Mobility control during chemical flooding is one of the most important factors for enhanced oil recovery using chemical processes. Polymers are used to increase the viscosity of the injected fluid and improve the sweep efficiency by having a favorable mobility ratio during chemical flooding. Characterization of rheological properties of the surfactant-polymer (SP) and alkali-surfactant-polymer solutions is important for understanding the behavior of chemical slug in porous media.
An experimental study was conducted to measure the rheological properties of chemical flooding solution over a wide range of parameters. Effects of temperature, salt type, salt concentration, surfactant type and surfactant concentration on dilute aqueous solution of polymer used for high salinity enhanced oil recovery applications were investigated in details. In some cases the chemical slug was prepared in seawater and viscosity measurement was conducted at 90°C.
Amphoteric surfactant was used and showed compatibility with polymer solution and can be used in chemical flooding. Effect of concentrations of two types of surfactants, anionic and amphotaric on chemical slug viscosity was studied. Amphotaric surfactant was found to have a preferable rheological attributes when compared to anionic surfactant. Amphoteric surfactant can maintain viscosity of chemical solution at high salinity and no reduction in viscosity was noticed when this type of surfactant was added to the solution. On the other hand, reduction in viscosity was measured when anionic surfactant was added to the solution. Dynamic properties showed reduction when salts were added to the solutions.