A method for increasing the extraction rate of coal seams with high residual gas content in underground coal mines

Abstract

The invention discloses a method for improving the extraction rate of a high residual gas content coal seam of an underground coal mine. The method comprises the following steps that a mounting hole is drilled; a hole opening sealing connection pipe fitting is mounted and fixed; construction of a gas extraction drill hole is conducted; CaC2 is stored in the gas extraction drill hole; a mine waterpressing pipeline is connected with the hole opening sealing connection pipe fitting, water is jetted into the gas extraction drill hole, and the hole opening sealing connection pipe fitting is closedafter jet is finished; CaC2 in the gas extraction drill hole and the water are subjected to reaction to generate Ca(OH)2 and C2H2, a large amount of heat is generated at the same time, under the thermal effect, coal seam gas is accelerated to conduct desorbing; and the hole opening sealing connection pipe fitting is connected with an extraction pipe, and gas extraction is conducted through pipe-linking. According to the method for improving the extraction rate of the high residual gas content coal seam of the underground coal mine, the temperature in the drill hole is further improved to promote gas desorption of the coal seam, and the gas extraction rate is improved accordingly; and interval hole drilling implement or concentrated hole drilling implement can be adopted according to occurrence characteristics of the coal seam and the drill hole arranging form. The method for improving the extraction rate of the high residual gas content coal seam of the underground coal mine has the characteristics of safety, high efficiency, reliability and small engineering quantity, and can be widely used in the field of gas extraction of the underground coal mine.

Description

technical field [0001] The invention belongs to the technical field of gas drainage in coal mines, and in particular relates to a method for increasing the extraction rate of coal seams with high residual gas content in underground coal mines. Background technique [0002] my country is rich in coalbed methane (gas) resources, and there are 3.5×10 coalbed methane buried below 2000 m 13 m 3 , has great development potential. But at the same time, gas disasters mainly caused by coal and gas outbursts have seriously hindered the safe production of coal mines. Gas drainage is an effective technical measure to reduce or even eliminate the potential threats of various gas disasters and effectively utilize coalbed methane (gas). However, due to the low permeability of more than 95% of high-gas coal seams in my country, only 10 -3 ~10 -4 mD, the original and residual gas content is large, resulting in the average gas extraction rate of this coal seam in my country is less than...

AI Technical Summary

Problems solved by technology

However, due to the low permeability of more than 95% of high-gas coal seams in my country, only 10 -3 ~10 -4 mD, the original and residual gas content is large, resulting in the average gas extraction rate of this coal seam in my country is less than 10%, and there is a considerable gap compared with the average extraction rate of 30% in other advanced countries]

At present, coal seam "permeability enhancement" technologies such as hydraulic fracturing and hydraulic punching are mainly used to improve the gas extraction rate. Although these methods can increase the permeability of coal seams, it is difficult to reduce the residual gas content of coal seams.

[0003] There are two main controlling factors for coal seam gas desorption: one is pressure and the other is temperature; both pressure relief and temperature rise can improve the desorption efficiency of coal seam gas, thereby improving the effect of gas drainage. However, even if the pressure is relieved to solve the problem of high residual gas content coal seams, it is difficult to improve the drainage efficiency of high residual gas content coal seams

Images