CN112647944A - Equipment and method for controlling underground ore limestone top plate through acidizing and fracturing - Google Patents
Equipment and method for controlling underground ore limestone top plate through acidizing and fracturing Download PDFInfo
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- CN112647944A CN112647944A CN202011526695.9A CN202011526695A CN112647944A CN 112647944 A CN112647944 A CN 112647944A CN 202011526695 A CN202011526695 A CN 202011526695A CN 112647944 A CN112647944 A CN 112647944A
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- 239000006028 limestone Substances 0.000 title claims abstract description 87
- 235000019738 Limestone Nutrition 0.000 title claims abstract description 86
- 238000000034 method Methods 0.000 title claims abstract description 27
- 239000003245 coal Substances 0.000 claims abstract description 62
- 239000002253 acid Substances 0.000 claims abstract description 58
- 238000007789 sealing Methods 0.000 claims abstract description 35
- 239000011435 rock Substances 0.000 claims abstract description 13
- 239000002775 capsule Substances 0.000 claims description 30
- 239000002184 metal Substances 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- 239000012530 fluid Substances 0.000 claims description 20
- 238000005553 drilling Methods 0.000 claims description 16
- 239000007788 liquid Substances 0.000 claims description 14
- 238000005259 measurement Methods 0.000 claims description 12
- 238000009434 installation Methods 0.000 claims description 11
- 238000012544 monitoring process Methods 0.000 claims description 8
- 239000012466 permeate Substances 0.000 claims description 5
- 239000011148 porous material Substances 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 238000009826 distribution Methods 0.000 claims description 4
- 238000002347 injection Methods 0.000 claims description 4
- 239000007924 injection Substances 0.000 claims description 4
- 238000003825 pressing Methods 0.000 claims description 2
- 238000010276 construction Methods 0.000 abstract description 22
- 230000000694 effects Effects 0.000 abstract description 11
- 238000005065 mining Methods 0.000 abstract description 7
- 230000008569 process Effects 0.000 abstract description 2
- 238000005260 corrosion Methods 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 6
- 238000005520 cutting process Methods 0.000 description 5
- 230000009471 action Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000002360 explosive Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 230000003313 weakening effect Effects 0.000 description 3
- 238000005422 blasting Methods 0.000 description 2
- 238000007596 consolidation process Methods 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 229910021532 Calcite Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 229910001570 bauxite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 125000005587 carbonate group Chemical group 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000010433 feldspar Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C41/00—Methods of underground or surface mining; Layouts therefor
- E21C41/16—Methods of underground mining; Layouts therefor
- E21C41/18—Methods of underground mining; Layouts therefor for brown or hard coal
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Abstract
The invention discloses equipment and a method for controlling a mine ore limestone top plate through acidizing and fracturing, and relates to the technical field of mining. Firstly, respectively constructing a group of parallel drill holes on the side close to the coal wall and the side close to the goaf between the working face frames; then sealing the drill hole, starting a high-pressure pump to inject acid liquor into the drill hole, stopping injecting when the pressure of the pipeline reaches 10MPa, and maintaining the pressure for 5-10 min; after the pressure maintaining is finished, the high-pressure pump is started again to carry out lime stone top plate acidizing and fracturing for 30 min; after fracturing, closing the high-pressure pump, and maintaining the pressure for 5-10 min; after the pressure maintaining is finished, the pressure of the pipeline is relieved, and the hole packer is taken out; and repeating the steps until fracturing of all drilled holes is completed. The invention adopts the acidizing and fracturing way to treat the hard limestone top plate of the underground mine, and the limestone is corroded by acid liquor, so that the construction pressure in the fracturing process can be reduced, the opening degree of a fracturing crack can be increased, the occlusion effect of rock blocks on two sides of the fractured crack is reduced, and the full collapse of the limestone top plate is facilitated.
Description
Technical Field
The invention relates to the technical field of mining, in particular to equipment and a method for controlling a mine ore limestone top plate through acidizing and fracturing.
Background
When a hard rock stratum is directly formed above the coal seam or a thin direct roof, the hard roof is difficult to collapse in time along with the mining of the coal seam, and a large-area suspended roof is formed in a goaf. The large-range roof-hanging suddenly collapses and easily generates impact load, large-area pressure of the top plate, storm wind and the like, and even induces rock burst. The non-coal well industrial and mining also has the problem of disaster caused by a large amount of hard suspended roofs of the goafs to be treated.
The traditional method for treating the suspended roof of the goaf is forced caving by artificial explosive blasting. However, the method has the advantages of large engineering quantity and explosive quantity, high cost, poor controllability and the like, and has potential safety hazards for high-gas mines. Coal mine safety regulations have mandated that the use of explosives for blasting hard roofs in mining-affected areas is prohibited.
The coal rock mass structure transformation is a core common science problem related to the technical problems of hard roof control, top coal weakening, ore pressure impact, low-permeability coal seam gas extraction, coal and gas outburst and the like in a coal mine. The roof structure is reformed through hydraulic fracturing, so that the roof of the goaf can be controlled to fall off in time, an effective technical approach for solving the problem of hard roof of the goaf of the coal mine is achieved, the roof structure is widely applied at present, and the roof structure has remarkable technical and economic advantages.
At present, the underground coal mine hard roof hydraulic fracturing control technology is mostly applied to compact sandstone roof control, and the rated pressure of the adopted hard roof hydraulic fracturing control complete equipment is 60MPa, so that the requirement of on-site hard roof fracturing can be basically met. For hard thick limestone roof control, the conventional hydraulic fracturing method and equipment have the following problems: 1. limestone is carbonate rock with calcite as a main component, has single component and good consolidation, and sandstone consists of quartz, feldspar and other minerals, has complex components and relatively poor consolidation. Therefore, the strength of the compact limestone is higher than that of the compact sandstone, so that the fracture pressure and the construction pressure in the hydraulic fracturing process of the limestone top plate are high, and the fracture pressure of the limestone top plate in the site fracturing construction exceeds 60 MPa. When the fracturing equipment works for a long time under the over-rated pressure, the service life of the fracturing equipment such as a high-pressure pump and a pipeline is seriously consumed, and the increase of the rated pressure of the fracturing equipment can cause the increase of equipment and material cost. 2. The hard thick limestone has high strength, good integrity and large thickness, the opening of a conventional hydraulic fracturing crack is small, the hydraulic fracture is closed under the action of ground stress along with the flowback of fracturing fluid after the hydraulic fracturing is finished, rock masses on two sides of the hydraulic fracture are still extruded and occluded with each other to form a relatively stable structure, and the collapse effect of a suspended roof after the fracturing is not ideal.
Disclosure of Invention
In view of the above, the invention discloses equipment and a method for controlling a downhole ore limestone roof through acidizing and fracturing, and aims to solve the problems that the hydraulic fracturing construction pressure of a hard thick limestone roof is high, the caving effect of a limestone suspended ceiling after conventional hydraulic fracturing is not ideal and the like, so that the fracturing construction pressure of the hard thick limestone roof is reduced, and the caving effect of the suspended ceiling after fracturing is improved.
The equipment for controlling the underground ore limestone roof by acidizing and fracturing comprises an acidizing and fracturing pump and a hole sealing device, wherein the acidizing and fracturing pump is connected with the hole sealing device; the acidizing fracturing pump comprises an acid liquid tank, a liquid distribution tank, a high-pressure pump control cabinet, a fracturing measurement and control instrument, a high-pressure rubber pipe, a high-pressure sealing installation rod and a conversion joint; the high-pressure pump and the fracturing measurement and control instrument are respectively electrically connected with a high-pressure pump control cabinet, one end of the high-pressure rubber pipe is connected with the high-pressure pump, the other end of the high-pressure rubber pipe is connected with a high-pressure sealing installation rod through an adapter, and the high-pressure sealing installation rod extends into the drill hole and is used for injecting acid liquor; the high-pressure rubber pipe is provided with a flow sensor, a concentration sensor, a pressure sensor, a one-way valve and a pressure release valve, wherein the flow sensor, the concentration sensor and the pressure sensor are respectively and electrically connected with the fracturing measurement and control instrument; the hole sealing device comprises a hole sealing device, a hand pump and a high-pressure fine hose for connecting the hole sealing device and the hand pump.
Preferably, the hole packer comprises an expansion capsule, a metal pipe, a fixed sleeve and a sliding sleeve; the fixed sleeve is fixedly connected to one end of the metal pipe; the sliding sleeve is sleeved on the metal pipe and can slide along the metal pipe; the expansion capsule is sleeved on the metal tube, and two ends of the expansion capsule are fixedly connected with the fixed sleeve and the sliding sleeve respectively; the sliding sleeve is provided with a water inlet pipe, two ends of the water inlet pipe are respectively connected with the high-pressure fine hose and the expansion capsule, the hand pump is pressed, high-pressure water is injected into the expansion capsule through the high-pressure fine hose and the water inlet pipe, the expansion capsule expands and longitudinally contracts, and the drilled hole can be sealed; the metal pipe is connected with the high-pressure seal mounting rod, the high-pressure pump is started, and acid liquor is injected into the bottom of the drill hole through the high-pressure rubber pipe, the high-pressure seal mounting rod and the metal pipe.
Preferably, sealing rings are arranged between the expansion capsule and the sliding sleeve and between the expansion capsule and the fixed sleeve.
Preferably, the equipment further comprises a monitoring camera arranged outside the drill hole, and the monitoring camera is electrically connected with the fracturing measurement and control instrument.
The invention also discloses a method for performing acidizing and fracturing on the underground ore limestone top plate by using the equipment for controlling the underground ore limestone top plate through acidizing and fracturing, which comprises the following steps of:
the method comprises the following steps: and respectively constructing a group of parallel drill holes on the side close to the coal wall and the side close to the goaf between the working face frames.
Step two: and installing an acidizing fracturing pump, debugging and configuring the acidizing fracturing fluid according to the designed concentration.
Step three: and connecting the hole packer with the high-pressure fine hose, conveying the hole packer into a designed hole sealing position at the bottom of the drilled hole through the high-pressure seal mounting rod, pressing the hand pump to inject water into the expansion capsule through the high-pressure fine hose to expand and longitudinally contract the expansion capsule, and sealing the drilled hole.
Step four: the high-pressure sealing installation rod, the adapter, the high-pressure rubber pipe and the high-pressure pump are sequentially connected.
Step five: and closing a pressure release valve on the high-pressure rubber pipe, starting the high-pressure pump, continuously injecting acid liquor into the drill hole, and stopping injection when the pipeline pressure monitored by the pressure sensor reaches a set value.
Step six: the pressure of the fracturing fluid in the drill hole is maintained through a one-way valve arranged on the high-pressure rubber pipe, and the acid liquor permeates into surrounding rocks through the wall of the drill hole.
Step seven: and after the pressure maintaining of the drilled hole is finished, the high-pressure pump is started again to inject acid liquor into the drilled hole, and the limestone top plate is subjected to acidizing and fracturing.
Step eight: and after the fracturing is finished, closing the high-pressure pump, and maintaining the pressure of the fracturing fluid in the drill hole through a one-way valve on the high-pressure rubber pipe so that the high-pressure acid fluid in the crack further seeps into limestone pores on two sides of the crack.
Step nine: and after the pressure maintaining is finished, opening a pressure relief valve on the high-pressure rubber pipe, and relieving the pressure of the pipeline.
Step ten: and (4) taking out the hole packer, installing the hole packer in the next drill hole, and repeating the third step to the ninth step until fracturing of all the drill holes is completed.
Preferably, the method is suitable for fracturing the limestone suspended ceiling of the goaf and pre-fracturing the limestone top plate above the coal bed; if the limestone suspended roof fracturing is carried out in the goaf, drilling holes close to the coal wall side and constructing a vertical top plate, drilling holes close to the goaf side and constructing oblique goafs, and arranging the two groups of drilling holes in a staggered manner; and if the limestone top plate above the coal seam is pre-cracked, drilling holes close to the side of the mining area to be vertical to the top plate, drilling holes close to the side of the coal wall to be inclined to the top plate in front of the working face, and constructing a group of parallel anchor cable holes in the vertical top plates in the two end areas of the working face in a staggered mode.
Preferably, in the second step, the acid-fracturing fluid is 15% -20% of dilute hydrochloric acid.
Preferably, in the fifth step, when the line pressure monitored by the pressure sensor reaches 10MPa, the acid liquor injection is stopped.
Preferably, in the sixth step and the eighth step, the pressure of the fracturing fluid in the drill hole is maintained for 5-10 min.
Preferably, in the seventh step, the high-pressure pump is restarted to inject acid liquor into the drilled hole, and the acidizing and fracturing time of the limestone top plate is 30 min.
Compared with the prior art, the equipment and the method for controlling the underground ore limestone roof by acidizing and fracturing have the advantages that:
(1) according to the method, the mine limestone hard roof is treated in an acidizing and fracturing manner, and the limestone is corroded by acid liquor, so that on one hand, the limestone strength of the hole wall of a drilled hole can be reduced, the fracturing pressure and crack expansion pressure of the hard limestone roof are reduced, and finally the aim of reducing the construction pressure of the hard limestone roof fracturing is achieved; on the other hand, acid liquor is used as fracturing fluid to carry out acid fracturing on the hard limestone top plate, when large-range artificial cracks are generated in the limestone top plate, the wall surfaces of the cracks are corroded through the contact of the acid liquor and the wall surfaces of the cracks, and the opening degree of the artificial cracks is increased; due to the heterogeneity of the rock, after the acid solution corrosion, different corrosion pits appear on the surface of the crack, an uneven wall surface is formed, the crack is drained back along with the fracturing fluid after the fracturing, the artificial crack after the acid solution corrosion forms self-supporting, and a larger opening degree can be still kept, so that the occlusion effect of rock blocks on two sides of the crack after the fracturing is reduced, the timely and sufficient collapse of the suspended ceiling is facilitated, and the purpose of improving the collapse effect of the suspended ceiling of the limestone in the goaf is finally realized.
(2) Drilling and pressure maintaining are carried out before and after fracturing; pressure is maintained before fracturing, so that acid liquor can permeate into rock pores around the hole wall through the limestone roof drill hole, and the limestone strength of the hole wall of the drill hole is reduced, so that the construction pressure of subsequent acidizing and fracturing is reduced; and pressure is maintained after fracturing, so that acid liquor can fully erode the wall surface of the crack, the opening degree of the crack is increased, and the limestone suspended ceiling caving effect in the goaf is further improved.
(3) The fracturing method disclosed by the invention is simple to operate, convenient to construct, safe and reliable, is beneficial to timely and fully caving the limestone roof, realizes safe and controllable roof caving, guarantees safe and efficient mining of a mine, can be applied to treatment of the limestone roof of a coal mine and a non-coal mine, and has wide practicability.
(4) The fracturing equipment used by the invention comprises the acidizing fracturing pump, the hole sealing device and the monitoring camera, the acidizing fracturing pipeline and the hole sealing pipeline are independent, so that the corrosion of acid liquid to the hole sealing device is avoided, the problem that the traditional one-way hole sealing device is easy to punch is solved, and the construction stability is improved.
Drawings
For a clearer explanation of the embodiments or technical solutions of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for a person skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a block diagram of an acidizing fracturing pump.
Fig. 2 is a diagram of a hole packer.
Fig. 3 is a layout diagram of hard thick limestone suspended acidizing fracturing boreholes in a mine goaf in example 1.
Fig. 4 is a sectional view taken along line a-a in fig. 3.
Fig. 5 is a layout view of limestone top plate pre-splitting drill holes above a coal seam in example 2.
Fig. 6 is a cross-sectional view taken along line B-B of fig. 5.
In the figure: 1-coal bed; 2-limestone top plate; 3-a bottom plate; 4-return air gallery; 41-drilling an anchor cable at the end of a return air gallery; 5-a transportation roadway; 51-drilling an anchor cable at the end of a transportation roadway; 6-coal face; 7-drilling; 8-hole packer; 81-expansion capsules; 82-hole packer cavity; 83-a metal tube; 84-a fixation sleeve; 85-a sliding sleeve; 86-a threaded joint; 87-hydraulic quick disconnect; 9-high pressure seal mounting rod; 10-a crossover joint; 11-high pressure hose; 12-high pressure fine hose; 13-hand pump; 14-a pressure relief valve; 15-a one-way valve; 16-a pressure sensor; 17-a concentration sensor; 18-a flow sensor; 19-a surveillance camera; 20-a fracturing measurement and control instrument; 21-a high pressure pump; 22-liquid distribution box; 23-acid liquor tank; 24-high pressure pump control cabinet.
Detailed Description
The following provides a brief description of embodiments of the present invention with reference to the accompanying drawings. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without any inventive work belong to the protection scope of the present invention.
Fig. 1-6 illustrate a preferred embodiment of the present invention, which is parsed in detail.
The equipment for controlling the mine ore limestone roof by acidizing and fracturing as shown in figures 1 and 2 comprises an acidizing and fracturing pump, a hole sealing device and a monitoring camera.
As shown in fig. 1, the acidizing fracturing pump comprises an acid liquid tank 23, a liquid distribution tank 22, a high-pressure pump 21, a high-pressure pump control cabinet 24, a fracturing measurement and control instrument 20, a high-pressure rubber pipe 11, a high-pressure seal mounting rod 9 and an adapter 10. The high-pressure pump 21 and the fracturing measurement and control instrument 20 are respectively electrically connected with a high-pressure pump control cabinet 24, one end of a high-pressure rubber pipe 11 is connected with the high-pressure pump 21, the other end of the high-pressure rubber pipe is connected with a high-pressure sealing installation rod 9 through an adapter 10, and the high-pressure sealing installation rod 9 extends into the drill hole 7. And starting the high-pressure pump 21, and allowing the acid liquor to enter the drill hole 7 through the high-pressure rubber tube 11 and the high-pressure seal mounting rod 9. The high-pressure rubber pipe 11 is provided with a flow sensor 18, a concentration sensor 17, a pressure sensor 16, a one-way valve 15 and a pressure release valve 14, wherein the flow sensor 18, the concentration sensor 17 and the pressure sensor 16 are respectively and electrically connected with a fracturing measurement and control instrument 20.
As shown in fig. 2, the hole sealing device includes a hole sealer 8, a hand pump 13, and a high-pressure fine hose 12 for connecting the hole sealer 8 and the hand pump 13. Wherein, the hole packer 8 comprises an expansion capsule 81, a metal tube 83, a fixed sleeve 84 and a sliding sleeve 85. The fixing sleeve 84 is fixedly attached to one end of the metal pipe 83. The sliding sleeve 85 is sleeved on the metal pipe 83 and can slide along the metal pipe. The expansion capsule 81 is sleeved on the metal tube 83, and both ends thereof are fixedly connected with the fixed sleeve 84 and the sliding sleeve 85 respectively. The sliding sleeve 85 is provided with a water inlet pipe, one end of the water inlet pipe is communicated with the expansion capsule 81, and the other end of the water inlet pipe is connected with the high-pressure fine hose 12 through a threaded joint 86. The hand pump 13 is pressed, high-pressure water is injected into the expansion capsule 81 through the high-pressure thin hose 12 and the water inlet pipe, and the expansion capsule 81 expands and longitudinally contracts to block the drilled hole 7. One end of the metal pipe 83 is connected with the high-pressure seal mounting rod 9 through the hydraulic quick connector 87, the high-pressure pump 21 is started, and acid liquor is injected into the bottom of the drill hole 7 through the high-pressure rubber pipe 11, the high-pressure seal mounting rod 9 and the metal pipe 83. Sealing rings are arranged between the expansion capsule 81 and the sliding sleeve 85 and the fixed sleeve 84 to prevent high-pressure water in the expansion capsule 81 from leaking. The monitoring camera 19 is arranged outside the drill hole 7 and electrically connected with the fracturing measurement and control instrument 20 and used for monitoring the fracturing condition of the drill hole 7.
The invention further discloses a method for performing acidizing and fracturing on the underground ore limestone top plate by using the equipment for controlling the underground ore limestone top plate through acidizing and fracturing, which is suitable for fracturing the limestone suspended top in the goaf and pre-fracturing the limestone top plate 2 above the coal seam 1.
Example 1
And (3) controlling limestone suspended ceiling in the goaf by acidizing and fracturing:
the average thickness of a coal seam 1 mined in a construction coal mine is 3m, the dip angle of the coal seam 1 is 3-8 degrees, the top plate of the coal seam 1 is limestone, the average thickness is 8m, and the bottom plate 3 is mudstone, bauxite mudstone and sandy mudstone, and the average thickness is 4.69 m. The length of a coal face 6 cutting hole is 150m, the cutting hole is a rectangular section, the clear width is 7.0m, the clear height is 3.0m, and the azimuth angle is 1 degree.
The acid fracturing specifically comprises the following steps:
the method comprises the following steps: as shown in fig. 3 and 4, a group of parallel drill holes 7 are constructed between the coal face 6 frames and close to the vertical top plate on the coal wall side for acidizing, fracturing and cutting off the coal wall support and reducing the caving step of the limestone cantilever. A group of parallel drill holes 7 are constructed between the frames of the coal face 6 and close to the side of the goaf for sufficiently weakening the limestone suspended roof by acidizing and fracturing, and the two groups of drill holes 7 are arranged in a staggered mode. The position of the side drill hole 7 close to the coal wall is 0.5m away from the coal wall, the position of the final hole is 1m away from the top plate, the length of the drill hole 7 is 7m, and the diameter of the drill hole 7 is 50 mm. The distance between the position of the hole close to the side drill hole 7 of the goaf and the rear end of the top beam of the hydraulic support is 0.5m, the position of the final hole is 1m away from the top plate, the length of the drill hole 7 is 14m, the inclination angle is 30 degrees, and the diameter of the drill hole 7 is 50 mm. During drilling, firstly, the construction of a side drill hole 7 of the coal face 6 close to the coal wall is carried out, then the construction of the side drill hole 7 of the coal face 6 close to the goaf is carried out, and the construction of the two groups of drill holes 7 is alternately carried out. The fracturing sequence is the same as the construction sequence of the drill hole 7, the fracturing sequence and the drill hole 7 are synchronously operated and operated in parallel, the construction speed is matched, and the drill hole 7 can be constructed in advance.
Step two: and installing an acid fracturing pump, debugging and preparing 15-20% of dilute hydrochloric acid.
Step three: connecting the hole packer 8 with a high-pressure fine hose 12, and then conveying the hole packer 8 into a designed hole sealing position at the bottom of the drill hole 7 through the connection of the plurality of sections of high-pressure seal mounting rods 9. The hand pump 13 is pressed to inflate the inflatable bladder 81 by injecting water through the high pressure fine hose 112 and the inlet tube to seal the borehole 7.
Step four: the high-pressure seal installation rod 9, the adapter 10, the high-pressure rubber pipe 11 and the high-pressure pump 21 are connected in sequence.
Step five: closing a pressure release valve 14 on the high-pressure rubber tube 11, starting a high-pressure pump 21, continuously injecting acid liquor into the drill hole 7, and stopping injecting the acid liquor when the pipeline pressure monitored by the pressure sensor 16 reaches 10 MPa.
Step six: the pressure of the fracturing fluid in the drill hole 7 is maintained for 5-10min through a one-way valve 15 arranged on the high-pressure rubber pipe 11, the acid liquor permeates into surrounding rocks through the wall of the drill hole 7, and the limestone strength of the wall of the drill hole 7 is reduced, so that the construction pressure of subsequent acidizing and fracturing is reduced.
Step seven: and after the pressure maintaining of the drill hole 7 is finished, the high-pressure pump 21 is started again to inject acid liquor into the drill hole 7, and the limestone top plate 2 is acidized and fractured for 30 min. On one hand, more artificial cracks can be generated and expanded on the wall of the drilled hole 7 under the action of high-pressure acid liquid, the structure of the limestone top plate 2 is modified, the integrity of the limestone top plate is damaged, and the strength of the limestone top plate is reduced; on the other hand, the opening of the artificial crack can be increased through the erosion effect of the acid liquid on the wall surface of the artificial crack.
Step eight: after fracturing is finished, the high-pressure pump 21 is closed, the fracturing fluid in the drill hole 7 is kept for 5-10min through the one-way valve 15 on the high-pressure rubber pipe 11, the high-pressure acid fluid in the crack further seeps into limestone pores on two sides of the crack, the corrosion area of the acid fluid is enlarged, the strength of the wall surface of the crack is reduced, the opening degree of the crack is further increased, and the caving effect of the limestone suspended ceiling in the fractured goaf is improved.
Step nine: and after the pressure maintaining is finished, opening the pressure relief valve 14 on the high-pressure rubber pipe 11, and relieving the pipeline pressure.
Step ten: and (4) removing the water pressure in the expansion capsule 81, taking out the hole packer 8, installing the hole packer in the next drill hole 7, and repeating the steps from three to nine until the fracturing of all the drill holes 7 is completed.
Example 2
The limestone roof 2 above the pre-cracked coal seam is acidified to weaken the strength of the limestone roof, so that the limestone roof is promoted to fully collapse in time along with the mining of the coal seam 1, the formation of a large-range suspended roof in the mined-out area after the coal seam is erected is avoided, and the disaster-causing hidden danger of the suspended roof in the mined-out area is eliminated fundamentally.
The average thickness of a coal seam 1 mined in a construction coal mine is 5m, the top plate of the coal seam 1 is limestone, and the average thickness is 12 m. The length of a coal face 6 cutting hole is 200m, the clear width is 7.6m, and the clear height is 3.2 m. And a combined supporting mode is adopted.
The acid fracturing specifically comprises the following steps:
the method comprises the following steps: as shown in fig. 5 and 6, a group of parallel drill holes 7 are constructed between the frames of the coal face 6 and close to the vertical top plate at the goaf side for acidizing, fracturing and cutting off coal wall supports and reducing the caving step of limestone suspended roofs. A group of parallel drill holes 7 are formed in the top plate close to the coal wall side and obliquely in front of the coal face 6 among the frames of the coal face 6 and used for sufficiently weakening the limestone top plate 2 through acidizing and fracturing, and the two groups of drill holes 7 are arranged in a staggered mode. The distance between the position of the hole close to the side drill hole 7 of the goaf and the rear end of the top beam of the hydraulic support is 0.5m, the distance between the position of the final hole and the top plate is 1m, the length of the drill hole 7 is 11m, and the diameter of the drill hole 7 is 50 mm. The position of the side drill hole 7 close to the coal wall is 0.5m away from the coal wall, the position of the final hole is 1m away from the top plate, the length of the drill hole 7 is 22m, the inclination angle is 30 degrees, and the diameter of the drill hole 7 is 50 mm. A group of transportation drift end anchor cable drill holes 51 and a group of return air drift end anchor cable drill holes 41 are respectively constructed in a transportation drift 5 and a return air drift 4 which are perpendicular to a top plate at two ends of a coal face 6, the hole opening position is 0.5m away from a coal pillar, the final hole position is 1m away from the top plate, the hole length is 11m, and the hole diameter is 32 mm. During drilling, firstly, side drilling 7 construction is carried out on a working face close to a goaf area, then side drilling 7 construction is carried out on the working face close to a coal pillar, construction of two groups of drilling 7 is carried out alternately, and finally anchor cable holes at two ends are constructed. The fracturing sequence is the same as the construction sequence of the drill hole 7, the fracturing sequence and the drill hole 7 are synchronously operated and operated in parallel, the construction speed is matched, and the drill hole 7 can be constructed in advance.
Step two: and installing an acid fracturing pump, debugging and preparing 15-20% of dilute hydrochloric acid.
Step three: connecting the hole packer 8 with a high-pressure fine hose 12, and then conveying the hole packer 8 into a designed hole sealing position at the bottom of the drill hole 7 through the connection of the plurality of sections of high-pressure seal mounting rods 9. The hand pump 13 is pressed to inject water through the high pressure fine hose 12 and the water inlet tube into the expansion capsule 81 to expand it and seal the borehole 7.
Step four: the high-pressure seal installation rod 9, the adapter 10, the high-pressure rubber pipe 11 and the high-pressure pump 21 are connected in sequence.
Step five: closing a pressure release valve 14 on the high-pressure rubber tube 11, starting a high-pressure pump 21, continuously injecting acid liquor into the drill hole 7, and stopping injecting the acid liquor when the pipeline pressure monitored by the pressure sensor 16 reaches 10 MPa.
Step six: the pressure of the fracturing fluid in the drill hole 7 is maintained for 5-10min through a one-way valve 15 arranged on the high-pressure rubber pipe 11, the acid liquor permeates into surrounding rocks through the wall of the drill hole 7, and the limestone strength of the wall of the drill hole 7 is reduced, so that the construction pressure of subsequent acidizing and fracturing is reduced.
Step seven: and after the pressure maintaining of the drill hole 7 is finished, the high-pressure pump 21 is started again to inject acid liquor into the drill hole 7, and the limestone top plate 2 is acidized and fractured for 30 min. On one hand, more artificial cracks can be generated and expanded on the wall of the drilled hole 7 under the action of high-pressure acid liquid, the structure of the limestone top plate 2 is modified, the integrity of the limestone top plate is damaged, and the strength of the limestone top plate is reduced; on the other hand, the opening of the artificial crack can be increased through the erosion effect of the acid liquid on the wall surface of the artificial crack.
Step eight: after fracturing is finished, the high-pressure pump 21 is closed, the fracturing fluid in the drill hole 7 is kept for 5-10min through the one-way valve 15 on the high-pressure rubber pipe 11, so that high-pressure acid in the crack further seeps into limestone pores on two sides of the crack, the corrosion area of the acid is enlarged, the strength of the wall surface of the crack is reduced, the opening degree of the crack is further increased, and the caving effect of the limestone top plate 2 after fracturing is improved.
Step nine: and after the pressure maintaining is finished, opening the pressure relief valve 14 on the high-pressure rubber pipe 11, and relieving the pipeline pressure.
Step ten: and (4) removing the water pressure in the expansion capsule 81, taking out the hole packer 8, installing the hole packer in the next drill hole 7, and repeating the steps from three to nine until the fracturing of all the drill holes 7 is completed.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The equipment for controlling the underground ore limestone top plate by acidizing and fracturing is characterized by comprising an acidizing and fracturing pump and a hole sealing device; the acidizing fracturing pump comprises an acid liquid box (23), a liquid distribution box (22), a high-pressure pump (21), a high-pressure pump control cabinet (24), a fracturing measurement and control instrument (20), a high-pressure rubber pipe (11), a high-pressure sealing installation rod (9) and a conversion joint (10); the high-pressure pump (21) and the fracturing measurement and control instrument (20) are respectively electrically connected with a high-pressure pump control cabinet (24), one end of a high-pressure rubber pipe (11) is connected with the high-pressure pump (21), the other end of the high-pressure rubber pipe is connected with a high-pressure sealing installation rod (9) through a conversion joint (10), and the high-pressure sealing installation rod (9) extends into a drill hole (7) and is used for injecting acid liquor; the high-pressure rubber pipe (11) is provided with a flow sensor (18), a concentration sensor (17), a pressure sensor (16), a one-way valve (15) and a pressure release valve (14), wherein the flow sensor (18), the concentration sensor (17) and the pressure sensor (16) are respectively and electrically connected with a fracturing measurement and control instrument (20); the hole sealing device comprises a hole sealing device (8), a hand pump (13) and a high-pressure fine hose (12) for connecting the hole sealing device (8) and the hand pump (13).
2. The acidizing and fracturing control well working ore limestone top plate apparatus according to claim 1, characterized in that said hole packer (8) comprises an expansion capsule (81), a metal pipe (83), a fixed sleeve (84) and a sliding sleeve (85); the fixed sleeve (84) is fixedly connected to one end of the metal pipe (83); the sliding sleeve (85) is sleeved on the metal pipe (83) and can slide along the metal pipe; the expansion capsule (81) is sleeved on the metal pipe (83), and two ends of the expansion capsule are fixedly connected with the fixed sleeve (84) and the sliding sleeve (85) respectively; the sliding sleeve (85) is provided with a water inlet pipe, two ends of the water inlet pipe are respectively connected with the high-pressure thin hose (12) and the expansion capsule (81), the hand pump (13) is pressed, high-pressure water is injected into the expansion capsule (81) through the high-pressure thin hose (12) and the water inlet pipe, the expansion capsule (81) expands and longitudinally contracts, and the drilled hole (7) can be sealed; the metal pipe (83) is connected with the high-pressure seal mounting rod (9), the high-pressure pump (21) is started, and acid liquor is injected into the bottom of the drill hole (7) through the high-pressure rubber pipe (11), the high-pressure seal mounting rod (9) and the metal pipe (83).
3. The apparatus for acid fracturing control of a mineworker ore limestone roof as claimed in claim 2, wherein sealing rings are provided between the expansion capsule (81) and the sliding sleeve (85) and the fixed sleeve (84).
4. The equipment for acidizing and fracturing a control of a mine ore limestone roof as claimed in claim 1, wherein said equipment further comprises a monitoring camera (19) placed outside the borehole (7), said monitoring camera (19) being electrically connected to the fracturing monitor and control instrument (20).
5. A method of acid fracturing a well bore ore limestone roof using the apparatus for acid fracturing a control well bore ore limestone roof of any one of claims 1 to 4, comprising the steps of:
the method comprises the following steps: respectively constructing a group of parallel drill holes (7) between 6 frames of the coal face close to the coal wall side and the side close to the goaf;
step two: installing an acid fracturing pump, debugging and configuring acid fracturing fluid according to the designed concentration;
step three: connecting the hole packer (8) with a high-pressure fine hose (12), and conveying the hole packer (8) to the designed hole sealing position at the bottom of the drill hole (7) through a high-pressure sealing mounting rod (9); pressing the hand pump (13) to inject water into the expansion capsule (81) through the high-pressure thin hose (12) to expand and longitudinally contract the expansion capsule, and sealing the drilled hole (7);
step four: a high-pressure seal mounting rod (9), a conversion joint (10), a high-pressure rubber pipe (11) and a high-pressure pump (21) are connected in sequence;
step five: closing a pressure release valve (14) on the high-pressure rubber tube (11), starting a high-pressure pump (21), continuously injecting acid liquor into the drill hole (7), and stopping injection when the pipeline pressure monitored by a pressure sensor (16) reaches a set value;
step six: the fracturing fluid in the drill hole (7) is kept pressure through a one-way valve (15) arranged on the high-pressure rubber pipe (11), and the acid liquor permeates into surrounding rocks through the wall of the drill hole (7);
step seven: after the pressure maintaining of the drill hole (7) is finished, the high-pressure pump (21) is restarted to inject acid liquor into the drill hole (7) for acidizing and fracturing the limestone top plate (2);
step eight: after fracturing is finished, closing the high-pressure pump (21), and maintaining the pressure of the fracturing fluid in the drill hole (7) through a one-way valve (15) on the high-pressure rubber pipe (11) to further enable the high-pressure acid liquid in the crack to seep into limestone pores on two sides of the crack;
step nine: after the pressure maintaining is finished, opening a pressure relief valve (14) on the high-pressure rubber pipe (11) and relieving the pressure of the pipeline;
step ten: and (4) taking out the hole packer (8), installing the hole packer in the next drilling hole (7), and repeating the third step to the ninth step until the fracturing of all the drilling holes (7) is completed.
6. The method of claim 5, wherein the method is suitable for fracturing of goaf limestone ceiling and pre-fracturing of limestone roof (2) above coal seam (1); if the limestone suspended roof fracturing is carried out in the goaf, constructing a vertical top plate of a side drill hole (7) close to the coal wall, constructing a side drill hole (7) close to the goaf obliquely to the goaf, and arranging the two groups of drill holes (7) in a staggered manner; if the limestone top plate (2) above the coal seam (1) is pre-cracked, a side drill hole (7) close to a goaf is perpendicular to the top plate, a side drill hole (7) close to a coal wall is obliquely constructed on the top plate in front of a coal face (6), two groups of drill holes (7) are arranged in a staggered mode, and a group of parallel anchor cable holes are respectively constructed on the perpendicular top plates in two end areas of the coal face (6).
7. The method as claimed in claim 5, wherein in step two, the acid-fractured fracturing fluid is 15-20% diluted hydrochloric acid.
8. The method according to claim 5, characterized in that in step five, the acid liquor injection is stopped when the line pressure monitored by the pressure sensor (16) reaches 10 MPa.
9. The method according to claim 5, characterized in that in step six and step eight the fracturing fluid in the borehole (7) is maintained for 5-10 min.
10. The method according to claim 5, characterized in that in step seven, the high-pressure pump (21) is restarted to inject acid liquid into the drill hole (7), and the lime stone top plate (2) is acidized and fractured for 30 min.
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| CN114856684A (en) * | 2022-05-24 | 2022-08-05 | 中国矿业大学 | Fracturing cooperative control method for gas extraction of longwall mining end suspended roof and goaf |
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