CN212054655U - Gas extraction system of coal seam substep water injection nitrogen injection fracturing - Google Patents
Gas extraction system of coal seam substep water injection nitrogen injection fracturing Download PDFInfo
- Publication number
- CN212054655U CN212054655U CN202020497984.XU CN202020497984U CN212054655U CN 212054655 U CN212054655 U CN 212054655U CN 202020497984 U CN202020497984 U CN 202020497984U CN 212054655 U CN212054655 U CN 212054655U
- Authority
- CN
- China
- Prior art keywords
- pipe
- water injection
- injection
- nitrogen
- fracturing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000007924 injection Substances 0.000 title claims abstract description 204
- 238000002347 injection Methods 0.000 title claims abstract description 204
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 182
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 167
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 92
- 239000007789 gas Substances 0.000 title claims abstract description 58
- 238000000605 extraction Methods 0.000 title claims abstract description 43
- 239000003245 coal Substances 0.000 title claims abstract description 35
- 238000007789 sealing Methods 0.000 claims abstract description 25
- 239000002775 capsule Substances 0.000 claims abstract description 19
- 238000012544 monitoring process Methods 0.000 claims description 11
- 230000035699 permeability Effects 0.000 abstract description 7
- 230000000694 effects Effects 0.000 description 12
- 238000005553 drilling Methods 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 6
- 238000010276 construction Methods 0.000 description 5
- 238000009434 installation Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 238000005520 cutting process Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000007792 addition Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000008400 supply water Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Images
Abstract
A gas extraction system for coal seam fractional water injection and nitrogen injection fracturing relates to the technical field of gas extraction. The system comprises a nitrogen injection device, a water pressure device, a gas extraction device and a hole sealing device, wherein the nitrogen injection device is connected with a header pipe through a nitrogen injection pump, and a nitrogen injection pipe is arranged on the header pipe in parallel. The water pressure device is connected with a water injection main pipe through a water injection pump, a plurality of water injection branch pipes are arranged on the water injection main pipe in parallel, and a pressure gauge, a valve and a flowmeter are arranged on the water injection branch pipes. The hole sealing device comprises a capsule hole sealing device and a connecting pipe, the connecting pipe is communicated with the water injection branch pipe and the capsule hole sealing device, and a valve and a pressure gauge are arranged on the connecting pipe. The gas extraction device is communicated with the water injection main pipe and is provided with a gas discharger. The collecting pipe is arranged in the pipeline of the water injection main pipe, the nitrogen injection pipe is arranged in the pipeline of the water injection branch pipe, and the capsule hole packer is sleeved on the outer surface of the pipeline of the water injection branch pipe. The gas extraction system integrates nitrogen injection, water injection and gas extraction, can inject nitrogen to generate water wedge fracturing permeability increase, and improves extraction efficiency.
Description
Technical Field
The utility model belongs to the technical field of the gas drainage technique and specifically relates to a gas drainage system of nitrogen fracturing is annotated to coal seam substep water injection.
Background
Coal mine gas is a heavy-pressure disaster factor influencing mine safety production, the existing hydraulic fracturing technology is a relatively effective coal seam permeability-increasing technology, and the method can well control the gas on a working face. However, due to the complex geological conditions of the coal seam, the water injection fracturing effect is good and bad, and particularly, due to the large elastic deformation of the soft coal body, the fracturing effect is not good. At present, the permeability of soft coal is increased by adopting a hydraulic cutting technology, but the hydraulic cutting technology is not simple and convenient to operate like a hydraulic fracturing technology, and a large amount of waste water is generated by the hydraulic cutting technology to pollute the environment of a working face. The existing hydraulic fracturing, gas extraction and hole sealing devices are independently constructed and operated, so that the construction coordination is poor, and the quick and efficient construction cannot be realized. Therefore, it is very necessary to design a gas extraction system capable of realizing rapid, efficient and environment-friendly coal seam fracturing and permeability improvement.
SUMMERY OF THE UTILITY MODEL
In order to solve the problem of arranging that annotate nitrogen, water injection, gas drainage system combine, produce the water wedge fast and be used for the fracturing anti-reflection, improve and take out and adopt efficiency, the utility model provides a gas drainage system of nitrogen fracturing is annotated to coal seam substep water injection, concrete technical scheme as follows.
A gas extraction system for coal seam step-by-step water injection, nitrogen injection and fracturing comprises a nitrogen injection device, a water pressure device, a gas extraction device and a hole sealing device; the nitrogen injection pump of the nitrogen injection device is connected with a manifold pipe, a nitrogen injection pipe is arranged on the manifold pipe in parallel, and a pressure gauge, a valve and a flowmeter are arranged on the nitrogen injection pipe; the water injection pump of the water pressure device is connected with a water injection main pipe, a plurality of water injection branch pipes are arranged on the water injection main pipe in parallel, and a pressure gauge, a valve and a flowmeter are arranged on the water injection branch pipes; the hole sealing device comprises a capsule hole sealing device and a connecting pipe, the connecting pipe is communicated with the water injection branch pipe and the capsule hole sealing device, and a valve and a pressure gauge are arranged on the connecting pipe; the gas extraction device is communicated with the water injection main pipe and is also provided with a gas discharger; the collecting pipe is arranged in a pipeline of the water injection main pipe, the nitrogen injection pipe is arranged in a pipeline of the water injection branch pipe, and the capsule hole packer is sleeved on the outer surface of the pipeline of the water injection branch pipe; the water injection branch pipe and the nitrogen injection pipe extend into the fracturing drill holes, and monitoring drill holes are arranged between the fracturing drill holes.
Preferably, the collecting pipe is fixed on the inner side of the pipe wall of the water injection main pipe, and the nitrogen injection pipe is fixed on the inner side of the pipe wall of the water injection branch pipe.
It is also preferable that the diameter of the water injection main pipe is greater than 2 times the diameter of the collecting pipe, and the diameter of the water injection branch pipe is greater than 2 times the diameter of the nitrogen injection pipe.
It is also preferable that the diameter of the collecting pipe is greater than 2 times the diameter of the nitrogen injection pipe, and the diameter of the water injection main pipe is greater than 2 times the diameter of the water injection branch pipe.
It is further preferred that the length of the nitrogen injection pipe extending into the fracturing bore is greater than the length of the water injection branch pipe extending into the fracturing bore.
It is further preferred that the water injection branch pipe is connected to the water injection main pipe through a connection flange.
Further preferably, a pressure gauge is arranged on the water injection main pipe, and a valve is arranged between the water injection main pipe and the gas extraction device.
The utility model provides a pair of gas drainage system beneficial effect of seam substep water injection notes nitrogen fracturing is: the nitrogen injection, water injection and gas extraction system is arranged in a centralized manner, and particularly the nitrogen injection pipe is arranged inside the water injection branch pipe, so that a water wedge is generated by nitrogen injection in the hydraulic fracturing process for fracturing permeability increase, the fracturing effect is improved when water injection is continued, and the gas extraction efficiency is improved; in addition, the hole sealing device and the water pressure device share the water pump, hole sealing operation is facilitated, the water injection pipeline continues to extract after fracturing is completed, and one pipe is multipurpose. In addition, the system also has the advantages of flexible operation, high permeability increasing efficiency, low water consumption and the like.
Drawings
FIG. 1 is a schematic diagram of a gas extraction system for coal seam step-by-step water injection, nitrogen injection and fracturing;
FIG. 2 is a schematic diagram of a fracture borehole placement;
in the figure: 1-nitrogen injection pump, 2-header pipe, 3-nitrogen injection pipe, 4-water injection pump, 5-water injection main pipe, 6-water injection branch pipe, 7-capsule hole packer, 8-connecting pipe, 9-gas extraction device, 10-gas discharger, 11-pressure gauge, 12-valve, 13-flowmeter, 14-coal bed, 15-fracturing borehole, 16-monitoring borehole, 17-one-way valve and 18-bell mouth.
Detailed Description
The concrete embodiment of the gas extraction system for coal seam stepped water injection and nitrogen injection fracturing provided by the present invention is described with reference to fig. 1 to 2.
The utility model provides a specific structure of gas drainage system of coal seam substep water injection nitrogen injection fracturing includes nitrogen injection device, water pressure device, gas drainage device and hole sealing device, and water pressure device is used for the coal seam water injection and constructs hydraulic fracturing, and nitrogen injection device and water pressure device cooperation increase the coal fragility, improve water wedge effect and high pressure and split anti-reflection efficiency, and gas drainage device utilizes water pipe of water pressure device to take out and adopt gas, and hole sealing device and water pressure device share the water pump and cooperate the shutoff drilling. The system is characterized in that nitrogen injection, water injection and gas extraction systems are arranged in a centralized mode, so that a water wedge is generated by nitrogen injection in the hydraulic fracturing process and used for fracturing permeability improvement, the fracturing effect is improved when water injection is continued, and the gas extraction efficiency is improved.
Wherein annotate nitrogen pump 1 of nitrogen device and connect manifold 2, manifold 2 is last to have arranged in parallel and annotates nitrogen pipe 3, annotates nitrogen pipe 3 and is provided with manometer 11, valve 12 and flowmeter 13, and valve 12 sets up the low reaches at annotating nitrogen pipe 3, and manometer 11 sets up the upper reaches at valve 12, and flowmeter 13 sets up the low reaches at valve 12. Water pressure device's water injection pump 4 is connected water injection main pipe 5, and water injection main pipe 5 is gone up the parallel arrangement and is had a plurality of water injection branch pipes 6, can be according to the installation of 15 arranging quantity of fracturing drilling, is provided with manometer 11, valve 12 and flowmeter 13 on the water injection branch pipe 6, and valve 12 sets up the low reaches in water injection branch pipe 6, and manometer 11 sets up the upper reaches at valve 12, and flowmeter 13 sets up the low reaches at valve 12. The hole sealing device comprises a capsule hole sealing device 7 and a connecting pipe 8, the connecting pipe is communicated with a water injection branch pipe 6 and the capsule hole sealing device 7, a water injection pump 4 can directly supply water to the capsule hole sealing device, and therefore hole sealing operation is facilitated, and a valve 12 and a pressure gauge 11 are arranged on the connecting pipe and used for controlling hole sealing construction and monitoring hole sealing effects. The gas extraction device 9 is communicated with the water injection main pipe 5, after hydraulic fracturing, the gas extraction device 9 provides negative pressure so as to extract gas in a coal seam through the water injection pipe, and the gas extraction device 9 is further provided with a gas discharger 10 for releasing the collected gas. The manifold 2 disposes in the pipeline of water injection main pipe 5, and notes nitrogen pipe 3 disposes in the pipeline of water injection branch pipe 6, will annotate the pipeline arrangement of nitrogen and can not influence the water injection in the pipeline of water injection to made things convenient for the installation of notes nitrogen pipeline, compared in independent notes nitrogen and water injection operation, this kind of operation mode is more nimble, and annotate nitrogen in same drilling and produce the effect in water wedge fracturing coal seam better. The capsule hole packer 7 is sleeved on the outer surface of the pipeline of the water injection branch pipe 6, and the capsule hole packer 7 is arranged on the water injection branch pipe 6 in a certain length according to the requirement and extends into the fracturing drill hole along with the water injection branch pipe 6. The water injection branch pipes 6 and the nitrogen injection pipes 3 extend into fracturing drill holes, monitoring drill holes 16 are arranged between the fracturing drill holes 15, and the monitoring drill holes 16 are used for monitoring fracturing effects.
The collecting pipe 2 can be fixed on the inner side of the pipe wall of the water injection main pipe, and the nitrogen injection pipe 3 can be fixed on the inner side of the pipe wall of the water injection branch pipe 6. In addition, the nitrogen injection pipe 3 can also be fixed at the axial position of the water injection branch pipe through a fixed rod. The diameter of the water injection main pipe 6 is 2 times larger than that of the collecting pipe, and the diameter of the water injection branch pipe 6 is 2 times larger than that of the nitrogen injection pipe, so that the installation of the nitrogen injection pipe 3 in the water injection pipe is ensured, and the overall stability of the water injection nitrogen injection system is ensured. The diameter of manifold 2 is greater than 2 times of 3 diameters of notes nitrogen pipe, and the diameter of water injection main pipe 5 is greater than 2 times of 6 diameters of water injection branch pipe to manifold 2 can guarantee to connect a plurality of notes nitrogen pipe simultaneous construction, and water injection main pipe 5 is under construction simultaneously at a plurality of pressure drilling. The length of the nitrogen injection pipe 3 extending into the fracturing drill hole is larger than that of the water injection branch pipe 6 extending into the fracturing drill hole, so that the nitrogen injection pipe 3 can extend to a fracturing area for nitrogen injection, and a water wedge is rapidly generated for increasing the permeability of the fracturing.
The water injection branch pipe 6 is connected with the water injection main pipe 6 through a connecting flange, so that the installation of the water injection branch pipe and the installation and maintenance of the nitrogen injection pipe are facilitated. A check valve 17 may be further provided at the end of the nitrogen injection pipe 3 to prevent water in the bore from flowing into the nitrogen injection pipe 3. In addition, a bell mouth 18 can be arranged at the tail end of the part of the nitrogen injection pipe 3 extending into the fracturing drill hole, and the bell mouth 18 is abutted against the coal body, so that the backflow of the injected nitrogen is avoided; or the connecting flange through the water injection branch pipe 6 is opened, the nitrogen injection pipe 3 is pulled back, the bell mouth 18 of the nitrogen injection pipe and the pipe orifice clamping of the water injection branch pipe 6 are clamped, the backflow of the injected nitrogen can be effectively avoided, and the pipeline is damaged. The water injection main pipe 6 is provided with a pressure gauge 11, a valve is arranged between the water injection main pipe 6 and the gas extraction device 9, and gas extraction can be controlled by opening and closing the valve. The part of the water injection branch pipe 6 outside the drilled hole can also be led out of a drain pipe to discharge the residual water in the pipeline.
In order to further explain the gas extraction system for the coal seam step-by-step water injection, nitrogen injection and fracturing, the use method and the steps thereof are further explained.
Step one, arranging fracturing drill holes and monitoring drill holes, marking the fracturing drill holes and the monitoring drill holes in a roadway, and constructing;
and step two, installing a gas extraction system for coal seam step-by-step water injection, nitrogen injection and fracturing, installing a capsule hole packer into the pressure drill hole along with a water injection branch pipe, immediately connecting the capsule hole packer into a water injection main pipe through a connecting pipe, injecting water into the capsule hole packer through a water injection pump, and completing hole sealing by the capsule hole packer when the water pressure of a pressure gauge on the connecting pipe is increased to 5 MPa.
And step three, injecting nitrogen into the fracturing drill holes by using a nitrogen injection device, wherein the nitrogen enters the coal body along the cracks of the drill holes, so that the coal body is rapidly frozen, and the brittleness of the coal body is increased. And (4) immediately injecting water and fracturing after stopping nitrogen injection, injecting water through the water injection branch pipe of the water pressure device, and observing a pressure meter and a flowmeter on the water injection branch pipe. And setting the initial water injection pressure to be 10MPa, monitoring the drilling holes, and if no leakage is found in the monitored drilling holes, increasing the pressure to 50 MPa. If the hardness of the coal body is too high, the hydraulic fracturing is adjusted to be 90 MPa. The effect of fracturing is judged to the weeping condition through monitoring drilling, when fracturing efficiency is not high, can carry out the water injection earlier, stops behind the water injection period time, annotates nitrogen fast at random, makes the water in the gap expand rapidly and freeze, and ice has played the effect of proppant. And then, water injection is continued, ice in the gap plays a role of a water wedge, the coal body is burst by the effect similar to the wedge, and the effect of cracking is improved.
And step four, after fracturing is finished, closing a valve between the water injection pump and the gas extraction device, and meanwhile, connecting a drainage pipe of the gas extraction device to a negative pressure state, wherein the connected extraction negative pressure can be set to be about 2MPa for extraction.
Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and the changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also belong to the protection scope of the present invention.
Claims (7)
1. A gas extraction system for coal seam step-by-step water injection, nitrogen injection and fracturing is characterized by comprising a nitrogen injection device, a water pressure device, a gas extraction device and a hole sealing device; the nitrogen injection pump of the nitrogen injection device is connected with a manifold pipe, a nitrogen injection pipe is arranged on the manifold pipe in parallel, and a pressure gauge, a valve and a flowmeter are arranged on the nitrogen injection pipe; the water injection pump of the water pressure device is connected with a water injection main pipe, a plurality of water injection branch pipes are arranged on the water injection main pipe in parallel, and a pressure gauge, a valve and a flowmeter are arranged on the water injection branch pipes; the hole sealing device comprises a capsule hole sealing device and a connecting pipe, the connecting pipe is communicated with the water injection branch pipe and the capsule hole sealing device, and a valve and a pressure gauge are arranged on the connecting pipe; the gas extraction device is communicated with the water injection main pipe and is also provided with a gas discharger; the collecting pipe is arranged in a pipeline of the water injection main pipe, the nitrogen injection pipe is arranged in a pipeline of the water injection branch pipe, and the capsule hole packer is sleeved on the outer surface of the pipeline of the water injection branch pipe; the water injection branch pipe and the nitrogen injection pipe extend into the fracturing drill holes, and monitoring drill holes are arranged between the fracturing drill holes.
2. The gas extraction system for coal seam stepped water injection, nitrogen injection and fracturing as claimed in claim 1, wherein the header pipe is fixed inside the pipe wall of the main water injection pipe, and the nitrogen injection pipe is fixed inside the pipe wall of the branch water injection pipe.
3. The gas extraction system for coal seam stepped water injection, nitrogen injection and fracturing as claimed in claim 2, wherein the diameter of the water injection main pipe is 2 times larger than that of the collecting pipe, and the diameter of the water injection branch pipe is 2 times larger than that of the nitrogen injection pipe.
4. The gas extraction system for coal seam stepped water injection, nitrogen injection and fracturing as claimed in claim 2, wherein the diameter of the collecting pipe is 2 times larger than that of the nitrogen injection pipe, and the diameter of the water injection main pipe is 2 times larger than that of the water injection branch pipe.
5. The gas extraction system for coal seam step-by-step water injection, nitrogen injection and fracturing as claimed in claim 3 or 4, wherein the length of the nitrogen injection pipe extending into the fracturing bore hole is greater than the length of the water injection branch pipe extending into the fracturing bore hole.
6. The gas extraction system for coal seam stepped water injection, nitrogen injection and fracturing as claimed in claim 3 or 4, wherein the water injection branch pipe is connected with the water injection main pipe through a connecting flange.
7. The gas extraction system of coal seam fractional water injection, nitrogen injection and fracturing as claimed in claim 1, wherein the water injection main is provided with a pressure gauge, and a valve is arranged between the water injection main and the gas extraction device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020497984.XU CN212054655U (en) | 2020-04-07 | 2020-04-07 | Gas extraction system of coal seam substep water injection nitrogen injection fracturing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020497984.XU CN212054655U (en) | 2020-04-07 | 2020-04-07 | Gas extraction system of coal seam substep water injection nitrogen injection fracturing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212054655U true CN212054655U (en) | 2020-12-01 |
Family
ID=73542568
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020497984.XU Expired - Fee Related CN212054655U (en) | 2020-04-07 | 2020-04-07 | Gas extraction system of coal seam substep water injection nitrogen injection fracturing |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212054655U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112761586A (en) * | 2021-01-22 | 2021-05-07 | 中国矿业大学 | Drilling methane self-circulation blasting fracturing enhanced extraction method |
| CN113446050A (en) * | 2021-06-23 | 2021-09-28 | 煤炭科学技术研究院有限公司 | Long-injection short-pumping layered three-dimensional displacement gas extraction method and system |
-
2020
- 2020-04-07 CN CN202020497984.XU patent/CN212054655U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112761586A (en) * | 2021-01-22 | 2021-05-07 | 中国矿业大学 | Drilling methane self-circulation blasting fracturing enhanced extraction method |
| CN113446050A (en) * | 2021-06-23 | 2021-09-28 | 煤炭科学技术研究院有限公司 | Long-injection short-pumping layered three-dimensional displacement gas extraction method and system |
| CN113446050B (en) * | 2021-06-23 | 2023-09-26 | 煤炭科学技术研究院有限公司 | Long-injection short-extraction layered three-dimensional displacement gas extraction method and system |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103696800B (en) | A kind of brill cuts pressure and takes out method | |
| CN102121395B (en) | Method for integrated comprehensive management of gas in low-permeability single coal bed | |
| CN102287163B (en) | Drilling-sealing method and sealing device of coal mine underground ultrahigh pressure fracturing hole | |
| CN102140901B (en) | High pressure resistant drilled hole sealing method | |
| CN101294500B (en) | Heavy pressure slip-casting hole-sealing method for large-diameter extraction borehole | |
| CN105422164B (en) | Hydrofracturing is anti-reflection to aid in coal seam efficient water injection method and apparatus | |
| CN212054655U (en) | Gas extraction system of coal seam substep water injection nitrogen injection fracturing | |
| CN106988719B (en) | Anti-reflection system and anti-reflection method for circularly injecting hot water and liquid nitrogen into coal seam | |
| WO2015054984A1 (en) | Method for enhanced fuel gas extraction by coal mine underground gas-liquid dual-phase alternating phase-driven fracturing of coal body | |
| CN106285599B (en) | A kind of anti-reflection draining coal seam gas method of waterpower changing of the relative positions release | |
| CN104234740B (en) | A kind of low middle pressure air displacement high pressure coal seam gas train and method thereof | |
| CN104314508A (en) | Hole sealing method for coal bed gas drainage drill hole | |
| CN112696182A (en) | Drilling hole plugging, fracturing and water injection integrated structure and using method thereof | |
| CN104989356A (en) | Underground coal mine coal seam drilling high-pressure gas fracturing and permeability increasing method and system | |
| CN103993902B (en) | A kind of mash gas pumping drilling two step slip-casting hole-sealing method | |
| CN104405358A (en) | Method for fracturing coal seam by employing high-pressure gas | |
| CN109488299B (en) | Hydraulic fracturing softening device and method for hard rock of fully-mechanized rock-digging roadway | |
| CN108086945A (en) | A kind of layer-through drilling separate type whole process gas drainage hole sealing device and its method for sealing | |
| CN205858333U (en) | A kind of three plug hydraulic fracturing detecting earth stress systems | |
| CN103912304A (en) | Method for locally extracting gas of soft coal seams | |
| CN201165660Y (en) | Steel pipe hole bottom grouting apparatus | |
| CN107725102A (en) | A kind of water under high pressure and dry ice synergy permeability improvement device and method | |
| CN105134285A (en) | Three-blocking and two-injecting gas extraction hole sealing method | |
| CN205638532U (en) | But colliery is reuse's integrative hole sealing device of gas drainage water injection in pit | |
| CN201696048U (en) | Coal seam gob fracture zone water-injection observation system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20201201 |