Method for directly testing permeability of underground coal seam

Abstract

A method for directly testing the permeability of an underground coal seam sequentially includes the following steps: (1) constructing a crossing seam hole with the diameter of D and the radius of r and vertical to a coal seam in a coal mine underground rock tunnel as an gas supplying hole; (2) uniformly constructing six gas outlet holes in the circumference having a distance R to the boring centerline of the gas supplying hole; (3) respectively firmly sealing the gas supplying hole and the six gas outlet holes; (4) connecting the six gas outlet holes through a sealed gas outlet pipeline together, connecting to an gas outlet tube, directly connecting the gas outlet tube to underground gas, windpipe, the trachea and underground gas directly connected, allowing the pressure to be unchanged and p2, and installing a sensor for monitoring the flow and the concentration of nitrogen on the gas outlet tube; (5) connecting high-pressure high-purity nitrogen with the gas supplying hole through an gas supplying connecting pipeline; (6) recording the flow qk when a gas flowing out of the gas outlet tube is high purity nitrogen; and (7) calculating by adopting a steady flow process based on Darcy's law to obtain the real data of the permeability of the underground coal seam. The method has the advantages of fast data obtaining, reality and reliability.

Description

technical field [0001] The invention belongs to the technical field of gas (coal bed methane) basic parameter testing. Mainly aiming at the difficulty and poor accuracy of coal reservoir permeability testing, based on Darcy's law, a direct test method for underground coal seam permeability is established, which provides a new method for underground coal reservoir permeability. This method is quick and easy to obtain data. , true and reliable, etc., laying the foundation for the design and evaluation of underground coal mine drainage and surface coalbed methane development parameters. Background technique [0002] Permeability is an important parameter of reservoirs. Traditional acquisition methods include seismic, core analysis, well logging and well testing. The main disadvantages are time-consuming, expensive, and test results are easily affected by many factors. For coal reservoirs, the test results are not representative. The permeability of coal reservoirs is related ...

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Problems solved by technology

[0002] Permeability is an important parameter of reservoirs. Traditional acquisition methods include seismic, core analysis, well logging and well testing. The main disadvantages are time-consuming, expensive, and test results are easily affected by many factors. For coal reservoirs, the test results are not representative

The permeability of coal reservoirs is related to the success or failure of surface coalbed methane development and underground gas control measures. In view of the strong heterogeneity of coal reservoirs and the large difference in permeability, especially controlled by the structure of coal bodies, the traditional indoor sampling simulation The permeability measured by well testing and limited scope cannot represent the change trend of reservoir permeability, so how to quickly track and evaluate reservoir permeability is particularly important

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