Adsorbed methane significantly affects shale gas reservoir estimates and shale gas transport in shale formations. Hence, a practical model for accurately representing methane adsorption behavior at high-pressure and high-temperature in shale is imperative. In this study, a reliable mathematical framework that estimates the absolute adsorption directly from low-pressure excess adsorption data is applied to describe the excess methane adsorption data in literature. This method provides detailed information on the volume and density of adsorbed methane. The obtained results indicate that the extensively used supercritical Dubinin-Radushkevich model with constant adsorbed phase density underestimates absolute adsorption at high pressure. The adsorbed methane volume increases both the pressure and expands with the temperature. The adsorbed methane density reduces above 10 MPa, and approaches a steady value at high pressure. This study provides a novel method for estimating adsorbed shale gas, which is expected improve the prediction of shale gas in place and gas production.

吸附的甲烷显着影响页岩气储层估算和页岩地层中的页岩气输送。因此，建立一个准确表示页岩高压高温下甲烷吸附行为的实用模型势在必行。在这项研究中，一个可靠的数学框架直接从低压过量吸附数据估计绝对吸附被应用于描述文献中的过量甲烷吸附数据。该方法提供了有关吸附甲烷的体积和密度的详细信息。所得结果表明，广泛使用的具有恒定吸附相密度的超临界 Dubinin-Radushkevich 模型低估了高压下的绝对吸附。吸附的甲烷体积会增加压力并随温度而膨胀。吸附甲烷密度在 10 MPa 以上降低，在高压下接近稳定值。该研究为吸附页岩气的估算提供了一种新方法，有望提高页岩气的储量预测和产气量。