Oil recovery refers to the process of extracting crude oil from underground reservoirs. This involves various techniques, including drilling wells and using pumps to bring the oil to the surface. The goal is to maximize the amount of oil that can be retrieved from a given site, which can be challenging due to the oil's viscosity and the geological conditions. There are two main types of oil recovery: primary and secondary. Primary recovery uses natural pressure and mechanical methods to extract oil, while secondary recovery involves injecting water or gas to push more oil to the surface. Both methods are essential for efficient oil production.