Bottom well flushing device for coalbed methane well

Abstract

The invention relates to a shaft bottom washing device for a coal-bed gas well. The shaft bottom washing device for the coal-bed gas well is composed of an outer oil tube, a diffusion tube, a connecting tube, a nozzle, a spray head and a mud dredger. The mud dredger is composed of mud loosening sheets, guide sheets and a cone-shaped body. The mud dredger is characterized in that the guide sheets are distributed around the cone-shaped body of the mud dredger; the mud loosening sheets are evenly installed on the cone-shaped body; in the process of placing down the oil tube through a wellhead workover rig, the guide sheets make contact with silt to make a rotary head rotate; in the process of going deep into a silt layer of the mud dredger, the mud loosening sheets are folded upwards under the resistance of the silt; in the process of lifting the oil tube through the wellhead workover rig, the bevel edges of the mud loosening sheets are unfolded naturally under the resistance of the silt layer, so that the effect of loosening the silt is achieved. The spray head is characterized in that the periphery of the spray head is provided with spray holes in an annular distribution mode, the spray head acts together with a jet pump master piece to make liquid delivery reach dynamic balance, and therefore it can be guaranteed that the amount of the liquid at the shaft bottom does not change and the pressure at the shaft bottom of the coal-bed gas well does not change either; meanwhile, the spray head coordinates with the mud dredger to make hydraulic washing be combined with mechanical loosening of the silt layer by the mud dredger. The shaft bottom washing device for the coal-bed gas well is reliable in operation process, and capable of effectively improving coal-bed gas well washing efficiency.

Description

technical field [0001] The invention relates to a well cleaning device at the bottom of a coal bed gas well, which belongs to the field of petroleum machinery. Background technique [0002] In the process of coalbed methane production, the solid particles in the coalbed will enter the bottom of the well with the produced water. After the sand and mud are deposited, they will block the perforation holes in the production layer, resulting in a decrease in gas production. According to the needs of the project, well washing work is required. In the well cleaning process of previous well cleaning devices, since the well cleaning fluid returns to the ground through the annular space between the tubing and the casing, the fluid level at the bottom of the well will become higher, resulting in an increase in bottom hole pressure. It is required that the bottom hole pressure cannot change too much, so the previous well flushing device does not meet the requirements. In addition, in ...

AI Technical Summary

Problems solved by technology

During the well cleaning process of the previous well cleaning device, since the well cleaning fluid returns to the ground through the annular space between the tubing and the casing, the fluid level at the bottom of the well will become higher, resulting in an increase in the bottom hole pressure. It is required that the bottom hole pressure cannot change too much, so the previous well cleaning device does not meet the requirements

In addition, in the past, the well flushing device only relied on hydraulic jetting to flush the sediment deposited at the bottom of the well, and the dredging efficiency was not high.

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