3 shows the schematic diagram of the setting tool, which will be necessary for installation and withdrawal of the sealing arrangement. The setting tool comprises of setting pipe (12), matching steel protrusions (13) and handle (14). During installation, the steel protrusions (13) gets engaged with the matching slots of the locking nut (5). The setting pipe (12) is rotated by the handle (14) to screw the locking nut (5).
Figure 4 shows the cross-section of the four rectangular steel protrusions (13) on the outer periphery at one end of the setting pipe. These protrusions match the peripheral rectangular slots of locking nut (5).
Figure 5 shows the cross-sectional view of the handle (14), welded to the setting pipe (12), which enables rotational movement to screw the locking nut for pressing the steel gasket and expandable flexible rings.
Figure 6 shows the sectional view of the concentric flange (6).
Figure 7 (a) and (b) shows the internally threaded retreating tapered nut (11).
Accordingly, the present invention provides device for sealing inside an upward drilled borehole for high pressure water injection in underground mines which comprises an externally threaded injection pipe (1) , characterized in that the said pipe(l) having an end flange (2) welded onto the said injection pipe (1) at the injection end top, the said injection pipe being provided at the flange end with a plurality of externally mounted expandable flexible rings (3) of circular cross section, the said rings (3) being held in position by a steel gasket (4) and a peripherally slotted locking nut (5) fitted to the said pipe (1), the said externally threaded injection pipe(l) being provided at the bottom end portion with an internally threaded retreating tapered nut (11) having a sealing ring (10) and a concentric flange (6) being provided with at least four threaded ground studs (8) and nuts (9).
gasket (7) is held over the retreating tapered nut (5) at the mouth of the injection borehole to be sealed with atleast 4 threaded grout studs (8) and tightened by the nuts (9). The tapered retreating nut (5) is then rotated counter clockwise so that sealing ring (10) gets tightened on the inner-matching groove of the flange(6).
One end of a flexible high-pressure hose with matching connectors is fitted to the outer end of the injection pipe and the other end of the flexible pipe connected to the delivery of a high-pressure pump. Water from the high-pressure pump goes through the injection pipe and pressurizes the borehole above the horizon of sealing inside the injection borehole. Water is injected in these boreholes under high pressure. This weakens the rock mass and eliminates the problem of delayed caving and ensures regular caving of roof rocks behind the supports.
Withdrawal of the device of the present invention for re-use is carried out as follows :
The nuts (9) on the studs (8) are unscrewed to release the concentric flange (6). The retreating tapered nut (5) is unscrewed and taken out. The setting tool (12,13,14) is used to unscrew the locking nut (5) and the sealing device is thus loosened and taken out of the hole for reuse in the next borehole for water injection. The total sealing arrangement can be withdrawn except for the studs (8), which are grouted on the mine roof.
The novelty of the device of the present invention is that it seals a borehole for high pressure water injection and thereafter is, easily withdrawable for reuse, which is convenient, less time taking and cost effective. No specialised training is required for its user. The inventive step resides in the incorporation of a plurality of expandable flexible rings which get expanded diametrically when compressed between the top end flange and steel gasket by tightening the locking nut. This not only enables sealing of an injection borehole for water injection under high pressure above the sealing horizon of the injection borehole, but also easy removal and reuse of the device.
The main advantages of the present invention are: -
1) The device effectively seals a borehole for injecting water at a high pressure
inside a drilled hole.
2) The sealing of the hole can be done deep inside the overlying stratum and
not near the mouth of the hole. This prevents any unwanted effect of water
injection in the immediate roof rock.
3) It can be easily withdrawn from the hole and can be easily reinstalled in
another hole. Allows multiple use.
4) It is very handy and economic.
5) Needs no specialized training for user.
6) The total system is bolted to the grouted studs at the mouth. This provides
improved safety for workmen in high-pressure workings.

We Claim:
1. Device for sealing inside an upward drilled borehole for high pressure water injection in
underground mines which comprises an externally threaded injection pipe (1), characterized in
that the said pipe(l) having an end flange (2) welded onto the said injection pipe (1) at the
injection end top, the said injection pipe being provided at the flange end with a plurality of
externally mounted expandable flexible rings (3) of circular cross section, the said rings (3)
being held in position by a steel gasket (4) and a peripherally slotted locking nut (5) fitted to the
said pipe (1), the said externally threaded injection pipe(l) being provided at the bottom end
portion with an internally threaded retreating tapered nut (11) having a sealing ring (10) and a
concentric flange (6) being provided with at least four threaded ground studs (8) and nuts (9).
2. Device for sealing as claimed in claim 1 wherein the expandable flexible rings used are of
material such as neoprene rubber and of size 1 -2 mm smaller than the diameter of the borehole
to be sealed.
3. Device for sealing as claimed in claim 1 wherein the peripherally slotted locking nut (5) is
provided with a setting/tightening tool which consists of a setting pipe (12) having a plurality of
rectangular steel protrusions (13), matching the locking nut slots, on one end and handle (14)
welded to the said setting pipe (12) on the other end.
4. Device for sealing inside an upward drilled borehole for high-pressure water injection in
underground mines substantially as herein described with reference to the drawings
accompanying this specification.

Documents:

855-del-2001-abstract.pdf

855-del-2001-claims.pdf

855-del-2001-correspondence-others.pdf

855-del-2001-correspondence-po.pdf

855-del-2001-descripiton (complete).pdf

855-del-2001-drawings.pdf

855-del-2001-form-1.pdf

855-del-2001-form-18.pdf

855-del-2001-form-2.pdf

855-del-2001-form-3.pdf

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Patent Number

220660

Indian Patent Application Number

855/DEL/2001

PG Journal Number

30/2008

Publication Date

25-Jul-2008

Grant Date

30-May-2008

Date of Filing

16-Aug-2001

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

Inventors:

#	Inventor's Name	Inventor's Address
1	SRI RAJESHWAR PRASAD
2	DR. KESHAR PRASAD YADAVA
3	SRI ANIL KUMAR RAY
4	SRI GAURI SHANKAR PRASAD SINGH
5	SRI GAUTAM BANERJEE

PCT International Classification Number

E21B 33/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA