One-way decreasing pressure control drainage method for ground extraction of coalbed methane in coal mine area

Abstract

The invention provides a one-way decreasing pressure control drainage method for ground extraction of coalbed methane in a tectonic coal mine area. The one-way decreasing pressure control drainage method for ground extraction of the coalbed methane in the tectonic coal mine area includes the steps of step one, a drainage stage: draining liquid in a wellbore to enable wellbore pressure to reach desorption pressure; step two, a pressure building stage: the descending speed of the liquid level is reduced, and the desorption range is expanded in the influence range of the drainage stage as much aspossible; step three, a pressure control stage: the bottom hole pressure is controlled in the deflation process, so that reservoir damage caused by pressure excitation is avoided; step four, a stableproduction stage: the time of the stable production stage is prolonged by controlling the bottom hole pressure; and step five, an attenuation stage: the gas production time is prolonged by actively decreasing the gas production rate progressively, so that rapid reduction of the gas production rate caused by too fast attenuation is avoided. According to the one-way decreasing pressure control drainage method for ground extraction of the coalbed methane in the tectonic coal mine area, the risk of coal and gas outburst is well reduced, and the safety of drainage and mining is improved.

Description

technical field [0001] The invention belongs to the technical field of extracting oil, gas and water from wells, and in particular relates to a one-way decreasing and pressure-controlled drainage method for surface drainage of coalbed methane in structural coal mining areas. Background technique [0002] Coal seam gas is a kind of clean energy, but it is also a source of disaster for coal mine production. How to realize the pre-pumping of gas before coal mining, to achieve the dual purposes of resource development and utilization and coal mine disaster reduction, the most important thing is to reduce the gas content of coal mines, release the gas pressure to a certain extent, and reduce the risk of coal mine gas outburst. focus of attention. [0003] my country is rich in coal-bed methane resources, and the large-scale development and utilization of coal-bed methane can greatly make up for the shortage of energy supply in my country. Most of the coal seams that store coalb...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a one-way decreasing pressure-controlled drainage method for surface drainage of coalbed methane in structural coal mining areas, so as to overcome the gaps in fracturing that may be caused by the prior art With the danger of coal and gas outburst, and the problem of affecting gas production