Displacement Mechanism of Polymer Flooding by Molecular Tribology

Whether polymer flooding can enhance displacement efficiency or not is still a problem under debate. Laboratory experiment, numerical simulation and core data analysis are the commonly used means to study polymer flooding displacement efficiency. We discuss the limitations of these methods and employ molecular tribology to study the problem. The black--white ball action principle, i.e. the atom action model for describing the friction principle, is used to analyse the microscopic mechanism of oil displacement and describe the molecular interactions and displacement power during polymer flooding. Both tribology theory and dynamic rheological test show that molecular interactions during polymer flooding are bigger than that during water flooding. It is concluded that displacement efficiency of water flooding may be higher than that of polymer flooding at particular area; while polymer flooding can weaken the heterogeneity significantly, decrease ineffective injection and enhance the total displacement efficiency.