Method for exploiting coal bed methane (CBM) by water transportation and pressure relief in butted well

Abstract

The invention discloses a method for exploiting coal bed methane (CBM) by water transportation and pressure relief in a butted well, relieving pressure. A coal water and gas discharging well (1) and a plurality of injection gas discharging wells (5) are arranged, wherein the coal water and gas discharging well (1) collects a discharged coal-water mixture and CBM, the injection gas discharging wells (5) are used for injecting water and collecting the CBM, a gas-coal-water separating device is arranged at the well mouth of the coal water and gas discharging well (1), the separated water is recycled, the injection gas discharging wells (5) are arranged a well-closing position for feeding water and discharging gas, the bottom of the coal water and gas discharging well (1) is caved, and the injection gas discharging wells (5) and the coal water and gas discharging well (1) are butted by a fluid pressure difference or mechanical drilling and other methods. Then, water is injected in the injection gas discharging wells (5), a stream flushes a coal body, moves to the coal water and gas discharging well (1), is discharged and forms a pressure-discharging space (6), and the rest coal layers yield the CBM. The technology can solve the problem of preliminarily pumping CBM from a floppy and low-permeability coal reservoir, eliminate the outburst risks and decrease the gas content of the coal body.

Description

technical field [0001] The invention relates to the technical field of coal-bed methane mining, and may also relate to the technical field of joint mining of coal and coal-bed methane on the ground, in particular to a coal-bed methane mining technology for soft, low-permeability, and high-gas coal reservoirs. Background technique [0002] my country's coalbed methane resources are about 36 trillion m 3 , which is equivalent to the amount of natural gas resources. Among them, soft, low permeability and high gassy coal reservoirs account for about 30% of the national coal resource reserves, and the coalbed methane resources contained in them account for about 50% of the national total. [0003] 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, ...

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Problems solved by technology

For such coalbed methane in soft, low permeability, high gas, and high outburst coal reservoirs, there is no effective method for early surface mining. The well-known methods of vertical well fracturing and cluster wells are very ineffective, which seriously restricts the development of such coalbed methane. development of coal fields

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