Alkali Surfactant Polymers
Section Head: Dr. Guoyin Zhang

Alkali-Surfactant-Polymer (ASP) flooding is an enhanced oil recovery (EOR) technique usually performed as a supplement to water-flooding. ASP is a modified form of Surfactant-Polymer (SP) flooding. Both recovery techniques involve the simultaneous, "slug," injection of a solution consisting of a surfactant and a water-soluble polymer, usually partially hydrolyzed polyacrylamide (HPAM), to improve oil mobility, control, and recovery in a chemical flood. The surfactant reduces the surface tension between the oil, the water used in the flood, and the rock, easing its release from the rock. The polymer modifies the viscosity of the otherwise adhesive oil and mobilizes it.

Where SP floods use a water solution that is typically surfactant-based, ASP flood solutions include an alkali component, such as Sodium Carbonate, and significantly less surfactant. The alkaline component of an ASP injection reacts with acidic oil to form natural soap. This soap naturally emulsifies the oil into the water of the injection slug, improving oil recovery. An additional benefit of ASP techniques is that they are less detrimental to the long-term production of the well. The lower surfactant concentration is less disruptive to the reservoir's sustainability.

Environmental factors, such as the acidity of the oil and the availability of soft water, determine viable circumstances for ASP techniques. These natural restrictions are further compounded by the large volume of pre-operational research that must be conducted; polymer identification, fluid analysis, ASP slug composition, and modeling/simulation are all conducted to optimize the technique. Multiple years are required for most field applications.

The Alkali Surfactant Polymer group performs research in improving the techniques and technologies used in ASP flooding. These efforts support PRRC goals to reduce the ecological impact of oil recovery operations and improve the technologies and techniques available to the oil industry.