Secondary recovery using mixtures of carbon dioxide and light hydrocarbons

Claim 2

The process of claim 2 wherein said light hydrocarbon is LPG.

Claim 3

The process of claim 1 wherein said driving agent is selected from the group consisting of air, nitrogen, combustion gas, separator gas, natural gas, methane, water and mixtures thereof.

Claim 4

A process for recovering oil from an oil-bearing reservoir traversed by at least one injection well and one production well comprising the steps of: a. injecting into said reservoir via said injection well a slug comprising carbon dioxide and a hydrocarbon, said hydrocarbon having from two to four carbon atoms per molecule, said slug being capable of forming a conditionally miscible transition zone with said oil at the pressure and temperature of said reservoir, said slug being injected in amounts sufficient to establish said transition zone, b. injecting into said reservoir via said injection well a driving agent and driving said slug and said oil through said reservoir towards said production well, c. producing said oil via said production well.

Claim 5

The process of claim 5 wherein step (a) is preceded by injection of a fluid to repressure said reservoir to the minimum conditional miscibility pressure at which said slug is miscible with said oil.

Claim 6

The process of claim 6 wherein said repressuring fluid is selected from the group consisting of air, nitrogen, combustion gas, natural gas, methane, water and mixtures thereof.

Claim 7

The process of claim 5 wherein said driving agent is selected from the group consisting of air, nitrogen, combustion gas, separator gas, natural gas, methane, water and mixtures thereof.

Claim 8

The process of claim 5 wherein said light hydrocarbon is selected from the group consisting of ethane, propane, liquefied petroleum gas, butane and mixtures thereof.