Down-hole horizontal hole exploitation system for mixing gas displacing coal gas, and the method

Abstract

The invention discloses a system and a method for exploitation of mixed-gas coal-bed methane exploitation in a horizontal hole in an oil well, and relates to a coal-bed methane exploitation technology. The exploitation method comprises the following procedures: 1. various gases are integrated into a mixed gas; the mixed gas comprises a or a plurality of strongly exchanged gases, which comprises H2S, SO2 and CO2; the mixed gas also comprises a or a plurality of weakly exchanged gases, which comprises N2, H2 and He; 2. the mixed gas is injected into a coal bed (3) through an injection hole (1) with high pressure; 3. gas comprising the coal-bed methane is obtained from an drainage hole (2) with a drainage device, until the methane content is lower than the economic exploitation content and safety content. The invention promotes the exploitation rate and unit output of the coal-bed methane, and produces quite an obvious effect in reducing the greenhouse gas emission. Meanwhile, the invention is provided with the effect of reducing the outstanding risks of gas, and is applicable in the low-penetration exploitable coal-bed methane exploitation field.

Description

technical field [0001] The invention relates to a coal-bed gas mining technology, in particular to a coal-bed gas mining system and method for displacing mixed gas in an underground horizontal hole. Background technique [0002] Coalbed methane belongs to unconventional natural gas, commonly known as gas, which is produced by CH 4 , CO 2 , O 2 , N 2 , CO, H 2 S. NO x A mixed gas composed of other gases, the main component is CH 4 (methane), accounting for 80 to 90%. It is a natural gas that is generated in the coal formation process and exists in the coal seam and the surrounding rock formations in the state of adsorption and dissociation. [0003] In 2005, nearly 2.3 billion m3 of coal mine gas was extracted underground nationwide 3 , the utilization is about 1 billion m 3 , releasing about 15 billion m of gas 3 . The direct consequence of low pre-pumping rate is: pollution of the environment (about 15 billion m3 during coal mining, processing and transportation)...

AI Technical Summary

Problems solved by technology

The effect of water displacement of coalbed methane remains to be discussed; CO 2 The effect of displacing coalbed methane is good, but it will cause the expansion of coal matrix, reduce the permeability of coal seam, affect the injectability of coal seam, and make injection difficult, so it is not suitable for low permeability coal seam in my country; N 2 The effect of displacing coalbed methane is good, but its replacement effect is limited; at the same time, CO 2 and N 2 The separation cost is relatively expensive, which affects the economics of coalbed methane displacement exploitation

[0007] In general, the effect of underground coalbed methane mining needs to be improved

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