Evaluation and Optimization Study on a Hybrid EOR Technique Named as Chemical-Alternating-Foam Floods

Abstract

A novel EOR method called Chemical-Alternating-Foam (CAF) floods was developed to overcome the drawbacks of the conventional foam flooding, e.g., insufficient amount of in-situ foams and severe foam collapse and surfactant retention. CAF flooding showed greater capability to reduce the brine permeability compared to the continuous foam flooding. The overall oil recovery of the CAF flooding was 10-15% higher compared to that of the conventional foam flooding with the same amount of CO2 chemicals injected. For the continuous CO2 foam flooding, the best displacement performance was obtained at the 60% water cut, while the CAF floods yielded the most amount of incremental oil at the 98% water cut. Under the experimental condition, the optimal foam quality, foam/chemical slug size ratio and cycle number for the proposed CAF floods were selected as 80%, 1:1 and 3, respectively. The proposed hybrid process is a viable and effective method significantly strengthening the conventional foam flooding.