Method of producing a stratified viscous oil reservoir

摘要

This invention discloses a more efficient and more self supporting method of producing oil from a viscous oil-bearing permeability stratified reservoir. In situ combustion with oxygen is carried out near a first injection well in a manner such that carbon dioxide substantially free of nitrogen is produced. The carbon dioxide substantially free of nitrogen produced by in situ combustion is then injected into a second injection well to swell, reduce the vicosity of in-place oil and displace oil from a separate part of the stratified reservoir. Water with or without other mobility and solubility control agents can be injected in either or both the combustion step and carbon dioxide displacement step. In situ combustion with or without nitrogen may thereafter be initiated adjacent the second injection well to produce the less permeable or more viscous oil-bearing strata to either produce oil left by carbon dioxide injection or to produce more nitrogen-free carbon dioxide. This additional carbon dioxide plus carbon dioxide produced in the second production well can then be injected into a third laterally spaced injection well to sweep and displace oil from another part of the reservoir. These steps may be repeated until the reservoir is economically depleted.