A Polymer Injectivity Model Establishment and Application for Early Polymer Injection

In China, early polymer injection has been proved to be an effective way to enhance oil recovery in Bohai offshore field. Since the near wellbore controls injectivity, two-phase flow function needs to be appropriately accounted for to predict polymer injectivity. In this paper, we account for polymer rheology and water–oil two-phase flow in the polymer injectivity model. To properly describe the fluid distribution, we define five regions with unique saturation profiles during polymer flooding and then established a polymer injectivity prediction model for both monolayer and multilayer reservoirs. Compared to the traditional numerical simulation method, the new model improves the injectivity prediction efficiency in early polymer injection. The new model is basically a rapid semi-analytical numerical simulator that can predict the dynamic polymer injectivity based on several field data obtained during an early polymer flood.