WO2018214659A1

WO2018214659A1 - Novel process for controlling downhole gas in abandoned mine

Info

Publication number: WO2018214659A1
Application number: PCT/CN2018/082635
Authority: WO
Inventors: 于志军; 刘双林; 祁铭; 赵彦; 田华; 向其芝; 马英武; 杨智彬; 黄佳福; 王苍龙; 杨勇; 李丽
Original assignee: 中节能宁夏新能源股份有限公司
Priority date: 2017-05-26
Filing date: 2018-04-11
Publication date: 2018-11-29
Also published as: EP3633142A1; CN107035401B; CN107035401A; EP3633142B1; EP3633142A4

Abstract

Disclosed is a novel process for controlling downhole gas in an abandoned mine. The process comprises the steps of 1) before an abandoned mine is closed, branching downhole drifts (1, 2, 3) are blocked, and steel pipe holes are prepared in the upper portions of blocking material walls to enable the interior to communicate with the exterior; 2) the steel pipe holes prepared in the blocking walls (4) of the multiple branching downhole drifts are connected with a downhole gas pumping and discharging main system (7) to conduct gas pumping and discharging; 3) blocked drift drainage water is communicated with main drift drainage water, a water storage tank (11) is constructed at a position at the bottom of the mine, a water drainage pump (12) and a water pipe are installed to pump and drain inflowing downhole water to the surface, and thereby normal pumping and drainage of inflowing downhole water can be achieved after the coal mine is closed; 4) a main entrance and a secondary entrance of the abandoned mine are closed, steel pipes are embedded in loess-filled masonry material rock walls in an adit inclined shaft, a main entrance and a secondary entrance of a vertical shaft are blocked with steel-reinforced concrete cover plates, and steel pipes are embedded into the main entrance and the secondary entrance of the vertical shaft to enable the interiors of the entrances to communicate with the exteriors of the entrances; and 5) downhole gas is discharged and extracted with surface gas discharging and extraction equipment. The process of the present invention can achieve the purposes of comprehensive control and utilization of downhole gas in an abandoned mine.

Description

A new process for gas control in abandoned mines

Technical field

The invention belongs to the field of mine gas control, and in particular relates to a new process technology for gas control of abandoned mines.

Background technique

Abandoned mine gas refers to the methane resources in the remaining coal seams, surrounding rock and underground closed space adsorption and free state in the mines closed due to the depletion of coal resources or other non-compliance with safety production requirements and policy. The development and utilization of abandoned mine gas is to take certain plugging measures before the mine is about to close, and use the original gas drainage system to extract gas from the ground. There are only some theoretical studies on abandoned mine treatment technology in China, and there are no successful experiences and projects. Although some mining areas have been used for surface drilling and drainage, the industrialization of the comprehensive utilization of abandoned mine gas in the true sense is still a blank. With the structural reform of the domestic coal industry and the elimination of production capacity, the number of shut down mines has increased year by year. The catastrophes such as gas escaping, collapse landslides, meteorite pollution, and underground water pollution are also becoming more and more serious. If the scientific treatment is not carried out, the ecological environment will be seriously threatened, and these shut down mines are rich in a large number of Gas resources, according to relevant statistics, the waste gas resources in the country reached trillions of cubic meters. If this technology is promoted nationwide and formed into industrialized development, it will help promote the development and utilization of unconventional natural gas resources during the 13th Five-Year Plan period, and at the same time help promote the transformation of Chinese coal enterprises, increase new jobs, and realize abandoned resources. Reuse, more importantly, solves the safety and environmental protection problems of abandoned mines and protects the ecological environment. The society is of great significance.

Summary of the invention

The object of the present invention is to provide an obstacle to the gas control of the existing abandoned mine shaft, and provide a roadway plugging, a reserved hole, a gas drainage system connection modification, a pumping system transformation, and a ground drainage system in the abandoned mine shaft. The mining equipment discharges the underground gas to achieve the effect of comprehensive utilization and utilization of the abandoned mine gas.

The process steps of the technical solution for achieving the object of the present invention are as follows:

1) Before the abandoned mine is closed, the roadway with relatively high gas spillage in the underground mine shall be blocked with the stone wall at the connection port with the main roadway and the pipeline shall be reserved, and the gas shall be exhausted and the water pumping shall be carried out:

a. Downhole roadway blocking: Before the abandoned mine is about to close, in the underground mining area, the working branch roadway and the main roadway connection, the inner side is first built with a stone wall, the thickness is about 0.8-1 meters, the middle Filled with loess, the thickness is 5 meters, and then the stone wall is built again, the thickness is about 0.8-1 meters. The whole pipeline should be pre-buried during the masonry process to make the roadway communicate with the inside and outside. A detachable closure is provided on the outside for inspection of the gas detector in the closed tunnel. If a high gas operation roadway is detected, the pipe is directly connected to the underground gas main pipe. Also, a drain hole should be provided on the lower side of the sealing wall to enable the water in the roadway to be discharged. After the original gas drainage pipeline system is reconstructed, it is connected with the ground drainage system to realize underground mining of abandoned mine gas;

b. Downhole water pumping: Under normal circumstances, the underground groundwater is continuously flowing out to the goaf. When the mine is in normal production, the underground water pumping is also a key point in the daily work of the mine production, but after the mine is shut down, the mine is closed. If the underground water is not discharged in time, the water will accumulate and will flood the mine roadway, so that the underground gas has no space to escape and can not be used. The invention redesigns the underground water gushing drainage system after the mine is shut down for production, so that the underground water can be pumped to the ground on the ground under the condition of no work, and the underground gas can be retained to accumulate and accumulate. The space avoids the accumulation of water in the mine and at the same time enables the gas control of abandoned mines.

The invention is to make a water seal overflow water tank in the lower part of the stone wall when the roadway is masonry to block the stone wall, and the water in the roadway is collected into the water tank, and the water level can be passed through when the liquid level reaches a certain height. The overflowing out of the blocked wall, at the same time, the relatively high concentration of gas accumulated in the stone wall will not flow out through the drainage trough, and the gushing water overflowing from the water seal overflow trough communicates with the drainage channel of the main roadway, and then mines down the mine. The lowest position is set up with a water storage tank. The water storage tank is generally made of stone and cement mortar. The volume of water storage determines the volume of the water storage tank according to the amount of water inflow from the mine. The water in the main roadway drains to this water storage. The warehouse, through the precise positioning on the ground, drills a pumping well into the water storage bin, installs the pump and connecting pipe through the wellbore at the ground wellhead, and extends into the inner and lower parts of the water storage about 2/3 deep, and the water is stored. When the water level in the warehouse reaches the inlet height of the pump, the pump starts pumping water, and the water in the water storage tank is pumped to the ground for reuse. Therefore, after the mine is closed, the underground water can still be pumped to the ground to save enough space to release the storage gas to achieve the purpose of comprehensive treatment and utilization of the abandoned mine gas.

2) Connect the pipeline reserved on the stone wall to the underground gas drainage pipeline to form the underground gas drainage pipeline system, and then use the original gas drainage system equipment on the ground to pump the gas accumulated under the abandoned mine:

A solid reinforced concrete cover plate larger than the wellbore section is poured into the wellhead of the vertical shaft. During the pouring process, two steel pipes are embedded in the middle, and one end extending into the inner side of the wellbore is open to communicate with the underground space. A flange cover is installed at one end of the outer side of the wellbore, and the bolt connection is closed. Inclined wells and flat rafts shall be constructed with a brick, stone or concrete wall 20m long within the wellhead. The thickness of the wall shall not be less than 0.6m. It shall be firm and reliable, and then filled with mud to the wellhead and then masonry, stone or stone. Concrete wall. After the mine is closed, the outer flange cover of the pre-embedded pipe is disassembled and inserted into the gas detector or sampling equipment to analyze the gas concentration in the well. If the gas is available, the nozzle is connected with the ground gas drainage pipe to realize the mine. After the closure, the gas stored in the underground is used for drainage.

3) Connect the blocked roadway drainage to the main roadway drainage, and construct a water storage tank at a low position in the underground position. Drill the drainage hole on the ground to the position of the underground water storage tank, install the pump and water pipe to pump the underground water. To the ground, after the mine is closed, the effect of normal pumping of underground water can be realized;

4) After the above work is completed, the inner and outer walls are closed by masonry, cement, sand, etc., and the inner and outer walls are closed with loess and clay filling compaction, while the opposite wells are at the wellhead. The reinforced concrete cover plate blocks the wellhead. During the whole plugging process, the pre-buried steel pipe protrudes into the mine in the upper part of the inclined inclined shaft. The vertical shaft pre-embeds the steel pipe in the center of the reinforced concrete cover to connect the inside and outside of the well, and the original gas on the ground. Pumping system equipment pipeline connection, to achieve the role of abandoned mine gas drainage treatment.

5) Through the ground original gas drainage system equipment and the underground gas drainage main pipeline connected and exhaust gas, to achieve the purpose of comprehensive utilization and utilization of underground gas in abandoned mines.

The invention has the following effects: the gas accumulation, the escape and the underground water accumulation in the abandoned mine shaft are eliminated by the underground mine roadway blocking, the underground gas pipeline reconstruction, the underground water pumping and drainage, the abandoned mine wellhead sealing and other gas comprehensive control measures. The disasters brought by the disaster can also reuse the abandoned mine gas resources to achieve economic benefits, environmental benefits and good social benefits.

DRAWINGS

Figure 1 shows a downhole gas pipeline system in the process of the present invention.

2 is a downhole water gushing drainage system of the present invention.

Figure 3 is a schematic view showing the closure of the shaft of the abandoned mine in the present invention.

4 is a schematic view of an inclined shaft sealing and gas drainage pipeline of an abandoned mine in the present invention.

As shown in the figure: 1. Downhole roadway 1, 2, underground roadway 2, 3,

underground roadway

3, 4, underground roadway blocking wall, 5, pre-buried pipeline, 6, pipe flange, 7, downhole Gas drainage main pipeline, 8, underground main roadway, 9, underground roadway drainage outlet, 10, underground main road drainage ditch, 11, underground storage tank, 12, drainage pump, 13, drainage well, 14, abandoned mine main Wellhead, 15, wellhead sealing cover, 16, reserved gas drainage pipeline, 17, abandoned mine main inclined shaft, 18, buried pipeline in the buried pipeline, 19, inside blocking stone wall,

20, loess or sand filled section, 21, outside blocking stone wall, 22, gas drainage ground total pipeline.

detailed description

As shown in Figure 1, a new technology for underground gas control in abandoned mines, before the abandoned mine is about to be closed, in the mining area of the abandoned mine, the operation area of the goaf, the mouth of the roadway 1, 2, 3 is inwardly about 8 At the meter, the sealing wall 4 is built separately. The specific method is to build a sealing wall with stone and cement mortar at a distance of 8 meters in the roadway. The thickness is about 0.8-1 meters. The roadway is blocked. The middle is filled with loess and compacted to a thickness of 5 meters. Then, the masonry stone and cement mortar are used to seal the wall, and the thickness is about 0.8-1 meters. In the process of masonry construction of the closed wall, one DN100-DN200 thick is buried at 0.2-0.3 meters from the top of the sealing wall. The pre-buried pipe 5 is connected to the main roadway 8 through the pre-buried pipe 5, and the pipe flange 6 is closed on the outside of the pre-embedded pipe, and the inner side of the roadway is opened, and the outer pipe flange of the pre-embedded pipe is disassembled. The gas detector can be detected in the closed roadway. If the gas concentration reaches the available conditions, the pipeline can be directly connected to the underground gas drainage main pipeline 7 through the flange, and then the underground gas and the gas can be pumped and discharged through the original gas drainage equipment on the ground.

As shown in Figure 2: the abandoned mine underground water pumping and drainage system, before the abandoned mine is closed, when the underground wall is blocked by the underground roadway, the underground drainage channel 9 is provided on the lower side of the sealing wall. In the flow-sealing type, a sump of cement mortar is applied to the inside of the roadway close to the sealing wall. The size is determined according to the amount of water flowing in the roadway, so that the water from the roadway is collected into the sump, when the water level is accumulated. When the overflow height is reached, the sub-lane is discharged from the overflow trough at the lower part of the sub-lane sealing wall, so that the gushing water in the sub-lane can be discharged, and the gas in the sub-district will not be discharged from the overflow-sealed drain 9. The gushing water overflowing from each lane is respectively flowed into the drainage ditch 10 of the cement mortar surface disposed in the main roadway, and the water storage tank 11 is disposed at a lower working position on the lower working surface of the mine, which is dug at the lowest position of the underground mine. A flat shovel is used to plaster the surface with cement mortar. The size, width and depth of the water tank are determined by the size of the underground tunnel, the capacity of the pumping system and the amount of water inflow. The general size of the water tank is 20 meters long, 3 meters deep and 3 meters deep. A water tank is composed in series, and a drainage well 13 is hit on the upper surface of the water tank, and is hit into the water tank, so that the water tank communicates with the ground through the drainage well 13 , and the drainage pump 12 and the outlet pipe of the drainage pump 12 are installed in the drainage well. It is connected to the surface water treatment device, and the downhole water accumulated in the underground water tank is discharged by the drainage pump to ensure that there is enough space under the well to release the storage gas, so as to achieve the purpose of comprehensive treatment and utilization of the abandoned mine gas.

As shown in FIG. 3, in the process of the present invention, at the main wellhead 14 of the abandoned mine, a closed wellhead is arranged, and a reinforced concrete well sealing cover plate 15 is set. The thickness of the reinforced concrete cover plate on the upper surface of the cover plate from the ground, the size of the steel bars used, The concrete labeling and proportioning should be based on the size of the wellhead span. It should be professionally designed by the professional structural design unit. According to the design documents, when making the reinforced concrete cover, it is necessary to pre-bury 1-2 in the middle of the cover plate 15. Steel pipe 3, the diameter of the steel pipe is DN300-500mm, one end of the pre-embedded pipe extends into the wellhead, the length needs to be more than 15 meters, the inner pipe mouth side is open, and the other end is above the reinforced concrete cover plate, 0.5-1 meters away from the ground. The welded pipe flange is bolted to close the flange with the flange cover and the flange. The flange cover is removed and the sampling instrument is inserted into the pipe to sample and analyze the gas concentration in the well. If it is available, the pipe and the ground gas drainage system can be used. The pipeline connection is used for the drainage and utilization of the gas stored in the underground to achieve the comprehensive control of the abandoned mine gas.

As shown in Fig. 4, in the process of the present invention, the abandoned mine is mainly an inclined well, and when the wellhead of the main inclined shaft 17 is blocked, the sealing stone wall is built with the stone and cement mortar at a depth of more than 25 meters from the wellhead. The thickness is not less than 1 m, and then compacted with loess or clay. The thickness of the loess or sand filling section 20 is more than 20 m, filled into the inclined well, and then the masonry cement mortar seals the inner sealing stone wall. 19. The thickness is not less than 1 m. During the whole sealing process, 1-2 steel pipes 2 are pre-buried in the upper part of the cornice. The diameter of the steel pipe is DN300-500mm. One end of the pre-buried pipe 18 extends into the wellhead 1 and the length needs to be greater than 20. Meter, and the bracket is reinforced, the nozzle is open, the other end is sealed outside the inclined stone wall 19 at the inclined wellhead, and the welded pipe flange is bolted to the flange and the flange by 0.5-1 meters away from the sealing wall. Plug the pipe, remove the flange cover and insert the sampling instrument into the pipe to sample and analyze the gas concentration in the underground. If it is available, connect the pipe to the original gas drainage ground pipe 22 on the ground, and arrange the gas stored in the underground. Use and use to achieve the role of gas control in abandoned mines.

Claims

A new process for gas control in abandoned mines: characterized in that the process is achieved by the following steps:

1) Before the closed mine is closed, the roadway with relatively high gas spillage in the underground mine shall be blocked with the stone wall at the connection port with the main roadway and the pipeline shall be reserved, and the gas shall be exhausted and the water pumping shall be carried out;

2) Connect the Texai gas pipeline reserved on the stone wall to the underground gas drainage pipe to form a downhole gas drainage pipe system, and then use the original gas drainage system equipment on the ground to pump the gas accumulated under the abandoned mine. row;

3) Connect the blocked roadway drainage to the main roadway drainage, and construct a water storage tank at a low position in the underground position. Drill the drainage hole on the ground to the position of the underground water storage tank, install the pump and water pipe to pump the underground water. To the ground, after the mine is closed, the effect of normal pumping of underground water can be realized;

4) After the above work is completed, the inner and outer walls are closed by the stone, cement and sand for the inclined shaft well, and the inner and outer walls are sealed with loess and clay. The opposite well is made of steel at the wellhead. The concrete cover plate seals the wellhead. During the whole plugging process, the pre-buried steel pipe protrudes into the mine in the upper part of the inclined inclined wellhead. The vertical well pre-embeds the steel pipe in the center of the reinforced concrete cover, connecting the inside and outside of the well, and the original gas pumping on the ground. The piping of the drainage system equipment is connected to realize the effect of the treatment and utilization of the abandoned mine gas drainage;

5) Through the ground original gas drainage system equipment and the underground gas drainage main pipeline connected and exhaust gas, to achieve the purpose of comprehensive utilization and utilization of underground gas in abandoned mines.