鄂尔多斯盆地延长组页岩吸附热力学特征

Adsorption thermodynamic property of Yanchang Formation shale in Ordos basin

为了研究陆相页岩的吸附机理,以鄂尔多斯盆地甘泉地区延长组页岩为研究对象,开展了不同温度下页岩等温吸附实验,分析了延长组页岩的吸附特性及等量吸附热特征,实现了页岩等温吸附量的预测。结果表明:超临界条件下,页岩等温吸附曲线极大值的出现与实验压力、比表面积及吸附气有关;与龙马溪组页岩相比,延长组页岩等量吸附热与吸附量呈正相关关系,符合幂函数拟合,且在相同吸附量下,延长组页岩等量吸附热较低,具有较强的非均质性和较弱的吸附作用力;等量吸附热不能反映吸附性能的强弱;基于等量吸附热的页岩等温吸附曲线预测方法在低实验温度、低气体压力条件下具有较高的预测精度。

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.