Adsorption thermodynamic property of Yanchang Formation shale in Ordos basin

In order to research the adsorption mechanism of continental shale, isothermal adsorption experiments under different temperature were carried out with shales of Yanchang Formation in Ordos basin to analysis the characteristics of isosteric heat of adsorption. Isothermal adsorption curves under different temperatures were predicted. The results showed that the appearance of the max value in adsorption isothermal curve under supercritical conditions depends on experimental pressure, specific surface area, and adsorbed gas. Compared with Longmaxi Formation shale, isosteric heat of adsorption showed positive correlation with adsorbing capacity, and accorded with power function fitting. At the same adsorbing capacity, Yanchang shale has low isosteric heat of adsorption, strong heterogeneity and faint adsorption driving force. The isosteric heat of adsorption can not reflect the adsorptive property. The prediction methods of adsorption isothermal curve has high forecasting precision under the condition of low temperature and and low pressure.