Large-temperature-difference freeze-thaw cycle method for production increase of surface borehole

Abstract

The invention discloses a large-temperature-difference freeze-thaw cycle method for production increase of a surface borehole. Firstly, magnetized water is injected into a gas extraction pipe of the surface borehole in a pulsating manner; high-pressure nitrogen drives the magnetized water to enter the coal body; liquid nitrogen freezing is carried out on the magnetized water for many times and themagnetized water and high-temperature nitrogen are melted; the freezing expansion force of the magnetized water and the direct large-temperature-difference effect of the liquid nitrogen and the high-temperature nitrogen are utilized to jointly crack the coal body; by means of interaction of high-temperature and high-pressure nitrogen, liquid nitrogen and magnetized water, an ultra-large temperature difference effect is formed, the coal cracking effect is achieved, finally, the coal cracking effect and the crack expansion range can be effectively improved, the coal permeability is increased, and therefore large-flow, high-concentration and long-time gas extraction through ground drilling is achieved.

Description

technical field [0001] The invention relates to a method for surface drilling to increase production, in particular to a large temperature difference freeze-thaw cycle method for surface drilling to increase production. Background technique [0002] The generally low permeability of coal seams in my country is the main reason for limiting the effectiveness of ground drilling for gas extraction. In order to improve the permeability of coal seams, hydraulic fracturing technology is generally used for coal seam anti-permeability treatment, but related research results show that: the cracks produced by hydraulic fracturing mainly expand along the direction perpendicular to the minimum principal stress, and the number of cracks produced is small, making it difficult to form relatively large fractures. Long fractures fail to produce bulk fracture effects on coal seam storage, and there are also disadvantages of high fracturing fluid pressure. At present, the application effect of...

AI Technical Summary

Problems solved by technology

In order to improve the permeability of coal seams, hydraulic fracturing technology is generally used for coal seam anti-permeability treatment, but related research results show that: the cracks produced by hydraulic fracturing mainly expand along the direction perpendicular to the minimum principal stress, and the number of cracks produced is small, making it difficult to form relatively large fractures. Long fractures, failed to produce bulk fracture effect on coal seam storage, and also have the disadvantage of high fracturing fluid pressure

At present, the application effect of this technology in most mining areas in my country is not ideal, and the relevant technical process needs to be further studied

In addition, the application number is 201410507011.9, and the Chinese invention patent titled "A Cooling and Heating Alternating System for Increasing Coal Seam Gas Drainage" proposes a system for increasing gas drainage drilling output by alternately injecting cold and hot, but the system can realize The lowest temperature is only -50°C, and the highest temperature is 200°C, but in this temperature range, the expansion range of cracks is limited, and the gas drainage effect is restricted

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