Experimental Study On Influencing Factors Of Gas Permeability Of Lignite

My country has very rich lignite coalbed methane resources,but insufficient understanding of the factors affecting lignite coalbed methane seepage restricts the development of coalbed methane.The permeability of coalbed methane is often expressed by permeability.The permeability is mainly affected by factors such as temperature,ground stress,fluid saturation,and coal seam physical properties.Therefore,it is of great significance to study the influence of stress and temperature on the permeability of lignite.In this paper,the TCXS-? gas-water phase permeability experiment equipment is used to conduct experiments on the permeability characteristics of lignite under stress and temperature.In addition,the permeability experiment and stress under the coupling of two different adsorbent gases of helium and nitrogen are considered.The gas-water permeability experiment under the action of temperature shows that the permeability of lignite does not change monotonously with temperature under the action of effective stress.Under the action of low effective stress,the permeability of lignite rises and then decreases as the temperature rises.Under the action of higher effective stress,the permeability of lignite fluctuates with increasing temperature.Under the action of high effective stress,the permeability of lignite first decreases and then slowly rises;under the action of lower temperature,lignite permeates when helium gas is introduced.The rate of lignite permeability is greater than the permeability of lignite when nitrogen is introduced.With the increase of effective stress and temperature,the decrease of lignite permeability under the action of helium is greater than the decrease of lignite permeability under the action of nitrogen;Under the action of stress and temperature,as the volumetric stress increases,the irreducible water saturation of lignite increases,the relative permeability of the gas phase increases,and the relative permeability of the water phase decreases.The volumetric stress has a stronger inhibitory effect on the water phase seepage;with the pore pressure Increase,the residual water saturation will decrease,the relative permeability of the water phase will increase,and the relative permeability of the gas phase will decrease;the residual water saturation will decrease with the increase of temperature,the rising rate of the relative permeability of the gas phase will increase,and the gas saturation will increase.High;as the temperature increases during the process from saturated water to residual water,the gasphase seepage flow rate also increases.Figure[41]Table[23]Reference[71]...