Effect of dynamic contact angle variation on spontaneous imbibition in porous materials

Abstract

We investigate the influence of contact angle variations on spontaneous imbibition of moisture in porous materials. While the contact angle is typically assumed constant when modelling the moisture transfer in porous media, experimental findings put this assumption into question. It has been shown that during imbibition the contact angle notably rises with increasing meniscus velocity. This phenomenon resultantly affects the moisture retention curve, the relation linking the local capillary pressure to the local moisture saturation, which in turn impacts the imbibition rate and moisture distribution. This study investigates these dynamic effects via a pore network technique as well as a continuum approach. It is shown that the impacts of pore-scale contact angle variations on the imbibition process can be reproduced at the continuum scale through a modified moisture retention curve including a dynamic term. Complementarily a closed-form equation expressing the dynamic capillary pressure in terms of local saturation and saturation rate is derived. The continuum approach is then finally employed to predict measured moisture saturation profiles for imbibition in Berea sandstone and diatomite found in literature, and a fair agreement between simulated and measured outcomes is observed.

A Novel Threshold Pressure Gradient Model and Its Influence on Production Simulation for Shale Oil Reservoirs

“…Specifically, the changes of effective stress and temperature can significantly affect pore structures in shale oil reservoirs, leading to changes in fluid properties (e.g., interfacial tension and viscous force) and flow paths, which have observable impacts on TPG. In addition, the dynamic contact angle is also a crucial factor affecting capillary pressure ,, and TPG value. Thus, the combined effects of effective stress, temperature, capillary pressure, pore structures, boundary layer, and dynamic contact angle are needed to study the TPG of tight porous media.…”