Distillative processing of CO.sub.2 and hydrocarbons for enhanced oil recovery

A method for treating hydrocarbon-rich CO.sub.2 gas containing carbon dioxide, methane, ethane, propane, butane, and heavier hydrocarbons for injection into an oil-bearing formation in an economical manner comprising the steps of:

• (a) introducing said hydrocarbon-rich gas stream into a multi-tray distillation column at an intermediate tray;
• (b) cooling an overhead vapor from said distillation column in a partial condenser to produce a two-phase stream;
• (c) separating said two-phase stream in a reflux drum to produce a reflux stream and a product stream;
• (d) introducing said reflux stream onto a top tray of said distillation column;
• (e) reboiling said distillation column with a reboiler;
• (f) injecting said product stream into a hydrocarbon-bearing formation;
• and
• (g) said steps of introducing said gas stream into a distillation column, chilling, separating, introducing said reflux stream onto a top tray of said distillation column, and reboiling carried out under conditions which most of said methane, ethane, and propane are contained in said product stream.

A method for treating hydrocarbon-rich CO.sub.2 gas for injection into an oil-bearing formation consisting essentially of the steps of:

• (a) introducing a feed stream into distillation equipment, said feed stream comprising a mixture of carbon dioxide, methane, ethane, propane, butanes, and heavier hydrocarbons;
• (b) distilling said feed stream with said distillation equipment to produce an overhead stream and a bottoms stream, said overhead stream containing substantially all of said carbon dioxide, methane, ethane and propane, and said bottoms stream containing substantially all of said heavier hydrocarbons;
• and
• (c) injecting said overhead stream into a hydrocarbon-bearing formation.