A method for alternately extracting coal seam gas from uphole and downhole

Abstract

The invention relates to a method for alternately extracting coal seam gas from above and below the well. Firstly, a row of vertical drilling is constructed at the position corresponding to the surface of the working face, and hydraulic fracturing and supercritical CO2 are sequentially adopted. 2 After fracturing, coal seam gas surface well drainage is carried out; multiple rows of bedding holes are constructed in the working face. When the surface well gas drainage enters the exhaustion period, the surface gas drainage equipment is removed and connected to the surface well gas injection system. The gas is injected into the coal seam in the well above the well, and the gas is drilled in the downhole along the bedding until the coal seam reaches the recovery standard; Due to the characteristics of low gas extraction cost of layer drilling, rationally plan the time-space connection relationship between surface vertical wells and downhole gas drainage in bedding holes, and change the vertical drainage wells that have entered the depletion period into gas injection wells, so as to improve the utilization rate of surface vertical wells and reduce gas consumption. Reduce the cost of gas drainage and promote the effective management of gas in mines with continuous tension in mining.

Description

technical field [0001] The invention relates to the technical field of coal seam gas drainage, in particular to a method for alternately extracting coal seam gas from above and below the well. Background technique [0002] Coal seam gas extraction methods can usually be divided into two categories: one is gas extraction above the well, and the other is gas extraction underground. Uphole gas drainage is mainly through the construction of vertical wells or horizontal wells on the ground to the coal seam for gas drainage. It has the characteristics of long drainage period, high extraction output, high extraction concentration, and is not affected by underground mining engineering. However, the engineering cost and later extraction equipment and pipeline maintenance costs are relatively high. Underground gas drainage is mainly carried out by drilling holes along or through layers in the underground roadway. It has the characteristics of simple construction, low cost of extracti...

AI Technical Summary

Problems solved by technology

Uphole gas drainage is mainly through the construction of vertical wells or horizontal wells on the ground to the coal seam for gas drainage. It has the characteristics of long drainage period, high extraction output, high extraction concentration, and is not affected by underground mining engineering. However, the engineering cost and post-drainage equipment and pipeline maintenance costs are relatively high

Underground gas drainage is mainly carried out by drilling holes along or through layers in the underground roadway. It has the characteristics of simple construction, low cost of extraction, and wide range of action, but the extraction efficiency is low and the extraction efficiency is low. The concentration of the gas extracted is not high, and the progress of the drainage project is greatly affected by the underground mining project

At present, coal seam gas is mostly extracted simultaneously up and down the mine or in one way, which makes the cost of coal mine gas treatment too high or the extraction efficiency low

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