Coal bed gas mining technology

Abstract

The invention discloses a coal-bed methane exploitation technology and is divided into the following steps. (1) A gas intake mine comprising a vertical shaft and a passage extending transversely is arranged. (2) Then one side or both sides of the passage extending transversely is provided with an air outtake mine. (3) Fracturing treatment is done through high-pressure fluid with the prior art. (4) A coal bed at the bottom of the air outtake mine is burnt, meanwhile, the high-pressure air or oxygen is injected to the air intake mine. Thereby an air passage formed by cracks of coal bed is established between the air intake mine and the air outtake mine by making use of pressure difference between the air intake mine and the air outtake mine and the characteristics that water and oxygen in the coal mine tend to get close to the burning point at the air outtake mine. (5) Mixed gas discharged from the air outtake mine is collected and treated and then the coal-bed methane is obtained. Part of the obtained coal-bed methane is taken to be burnt completely and thermal smoke from burning is reinjected to the air intake mine to ensure a stable gas supply from the air outtake mine. The invention overcomes the effects caused by unfavorable factors such as low permeability, low pressure and low saturation and realizes commercial production of coal-bed methane.

Description

technical field [0001] The invention belongs to the technical field of coal bed gas exploitation, and relates to a method for exploiting coal bed gas by using heat energy and carbon dioxide. Background technique [0002] Under specific geological conditions, such as the Qinshui Basin, the Ordos Basin, and the Lianghuai Coalfield, there are a large amount of coalbed methane with methane as the main component in underground coal seams. The development and utilization of coalbed methane will help adjust my country's energy structure and reduce greenhouse gas emissions. It is of great significance to improve the safety conditions of coal mines and solve the problem of coal mine gas disasters. [0003] At present, the production of coalbed methane is mainly carried out by drilling vertically on the ground or setting pinnate horizontal wells in the coal seam, that is, drilling vertically on the ground to the underground coal seam, and the coalbed methane in the underground coal sea...

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Problems solved by technology

[0004] It has been found through research that coal reservoirs in China have completely different geological conditions for coal formation and coalification from those in the North American continent. Due to the complex deformation and evolution history of coal basins, multi-stage superposition of crustal movement, complex and diverse tectonic activities, multi-stage evolution and multi-heat source superposition metamorphism The effect is obvious, so the geological conditions and reservoir physical properties of China's coalbed methane reservoirs show their inherent characteristics: low permeability, low pressure, low saturation, strong heterogeneity, coal fields with high-stress structural environments, and high-rank coal seams, etc. These characteristics will cause difficulties in the exploitation of coalbed methane. Among them, the low permeability cannot form a large-scale desorption-diffusion-seepage circle with the drainage well as the radius, and the low pressure and low saturation will cause little or no gas desorption. The homogeneity makes the influence area of ​​the wellbore extremely small, which limits the productivity of CBM wells. The high-stress structure of the coal field greatly reduces the permeability of the coal reservoir. The high-rank coal in the coal seam is due to its strong adsorption and low permeability conditions. It is difficult to achieve satisfactory results in the development of coalbed methane by conventional surface vertical wells

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