A device and method for improving permeability and drainage of gas in soft coal seam recovery working face

Abstract

A device for enhancing permeability and drainage of gas in a soft coal seam recovery working face, including a drill pipe, a high-pressure water injection pump, a sand filling device, an expandable packer, a ball sliding sleeve and a drill bit, and the high pressure water injection pump and the sand filling device are connected to the left end of the drill pipe. The expandable packer is set on the drill pipe, and the ball sliding sleeve is rotatably sleeved on the drill pipe and located between the adjacent expandable packers. Between the center of the ball sliding bush and the sandblasting nozzle, the drill pipe is provided with spray holes corresponding to the ball sliding bush, and the drill bit is arranged at the right end of the drill pipe.

Description

technical field [0001] The invention relates to the field of gas drainage in coal mines, in particular to a gas drainage enhancement device and method for a soft coal seam recovery working face. Background technique [0002] Mine gas is one of the main natural factors that seriously threaten the safe production of coal mines. Coal and gas outbursts and gas explosions are the most disasters affecting coal mine production today, causing large-scale casualties and huge property losses every year. With the increase of mining depth, the gas content and pressure of coal seams also gradually increase, especially for single, soft, low-permeability mining face, there is no effective coal seam gas efficient extraction technology. Therefore, how to effectively prevent and control gas accidents and actively control gas disasters has become the main research topic that restricts the current high-yield, efficient and safe production of coal mines. [0003] It is the fundamental measure t...

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Problems solved by technology

[0003] It is the fundamental measure to prevent and control the gas problem to carry out fracture network anti-permeability and gas drainage on single, soft and high gassy coal seam recovery working face. At present, there are two main methods of pre-exhausting coal seam gas: one is to pump the coal seam along the seam Drainage drilling is used for gas extraction, but for some single, soft high-gas coal seams, it is very difficult to construct long holes in the coal seam. Due to the soft quality of the recovered coal seam, it is very easy to appear blowout holes, The phenomenon of drilling holes, blocking holes, and drill sticking makes it difficult for the drilled holes constructed in the transport level road to pass through the stress zone of the original rock that naturally exists in the original rock and is not disturbed by human factors to reach the coal and rock mass around the mining space. The support stress concentration area on the side of the return air level roadway with increased internal stress, coupled with the lack of cracks and low permeability in the soft coal seam, make the extraction time of the pre-extraction coal seam gas directly by the existing technology short and the extraction time is short. The gas extraction rate is low, and sometimes it is impossible to extract the gas at all, resulting in the difficult situation of "gas can not be extracted", which makes the extraction effect very unsatisfactory; Gas, but due to high investment, large amount of tunnel engineering, complex production and auxiliary systems, etc., the production cost per ton of coal is relatively high. Considering safety and economic issues, this measure has not been widely promoted

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