Effect of polymer on the interaction of alkali with heavy oil and its use in improving oil recovery

The main objective of this study is to experimentally investigate the effect of polymer on the interaction of alkali with heavy oil and its use in enhancing heavy oil recovery. The results of sandpack flooding tests show that the combined polymer and alkali can lead to a remarkable increment in tertiary oil recovery compared to polymer-only flooding and alkaline-only flooding. However, there is an optimum polymer concentration to maximize the incremental oil recovery for the alkaline–polymer (AP) flooding. Besides, the sequential injection of alkaline slug-polymer slug can obtain better results than the co-injection of the polymer and alkali slug with the same injection volume of chemical formula. The microscopic studies indicate that the addition of polymer has detrimental effects on the generation of water droplets inside the oil phase (W/O droplet flow) during AP flooding, which results in lower sweep efficiency than alkaline-only flooding. Therefore, the AP flooding should take full advantage of the mechanism of W/O droplet flow and avoid the detrimental effects on the generation of W/O droplet flow with the addition of polymer, and thus can lead to a significant improvement of heavy oil recovery by AP flooding.