Life-Cycle Analysis of CO 2 EOR on EOR and Geological Storage through Economic Optimization and Sensitivity Analysis Using the Weyburn Unit as a Case Study † Jitsopa Suebsiri,* ,‡ Malcolm Wilson, § and Paitoon Tontiwachwuthikul § EnVironmental System Engineering and International Test Centre for CO 2 Capture, UniVersity of Regina, Regina, Saskatchewan, Canada S4S 0A2 At the global, national, and subnational levels, many policies have been created or are in the process of development to deal with greenhouse gas (GHG) emissions, particularly CO 2 . CO 2 enhanced oil recovery (EOR) is an option available to governments and industry to help meet emission reduction levels. In addition to increasing the production of oil, the CO 2 can be stored in the oil reservoir for a very long period of time. However, CO 2 capture and CO 2 EOR operation result in significant costs and energy penalties, for example, CO 2 capture from a point source, transportation to the site of use, and recycling produced CO 2 . This article evaluates the life cycle of CO 2 storage from delivery to the oil field through the production, transportation, and refining of the oil and identifies opportunities for optimization. Information from the IEA GHG Weyburn Monitoring and Storage Project is used to provide baseline information for the storage of CO 2 . The value of this life-cycle study lies in the development of an understanding of the “carbon” economics of the EOR process and the impact on net storage of changes to the value of different components in the chain. These results provide a mechanism whereby environmental consequences can be evaluated within economic decision- making. Introduction Greenhouse gases (GHGs), particularly carbon dioxide (CO 2 ), have been extensively studied as a result of concerns about glo- bal climate change. In 1997, an agreement among 84 countries, the Kyoto Protocol, was approved with a goal of achieving major greenhouse gas emissions reductions. Now in force, the Kyoto Protocol has legal standing to back its goal of emissions reduc- tions, unlike its predecessor, the United Nations Framework Convention on Climate Change (signed in 1992 and entered into force in 1994), which only provided guidelines for coun- tries’ emissions reductions. CO 2 emission reductions can be ac- complished through the application of energy efficiency and conservation, fuel switching, renewable energy, and capture and storage. The capture and storage of carbon is one of the approaches for CO 2 emission reduction being given serious consideration globally. The CO 2 must be captured from large industrial sources as a relatively pure gas before it can be stored. The rationale for this is two-fold. In the first place, certain contaminants can negatively impact the effects of CO 2 in enhanced oil recovery. (If this is the chosen storage mechanism, in saline aquifer storage, the purity concerns are less marked.) Second, the costs of compression can rise significantly if the levels of contami- nants are high; as an example, the cost of compressing an untreated flue gas for injection into the subsurface would be prohibitively high and would, in any event, waste what might turn out to be limited pore space in the subsurface. CO 2 for enhanced oil recovery (EOR) is a relatively mature process that has been commercially applied on an increasingly large scale in several petroleum basins during the past three decades. The advantages are not only using CO 2 to enhance oil recovery, but also storing CO 2 for the long term. Unfortunately, CO 2 enhanced oil recovery cannot be effectively applied to all types of reservoirs. Crude oils with a specific gravity less than 0.9218 (greater than 22° API) are best suited to enhanced oil recovery with CO 2 . 1 Additionally, depths should ideally be such that miscible flooding can occur to optimize recovery efficiency. In the case of a facility using fossil fuel, it is possible to remove the CO 2 before it is released into the atmosphere. The CO 2 would then be stored through EOR or injection into deep saline aquifers. The Weyburn oil field is investigated as an illustrative case in this study because of the public availability of large amounts of data resulting from an extensive four-year research project completed in 2004. This article focuses on applying life-cycle analysis (LCA) of CO 2 storage from delivery to the oil field through the production, transportation, and refining of the oil and identifies opportunities for optimization. The Weyburn unit has proven to be an exceptional natural laboratory for the study of CO 2 storage, based in part on the extensive historical field production and well data available, combined with the baseline data collected prior to the first CO 2 injection, the abundant core material, and the accessibility of the site. 2 The Weyburn unit, located 130 km southeast of Regina, Saskatchewan, Canada, as shown in Figure 1, is operated by EnCana Corporation on behalf of a large number of unit holders. The Weyburn reservoir produces crude oil, which has a specific gravity in the range of 0.850-0.9041 (25°-34° API), from the Mississippian Midale Beds of the Charles Formation that occur at a depth of around 1450 m. The original reservoir temperature (near 65 °C) and original pressures (around 14.5 MPa) indicate that CO 2 in the pool likely exists as a supercritical fluid. (The temperature and pressure are above the critical point of approx- imately 31 °C and 7 MPa.) In summary, the geological setting of the Weyburn oil pool is considered highly suitable for CO 2 - based EOR and long-term storage of CO 2 . The injected CO 2 has the potential to remain for a similar time scale as the hydro- carbons in the reservoir, which have been trapped for geological time scales. * To whom correspondence should be addressed. E-mail: suebsirj@uregina.ca. Tel.: (306) 596-4924. Fax: (306) 337-2301. † This paper is an expanded version of work presented at the 7th International Conference on Greenhouse Gas Control Technologies, Vancouver, Canada, Sep 2004. ‡ Environmental System Engineering. § International Test Centre for CO2 Capture. 2483 Ind. Eng. Chem. Res. 2006, 45, 2483-2488 10.1021/ie050909w CCC: $33.50 © 2006 American Chemical Society Published on Web 12/09/2005