NGL Recovery from CO2-EOR Streams

The need to reduce concentration of greenhouse gases has promoted the use of technologies for CO2 destination. Of particular interest is the use of CO2 present in natural gas streams in the context of the Brazilian pre-salt fields. This motivation guides the development of CO2 based processes that attribute extra revenue to the oil and gas production therefore reducing the penalty posed by CO2 capture. In this work, a feasibility analysis is performed on the process of recovering Natural Gas Liquids (NGL) from CO2 rich streams used in Enhanced Oil Recovery (EOR). For this purpose, a waste stream from synthetic natural gas production reported in the literature was analyzed. The proposed process arrangement employs natural gas processing techniques to recovering NGL from EOR streams rich in CO2. Among the technologies available, three are approached and applied to recover propane (C-3), butane (C-4) and natural gasoline (C5+) fractions: (a) Joule Thomson Process, (b) Turbo Expander Process and (c) Cryogenic Process. The comparative study presented includes process simulation in the environment UNISIM DESIGN (Honeywell), and sizing of main equipment for economic analysis, which includes calculation of capital and operational expenditures (CAPEX and OPEX). The study indicates the Cryogenic Process as the most feasible. Based on its superior performance, this process is applied to a case study concerning Tupi Pilot field, belonging to the Brazilian pre-salt layer, even though large uncertainties surround the actual data from the pre-salt reservoirs. With further consideration of revenues from Carbon Credits, the three processes and the case study are found to be economically feasible.