A kind of drainage method of coalbed methane well

Abstract

The invention discloses a coal bed gas well drainage method, which belongs to the technical field of coal bed gas development. According to the analytical pressure value of coalbed methane, the dynamic liquid level is quickly lowered to 10-30 meters above the analytical pressure of coalbed methane. Using the intelligent drainage method, the dynamic liquid level is always controlled to be 10-30 meters above the analytical pressure. If the dynamic liquid level drops rapidly, the drainage system will be reduced; if the dynamic liquid level rises, the drainage system will be increased to ensure that the gas does not decompose. Maintain the single-phase flow state of liquid water with the maximum pressure difference in the coal seam. When the water production rate drops significantly, about 70% of the water in the coal seam has been discharged at this time, forming a large-area pressure drop funnel, and controlling the liquid level below the bottom of the coal seam. ‑10 meters to ensure that all coal seam sections are exposed above the coal seam water, and maintain a gas-liquid two-phase flow in which the coal seam is dominated by coal seam gas and supplemented by water, which is conducive to the gas production to carry out the remaining 30% of the water in the coal seam; at the same time, By controlling the wellhead casing pressure to control the bottom hole flow pressure, the purpose of rationally adjusting the gas production can be achieved.

Description

technical field [0001] The invention relates to a coal bed gas well drainage method, which belongs to the technical field of coal bed gas development. Background technique [0002] The drainage principles formed in the initial stage of coalbed methane development are: smooth, continuous, and slow, and the fluid level drops by 3-5 meters per day as required. Under normal drainage conditions, wells with a depth of about 600 meters need continuous drainage for about 4 months to reach the analysis period; according to this principle, if the well depth reaches 1200 meters or more, it will take about 8 months to reach the analysis period. Analysis, the analysis of the pre-production time is relatively long. Drainage of coalbed methane wells is a process of draining downwater. The more pressurized water in the coal seam is discharged, the larger the area of ​​the pressure drop funnel will be, and the corresponding gas production will be more. According to the principle of seepage...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a coalbed methane drainage method, which solves the problems of slow drainage and long analysis time, avoids the problems of low liquid production caused by two-phase flow in the coal seam, and small pressure drop funnel area, and improves the gas production.

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