Farid Ahmadloo

The effect of pore throat size and injection flowrate on the determination and sensitivity of different capillary number values at high-capillary-number flow in porous media

This study examines the effect of pore throat size and injection flowrate on the values of the pore-scale capillary number, the Newtonian-fluid capillary number and the apparent capillary number (Nc1, Nc2 and Nc3, respectively) and their sensitivity to change in high-capillary-number flow through porous media, which occurs in polymer-assisted dilute surfactant flooding (PADSF). Additionally, the influence of pore throat size and injection flowrate on oil recovery at breakthrough and at the end of displacement (ultimate) and the relationship between the effective shear rate γeff and the porous medium-dependent shift factor α are discussed. The results indicated that Nc2 was the smallest and Nc3 was the largest value. The difference between Nc2 and Nc3 is due to the increase in apparent viscosity of the polymer-contained surfactant solution during the flow through porous media and the change in Nc3 should be utilized to characterize the macroscopic behavior of the PADSF. Generally, the decrease in pore throat size and the increase in injection flowrate caused an increase in the ultimate oil recovery and Nc3. Moreover, the oil recovery at breakthrough decreased with an increase in pore throat size and injection flowrate. Finally, the rate of change of γeff, with change in α, increased almost uniformly with a decrease in pore throat size and an increase in injection flowrate.

Phase Trapping Effects in Viscous-modified Low Interfacial Tension Flow during Surfactant-polymer Flooding in Heavy Oil Reservoirs

This study examines the effects of non-wetting phase trapping in viscous-modified low-interfacial tension flow during viscous surfactant waterflooding (or surfactant-polymer flooding) under three different injection flowrates in three initially preferential water-wet porous media (each with a different pore throat size) partially filled with heavy oil and brine. In two approaches developed in this study, dynamic mean pore-scale capillary number Nc1 is considered as the foremost criterion to characterize the effect of non-wetting phase trapping. In the first approach, which is a pore network approach, the effect of phase trapping on the value of Nc1 is neglected. In the second approach, which is a numerical method, the effect of phase trapping is included. By comparing the values of Nc1 from the pore network approach and numerical method, the effect of phase trapping is characterized. The change in Nc1 was found to be an appropriate tool to characterize the effects of phase trapping in viscous surfactant waterflooding.