A Novel Foam Flooding for Enhanced Oil Recovery in Fractured Low-Permeability Reservoirs: Performance Evaluation and Mechanism Study

Abstract

Summary Foam flooding is an effective enhanced oil recovery (EOR) technology and has been widely applied in conventional reservoirs. However, its application in fractured low-permeability reservoirs is rarely reported. Hence, this study has conducted a series of laboratory experiments to investigate the application potential of foam flooding and clarify its EOR mechanism in fractured low-permeability reservoirs. Based on reservoir conditions, our laboratory has developed a novel foam system consisting of nano-SiO2 particles, water-soluble thixotropic polymer (WTP), and sodium dodecyl benzene sulfonate (SDBS). With the aid of nuclear magnetic resonance (NMR) technology, it was found that the foam flooding can significantly enhance the oil recovery in fractured low-permeability cores. The injected novel foams can plug the cracks in core samples and improve the imbibition in nanopores. As a result, more oil would be displaced from the nanopores and micropores. In addition, the foaming agent in the bulk solution can moderately reduce the oil-water interfacial tension (IFT) and alter the wettability of rock surface, improving the flowability of oil and the imbibition effect. Most importantly, the field tests in Ordos Basin have proved a promising EOR potential and appreciable financial rewards of the SDBS/nano-SiO2/WTP foam system applied in fractured low-permeability reservoirs.