Method for generating coal gas underground through air fracture and micro negative pressure

Abstract

The invention provides a method for generating coal gas underground through air fracture and micro negative pressure, and belongs to the field of energy development. The method comprises the following steps that air inlet wells and a plurality of gas outlet wells are drilled, then a gasification tunnel is formed along drilled holes in the bottom of a coal seam to enable the air inlet wells and the gas outlet wells to be communicated, and therefore a gasification furnace is formed integrally; the coal seam is fractured through multi-level air pressure raising, igniter is added in an oxidation section between two adjacent wells, the igniter enables partial coal underground to burn, and generated mixed gas is exhausted to a ground well mouth through the gas outlet wells to obtain gas mixture of CO, H2 and CH4; in the burning process, micro negative pressure is formed in the gas outlets of the gas outlet wells and three working sections. The air fracture technology enables fractured coal to be loose, even and convenient to burn, environment pollution is not likely to happen, and gasification efficiency and gas output are guaranteed; the micro negative pressure prevents the generated gas from diffusing and escaping to other directions, and underground water pollution also can be avoided. The method can achieve the purposes of high coal recovery efficiency, low cost, environment friendliness and energy conservation.

Description

technical field [0001] The invention relates to a method for producing coal gas, in particular to an underground coal gasification method. Background technique [0002] my country's current energy structure is relatively unreasonable, and per capita energy resources are relatively insufficient. The per capita possession of coal and water resources is equivalent to 50% of the world's average level, while the per capita amount of oil and natural gas resources is only about 6% of the world's average level. Energy production Consumption is dominated by coal. [0003] Due to the relative scarcity of oil and natural gas resources, China's energy will still rely heavily on the development and utilization of coal resources in the foreseeable future, and China's coal reserves account for 11.1% of the world's total, which can be exploited for more than 200 years. In 2020, coal will account for more than 50% of China's energy consumption, and in 2050, coal will still account for about ...

AI Technical Summary

Problems solved by technology

[0011] 1. Fracturing is an important technology to ensure gasification efficiency and gas production. However, the existing conventional hydraulic fracturing technology makes the looseness and uniformity of coal after fracturing insufficient, which is not convenient for combustion, and cannot guarantee the gasification efficiency and gasification of UCG. gas production, and may cause certain water-sensitive pollution to each layer

[0012] 2. The current ignition method of underground coal gasification has difficulties such as complicated ignition process and difficult operation

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