Nitrogen injection stimulation coal seam pressure monitoring and methane desorption efficiency evaluation device and method

Abstract

The invention discloses a nitrogen injection stimulation coal seam pressure monitoring and methane desorption efficiency evaluation device and method. The device comprises a sealable sample cylinder and a reference cylinder which are arranged in a constant-temperature system parallelly, and the sealable sample cylinder and the reference cylinder are connected with a nitrogen bottle, a methane gasbottle and a helium bottle through gas incoming pipelines and connected with a vacuum pump through gas outgoing pipelines; each of the sample cylinder and the reference cylinder is provided with a pressure sensor for monitoring gas pressure therein, a strain monitoring system is mounted in the sample cylinder, and the sample cylinder is communicated with a gas chromatograph through a monitoring pipeline. Nitrogen is injected into a coal seam irregularly, and gas does not need to be injected into a coal rock gas reservoir, so that injection amount of non-hydrocarbon gas is reduced, and construction difficulty is lowered.

Description

technical field [0001] The invention belongs to the technical field of coal bed gas exploitation, and relates to a device and method for improving low-permeability coal seam pressure and methane desorption efficiency evaluation by injecting nitrogen huff and puff. Background technique [0002] In recent years, with the adjustment of the global energy structure, the exploitation of unconventional resources has gradually increased. As an important unconventional energy source, coalbed methane is of strategic significance for its economical and efficient exploitation. 90% of coalbed methane exists in the form of adsorbed gas. Therefore, the basis for the successful development of coalbed methane is the exploitation of adsorbed gas in coal seams. [0003] At present, there are two main methods of mining coalbed methane: ① Drainage and depressurization, which reduces the pressure of the coal seam through drainage and promotes the desorption of methane in the coal seam. This meth...

AI Technical Summary

Problems solved by technology

This injection method not only requires a large amount of non-hydrocarbon gas, but also has low permeability of the coal seam, making gas injection difficult, and it is difficult to ensure a sufficient volume of gas to be injected into the coal seam

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