Impact of time-dependent wettability alteration on the dynamics of capillary pressure

•We introduce exposure time-dependent wettability alteration (WA) model at the pore-level.•We coupled the model with a pore-scale model, namely bundle-of-tubes model.•Then we simulate WA induced dynamic capillary pressure curves.•Once we obtained the data we systematically develop a Darcy scale capillary pressure model that account the impact of pore-scale wettability dynamics. Wettability is a pore-scale property that has an important impact on capillarity, residual trapping, and hysteresis in porous media systems. In many applications, the wettability of the rock surface is assumed to be constant in time and uniform in space. However, many fluids are capable of altering the wettability of rock surfaces permanently and dynamically in time. Experiments have shown wettability alteration (WA) can significantly decrease capillarity in CO2 storage applications. For these systems, the standard capillary-pressure model that assumes static wettability is insufficient to describe the physics. In this paper, we develop a new dynamic capillary-pressure model that takes into account changes in wettability at the pore-level by adding a dynamic term to the standard capillary pressure function. We assume a pore-scale WA mechanism that follows a sorption-based model that is dependent on exposure time to a WA agent. This model is coupled with a bundle-of-tubes (BoT) model to simulate time-dependent WA induced capillary pressure data. The resulting capillary pressure curves are then used to quantify the dynamic component of the capillary pressure function. This study shows the importance of time-dependent wettability for determining capillary pressure over timescales of months to years. The impact of wettability has implications for experimental methodology as well as macroscale simulation of wettability-altering fluids.