Diffusion coefficient and isothermal adsorption/desorption curve test system and method

Abstract

The invention discloses a test system and method for the diffusion coefficient and isothermal adsorption / desorption curve of shale gas. The test system includes: a core holder, the to-be-tested core contained at the center of which separates two ends into two gas diffusion chambers; a confining pressure component, which is connected to the core holder to load confining pressure to the core to replace the formation pressure; two gas containers loaded with different gases to inflate the gas diffusion chambers at two ends of the core holder respectively; a pressure balancer, which is connected to the core holder to balance the pressure of the two gas diffusion chambers; a constant temperature box, which is used for keeping the temperature of the core holder, the gas containers and the pressure balancer constant; and an acquisition and test component, which is used for collecting the gas at both ends of the core at different time so as to test the diffusion coefficient and collecting the pressure at different time to obtain the isothermal adsorption / desorption data curve. The test system saves the equipment cost.

Description

technical field [0001] The invention relates to the technical field of research on the migration mechanism of shale gas, in particular to a testing system and method for the diffusion coefficient and isothermal adsorption / desorption curve of shale gas. Background technique [0002] Shale gas is natural gas extracted from shale formations. Shale gas is an important unconventional resource, and the global shale gas resource is about 456 trillion cubic meters. Among them, the shale gas resources in China's main basins and regions are about 15 trillion to 30 trillion cubic meters, which has huge development potential. [0003] The permeability of shale is extremely low, and the migration mechanism of shale gas is different from that of conventional natural gas, which has the characteristics of desorption and diffusion. The development characteristics of shale gas are closely related to the gas migration mechanism, so the study of diffusion and adsorption / desorption characteris...

AI Technical Summary

Problems solved by technology

The isothermal adsorption / desorption characteristic test mostly uses powder samples, which cannot reflect the influence of particle cementation state and stress field on the test results

Small-diameter cores are often used in the measurement of diffusion coefficient, which cannot reflect the heterogeneity of reservoir well

In addition, when the dual-gas method is used to test the diffusion coefficient, it is difficult to avoid the influence of pressure fluctuations at both ends of the core on the diffusion during the gas injection balance process of the diffusion chamber and sampling.

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