Efficient mining method for coal bed gas short horizontal well group of broken low-permeability coal seam

Abstract

The invention discloses an efficient mining method for a coal bed gas short horizontal well group of a broken low-permeability coal seam, and belongs to the technical field of coal and coal bed gas co-mining. The efficient mining method can solve the problems that an existing broken soft low-permeability coal seam coal bed gas development method is poor in extraction effect and difficult to commercialize and popularize. According to the efficient mining method, the modes that a conventional U-shaped horizontal well drainage well and an engineering well are in butt joint and conduct drainage and drilling correspondingly are changed, the short horizontal well group is creatively used for fracturing the coal seam roof, the drainage vertical well is arranged in an L-shaped short horizontal well group well field, the drainage vertical well fractures the coal seam, well roof fracturing cracks of the short horizontal well are in communication, the mining cost is effectively reduced, the fracturing fluid flow-back rate is increased, the continuous high yield of the gas yield of the well group is guaranteed, the high yield duration time is obviously longer than that of the conventional U-shaped well, the cost is reduced by half of that of the conventional U-shaped well, and therefore commercial mining of the broken and soft low-permeability coal reservoir coal bed methane is achieved.

Description

technical field [0001] The invention belongs to the technical field of co-mining of coal and coalbed methane, and in particular relates to a method for efficiently mining short horizontal well groups of coalbed methane in broken low-permeability coal seams. Background technique [0002] Due to the complex structure, broken coal body and soft texture of the broken soft low permeability coal seam, the coal seam has poor air permeability and strong adsorption capacity for coal seam gas. How to efficiently extract the gas from the broken soft low permeability coal seam has always been a problem A technical problem of gas extraction. Currently, coalbed methane wells, whether they are vertical wells, cluster wells, or horizontal wells, are hydraulically fractured directly in the coal seam. According to hydraulic fracturing theory, the expansion and extension of fracturing fractures is related to factors such as in-situ stress, existing fractures, rock formation strength and britt...

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Problems solved by technology

[0005] The present invention aims at the problem of poor drainage effect and difficulty in commercial promotion of the existing coalbed methane development method in broken, soft and low-permeable coal seams, and provides a high-efficiency mining method for short horizontal well group of coalbed methane in broken and low-permeable coal seams

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