Predicting the onset of inertial effects in sandstone rocks

This study presents a method to determine the onset of inertial effects at the microscopic level, to distinguish between Darcy and non-Darcy flow regi ons within porous media at the pore level, and to quantify the effects of r etained polymer on gas mobility. Capillary pressure and polymer flood exper iments were conducted using Elgin and Okesa sandstone samples. The pore-siz e distributions were used to study the high-velocity flow effects. A modifi ed capillary-orifice model was used to determine the non-Darcy flow effects at the pore level, with and without residual polymer. The overall flow behavior at any flow rate may be described as the average of all contributions from the Darcy and the non-Darcy terms in all pores. R esults of this study suggest that the conventional Reynolds number may lead to incorrect analysis of flow behavior when evaluating non-Darcy flow effe cts in porous media. The Forchheimer number, defined as the ratio of inerti al forces to viscous forces, is found more adequate for analyzing microscop ic flow behavior in porous media.