Spontaneous imbibition of water into cylindrical cores with high aspect ratio: Numerical and experimental results

Spontaneous imbibition of water into oil-saturated porous chalk having a cylindrical shape with the top and bottom faces closed for fluid exchange was modeled by solving a diffusion-like equation with the assumption of constant capillary diffusivity coefficient (CDC). The calculated oil recoveries vs. time curves have the same shape as the experimental curves and fit them very well over the whole saturation range. Furthermore, the analytical solution of the diffusion-like equation describes water saturation profiles, which are in qualitatively agreement with results reported in the literature. The model presented is able to account for different wettabilities of the rock material due to variations in the capillary diffusivity coefficient. The model is a useful tool when analyzing oil recovery rates measured from cylindrical cores in the laboratory.