Enhanced oil recovery (EOR), also known as “tertiary recovery,” is a process for extracting oil that has not already been retrieved through the primary or secondary oil recovery techniques. Although the primary and secondary recovery techniques rely on the pressure differential between the surface and the underground well, enhanced oil recovery functions by altering the chemical composition of the oil itself in order to make it easier to extract.Enhanced oil recovery techniques are complex and expensive and therefore are employed only when the primary and secondary recovery techniques have exhausted their usefulness. Indeed, depending on factors such as the cost of oil, it may not be economical to employ EOR at all. In those cases, oil and gas might be left in the reservoir because it is simply not profitable to extract the remaining amounts.