Method for preventing coal dust blocking coal bed crack

Abstract

The invention discloses a method for preventing a coal dust blocking coal bed crack. The method is suitable for high-efficiency mining of a coal bed gas well. The method is characterized in that a dust depressor with the size being 5 m<3> to 10 m<3> and clean water with the size being 90 m<3> to 120 m<3> are evenly mixed to be prepared into mixed liquid, and a water injection pump is used for injecting the mixed liquid into the coal bed crack through a shaft; after the mixed liquid is completely injected, a valve arranged at the upper end of the shaft is closed, after 3 h-6 h, the valve arranged at the upper end of the shaft is opened, and the mixed liquid carrying coal dust is extracted to the ground through a water suction pump; when the mixed liquid extracted by the water suction pump still contains a large amount of coal dust, operation is repeatedly conducted till no coal dust is contained in the extracted mixed liquid; and when the mixed liquid extracted by the water suction pumpdoes not contain the coal dust, the valve is closed, and construction is over. By means of the method, the defect that the crack blocked by the coal dust in a fracturing well coal bed cannot be subjected to dredging and blocking releasing when well cleaning and dredging are conducted through clean water, high-efficiency blocking releasing can be conducted on the blocked coal bed gas well, and thepurpose of recovering or even increasing the gas production rate of the blocked well is achieved.

Description

technical field [0001] The invention relates to the technical field of coal bed gas exploitation, in particular to a method for solving the problem of pulverized coal blocking coal seam cracks. Background technique [0002] The control of pulverized coal is an important link in the drainage and production of coalbed methane wells. Mechanical failures caused by excessive pulverized coal output will lead to frequent pump inspection operations, resulting in large bottomhole pressure fluctuations and damaging the fluidity of gas, water and pulverized coal. Continuity in turn affects the gas production potential of the well and increases drainage costs. Most of the coalbed methane is stored in the coal matrix in the form of adsorption, and it is necessary to reduce the storage pressure to desorb the coalbed methane. The characteristics of coal storage determine that the core of coalbed methane well drainage is the control of bottom hole pressure and coal powder. [0003] Coal po...

AI Technical Summary

Problems solved by technology

[0005] The present invention provides a low-cost, simple-process method for solving the problem of pulverized coal clogging coal seam cracks. The present invention overcomes the disadvantage that clean water washing and dredging cannot dredge and unblock cracks blocked by coal pulverized coal in fracturing wells. It can effectively remove the plugging of blocked coalbed methane wells, achieve the goal of restoring or even increasing the gas production of blocked wells, and make most low-yielding coalbed methane wells have commercial exploitation value