A coal bed gas extraction device

Abstract

The invention relates to the technical field of coalbed methane exploration and development, and discloses a coalbed methane drainage and production device, which comprises a casing, an outer pipe, an inner pipe, a sucker rod, a packer and a pumping pump penetrating the upper coal seam and the lower coal seam, The extraction pump includes an outer pump body and an inner pump body. The inner pump body is provided with a piston in a transverse seal, and the piston is connected with the sucker rod. The inner pump body is provided with an upper inlet, an upper outlet, a lower inlet and a lower outlet, and the upper inlet is connected with a The upper liquid inlet pipe, the upper outlet is connected with the upper liquid outlet pipe, the lower inlet is connected with the lower liquid inlet pipe, the lower outlet is connected with the lower liquid outlet pipe, the upper liquid inlet pipe, the upper liquid outlet pipe, the lower liquid inlet pipe and the lower liquid outlet pipe are all An annular baffle and a one-way valve plate are provided, the one-way valve plate is arranged on the left side of the annular baffle, the top of the one-way valve plate is connected with the annular baffle through a pin shaft, and a torsion spring is provided on the outer shell of the pin shaft. The invention can realize the combined drainage and production of the double coal seams, the coal seam water of the double coal seams does not interfere with each other, and the mechanical energy during the downstroke of the sucker rod is fully utilized.

Description

technical field [0001] The invention relates to the technical field of coalbed methane exploration and development, in particular to a coalbed methane drainage device. Background technique [0002] During the process of drainage and gas production of coalbed methane wells, the stress of the coal seam is constantly changing. With the continuous drainage and pressure reduction, the stress difference effect will occur. When the effective stress increases to a certain value, the permeability of the coal seam will drop to a state where it is difficult for the coal seam water to flow. In single coal seam drainage, the pressure difference effect can be avoided by reasonably controlling the drainage speed and the position of the dynamic liquid surface. Damage to coal seams, but in actual development, coalbed methane wells often encounter two coal seams. If the pressure gradient of coal seams is inconsistent or the distance between coal seams is large, the upper coal seam generally p...

AI Technical Summary

Problems solved by technology

When the effective stress increases to a certain value, the permeability of the coal seam will drop to a state where it is difficult for the coal seam water to flow. In single coal seam drainage, the pressure difference effect can be avoided by reasonably controlling the drainage speed and the position of the dynamic liquid surface. Damage to coal seams, but in actual development, coalbed methane wells often encounter two coal seams. If the pressure gradient of coal seams is inconsistent or the distance between coal seams is large, the upper coal seam generally produces gas first, and as the liquid level drops , the lower coal seam begins to produce gas, it is difficult to ensure that the two coal seam production layers desorb and produce gas at the same time, and sometimes even the upper coal seam drainage radius is shortened, resulting in speed-sensitive dust and sand discharge, proppant particles embedded in the coal seam, and crack closure speed up, etc., resulting in a rapid decline in coal seam permeability, seriously affecting the gas production effect

In addition, the existing coalbed methane drainage usually uses the mechanical energy output by the motor to lift the sucker rod to a certain height, and then the sucker rod descends under the action of its own gravity. Kinetic energy is not utilized, resulting in a waste of energy

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