An extractive distillation technique for producing CO2 enriched injection gas in enhanced oil recovery (EOR) fields

Sharp Separation of CO2 (carbon dioxide) from CO2-rich gases issuing from enhanced oil recovery (EOR) fields is investigated by different processing alternatives. A new extractive distillation technique without using an external solvent is introduced for debottlenecking of CO2 separation problem encountered in cryogenic distillation units. The technique involves the addition of a portion of produced C4+ (NGL) stream (natural gas liquid stream comprising iso-butane and heavier components) to the top section of a CO2 stripper followed by C2/C3 (ethane and propane) stripping of recovered C2+ (ethane and heavier components) stream. Detail description of the proposed technique for producing greater than 96% CO2-rich injection gas without external solvent is presented. According to the proposed approach, high quality C2/C3 and C4+ products with the corresponding purities of 89.6% and 99.6% suitable as feedstocks for gas and petrochemical processing units are also obtained. Sharp separation of CO2 from recovered hydrocarbon mixtures by the proposed technique and recycling it to petroleum reservoirs is an important issue regarding the optimization of EOR processes and greenhouse gas emission control.