Capillary Pressure-Saturation relation derived from the Pore Morphology Method

Abstract: A computationally efficient method to calculate the capillary pressure-saturation relations of immiscible multiphase flow on two-dimensional pore morphologies is presented here. The method is an extension of the Pore Morphology Method that includes wetting angle and trapped mechanism of the displaced fluid, and calculation of material properties by density functional theory. After validating the method with micro-chip fluid injection experiments, the method is used to relate pore morphology to capillary pressure-saturation relation using square-lattice pore morphologies. Because the method uses only morphological binary operations, it is more efficient than well-established high-resolution voxel dynamics methods such as Lattice Boltzmann Methods and Level-set computational fluid dynamics. Apart from pore morphology, only the material parameters related to contact angle (wettability) and interfacial tension are required to connect the pore-saturation relation and pore throat distribution. We investigate the effect on interfacial tension, wettability, sample size, and pore throat distribution on entry pressure and residual saturation.