Study of High Pressure Isothermal Methane Adsorption on Shales

Abstract

In order to research the problem that the Langmuir model cannot well described the experiment results of high pressure isotherm adsorption about shale gas, the Longmaxi formation shale samples which came from the CD-2 well in the Chengkou area, northeast of Chongqing were selected to the high pressure isothermal methane adsorption experiments under the reservoir temperature and pressure conditions, and used the liquid methane density under the atmospheric pressure boiling point as adsorption phase density to correct the excess adsorption capacity. The experiment results show that the excess adsorption capacity increase at the beginning and then decrease with the pressure rise and that's the characteristic of supercritical methane adsorption. Under the high pressure isothermal conditions, the excess adsorption capacity is different from the absolute adsorption capacity, the liquid methane density under the atmospheric pressure boiling point could be selected as adsorption phase density to calculate the absolute adsorption capacity. Langmuir model can be used to explain the absolute adsorption capacity of methane under the high pressure isotherm adsorption.