A high-power electric detonation-assisted hydraulic fracturing anti-permeability method in underground coal mines

Abstract

The invention relates to a coal mine underground high-power electric knock assisted hydraulic fracturing permeability enhancement method suitable for increasing extraction radius and total extraction amount of gas extraction drilling. The method comprises the following steps that: a borehole extends from one side of a laneway to a coal seam is constructed; a high-voltage pulse discharger which is installed at the front end of a fracturing steel pipe is sent to the bottom of the borehole; a hole packer, which is separated from the orifice of the borehole by 2 to 3m, is installed on the borehole; the outer end of the fracturing steel pipe is connected with a high-pressure pump station through a high-pressure rubber hose; and the high-voltage pulse discharger is connected with a high-voltage electric pulse generator through a cable; after water with a certain pressure is injected into the borehole, the high-voltage electric pulse generator is started so as to apply high-power electric knock assisted hydraulic fracturing to the coal seam; after the high-power electric knock assisted hydraulic fracturing, the high-voltage pulse discharger and the fracturing steel pipe are quitted; and a gas extraction pipeline is connected into the borehole. According to the method of the invention, high energy released by high-voltage electric pulses is utilized to form shock waves in the water, and therefore, a large number of cracks can be formed in the coal seam, and primary cracks are extended. With the method adopted, the permeability coefficient of a coal body can be increased by 100 to 300 times, and single-hole gas extraction efficiency can be effectively improved.

Description

technical field [0001] The invention relates to a high-power electric detonation-assisted hydraulic fracturing and permeability-increasing method in a coal mine, which is particularly suitable for increasing the drainage radius and the total drainage amount of gas drainage boreholes. Background technique [0002] Coal and gas outburst is one of the most serious disasters faced by coal mines in my country. Gas extraction is the main measure to prevent coal and gas outburst. The extracted gas can also be used as a high-quality energy source. However, the geological conditions of coal seams in my country are complex, and the permeability of coal seams is low. Mine gas drainage generally faces the problems of high drainage cost and low drainage efficiency. In order to improve gas extraction efficiency, technologies such as hydraulic fracturing, hydraulic slotting and deep hole blasting are widely used in coal seam pressure relief and permeability enhancement, but these technolog...

AI Technical Summary

Problems solved by technology

However, the geological conditions of coal seams in my country are complicated, and the permeability of coal seams is low. Mine gas drainage generally faces the problems of high extraction cost and low extraction efficiency.

In order to improve the efficiency of gas drainage, technologies such as hydraulic fracturing, hydraulic slotting and deep hole blasting are widely used in coal seam pressure relief and permeability enhancement, but these technologies have certain problems

Conventional hydraulic fracturing technology forms fewer fractures in the coal seam, and the extension range of the fractures is small, and the overall fracturing effect is not good, which eventually leads to a small drilling radius and low extraction efficiency

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