Gas adsorption characteristics in deep marine shale gas reservoirs based on molecular simulation

Abstract

It is of great significance to clarify the adsorption law of shale gas under in-situ conditions for the development of deep marine shale gas reservoirs. However, temperature and pressure in deep reservoirs are far higher than those in the range of normal experiments, so the adsorption characteristics of shale gas in the high-pressure section have not been revealed. In this paper, we construct a kerogen model which conforms to the adsorption law of real marine shale samples by using molecular simulation technology, and simulate the methane adsorption at high temperature and high pressure (HTHP) under in-situ conditions. The adsorption characteristics of methane at HTHP under the influence of primary water are comprehensively revealed, and a corresponding reliable isothermal adsorption model is established. The results show that the influence of kerogen molecular number must be fully considered in the construction of kerogen model, otherwise large errors will occur. The shale gas adsorption capacity is stable under the influence of temperature and changes more significantly with the pressure. In kerogen with polar functional group water can significantly reduce methane adsorption, especially under high pressure. The research results can provide a theoretical basis for the adsorption gas evaluation for deep marine shale gas reservoirs.