Conceptual process design of CO₂ recovery plants for enhanced oil recovery applications

Processes for recovering CO₂ (carbon dioxide) from CO₂-rich gas are important in the CO₂ EOR (enhanced oil recovery) field. From an environmental point of view EOR through the injection of CO₂ is very beneficial because it allows for the storage of part of the CO₂ injected while increasing oil recovery. To make this process even more environmentally friendly, the fraction of CO₂ which exits (is produced from) the oil well can be captured and recycled for reinjection giving a more efficient CO₂ storage strategy. The mixture of gases produced from an oil well contains light hydrocarbons, heavy hydrocarbons, water, and CO₂. Dehydration units and numerous other separation units for separating CO₂ and hydrocarbons can be used to recover CO₂, so various potential configurations should be investigated to find the one which is most appropriate. In this study, the TEG (triethylene glycol) and adsorption dehydration processes are used for gas dehydration and a combination of amine, Selexol and distillation processes are used for CO₂ separation. Unisim is used to simulate the processes and they are evaluated economically in terms of plant installation costs and energy consumption. A case study is presented to demonstrate the feasibility of various design configurations.