Experimental Study on the Influence of Moisture Content during Gas Depressurization Extraction

Abstract

Although there are many reports about the influence of moisture in the process of gas extraction, studies about the influence of moisture on gas flow, permeability, and coal deformation by experimental system analysis are lacking. Physical simulations of gas depressurization extraction using triaxial servo-controlled seepage equipment for hot-fluid-solid coupling were conducted. The gas flow rate, permeability, and strain were analysed during gas depressurization extraction. The relationship between gas flow rate and gas pressure was a quadratic polynomial. Permeability and strain changed continuously with the decrease of gas pressure and interacted with each other during gas depressurization extraction. In the initial stage, the effective permeability decreased. With the continuous decrease of gas pressure, the permeability gradually recovered. When the gas pressure dropped to about 0.6 MPa, the permeability increased rapidly and the corresponding volumetric strain increased gradually. With the increase of moisture content, the relationship between gas flow rate and gas pressure became less significant. The experiments showed that the higher the moisture content, the lower the effective permeability and the larger the volumetric strain.

Experimental Investigation on Mechanics and Seepage Characteristics of Tectonic and Intact Coal Containing Gas

“…Zhang et al [18,19] studied the stress-permeability behavior of single persistent fractured coal samples in the fractured zone. Chen et al [20] carried out gas depressurization extraction experiments using tectonic coal and analyzed the evolution of permeability and deformation of coal during gas depletion. Zhang et al [21,22] conducted physical simulation of gas extraction using large-scale tectonic coal and explored the law of coal gas pressure, temperature, permeability, and gas flow rate.…”