Boosting Oil Recovery, Efficiency, and Economics in Heterogeneous Reservoirs by Deploying Modular Polymer Injection Units

The El Alba Valle project is a block of Manantiales Behr reserve within the Golfo San Jorge Basin, Argentine. The high heterogeneity of the reservoir and the high relatively oil viscosities (>200 cp) have led to significant amounts of bypassed oil. Water injection tends to preferentially flow into high-permeability zones, leaving behind substantial volumes of unproduced oil, making this oil a primary target for polymer flooding. The goal of this project is to improve oil recovery efficiency through the deployment of polymer injection units (PIUs), which have already been successfully relocated from the Grimbeek field.

The project relies on 3D subsurface models that has 5.000.000 cells to translate the geological characteristics of the fluvial system into grids of petrophysical properties. These models help prioritize areas for polymer injection by estimating the location of bypassed oil. The primary target is a fluvial system within the Comodoro Rivadavia Formation. This formation is characterized by N-S oriented sand-filled channels, where bypassed oil was indicated by strongly differential saturation changes from layer to layer.

The pilot includes 10 injector wells, 30 producer wells, and one polymer injection unit. The modular PIUs allow flexibility, enabling their relocation across different blocks. The use of PIUs has resulted in important improvements after six months of injection at a concentration of 5000 ppm and a total rate of 1.200 m3/d, with significant reductions in water cut.

In addition, the successful response to polymer injection allowed the project team to declare an increase in reserves. This achievement resulted in 9 % in incremental oil recovery factor within the 3P reserves, distributed as following; 18 % in P1, 36 % in P2 and 46 % in P3.

The strategy in Manantiales Behr is demostrating that rotating PIUs across multiple fields could optimize recovery without needing extensive changes to surface facilities. The expansion plan includes targeting other sweet spots for injection and further rotation of PIUs, which improves the project’s economics and has importan implication for the commercial case. This strategy, combining with detailed reservoir studies and flexible injection systems, is expected to yield better results in terms of production and cost-efficiency.

The project marks a shift from traditional water injection to more sustainable polymer flooding techniques, which have demonstrated improved recovery factor and efficiency in dealing with heterogeneous reservoirs like Alba Valle, while reducing the CO2 footprint relating to cicling large amounts of water because of the inefficient resevoir displacement.