An extractive distillation technique for producing CO_2 enriched injection gas in enhanced oil recovery (EOR) fields

摘要

Sharp Separation of CO_2 (carbon dioxide) from CO_2-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 CO_2 separation problem encountered in cryogenic distillation units. The technique involves the addition of a portion of produced C_4 (NGL) stream (natural gas liquid stream comprising iso-butane and heavier components) to the top section of a CO_2 stripper followed by C_2/C_3 (ethane and propane) stripping of recovered C_2 (ethane and heavier components) stream. Detail description of the proposed technique for producing greater than 96% CO_2-rich injection gas without external solvent is presented. According to the proposed approach, high quality C_2/C_3 and C_4 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 CO_2 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.