Thermal oil recovery method

Abstract

Viscous oil may be recovered from subterranean, viscous oil-containing formations by injecting a heated aqueous fluid into the formation to raise the temperature of the viscous petroleum, and to displace it toward a remotely located production well. The heated aqueous fluid, which may be liquid, gaseous or a mixture thereof, is obtained from a deeper, higher temperature permeable oil formation. At least two spaced apart fluid flow communication means are established between the surface of the earth and the deeper, high temperature formation. At least two spaced apart separate communication means are established between the surface of the earth and the shallow viscous oil formation. Ordinarily the deeper, high temperature oil formation is one in which secondary recovery, e.g., waterflooding, will be ended or approaching the point where further production of oil and water is not commercially justified. At the conclusion of waterflooding, however, a typical oil formation will still have from 30-70% of the oil originally in place left in the formation. Any suitable heat transfer fluid, usually field water, is injected into the deep, high temperature formation where it passes through the permeable formation and in consequence of contacting the higher temperature mineral matrix of the formation, its temperature is elevated prior to exiting from the formation via the second communication means. Hydrocarbons are also recovered with the water, including some dissolved in the water at the high temperature and pressure of the deep formation.