Physically-based quasi-static pore network simulator of drainage and imbibition in two and three-phase flow of immiscible fluids

This research focuses on the modelling of multiphase flow in pore networks that capture essentials of topology and geometry of natural sedimentary rocks. We have developed quasi-static models to simulate single-phase flow, two-phase primary drainage and secondary imbibition, and three-phase drainage in disordered networks. In particular, these models calculate capillary pressures, relative permeabilities, saturation paths, flow regimes, and spatial clusters of the different fluids in the network. In quasi-static models, capillary forces dominate, gravity modifies the magnitude of capillary pressure, and the effects of viscous forces are ignored. To calculate the relative permeabilities, the microscopic fluid distributions are frozen at each level of the capillary pressure. The hydraulic conductances of the resulting flow networks are then calculated independently.; All flow simulations are performed using percolation theories: bond invasion percolation in primary drainage, bond-site invasion percolation with ordinary percolation on a dual network and compact cluster growth in secondary imbibition, and cluster-based invasion percolation with trapping in three-phase drainage. We also compare absolute permeability, capillary pressures, and relative permeabilities obtained from our pore network model with those obtained by other pore network models and laboratory experiments. The agreement is very promising.; We investigate the impact of changing the different parameters that control secondary imbibition processes of mixed-wet sediments. In particular, we study how different contact angles, fractions of oil-wet pores, interfacial tensions, and initial water saturations could impact spontaneous and forced imbibition processes. Both advancing contact angles and the fraction of oil-wet pores have dramatic effects on the oil and water relative permeabilities. Nonuniform oil/water interfacial tension has negligible impact on trapped oil saturation and relative permeabilities to oil and water. The sediment's initial water saturation has a slight effect on two-phase flow in water-wet sediments. However, with more oil-wet pores introduced into the sediment, initial water saturation starts to have profound effect on two-phase flow characteristics, especially on water and oil relative permeabilities. (Abstract shortened by UMI.)...