A device for measuring gas diffusion coefficient in coal shale

Abstract

The invention discloses a device for measuring a gas diffusion coefficient in coal shale. The device comprises an experimental cabin, wherein the interior of the experimental cabin is divided into a left experimental chamber and a right experimental chamber through a double-layer sealing partition board; a storage pump for storing gas, a gas chromatograph gas path system for measuring gas concentrations in the left experimental chamber and the right experimental chamber and a gas pressure change detection device for measuring pressure values in the left experimental chamber and the right experimental chamber are mounted between double layers of the double-layer sealing partition board in an integrated manner; sample clamping sealing mounting holes are formed in the upper inner walls of thewall surfaces of the left experimental chamber and the right experimental chamber. Through integration of each detection device onto the same experimental cabin, experimental operation steps are simplified and external factors affecting an experiment are reduced; through the combination of two ways of the gas diffusion coefficient, simultaneous measurement is performed and the operation is affected, so that cumbersome data calculation can be reduced and influence of external objective factors is reduced.

Description

technical field [0001] The invention relates to the technical field of gas development in coal shale, in particular to a gas diffusion coefficient measuring device in coal shale. Background technique [0002] Coal bed methane (or shale gas) refers to the hydrocarbon gas that occurs in coal (shale) rocks, with methane as the main component, mainly adsorbed on the surface of matrix particles, and partially free in pores or dissolved in rock formation water. [0003] Coalbed methane (or shale gas) has the following characteristics: [0004] (1) It basically does not contain heavy hydrocarbons above C2, and there is no inorganic impurity in the output; [0005] (2) In the underground, it mainly exists in coal shale in the state of adsorption of macromolecular groups, and has a good production base; [0006] (3) Coalbed methane mining is to reduce formation pressure through drainage, so that coalbed methane can be desorbed-diffused-flowed in the coal seam, while conventional na...

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Problems solved by technology

[0007] (4) The initial production output of coalbed methane is low, but the cycle is long, which can reach decades; the initial output of natural gas is high, and the production cycle is usually less than 10 years;

[0016] However, this technique destroys the unique spatial structure of coal shale itself, resulting in a large difference between the detection results and the diffusion coefficient of the actual coal shale matrix; there is another technique that preserves the original sample spatial structure of coal shale, However, the airtightness of the instrument is unstable, and it is difficult to achieve the requirement of accurate measurement of diffusion; the existing gas pressure change and concentration methods still cannot solve many objective influencing factors of the experiment, and cannot guarantee the measurement accuracy

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