A method for extracting gas and accumulated water from the lower coal seam and the upper multi-goaf area by a double-branch well

Abstract

The invention relates to a method for drawing gas and ponding from lower coal seam and upper goafs of a double lateral well, belongs to the fields of goaf ponding and gas drawing and utilization, andsolves the problem that a mature technology lacks in simultaneous gas and ponding drawing in present coal seam and goafs. Under a modern high-strength intensive exploitation condition, ponding and gasin the upper goafs and part of gas in the lower coal seam are drawn out at the same time, an extraction drilling well is used in high efficiently, and one shaft is extracted for multiple times, and is multipurpose. Ponding formed in the goafs is used while gas resource is extracted, and potential threat of ponding in the upper goafs in exploitation in the lower coal seam is eliminated. The gas inthe lower coal seal is extracted in advance, and the gas concentration and pressure during exploitation of the lower coal seam is reduced effectively. Thus, the method can be used to achieve a safe,efficient and resource maximized utilization production target, a lot of economic benefit is realized, and method has a high popularization value.

Description

technical field [0001] The invention belongs to the field of goaf accumulated water and gas extraction and utilization, and in particular relates to a method for extracting gas and accumulated water from a lower coal seam and an upper multi-mined-out area by a double branch well. Background technique [0002] With the promotion and application of comprehensive mechanized coal mining methods, the gobs produced by coal mining in my country have grown rapidly and become increasingly regular, level and clustered. The relatively regular distribution form creates convenient conditions for large-scale collection and utilization of accumulated water and gas in goafs. 70% of the goafs in my country are high-gas goafs, and the internal gas reserves are as high as 210 billion cubic meters, and most of the goafs have water accumulation to varying degrees. These water accumulations are huge and constitute The huge potential threat of mining the lower coal seam. According to the statisti...

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Problems solved by technology

[0004] In order to solve the problem of the lack of mature technology for the simultaneous extraction of gas and accumulated water in the goaf of the existing coal seam, the present invention provides a method for extracting gas and accumulated water from the lower coal seam and the upper multi-mined-out area of ​​the double-branch well

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