Development of an Original Computational Framework for Predicting Multiphase Fluid Flow in Porous Media Relevant to Enhanced Oil Recovery in the Niger Delta

Enhanced oil recovery processes in the Niger Delta oil fields involve complex multiphase fluid dynamics in heterogeneous porous media at reservoir scale, where the interplay of viscous, capillary, and gravity forces governs displacement efficiency. Existing computational models inadequately represent pore-scale heterogeneity and its upscaling to reservoir simulation grids for the specific lithological character of Niger Delta turbidite sand reservoirs. This research develops an original computational framework for predicting multiphase fluid flow in Niger Delta porous media that integrates pore-network modeling with digital rock physics analysis of X-ray micro-computed tomography images of core samples from four Niger Delta reservoir formations. Pore network models were extracted from three-dimensional micro-CT images at 2 micron voxel resolution using watershed segmentation algorithms. A new pore-scale displacement model incorporating thin-film dynamics and wettability alteration kinetics was formulated and implemented in a parallelized C++ simulation code. The pore-scale results were upscaled to Darcy-scale relative permeability and capillary pressure functions using volume averaging theory, and a novel correction for sub-resolution microporosity was derived analytically and validated against mercury injection capillary pressure measurements. Predictions of relative permeability curves from the new framework show 34 percent better agreement with published core flood experimental data for Niger Delta sandstones than commercial simulation software using conventional Brooks-Corey parameterizations. The framework provides physically grounded input functions for enhanced oil recovery reservoir simulations and is designed for integration into the Nigerian National Petroleum Company Limited reservoir engineering workflow. Keywords: multiphase flow, porous media, Niger Delta, pore-network model, enhanced oil recovery