Capillary effects on phase behavior of liquid and gaseous propane and dynamics of hydrate formation and dissociation in porous media

Using a precision adiabatic calorimetry method the phase behavior of liquid and gaseous propane with water in bulk as well as in dry and water saturated porous media have been studied in the temperature range from 240 to 350 K and the pressure range from 0.1 to 12 MPa. Quartz powder with a grain size from 25 to 38 mk as a porous medium was used. Water saturation of the porous medium was about 0.247 ± 0.001 of porous volume. From thermodynamic point of view such water saturation of the porous volume is sufficient to consider the pore water phase practically as a bulk phase. A composite porous medium is formed from the quartz powder grains covered by a water film. In fact, the water film is a mechanical continuation of the quartz powder grains. The water film forms a configuration (a curvature) of the porous space as well predetermines a surface wettability of the composite porous medium. We study capillary effect in composite porous media due to capillary condensation and capillary evaporation of propane, both on a lyophilic surface and on a lyophobic surface of water film. Based on the experimental data of specific heat and temperature derivative of pressure at constant volume, the phase diagrams of propane in bulk and in water saturated and dry quartz powder have been constructed (including the gas hydrate field of phase diagram).