深部煤储层吸附气与游离气赋存的温压作用OA

In order to accurately characterize the content of adsorbed gas and free gas in deep coal reservoirs in com-plex temperature and pressure conditions,a model for predicting local methane density distribution in micro-nano pores and adsorbed gas content at the core scale is constructed based on the principle of global molecular chemical potential equilibrium under synergistic influence of wall-molecule interaction and inter-molecular interaction.The results show that increasing reservoir pressure enhances the gas content in micropores,with average methane densi-ty increased by 202 mol/(m³·MPa)in 1.5 nm diameter pores,while the temperature increase leads to an average methane density decrease of 33 mol/(m³·K).In conditions of temperature and pressure in deep coal reservoir(353 K,15～30 MPa),the proportion of free gas increases to 13%～23%with the increase of reservoir pressure.Small pores(pore diameter of 1.5 nm)exhibit stronger adsorption capacity compared to larger pores(pore diameter of 3 nm),with the absolute adsorbed gas in small pores 7.7%higher than that in larger pores at temperature of 353 K and pressure of 20 MPa.The research provides reference for geological reserves calibration and development plan design for deep coalbed methane.