Effects of Temperature and Pressure on Spontaneous Counter-Current Imbibition in Unsaturated Porous Media

Capillary spontaneous imbibition main occurs in fractured reservoirs, low permeability reservoirs and unconventional reservoirs simultaneously accompanied with high temperature and pressure. In this paper, we present computations of spontaneous imbibition based on the classical fractional flow theory and proposed temperature and pressure-dependent IFT relationships. Our work emphasizes that there are some discrepancies if we evaluate the spontaneous imbibition characteristics under geological conditions based on the traditional air/water/rock system experiments at the atmospheric environment. In detail, both of the increasing temperature and pressure can decrease the IFT (capillary driving force), and the pressure effect is more significant. The increasing temperature will facilitate the water intake, as the results of competition between the positive role of enhanced wetting fluidity and negative role of reduced IFT, while the increasing pressure will slow down the water propagation due to the cooperatio...