Abstract: The disclosed invention is a method of recovering hydrocarbons by determining the critical concentrations of various crude oil components to carbon dioxide to achieve first contact miscibility of a mixture of said crude oil components and carbon dioxide with the underground hydrocarbons at formation temperature and a selected pressure substantially lower than first contact miscibility pressure of carbon dioxide with the hydrocarbons; injecting into the formation a premixed transition zone slug comprising carbon dioxide and said crude oil components at said critical concentrations, formation temperature and said selected pressure; and injecting a drive fluid into the formation after the premixed transition zone slug.

Abstract: Recovery of oil from a dipping subterranean oil-bearing reservoir is effected by the injection of a first slug of a light hydrocarbon at a high rate to insure mixing with the reservoir oil adjacent the injection well followed by the injection of a second slug of carbon dioxide at a low rate to form a conditionally miscible transition zone with the altered reservoir oil and thereafter by the injection of a drive agent.