Simulation test device and method for coalbed methane production capacity change caused by discontinuous drainage

Abstract

The invention relates to a simulation test device for the coalbed methane production capacity change caused by discontinuous drainage. The device comprises a wellhead device simulation device, a permeability test device, a water pressure propagation simulation device, a gas desorption simulation device, an experimental cabinet and a data acquisition and processing device. The internal space in theexperimental cabinet is divided into an experimental detection chamber, three experimental driving chambers and a control chamber through partition plates; the permeability test device is arranged inthe experimental detection chamber; the wellhead device simulation device, the water pressure propagation simulation device, and the gas desorption simulation device are arranged in all experimentaldriving chambers and are communicated with the permeability test device. In addition, the experimental steps include equipment assembling, initial experiment parameter setting, displacement operation,experimental detection, data analysis and experiment ending. On the one hand, the working efficiency and the detection precision of the detecting operation can be improved; and on the other hand, thetest risk is low, the test method is convenient and accurate and has the high similarity with the coalbed methane drainage gas production mechanism, and dynamic monitoring can be realized.

Description

technical field [0001] The invention belongs to the technical field of coal mine safety, in particular to a simulation test device and method for coalbed methane productivity change caused by discontinuous drainage. Background technique [0002] Surface coalbed methane wells reduce the pressure of the reservoir by draining water in the coal seam, and then desorb the coalbed methane to produce it. Drainage work takes the longest time in the entire coalbed methane development process. When coalbed methane wells are drained, it is inevitable that there will be discontinuous drainage and production of coalbed methane wells caused by generator failure, power failure, pump inspection and workover operations, etc. In the stage of single-phase water flow, when the drainage equipment stops operating, the dynamic liquid level in the coalbed methane well will rise, the water in the coal seam will gradually change from a flowing state to a static state, and the effective stress value on...

AI Technical Summary

Problems solved by technology

However, after the on-site coalbed methane well is shut down, it takes a certain amount of time for the water in the coal seam to flow from slow to static. The difference in the stoppage time leads to differences in the water flow distance and flow rate in the coal seam, which in turn leads to its impact on the coal seam permeability and production capacity. At the same time, CBM wells may shut down in the stage of single-phase water flow, or in the stage of gas / water two-phase flow. Part of the free gas is adsorbed again, affecting the normal production of coalbed methane, thus affecting the productivity of coalbed methane wells

At present, the experiments done in the laboratory are unable to test the series of changes caused by the flow state changes of water, gas and other fluids after the shutdown of coalbed methane wells at different production stages, and cannot accurately answer the single phase of coalbed methane wells. Changes in coalbed methane production capacity caused by different drainage stages such as the water flow stage or the gas / water two-phase flow stage and the number of stoppages

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