A method and device for preventing and controlling gas overrun in thick coal seam mining

Abstract

The invention discloses a method and a device for preventing and controlling gas transfinite in a thick-coal-seam mining process. According to the method, firstly, a more developed coal seam joint position is selected as a hole drilling position; angles of a drill hole and a spray nozzle are selected according to the direction of the maximum main stress of an original place, so that the hydraulic seam cutting direction forms an angle being 30 to 60 degrees with the direction of the maximum main stress of the original place; then, the drilling and the hole reinforcing are carried out; on the basis, hole forming is carried out; hydraulic seam cutting is carried out after the hole forming; next, hole sealing is carried out; and a drill hole is subjected to hydraulic fracturing after the hole sealing. The method and the device have the advantages that the implementation effect is good; the hydraulic seam cutting and the hydraulic fracturing are effectively combined; through selecting the drilling position, the drilling angle and the spray nozzle angle, the drilling hole collapse rate is reduced; the occurring probability of blank zones in a thick coal seam is effectively reduced through controlling the hydraulic seam cutting direction; the permeability and the gas permeability of the coal seam are improved, so that the gas extraction capability and the gas extraction effect are improved; further, the coal seam gas emission quantity is reduced; and the goal of preventing and controlling the gas transfinite in the thick-coal-seam mining process is achieved.

Description

technical field [0001] The invention belongs to the technical field of gas safety prevention and control in the coal seam mining process, and in particular relates to a method and device for preventing and controlling gas overrun in the thick coal seam mining process. Background technique [0002] Under normal circumstances, coal seams with a thickness of 3.5-7m are thick coal seams. my country is rich in thick coal seam resources, and its reserves account for 34% of the total reserves. The coal output through thick coal seam mining also occupies a high share. [0003] However, in the process of coal seam mining, with the increase of mining depth, the problem of gas exceeding the limit is becoming more and more serious, especially in thick coal seams. The limit has become the bottleneck problem of coal mine safety production. [0004] Aiming at the problem of gas exceeding the limit, scholars at home and abroad have studied to prevent and control gas exceeding the limit in ...

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Problems solved by technology

[0006] At present, the problems encountered by hydraulic fracturing in the solution of gas overrun in thick coal seams: 1. High-pressure water causes displacement and deformation of the borehole wall, which on the one hand causes large-area pressure relief, and on the other hand forms abnormal formations in thick coal seams. Determine the location of the high-pressure abnormal zone, which leaves a safety hazard for mining and production; 2. Since the crack initiation location is at the weak stress surface, which is greatly affected by the stress distribution of the coal seam, the crack initiation when fracturing is carried out through drilling The location and direction of extension are not clear. Due to the complexity of the coal seam in the formation, the cracks in it will turn or extend to the roof and floor, causing the cracks to expand in an orderly manner. The thick coal seam cannot be uniformly enhanced, and the cracks formed are single, The number is small, and there are large areas of blank zones; 3. Even if the cracks are formed, because the maximum principal stress is not considered, the cracks will be closed again in a short time, thus affecting the overall gas drainage effect, making the gas drainage volume Decrease rapidly and generally return to the original level within a short time of extraction

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