Methane (CH4) Wettability of Clay-Coated Quartz at Reservoir Conditions

Abstract

Methane (CH4) wettability of shale is a key parameter which determines pore and reservoir-scale fluid distributions, CH4 reserves estimation, and ultimate recovery efficiency from shale gas reservoirs. Clay minerals usually fill the pore spaces or are adsorbed on the surface of shale rock, thus influencing CH4 wettability. However, a systematic investigation of the influence of clay on CH4 shale wettability is lacking. Herein, we investigated the role of clay, pressure, temperature, and salinity on CH4 wettability of clay-coated quartz (i.e., a well-defined model system for shales). Results indicated that the advancing and receding water contact angles for clean, kaolinite-coated, and montmorillonite-coated quartz increased with pressure. However, the effect of temperature on wettability is complex, and thus the advancing water contact angle for clean quartz increased with temperature while an opposite trend was found for clay-coated quartz. At low temperature (i.e., 300 K), clay coating dewetted the quar...