Solvent temperature: An injection condition to bring multiple changes in the heavy oil exploitation process based on the cyclic solvent injection (CSI) recovery method

Abstract

Heavy oil is a major fossil fuel resource to fulfill global growing fuel consumption. Hot solvent injection is an effective heavy oil production method. Hot solvent application feasibility has been previously compared between cyclic solvent injection (CSI) method and vapor solvent extraction (VAPEX) method where CSI method is advantageous in terms of oil recovery. However, previous studies have focused on the solvent temperature sensitivity analysis only in the VAPEX method. In this study, the solvent temperature study has been conducted discussing the multiple effects of temperature on both foamy oil and production performance in CSI method. A conventional CSI experiment (20°C) and two hot solvent-based CSI experiments (55 and 70°C) are conducted. The results demonstrate that, although the oil recovery of three tests is close to each other, oil rate and foamy oil strength will increase with the solvent injection temperature during the high oil rate phase. However, at a high injection temperature level, the maintenance of foamy oil is difficult due to high-temperature effect on foamy oil stability. Medium-high temperature level (55°C) is considered optimal temperature regarding the solvent extraction efficiency based on the gross utilization factor data.