- https://doi.org/10.1016/j.ces.2021.116464
- 10.1016/j.ces.2021.116464
Abstract — High-resolution X-ray imaging combined with a steady-state oil-brine flow experiment is used to demonstrate how pore-scale displacement affects macroscopic properties – relative permeability and capillary pressure – in an altered-wettability microporous carbonate. The resolvable macropores are largely oil-wet with an average thermodynamic contact angle of 120°. Locally either oil or brine almost fully occupied the macro pores, with some displacement of oil by brine in the micro-porosity. We observed a typical oil-wet flow behaviour consistent with the contact angle measurement. The brine tended to occupy the larger macro pores, and was also connected in micro-porosity, leading to a higher brine relative permeability than under water-wet conditions, implying less favourable oil recovery. However, the residual oil saturation was lower compared to the water-wet sample, and a mixed-wet sandstone. Finally, the capillary pressure was negative and seven times larger in the carbonate than the sandstone, despite having a similar average pore size.