Polymer Injection Enhanced Oil Recovery (EOR) in Complex Fields: Challenges, Lessons Learned and Future Applications

Abstract The main objective of this study is to compile the lessons learned from a polymer injection pilot project in a mature oil field mainly regarding the operational challenges encountered, mitigation strategies implemented, and the effective management of the reservoir, in a way that would provide useful insights for the deployment of the polymer injection in both the early or late stages of production of other similar reservoirs. The polymer injection pilot project operated under severe operational challenges and constraints, such as poor water quality, well integrity issues and injector scaling/ plugging. Several approaches were implemented to mitigate these problems, including but not limited to the injection of high concentration polymer slugs in the reservoir, temporarily shutting-in polymer injectors and altering the injection rates with respect to the reservoir pressure to prevent the pressure-induced alteration of the formation. These methods were used to maximize the effectiveness of the polymer injection process, while avoiding the altering of the reservoir properties or the damaging the surface equipment. The polymer injection pilot project has yielded valuable data on the polymer injection's performance, injection well response and fluid dynamics in the reservoir under operational constraints, both surface and subsurface related, substantially enhancing our understanding of the reservoir and its mechanics. The data regarding the management of the polymer injection under operational constraints like high suspended solids concentration or high salinity has been documented and could provide support in the development of similar fields. Several parameters were monitored and analysed daily, like the produced and injected volumes, the injection pressures, the polymer solution's viscosity and the polymer concentration in the produced fluids. These analyses provide a window into the inner workings of the reservoir and the behavior of the polymer in this specific environment. This paper provides valuable insights by addressing operational challenges in polymer injection EOR projects, particularly in fields with water quality issues and infrastructure limitations. By showcasing strategies to overcome these challenges and leveraging pilot project data, it emphasizes the value of integrating polymer injection early in field development, while not excluding the method for more mature fields. The findings aim to guide similar projects, offering practical recommendations to optimize recovery and operational reliability.