Modeling the spontaneous imbibition of non-Newtonian fluids into the fractal porous media of tight reservoirs

This study proposes a new fractal model to describe the spontaneous-imbibition process of non-Newtonian fluids in tight reservoirs. In the new fractal model, the imbibed mass can be mainly expressed as a function of pore-geometry parameters, the rheological properties of non-Newtonian fluid, and contact angle. We validated the new model against experiments, which were conducted on three core samples collected from a tight reservoir in the Ordos Basin. Comparative analysis shows a relatively good match in imbibition profiles obtained by modeling and experiments at the early stage of imbibition. Unlike the Newtonian fluids, the modeling results suggest a non-linear relationship between imbibition distance and the square root of time when the tortuosity and non-Newtonian fluids are considered. This study may thus provide new insights into modeling the fracturing-fluid flow in tight reservoirs.