Discharge and mining control method and device of exposing combination development coal-bed gas well upper production layer

Abstract

The invention provides a discharge and mining control method and device of exposing a combination development coal-bed gas well upper production layer, and belongs to coal-bed gas ground mining control method and device. The discharge and mining process can be divided into six stages, namely, initial stage liquid drainage, pressure holding and production increasing, pressure control and production stabilizing, aerogenesis and attenuation, liquid drainage via the coal layer and pressure control and production increasing. In the initial stage liquid drainage stage, the decreasing range of the liquid level is controlled so as to drain more formation water and fracturing liquid; in the pressure holding and production increasing stage, a casing pressure upper limit is set, and daily gas production is gradually increased; in the pressure control and production stabilizing stage, the decreasing range of flowing pressure is stabilized, and drastic fluctuation of daily gas production and daily liquid production is avoided; in the aerogenesis and attenuation process, the flowing pressure is slowly decreased till the daily gas production is gradually decreased below a commercial airflow standard; in the liquid drainage via the coal layer stage, the liquid height is decreased so as to expose an upper production layer, and recovery of the casing pressure is eradicated; in the pressure control and production increasing stage, the casing pressure is kept stable or slightly decreased so that the daily gas production is gradually increased. By means of the discharge and mining control method and device of exposing the combination development coal-bed gas well upper production layer, the problem that the upper production layer is prone to damage after being exposed is solved, and the time of a combination development coal-bed gas well for achieving high and stable yield can be significantly prolonged.

Description

technical field [0001] The invention belongs to a method and a device for controlling the ground mining of coalbed methane, in particular to a method and device for controlling the drainage and production of the exposed upper production layer of a coalbed methane well in combined seam development. Background technique [0002] my country is rich in coalbed methane resources, and the geological resources of shallow coalbed methane with a buried depth of 2000m are predicted to reach 36.8×10 12 m 3 , equivalent to conventional natural gas resources. Large-scale development of coalbed methane can alleviate the shortage of conventional oil and gas energy in my country, reduce the probability of coal mine gas accidents, reduce greenhouse gas emissions in coal mine production, and produce significant economic, environmental, safety and social benefits. [0003] Southwest my country, represented by eastern Yunnan and western Guizhou, is rich in coalbed methane resources and has gr...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a drainage control method and device for the exposure of the upper production layer of a coalbed methane well in combined bed development, so as to solve the problem in the prior art that the upper production layer is easily damaged after being exposed under the combined bed development condition, and the combined bed It is difficult to develop coalbed methane wells with long-term high and stable production

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