Chemical methods for heavy oil recovery

Many mobile heavy oil reservoirs in Saskatchewan and Alberta are unsuitable for the application of thermal recovery methods, such as steam injection, for a number of reasons including formation thicknesses of less than 10 m. Oil recovery from such reservoirs can be accomplished by the use of nonther mal methods, among which chemical flooding has considerable importance. Thi s paper discusses recent laboratory results using chemical flooding techniq ues. At the same time, limitations of such methods, limited field experienc e in heavy oil formations, and possible improvements are also considered. Among the chemical flooding methods, alkaline and surfactant flooding techn iques are more important, partly because the chemicals involved are less ex pensive, and also much has been learned from past experience in laboratory and field. The laboratory studies discussed consisted of surfactant floods and huff n'puff of two Lloydminster heavy oils. The recoveries in the flood s were as high as 33%. The other recovery method discussed involved cyclic stimulation using two surfactants. Oil recoveries as high as 12% were achie ved. Though recovery was low, such an approach can be cost-effective in spe cial circumstances.