Method for strengthening gas extraction through cooperation of hydraulic punching and cave forming and steam injection

Abstract

The invention discloses a method for strengthening gas extraction through cooperation of hydraulic punching and cave building and steam injection, which comprises the following steps: firstly, drilling a layer-crossing drill hole in a coal seam, injecting high-pressure water into the drill hole for hydraulic punching, so as to form a punching hole in the drill hole, and forming a plurality of cracks around the punching hole; then discharging residues and waste water in the punching hole through a gas-slag separator, and extracting gas; after gas extraction is conducted for a certain time, high-temperature and high-pressure steam is injected into the punching hole, the high-temperature and high-pressure steam exchanges heat with the coal seam after entering the punching hole, the steam enters cracks of the coal seam to further apply pressure, and the cracks of the coal seam are further expanded and developed to achieve secondary fracturing after being subjected to the effects of high temperature and high pressure; and finally, under the multiple actions of high-temperature hydraulic punching, secondary fracturing of high-temperature and high-pressure steam and reduction of coal seam adsorbability, yield increase of gas extraction is achieved. According to the method, the coal seam gas extraction effect can be effectively improved and lasts for a long time, and meanwhile the workload of drilling construction is reduced.

Description

technical field [0001] The invention belongs to the technical field of coal seam gas extraction, and in particular relates to a method for enhancing gas extraction by hydraulic punching and cavitation combined with steam injection. Background technique [0002] Mine gas is the main factor causing disasters such as coal and gas outburst and gas explosion, which seriously threatens the safe production of coal mines. Coal seam gas drainage is the most direct and effective means to eliminate the danger of coal seam outburst. At present, in most mines in my country, the most widely used method is underground drilling gas drainage method, which has the characteristics of low cost, flexible construction, strong pertinence, and remarkable effect. [0003] Downhole borehole gas drainage methods mainly include protection layer mining, hydraulic fracturing, hydraulic slotting, hydraulic punching, deep hole blasting, etc. Among them, hydraulic punching uses high-pressure water jets to...

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Problems solved by technology

However, continuous injection of a certain amount of hot water in this way will block the cracks produced by hydraulic punching and cavitation in the coal seam, resulting in a "water lock" effect, which hinders gas drainage.

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