Optimal Production Strategies for the Development of Mature Oil Fields through Polymer Flooding

Abstract

Polymer flooding is one of the most extensively applied techniques for enhanced oil recovery (EOR) that relies on increasing the injected fluid viscosity by adding polymers in different concentrations. The aim is to improve the mobility ratio between the oil and the displacing fluid, reducing channeling effects and boosting sweep efficiency. In this work, a mixed-integer nonlinear optimization approach is developed in order to address production planning decisions, also assessing the convenience of polymer flooding in EOR projects on screening stages. This decision-making tool allows establishing optimal polymer injection strategies, setting fluid injection rates and polymer concentrations, selecting wells, and scheduling slug change operations over the planning horizon, with the aim of maximizing the net present value of the project. We propose a novel formulation combining transport phenomenon models, well productivity forecast, and geometric abstraction of the reservoir in order to address both technical and economic decisions with low computational effort. Results show that optimized strategies may outperform typical operations by up to 17% and can be found in shorter central processing unit times in comparison to traditional reservoir simulation approaches. The model has been used to tackle problems with up to 7 wells and can be tuned to different reservoir conditions.