Chemical flooding is an enhanced oil recovery technique used in the petroleum industry. It involves injecting specific chemicals, such as surfactants or polymers, into oil reservoirs to improve the flow of oil. These chemicals help reduce the surface tension between oil and water, allowing more oil to be extracted from the reservoir. This method is particularly useful in mature oil fields where natural pressure has decreased. By altering the properties of the fluids in the reservoir, chemical flooding can increase the efficiency of oil extraction, making it a valuable strategy for maximizing production from existing wells and extending the life of oil fields.