Paths to ultimate enhanced oil recovery by chemical flooding

<p indent="0mm">Chemical flooding remains a key technology for enhancing oil recovery in China’s medium- and high-permeability reservoirs, playing a critical role in sustaining crude production and ensuring long-term oilfield viability. This paper reviews the evolution of chemical flooding technologies, examines current technical bottlenecks, and outlines a strategic framework for maximizing oil recovery. Over the past decades, substantial progress has been made, with the polymer flooding, surfactant-polymer (SP) flooding, and alkali-surfactant-polymer flooding evolving into mature industrial applications. However, as reservoir development advances, new challenges have emerged, including increasing reservoir heterogeneity, complex microscopic residual oil distribution, and limitations in surfactant adaptability. Overcoming these challenges requires a deeper understanding of fundamental mechanisms and continuous technological innovation to further enhance recovery efficiency. Moving forward, breakthroughs in intelligent targeting, chemical miscibility enhancement, and adaptive flow control-leveraging artificial intelligence and data-driven optimization be essential to unlocking the full potential of chemical flooding and pushing limited enhanced oil recovery performance toward its theoretical limits.