Influence of Connate Water and Condensate Saturation on Inertial Effects in Gas/Condensate Reservoirs

Summary In the near-wellbore region of gas/condensate wells, high-pressure gradients induce both large condensate saturation and high gas velocities which may lead to significant deviations from Darcy's law for gas permeability. At the present time, no physically relevant model exists which takes into account these non-Darcian two-phase flow phenomena. Using a specific laboratory equipment, a laboratory study has been performed with the aim to estimate the influence of pore structure and connate water saturation Swi on the gas inertial coefficient βg, and to integrate the effect of the condensate dropout in the Forchheimer flow equation. Experiments were conducted on sandpacks and sandstone core samples. For dry gas floods, the measured βg values were found in good agreement with previous published data. For gas floods in presence of Swi, βg was found to increase with Swi and a new correlation between βg and a mean-pore radius r¯ is proposed. Gas/ condensate (C1–C3 mixtures) steady-state experiments showed that βg values increased with the total liquid saturation.