High-gas-content coal seam punching cutting pressing and sucking integral pressure relief and antireflection gas extraction method

Abstract

The invention provides a high-gas-content coal seam punching cutting pressing and sucking integral pressure relief and antireflection gas extraction method. According to the method, firstly, a floor crossing hole is constructed in a coal seam; then, drill retreating is carried out; a special drill pipe and a special drill bit for hydraulic punching are replaced in a drill hole; high-pressure water of 5 to 35MPa is introduced into the drill pipe; the drill bit is rotated and is moved to and fro, and hydraulic punching is implemented on the coal seam; and punching holes with the diameter of 0.3 to 1m are formed around the drill hole. During the drill retreating, the drill bit is moved to a coal seam section with little punching coal yield; the drill bit rotates in situ; the coal seam is cut through the high-pressure water; and flat seam cutting seam grooves are formed. The special drill pipe and the special drill bit for the hydraulic punching retreat; special hydraulic fracturing equipment is connected; and the drill hole is subjected to hydraulic fracturing according to a conventional method; and after the fracturing, the drill hole is sealed according to a conventional method, and gas extraction is carried out. The method provided by the invention breaks through the limitation of a single hydraulic measure, and realizes the integral and uniform pressure relief through punching, seam cutting, fracturing and extraction integral operation, so that the single-hole pressure relief range is improved by more than 50 percent; the single-hole gas pure flow rate is improved by more than 40 percent; the single-hole gas extraction rate is improved by more than 30 percent; and obvious economic benefits and wide application prospects are realized.

Description

technical field [0001] The invention relates to a pressure-relief and anti-permeability gas drainage method integrating punching, cutting, pressure and extraction of high gas coal seams, which is especially suitable for gas drainage of high gas and low permeability coal seams. Background technique [0002] Mine gas disasters (gas gushing, gas explosion, coal and gas outburst, etc.) are the main factors restricting the efficient and intensive mining of coal mines. Gas drainage is the fundamental measure to reduce gas accidents, improve gas energy utilization and reduce greenhouse gas emissions. In recent years, the hydraulic anti-permeability technology in coal seams has been widely used in the gas drainage of high gas and low permeability coal seams in my country due to its remarkable effect and strong practicability, such as hydraulic punching technology, hydraulic slotting technology and hydraulic pressure cracking technology etc. Engineering practice shows that there are...

AI Technical Summary

Problems solved by technology

Engineering practice shows that there are great limitations in adopting a single hydraulic measure: hydraulic punching forms a certain pressure relief space through high-pressure water impact, crushing and discharging part of the coal body. However, for coal seams with uneven soft and hard distribution, punching holes often It presents an irregular shape, which leads to local stress concentration; hydraulic slits form flat slits by repeatedly cutting the coal body, and part of the coal body deforms and collapses after slits, the stress field is redistributed, and the coal body cracks gradually develop. However, the operation of hydraulic cutting alone is difficult and requires a large amount of engineering, especially for soft coal seams, where coal creep is serious, slots are difficult to form, cracks close quickly, and gas drainage is difficult to carry out continuously and efficiently; hydraulic fracturing can realize Large-scale pressure relief of coal seams, however, the direction of fracturing is difficult to control, and the distribution of fractures is extremely uneven. For hard coal, hydraulic fracturing pressure is high, and the operation is dangerous

In summary, although a single hydraulic measure can achieve coal seam pressure relief and permeability enhancement to a certain extent, it is difficult to achieve overall and uniform pressure relief of the coal seam, the effect of pressure relief and permeability enhancement is limited, and local stress concentration seriously threatens subsequent excavation and mining operations

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