PROCESSING OF CARBON DIOXIDE RICH GAS

Efforts to commercialise high carbon dioxide content natural gas have traditionally been unsuccessful due to high processing costs. However, increased demand for natural gas can make development of marginal, high carbon dioxide content gas fields an attractive proposition despite the high carbon dioxide disposal costs, usually to underground storage, so as to avoid emissions to atmosphere. In processing high carbon dioxide content natural gas, to ultimately inject the produced carbon dioxide into underground storage, having product carbon dioxide at high pressure and in the liquid phase is very important so as to reduce the power consumption for carbon dioxide pressure boosting, reduce machinery cost and reduce both overall investment cost and operating cost. Conventional process technologies for carbon dioxide removal, based on chemical or physical solvents and/or semipermeable membranes, suffer in this regard due to the product carbon dioxide being gaseous and at low pressure. In contrast, low temperature fractionation offers important advantages in being able to upgrade natural gas whilst producing high purity carbon dioxide as a liquid at high pressure. This paper reviews low temperature fractionation technologies for processing carbon dioxide rich natural gas. It then considers the merits of using the extracted carbon dioxide for enhanced oil recovery (EOR), to obtain revenues, and the processing of the carbon dioxide rich associated gas that