A method for controlling bottomhole flow pressure of a coalbed methane well

Abstract

The invention discloses a control method for the bottom hole flowing pressure of a coal-bed gas well and belongs to the field of coal-bed gas discharge and recovery. The method comprises the steps that according to the target coal-bed gas well, the reasonable day pressure increasing amplitude is determined; the stroke frequency of an oil pumping unit is gradually increased till the multiple times when the day pressure increasing amplitude of the target coal-bed gas well is equal to the reasonable day pressure increasing amplitude are obtained; the multiple corresponding stroke frequencies of the oil pumping unit under the multiple times are obtained; through the corresponding accumulated discharge and recovery time and the corresponding oil pumping unit stroke frequency of every time and linear regression, the slope of a linear regression equation is obtained; the corresponding accumulated discharge and recovery time of any time is substituted in the linear regression equation to obtain the corresponding reasonable stroke frequency of the oil pumping unit under any time; and at any time, through the reasonable stroke frequencies, corresponding to the times, of the oil pumping unit, the bottom hole flowing pressure of the coal-bed gas well is controlled. According to the method, the changing trend of the bottom hole flowing pressure can be pre-judged, so that the flowing pressure is stable, effectiveness is improved, controlling and operating are easy, and the time and labor are saved.

Description

technical field [0001] The invention relates to the field of coal bed gas extraction, in particular to a method for controlling the bottom hole flow pressure of a coal bed gas well. Background technique [0002] Coalbed methane drainage reduces the pressure of coalbed methane by continuously discharging the water in the coal reservoir, so that the methane in the adsorbed state enters the wellbore through desorption, diffusion, and seepage to produce. Therefore, in order to make the coalbed methane drainage process stable and continuous, it is necessary to control the bottom hole pressure of the coalbed methane well. If the daily pressure drop of the bottom hole pressure is too large, it will cause the stress of the coal reservoir to be excited, and the permeability of the coal seam will be reduced. If the daily pressure reduction range of the bottom hole flow pressure is too small, the drainage efficiency will be reduced and the gas production time will be delayed. Therefo...

AI Technical Summary

Problems solved by technology

[0005] The existing technology can only adjust the stroke times of the pumping unit in a small range and multiple times to control the bottom hole flow pressure, which is poor in effectiveness, frequent in operation, and consumes a lot of manpower

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