Device and method for measuring isothermal desorption curve of coal rock under saturated water condition

Abstract

The invention discloses a device and method for determination of a coal rock isothermal desorption curve under saturated water condition. The device comprises a gas injection and vacuum pumping control subsystem, a water injection control subsystem, a true-triaxial rock core holding and control subsystem, and a dehydration metering subsystem. The gas injection pipe hole and water injection pipe hole of the true-triaxial rock core holding and control subsystem are respectively connected to the gas injection and vacuum pumping control subsystem and the water injection control subsystem, and the outlet end of the true-triaxial rock core holding and control subsystem is connected to the dehydration unit inlet end of the dehydration metering subsystem. The dehydration metering subsystem realizes respective metering of accumulative discharged gas and water mass. The method for determination of the coal rock isothermal desorption curve under saturated water condition is an experimental method carried out based on the device. Through true reappearance of the ground stress field, groundwater pressure field, temperature field and other underground environments where the coal rock is located, coal-seam gas desorption characteristic test is carried out, the device has a clear structure, the data acquisition is reliable, and the result is accurate and credible.

Description

technical field [0001] The invention belongs to the field of petroleum engineering, and in particular relates to a device and method for measuring isothermal desorption curves of coal rocks under saturated water conditions. Background technique [0002] Coal and rock reservoirs are generally buried deep underground, under specific environmental conditions, and are subject to multi-field coupling effects such as in-situ stress field, groundwater pressure field, and geothermal field. Coalbed methane development is to change the environmental conditions of coalbed methane occurrence through specific projects and development methods, so as to desorb the methane gas adsorbed in the coalbed. In addition, the injection of water is essential during the development process. The injection of water will destroy the groundwater dynamic conditions originally established in the coal seam and affect the desorption of coalbed methane. Therefore, the test should be as close as possible to th...

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Problems solved by technology

[0004] At present, the design environment of existing domestic coal-rock desorption analysis devices and methods is quite different from the actual environment conditions of coal-rock reservoirs, which cannot truly reflect the influence of in-situ stress field, groundwater pressure field and temperature field on coalbed gas desorption. , the influencing factors are not fully considered, resulting in a large deviation between the experimental data and laws of coal desorption and the actual drainage, so it cannot effectively guide the production of coalbed methane drainage

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