SP Flooding EOR: slug ratio affected oil recovery

Surfactant-Polymer (SP) Flooding is one of the chemical enhanced oil recovery (EOR) that catch the researcher and oil and gas industry’s interest nowadays to reduce the amount of residual oil saturation in the pore space of the rock matrix. Literally, the oil recovered by the primary and secondary recovery was only about one-third of the OOIP, by applying SP Flooding as the tertiary recovery the other two-third of the remaining oil in the reservoir can be extracted. Surfactant will be injected to mobilize the oil by altering the reservoir’s wettability from oil-wet to water-wet. Polymer on the other hand will increase the viscosity of formation water and increase the sweep efficiency during the oil recovery process. The aim of this study is to determine the effectiveness of industrial wastewater treatment surfactant, SULFOCAT BK80 as the potential materials for SP Flooding alongside with Xanthan Gum (XG) as polymer and injecting the optimum SP formulations with a different slug ratio. Selection of optimum BK80 and XG concentration is one of crucial stages that will be carry out in this study. Several experiments involving 16 SP formulations with constant salinity was carry out to determine the density, contact angle, viscosity and shear rate of the materials for the screening process purpose. Through the screening process, it was found that at a 3000 ppm BK80 and 400 ppm XG was the optimal surfactant and polymer solution for the SP Flooding process. The optimum SP solution was then injected in the sandpack after waterflooding with a slug ratio of 0.3PV BK80 + 0.3PV XG, 0.3PV BK80 + 0.4PV XG and 0.1PV BK80 + 0.6PV XG in Run 1, Run 2 and Run 3 respectively. The incremental of oil recovery for Run 1, 2 and 3 are 1.82% , 2.54 % and 2,84% respectively. It was found that with the same total volume of BK80, injecting a larger volume of polymer produced more oil by comparing between Run 1 and Run 2. The highest oil recovery of 63.47% was obtained when a ratio of 0.1PV of BK80 and 0.6PV XG was used and this somehow proved that polymer played a dominant role in SP Flooding compare to surfactant.