Perforation fracturing permeability-improvement method for high-stress low-porosity coal seam

Abstract

The invention discloses a perforation fracturing permeability-improvement method for a high-stress low-porosity coal seam, and belongs to the field of disaster prevention and control of mining working faces of coal mines. The method comprises the steps that firstly, coal body mechanical properties are measured, and related technical parameters such as the perforation depth, coal body crack initiation pressure, the fracturing permeability-improvement radius, the separation distance between drilled holes and the separation distance between perforations are determined; then, a coal seam perforation system is installed, and perforation operation is conducted on the coal seam perforation system; after perforation operation is accomplished, a hydraulic fracturing system is installed, fracturing is started, water is injected, and changes of a pressure value are observed until fracturing operation is accomplished. According to the method, a fracturing structure is additionally arranged in a coal body, elastic potential energy of the coal body can be released effectively, and a preparation is made for rock burst prevention and control work of the working faces; meanwhile, high-pressure water can play a good role in moistening the coal seam, the quantity of dust produced during mining of the coal seam is reduced, creation of a good working environment is facilitated, and physical health of underground workers is protected.

Description

technical field [0001] The invention belongs to the field of disaster prevention and control of coal mining working faces, and in particular relates to a perforation and fracturing anti-permeability method for high-stress and low-porosity coal seams. Background technique [0002] Gas disaster accident is one of the major accidents with the greatest harm and the highest proportion of fatalities in coal mining enterprises. The prevention and control of gas disaster is of great significance to mine construction and coal production. Borehole gas drainage is an effective means to prevent gas disasters such as gas explosions, coal and gas outbursts, etc. Since the coal seams in most geological regions in my country are low-porosity coal seams, it is necessary to implement anti-permeability work on coal seams, and use scientific means to increase the coal seams. Cracks in the coal body and increase the permeability of the coal body, so as to ensure the smooth progress of the gas dra...

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Problems solved by technology

[0003] At present, coal seam anti-reflection technologies widely used in my country mainly include explosive blasting anti-reflection technology and hydraulic anti-reflection technology. According to long-term production experience, traditional coal seam anti-reflection technologies have certain shortcomings. For example, the adaptability of explosive blasting anti-reflection technology is limited The heat generated by the blasting is easy to ignite and detonate the gas stored in the coal body. It is prohibited in high-gas mines and coal and gas outburst mines, and the intensive cross-drilling method requires a large amount of work. , has little effect on the development of secondary fractures in the coal body, and has poor permeability enhancement effect

Although the hydraulic anti-reflection technology has a high safety factor and has the dual effects of anti-reflection and wetting the coal body at the same time, the pressure provided by the water injection pump is limited, and there are few micro-cracks generated, so it is difficult to achieve the desired effect

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