Comparison of carbon balance measuring tools in an enhanced oil recovery project based on the carbon dioxide from the ammonia production process streams

Abstract A number of studies addressing the environmental impact of deploying carbon capture utilization and storage are focused on sources of CO 2 in the power sector. However, there is a lack of environmental studies on the use of CO 2 from process stream within the oil and gas industries. The carbon balance of an enhanced oil recovery project for the specific case of using CO 2 process stream of ammonia production from emission factors and regional databases in the Mexican oil and gas sector was assessed. Two independent tools to assess life cycle assessment according to guidelines ISO 14040/14044 were utilized: (i) use of Umberto software to quantify the environmental impact with ReCiPe model midpoint; and, (ii) The American Petroleum Institute method through the use of emissions factor for each source and emission gas of the activity/facility in a spread sheet. The results of the tools were compared and the dissimilarities analysed. The emissions profiles from all direct and indirect activities associated with the enhanced oil recovery system were compared with a “cradle-to-grave” model. The functional unit is one barrel of crude oil extracted and consumed. Global warming as the environmental indicator of both tools was used. Additionally, the energy balance of the project was estimated. The global warming impact of the enhanced oil recovery system was 0.51 tCO 2e /barrel (bbl) using the American Petroleum Institute tool, whilst the emissions using Umberto software were 0.54 tCO 2e /bbl. Also, for each MJ of energy produced a value of 72 tCO 2e /MJ oil and of 66 tCO 2e /MJ oil, were obtained. This study demonstrates that both tools delivered an accurate estimation of the greenhouse gas emissions in the enhanced oil recovery system for the oil and gas industries. However, American Petroleum Institute has the advantage that the calculations can be performed ´manually' in a spread sheet using emissions factor adjusted to the facilities and Country. Regarding the results of both tools, this work shows that American Petroleum Institute results have proven to be an efficient tool for practitioners and researchers that intend to analyse the greenhouse gas emission of carbon capture utilization and storage systems to estimate, with accuracy, the global warming impact.