Liquid CO2 phase transition multipoint fracturing and permeability increasing method

Abstract

The invention discloses a liquid CO2 phase transition multipoint fracturing and permeability increasing technology used in a coal seam, mainly solving a series of problems of poor coal seam permeability and difficult gas extraction. The method comprises the following steps: forming fracturing test drill holes in a coal seam, arranging liquid CO2 fracturing pipes in the fracturing test drill holes in a series connection mode, connecting two hole packers at the back surfaces of the liquid CO2 fracturing pipes, and pushing the liquid CO2 fracturing pipes and hole packers into the fracturing test drill holes by a push rod, wherein the liquid CO2 fracturing pipes are connected by conductive leads and connected with an exploder for a mine at the outer part of the test drill holes; and after the above arrangement, carrying out hole packing, heating the multiple liquid CO2 fracturing pipes by virtue of the exploder for a mine to convert a CO2 liquid into a high-pressure CO2 gas in short time, impacting coal to generate fracture, thus improving extraction efficiency of gas. The invention also comprises selection of an arrangement distance and time for the liquid CO2 fracturing drill holes and extraction drill holes.

Description

technical field [0001] The invention relates to a coal seam fracturing and anti-permeability method, specifically a liquid CO 2 Phase change multi-point fracturing antireflection method. Background technique [0002] Coal mines in my country are mostly mines with high gas and low permeability, and liquid CO 2 Phase change fracturing technology is an intrinsically safe and reliable new coal mine anti-reflection technology developed according to the characteristics and needs of coal mines in my country. This technology has carried out some industrial tests in some mines, and the original technology is liquid CO 2 Phase change single point fracturing has the following defects: [0003] (1) Liquid CO 2 The energy released by single-point fracturing is insufficient, the cracks formed by the damage to the coal seam are too small, and the gas permeability of the coal seam does not increase significantly; [0004] (2) Liquid CO 2 The influence range of single-point fracturing ...

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Problems solved by technology

[0007] The present invention solves the current problem of liquid CO 2 The energy released by single-point fracturing is insufficient, the cracks formed by the damage to the coal seam are too small, and the gas permeability of the coal seam does not increase significantly. To provide a liquid CO 2 Phase change multi-point fracturing anti-reflection method

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