Optimization method of injection and production parameters for polymer/surfactant binary flooding

Key words:  polymer/surfactant binary flooding  optimization of injection and production parameters  perturbation approximation gradient  net present value

Abstract:

Polymer/surfactant binary flooding has been widely applied in Shengli, Daqing and other oilfields in China. However, the general and uniform injection methods used in the oilfield have not fully taken into account the difference of the formation and geological conditions, which can readily cause a low flooding efficiency with high chemical cost. In this study, taking the net present value of a project as the objective function, and considering the constraint conditions of the field injection capacity and the restriction of the formation conditions, an optimization model of the injection and production for the binary flooding was established, which was solved by an optimal perturbation approximation gradient method. The results of a case study show that, under the conditions of a constant total injection cost of polymer and surfactant, by optimizing the concentration of polymer, the concentration of surfactant and slug size of each injection well, the accumulated oil production can be increased by 1.23％, and the net present value of the project can be increased by over 9 million yuan. The optimization results show that the optimization method of the injection and production parameters of polymer/surfactant binary flooding can be effectively used in the project design to improve the economic and technical benefits of the project.