Method for exploiting coal bed gas by hydraulic drilling and pressure relieving

Abstract

The invention discloses a method for exploiting coal bed gas by hydraulic drilling and pressure relieving. The method comprises the following steps of: drilling a large-caliber well to the coal bed(9), building a coal bed gas exploitation well(1) capable of adding water, discharging water and discharging gas, making a sleeve pipe(2) arranged on the drilling well, and performing mechanical drilling at the bottom of the well; making a well-sealing device arranged on an opening of the coal bed gas exploitation well(1), and making a ground water pump(3), a coal-water separating device(4) and a gas storage device(5) arranged; distributing water-discharging devices(8) and flushing robots(6) on both sides in the coal bed gas exploitation well(1), wherein the flushing robots(6) are connected with the ground water pump(3) by soft water pipes and can continuously flush the coal down in caves at the bottom of the well to form a pressure relieving space(7); discharging the coal-water mixture to the coal-water separating device(4) by the water-discharging devices(8); and discharging the coal bed gas continuously generated by the coal bed(9) after pressure relieving to the gas storage device(5) by the coal bed gas exploitation well(1). The method has the advantages of easily solving the problem of early exploiting the coal bed gas in the coal mass with looseness, extremely low permeability and high bursting, eliminating bursting risk and lowering a gas content of the coal mass.

Description

technical field [0001] The invention relates to the technical field of coal-bed methane exploitation, in particular to a method for mining coal-bed methane by hydraulic digging and pressure relief in soft, low-permeability and high outburst coal reservoirs. Background technique [0002] Coal seams in Yinggong and Dengfeng areas of Henan Province have complex structures, soft coal, and ductile deformation, which is mainly caused by interlayer sliding and is the product of strong plastic deformation. Intense tectonic damage makes the coal body scale-like or soil-like, with extremely poor permeability (both below 0.001mD), and because of its general characteristics of softness, low permeability, high gas and good storage conditions, coal and Gas outbreak area. For coalbed methane in such soft, low permeability, high gas, and high outburst coal reservoirs, there is no effective method of early surface mining. The well-known methods of vertical well fracturing and cluster wells ...

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Problems solved by technology

[0004] The hole diameter of the above technologies is limited, and there are factors of unsafety and environmental pollution to varying degrees, which are not suitable for the development of coalbed methane in soft, low permeability, high gas and high outburst coal reservoirs

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