Double-coal-bed layered pressure control device combining coal discharging and coal mining

Abstract

The invention relates to a double-coal-bed layered pressure control device combining coal discharging and coal mining. A coal-bed gas well often meets two coal beds, and often an upper coal bed generates gases first, a lower coal bed begins to generate gases with the descending of the floating liquid level, and the guarantee that two coal beds desorb and generate gases simultaneously is difficult. The double-coal-bed layered pressure control device combining coal discharging and coal mining comprises a pumping and mining pump, an oil pipe and an oil pumping rod, wherein the oil pipe comprises an upper oil pipe and a lower oil pipe, and a centering device is arranged on the outer wall of the upper oil pipe. The double-coal-bed layered pressure control device combining coal discharging and coal mining is characterized in that the pumping and mining pump is a combined pump, the lower oil pump is provided with a packer and an auxiliary communicating tube, and the auxiliary communicating tube is arranged at the upper portion of the parker. The double-coal-bed layered pressure control device combining coal discharging and coal mining has the advantages that interbed interference problem generated in the process of discharging and mining of the double coal beds is solved, desorption and gas-generating simultaneously are guarantee, and double-coal-bed layered pressure control device combining coal discharging and coal mining is suitable for combined mining of the coal-bed gas well in double-coal-bed areas.

Description

technical field [0001] The invention belongs to the technical field of coal bed gas drainage and production, and relates to a double coal seam layered pressure control combined drainage device. Background technique [0002] In the process of drainage and gas production of CBM wells, the change of coal reservoir stress is a complicated process. As the depressurization continues, there will be a stress differential effect. When the effective stress increases to a certain value, the permeability of the coal reservoir will drop to a state where it is difficult for the coal seam water to flow. During single coal seam drainage, the pressure can be avoided by reasonably controlling the drainage speed and the position of the dynamic liquid surface. The difference effect will damage the coal reservoir, but in the actual development, the coalbed methane well often encounters two coal seams. If the pressure gradient of the coal reservoir is inconsistent or the distance between the coa...

AI Technical Summary

Problems solved by technology

When the effective stress increases to a certain value, the permeability of the coal reservoir will drop to a state where it is difficult for the coal seam water to flow. During single coal seam drainage, the pressure can be avoided by reasonably controlling the drainage speed and the position of the dynamic liquid surface. The difference effect will damage the coal reservoir, but in the actual development, the coalbed methane well often encounters two coal seams. If the pressure gradient of the coal reservoir is inconsistent or the distance between the coal seams is large, the upper coal seam usually produces gas first. As the liquid level drops, the coal seam below begins to produce gas. It is difficult to ensure that the two coal seam production layers desorb and produce gas at the same time. Particle-embedded coal seams and faster fracture closure rate lead to a rapid decline in coal seam permeability and seriously affect gas production

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