A method for fixed-point and high-efficiency extraction of coalbed methane in goaf

Abstract

The invention provides a fixed-point efficient extraction method of goaf coal bed gas. The method comprises the steps that the construction well is drilled vertically from the ground to the bottom of agoaf, a casing pipe with sieve holes evenly arrangedon the lower part is inserted in the drill welldown into the bottom,and cement mortar is used to seal the upper part of the drill well. The bottom of a drainage pipeis sealed, the lower part of the drainage pipe isprovided with two sealing rings, and the drainage pipe between two sealing ringsis provided with round holes. The drainage pipe is insertedin the casing pipedown to the bottom of the goaf, the casing pipe, the sealing ring and the drainage pipe form a through air chamber,and the goaf coal bed gaswhich enters the drainage pipe through the sieve holes of the casing pipe is drainedbythe drainage pipe. The best drainage position is found through the up or down moving of the drainage pipe, and fixed point efficient drainageis achieved. The method greatly improves the drainage efficiency ofgoaf coal bed gas.

Description

technical field [0001] The invention belongs to the technical field of coal bed methane extraction, and in particular relates to a method for efficiently extracting coal bed methane in a goaf at a movable fixed point on the ground. Background technique [0002] my country's long-term large-scale and high-intensity coal mining has produced a large number of abandoned mines and huge goafs. About 70% of the abandoned mines are high-gas mines. The abandoned coal reserves in the goaf of abandoned mines are about 30 billion tons or more, and the coalbed methane reserves in the goaf are estimated to be hundreds of billions of m 3 . Draining coalbed methane in gobs can not only effectively reduce the amount of gas gushing out of mines, prevent mine disasters such as gas explosions, but also turn harm into wealth, use it as a clean energy, and reduce the environmental pollution caused by its discharge into the atmosphere. [0003] At present, as an important means of mine gas contr...

AI Technical Summary

Problems solved by technology

Because the extraction layer at the bottom of the surface drilling is difficult to determine, and the optimal extraction layer changes dynamically with the coalbed methane extraction, the extraction effect of the existing surface drilling coalbed methane extraction technology is unstable. Therefore, It is urgent to find a fixed-point and high-efficiency method for mining goaf coalbed methane

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