A Model-Based Production Strategy Selection Considering Polymer Flooding in Heavy Oil Field Development

Abstract

Abstract Polymer flooding is a chemical EOR technique in which polymer is added to injection water, increasing its viscosity, decreasing water-oil mobility ratio and hence improving sweep efficiency. This recovery method create unique conditions that are absent in traditional water flooding, which makes an adequate production strategy essential to the success of the project. This work is part of a complete decision analysis process with polymer flooding and the objective here is to present a methodology for production strategy selection considering water and polymer flooding as recovery mechanism options in heavy oil reservoir, guiding the decision maker to have an accurate tool to compare water and polymer flooding strategies and decide which one is the best option in determined project, using numerical simulation and economic analysis. The methodology is divided in seven steps based on variable hierarchy. The optimization process aims the maximization of NPV and the variables optimized are: number and location of wells, production systems capabilities, schedule of well drilling, production and injection rates, economic water cut limit for well shutdown, polymer concentration and slug size. The application of the methodology is made in a model that represents an offshore heavy oil Brazilian field. For comparison purposes, the methodology is also applied considering water flooding as recovery mechanism. The results show the feasibility in applying polymer flooding in early heavy oil field development with better economic return than water flooding. Moreover, this work shows the importance of applying the process separately for water and polymer flooding, otherwise wrong decisions can be made if simple comparisons are performed.