Method for evaluating shale gas adsorption through coal/shale ultrahigh pressure gas absorption and seepage experiment

Abstract

The invention discloses a method for evaluating shale gas adsorption through a coal/shale ultrahigh pressure gas absorption and seepage experiment. The method comprises the steps that a core is selected and put in a sample cylinder, a confining pressure pump is started to make the sample cylinder reach an experimental confining pressure, and vacuumizing is performed; the temperatures of the sample cylinder and a reference cylinder are stabilized at experimental temperature; helium gas is injected into the reference cylinder, and the pressure of the reference cylinder is measured; after the reference cylinder and the sample cylinder are balanced in pressure, the pressure of the sample cylinder is measured; the pressure of the reference cylinder is increased sequentially, and free space volume measurement of the sample cylinder is completed; systematic vacuumizing is performed; water steam is injected into the sample cylinder; methane having set pressure is injected into the reference cylinder, and the pressure of the reference cylinder is acquired; a balancing valve is turned on, and the pressure of the sample cylinder is acquired; the pressure of the reference cylinder is increased sequentially, and the shale gas adsorption experiment is completed under certain water saturation. By adopting the method, the porosity, the permeability, the adsorbing capacity and gas-water seepage of the experimental core, electrical resistivity change of the core in the experimental process and the influence of different water saturations on absorption and desorption amounts can be respectively measured.

Description

technical field [0001] The invention belongs to the technical field of shale gas adsorption, in particular to a coal / shale ultra-high pressure gas adsorption and seepage test evaluation method for shale gas adsorption. Background technique [0002] It is known that shale has a certain porosity and can contain a certain amount of oil or natural gas. Shale gas refers to the natural gas resources contained in shale. This part of resources belongs to unconventional oil and gas reservoirs. my country's shale gas reserves have reached 31.5 trillion cubic meters, and the exploitation potential is huge. At present, the determination of the adsorption curve of shale gas mainly refers to the determination method of the isothermal adsorption curve of coalbed methane to conduct similar experiments. During the experiment, the shale was ground into 60-80 mesh powder for the isothermal adsorption experiment, resulting in damage. However, the pore structure of the original core is not clea...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a coal / shale ultra-high pressure gas adsorption and percolation experiment evaluation method for shale gas adsorption, aiming to solve the problem that existing instruments for measuring shale gas adsorption have single functions and cannot change the water content of rock cores. It cannot imitate the physical conditions of high temperature and high pressure strata, so that the measured data has a large deviation from the corresponding data in the real stratum

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