ABSTRACT The design of field separation equipment under CO2 flood operations requires that many variables be addressed. During a CO2 flood, separators will be required to effectively separate large volumes of multi-component gas streams from produced oil and water. Many design assumptions which served well in non CO2 hydrocarbon service cannot be successfully applied to the design of field separation equipment in CO2 flood operations. To adequately size separators for CO2 service, specific attention must be given to design parameters such as K factors, gas density, liquid density, retention time for gas-liquid separation, CO2 and produced gas rates, and the type of vessel best suited for CO2 flood conditions. After a detailed study of the parameters involved in the design of field separation equipment for CO2 floods, several conclusions were reached. Conventional sizing charts are not applicable in CO2 operations.One to two minute retention time is not sufficient for gas-liquid separation in CO2 operations.K factors normally used for sizing separators should be derated for CO2 operations.Horizontal separators are better suited for CO2 flood operations than spherical or vertical separators.Computer sizing of separators is necessary to determine the optimum operating settings.