Creep-seepage evolution of coal under different temperatures, confining pressures, and gas pressures

Abstract

In order to realize the efficient mining of deep coalbed methane, through studying the creep deformation and permeability evolution laws of coal mass under different temperatures, confining pressures and gas pressures, we obtain the coupling relationship between creep and seepage of coal mass under the action of multiple factors. A self-designed rock triaxial creep and seep device was used to carry out a compressive creep and seepage experiment on coking coal under multi-factor variables. The results show that: temperature is positively correlated with the creep of coal sample: the change rate of radial and axial strain of coking coal sample increases with the increase of temperature, and the change will continue until the coal sample cracks at high temperature （110 ℃）. The maximum and minimum difference of gas permeability reduction rates of coke coal samples with confining pressures of 3 MPa and 4 MPa at temperatures of 30 ℃, 70 ℃,110 ℃ are 7.8%, 5.2%, 6.5% and 4.2%, 2.1%, 1.9%, respectively. The maximum reduction rate of permeability of coking coal sample increases with the increase of temperature. The average maximum reduction rates of permeability of coke coal samples at 110 ℃, 70 ℃ and 30 ℃ are 91%, 84.6% and 73.25%, successively.

Keywords

• coalbed methane extraction
• creep deformation of coal body
• coal permeability
• coupling relationship between coal creep and seepage
• triaxial compression creep seepage test