Wellhead pressure control method and control system for shale gas wells

Abstract

The invention discloses a wellhead pressure control method of a shale gas well and a control system thereof. The control method includes S1 calculating the ratio A of the pipeline back pressure to the wellhead oil pressure and the current critical flow pressure ratio at the wellhead of the gas well; S2 judging whether the ratio A is less than the critical pressure Flow pressure ratio, if yes, go to step S3, otherwise go to step S5; S3 collects the wellhead pressure of the shale gas well according to the set frequency, and calculates the pressure difference between the wellhead pressure and the initial wellhead pressure; S4 Adjust the opening of the nozzle valve, and then return to step S1; S5 collects the wellhead oil pressure and pipeline back pressure at the set frequency within the set time, and calculates the oil pressure of the wellhead oil pressure and pipeline back pressure within the set time The average value and the average value of back pressure; S6 calculates the ratio B between the average value of oil pressure and the average value of back pressure, adjusts the opening of the nozzle valve according to the relationship between the ratio B and the boundary of the critical flow pressure ratio, and then returns to step S1 .

Description

technical field [0001] The invention relates to gas exploitation technology, in particular to a method for controlling the wellhead pressure of a shale gas well and a control system thereof. Background technique [0002] For high-pressure gas wells, especially shale gas wells, the initial production pressure is high, and under the production mode of casing blowout, the initial gas production is large, and a large amount of liquid and sand are carried out, resulting in the closure of fractures near the well end and secondary sand production in the formation. At the same time, due to the closure of the fractures near the well end, the oil and gas at the far end lose their seepage channels, so the pressure and production decline rapidly, which greatly reduces the recoverable volume EUR estimated by a single well. [0003] At present, the domestic shale gas market is concentrated in the Sichuan-Chongqing region, where shale gas is deeply buried and the formation pressure coeffic...

AI Technical Summary

Problems solved by technology

[0004] In view of the above-mentioned deficiencies in the prior art, the shale gas well wellhead pressure control method and its control system provided by the present invention can solve the problems of excessively fast decline in single well production and continuous sand production in the production process through pressure adjustment

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