Co-extraction method for pillar-less coal and gas of advanced entry-retaining construction extraction engineering

Abstract

The invention relates to a co-extraction method for pillar-less coal and gas of advanced entry-retaining construction extraction engineering. The co-extraction method comprises the following steps: firstly, pre-constructing a drill hole on a front directional coal layer of a coal extraction working surface; confirming positions of top and bottom plate of the coal layer in a wedge-shape vertical crack area; before starting a gob-side entry retaining process, drilling gas extraction drill holes on the top plate, bottom plate and two sides of gob-side in front of the coal extraction working surface, and then forward pushing the coal extraction working surface to cross the gas extraction drill holes; while forward pushing, finishing the gob-side entry retaining behind the coal extraction working surface; and sealing the gas extraction drill holes on the top plate, bottom plate and two sides of gob-side when a flow value of to-be-extracted gas pressure is greatly reduced. The drilling construction in the retaining entry is unnecessary, the demand on the size of the cross section of the retaining entry is reduced, the demand on restraining volume of the cross section is reduced and the time for efficiently extracting gas is prolonged.

Description

technical field [0001] The invention relates to a coal-pillar-free coal and gas co-mining method for an advanced roadway retaining construction drainage project, and is especially suitable for the mining of low-permeability and high-gas coal seam groups in deep coal mines. Background technique [0002] Coal-pillar-free coal and gas co-mining technology adopted for coal seam groups with high gas, high ground pressure, and low permeability, fast and mechanized construction of high-strength supports along the gob edge of the first mining face to preserve the mining roadway, forming a continuous coal-pillar-free Mining, to achieve comprehensive pressure relief mining, arrange up and down in the retaining roadway to the high and low level drainage boreholes directly to the gas drainage enrichment area, to realize continuous drainage of pressure relief gas and synchronous advancement of the working face. The co-mining method of coal and gas without coal pillar is an important real...

AI Technical Summary

Problems solved by technology

[0003] At present, there are two main methods of co-mining coal and gas without coal pillars: one is rock roadway drilling method, that is, before coal mining, a rock roadway is pre-arranged on the roof or floor of the first mining coal seam, and drainage is arranged in the roadway. Engineering (mainly drilling), extracting pressure relief gas after coal mining, this method generally needs to excavate a rock roadway that is almost as long as the working face. Engineering reliability is difficult to guarantee and other shortcomings. In the case of tight mining replacement, it is difficult to have sufficient time to arrange rock drainage roadways, so there is no sufficient time to arrange roof and floor drainage projects to extract gas from adjacent coal seams.

In addition, gas drainage is generally carried out in pre-construction boreholes in rock roadways. Due to the low gas permeability of the original coal seam, the effect of pre-drainage of gas is poor.

[0004] The second is the roadway retention drilling method. After the coal mining face is advanced, one or two mining roadways are reserved, and then the gas drainage project (mainly drilling) is constructed in the gob-side retention roadway to extract the pressure relief gas from the adjacent coal seam. , since the gas drainage works are all carried out in gob-side entry retention, the requirements for the section size of the entry entry are high, and there are many processes involved in the entry entry process and the extraction process, it is difficult to coordinate management; the equipment for the gas drainage construction in the entry entry requires It takes up a lot of space, but in order to ensure the cross section of the roadway, it is necessary to erect multiple rows of single hydraulic props or other supporting materials. The two are contradictory, and the construction in the roadway is inconvenient.

Moreover, under the existing technical conditions, the gas drainage project is generally implemented after the completion of the gobside entry process and a certain distance behind the working face. Due to the time spent on equipment installation and the implementation of the gas drainage project, the gas drainage project limited time

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