Worm‐like micelles: A new approach for heavy oil recovery from fractured systems

Abstract

In this work, a new type of flooding system, “worm‐like micelles”, in enhanced heavy oil recovery (EOR) has been introduced. Application of these types of surfactants, because of their intriguing and surprising behaviour, is attractive for EOR studies. Fundamental understanding of the sweep efficiencies as well as displacement mechanisms of this flooding system in heterogeneous systems especially for heavy oils remains a topic of debate in the literature. Worm‐like micellar surfactant solutions are made up of highly flexible cylindrical aggregates. Such micellar solutions display high surface activity and high viscoelasticity, making them attractive in practical applications for EOR. In this study, worm‐like micellar solutions were used for flooding experiments in micromodels, initially saturated with heavy crude oil. The fractured micromodels with different fracture geometrical properties, different orientation angles and length, were used in the tests under oil‐wet condition. During experiments, high quality pictures of injection processes were recorded. Oil recoveries as a function of injected pore volumes and microscopic mechanisms during displacements were investigated from precise analyses of the provided pictures. It was observed that three mechanisms govern the EOR process during worm‐like micellar solution flooding: ultra‐low interfacial tension, high viscosity of the injecting fluid and in situ formation of macro‐emulsion. Considering these mechanisms, worm‐like micellar surfactants solutions are potentially good choices for EOR in heterogeneous systems such as fractured reservoirs. This study illustrates that the application of worm‐like micelles for heavy oil recovery in heterogeneous systems can reduce the risks involved with heterogeneity on flooding performance in such reservoirs.