Chemical flooding is an enhanced oil recovery technique used to extract more oil from underground reservoirs. This method involves injecting chemicals, such as surfactants or polymers, into the reservoir to reduce the surface tension of the oil, making it easier to flow towards production wells. The process improves the efficiency of oil extraction by altering the properties of the oil and the surrounding water. By using chemical flooding, operators can increase the amount of recoverable oil, extending the life of oil fields and maximizing resource utilization. This technique is part of a broader category known as enhanced oil recovery (EOR).