Surfactant-polymer flooding is one of Enhanced oil recovery methods using chemicals (surfactant and polymer) injection. This compound is selected because it has double impact as chemical flooding i.e., decreasing the oil-water interfacial tension, increasing the sweep efficiency by reducing water-oil mobility, and increasing viscosity with the effect of existence of surfactant. However, some properties may become critical parameters that affect the EOR processes successfulness such as formation rock type, water and oil viscosity, permeability, and thus laboratory experiment has to be done for investigating the optimum surfactant- polymer concentration.
This research is trying to find the optimum surfactant- polymer (SP) concentration of a given SP formulation that is able to produce a maximum recovery with laboratory experiment which will be compared with a reservoir simulation using a non commercial, specialized surfactant polymer simulator. In our experiments, the SP flooding experiment is tested using Polymer HDS concentrations of 500, 800, 1000, 1200, 1500, and 2000 mg/L, and Surfactant SNF concentrations of 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, and 0.6%. The tests are directed toward application to a China oil field at a reservoir temperature of 57oC.
This research concludes that the higher polymer concentration, the higher viscosity oil is resulted, the addition of surfactant concentrations from 0.2%, 0.24%, to 0.6% for concentration of polymer 1200 mg/L can increase viscosity before shearing from 30.135 cp to 39.445 cp and after shearing from 25.51 cp to 36.27 cp, can decrease the viscosity with the increase of shear rate. During the reverse process, viscosity increases as the shear rate decreases. For this higher polymer concentration of 1500 mg/L, the resulted viscosities are within 27% different.
Concentration of the surfactant can decrease the interfacial tension below 2 x 10-3 dyne/cm but the addition of polymer in surfactant solution will increase interfacial tension until 10-2 dyne/cm.
The polymer with concentration of 1500 mg/L with surfactant concentration of 0.24% provides more stability in viscosity, higher resistance factor, residual resistance factor, cummulative oil recovery, and capillary number, and reducing residual oil saturation, better than the polymer of 1200 mg/L with surfactant concentration 0.2%.
The simulation and laboratory experiment results are not so similar perfectly they have different physical phenomena explanations