Method for increasing gas extraction rate by permeability increasing of single thick coal seam

Abstract

Disclosed is a method for increasing gas extraction rate by permeability increasing of single thick coal seam. During a tunneling process of coal seam working face, gas extraction holes are drilled along coal seams and hole protecting tubes are inserted into the gas extraction holes after drilling and sealed so as to perform gas extraction. When tunneling length of a tunnel is less than 50m, a twist drill is used to drill on the bottom of the coal seam along an inclination at intervals of 0.3-0.5m of coal pillars, and drilling holes which are 1.0-1.5m in width and 0.1-0.2 time as high as the coal seam are formed. After the drilling holes are formed, curved sink from bottom to top occurs on the coal, a large quantity of gaps are generated, permeability coefficient of the coal is increased by more than 120 times on average, gas extraction flow is increased by more than 10 times on average, and average gas extraction concentration is larger than 55%. By the method, pressure relief of the single thick coal seam with high gas content and low permeability is achieved, permeability increasing range is wide, permeability increasing effect is fine, and the gas extraction rate is increased by 60%. In addition, the method is widely applicable.

Description

technical field [0001] The invention relates to a method for increasing the gas extraction rate, in particular to a method for enhancing the gas extraction rate in a single thick coal seam area, which is suitable for a single thick coal seam with high gas and low permeability. Background technique [0002] According to the "Eleventh Five-Year Plan" for the development and utilization of coalbed methane (coal mine gas), it is known that the outburst coal seam area in Yinggong Coalfield, the outburst coal seam area in Dengfeng Coalfield, the outburst coal seam area in Xinmi Coalfield, the outburst coal seam area in Jiaozuo mining area, and the outburst coal seam area in Jincheng mining area , Qinshui Coalfield coal seam area, Anyang-Hebi mining area outburst coal seam area, Fengfeng-Handan mining area outburst coal seam area, Hancheng mining area outburst coal seam area, Shitanjing-Shizuishan coal seam outburst area, Tonghua mining area outburst coal seam area, etc. Mining is ...

AI Technical Summary

Problems solved by technology

Hydraulic fracturing is to press high-pressure water into the coal seam through drilling holes, so that the coal seam forms a new crack circulation network and increases the gas permeability of the coal seam. Embedded in the coal body, and the soft coal body is easy to muddy after being soaked, and the fracturing fluid is not easy to discharge after entering the coal body, blocking the gas flow channel of the coal body, and the effect of improving the gas recovery rate is not obvious

Hydraulic slotting is the purpose of effectively transforming low-permeability coal seams through high-pressure water jet cutting, pressure relief, and increased permeability in the coal body; The effect is limited, and the effect of improving the gas extraction rate is general

Loosening blasting is to use the detonation pressure generated at the moment of explosion to make the coal around the hole crack, loosen and expand and deform, so as to improve the air permeability of the coal seam. However, after loosening blasting, it is easy to induce the problem of hole collapse and block the gas flow channel. High efficiency Gas extraction can only last for a few days, and the extraction effect is poor

Images