| Abstract: | Abstract The alkaline-surfactant-polymer (ASP) floods have been increasingly applied in the oil fields because of their high ultimate oil recovery. However, a major technical challenge is how to reduce the amount and the cost of chemicals used so that ASP floods can become cost-effective as well. On the other hand, field applications show that the chemical concentrations remain relatively high in the produced liquids of ASP floods. Therefore, successful detection and reuse of these produced chemicals can substantially reduce their capital cost and environmental impact. In this article, several experimental methods are developed to detect each chemical and quantify its concentration in the produced liquids. Also re-injection of the produced chemicals is conducted to further enhance oil recovery. First, the respective interactions of alkali, surfactant, and polymer with the oil-brine-sand system are studied. Second, the interfacial tension (IFT) is measured as a function of alkaline concentration by using the axisymmetric drop shape analysis technique for the pendant drop case. In addition, the synergistic effects of alkali and surfactant on reducing the IFT are studied. Third, coreflood tests are performed for alkaline, surfactant, alkaline-surfactant, polymer, and ASP floods to determine their respective tertiary oil recovery. Hence, how each chemical contributes to enhanced oil recovery is better understood. Fourth, the produced chemical concentrations are measured and compared with their injected concentrations to determine the potential of reusing these chemicals in practice. Finally, the follow-up coreflood tests are conducted by re-injecting the produced liquids into a new sand pack or Berea core. The re-injection coreflood test results show that the produced chemicals can be reused to effectively enhance oil recovery. |
