Evaluation of Technology and Policy Issues Associated with the Storage of Carbon Dioxide via Enhanced Oil Recovery in Determining the Potential for Carbon Negative Oil

Abstract

Numerous legal and regulatory frameworks in the U.S. and globally are acknowledging the opportunity for greenhouse gas (GHG) emissions reductions offered by combining the long-term storage of CO2 in association with carbon dioxide enhanced oil recovery (CO2-EOR), to support carbon capture and storage (CCS) as a climate mitigation technology. These include the U.S. Environmental Protection Agency (USEPA), the International Organization for Standardization (ISO), the State of California, and the Intergovernmental Panel on Climate Change (IPCC), among many.In this paper, a brief overview is provided of the literature on GHG lifecycle analyses (LCA) applied to CO2 storage in association with CO2-EOR. Then, various techniques for performing LCA related to CO2-EOR operations are summarized. Moreover, since most past LCA analyses of CO2-EOR projects were generally based on historical CO2-EOR operations, LCA based on assumptions from these operations are likely not to represent future emissions reduction opportunities where CO2 storage is a co-objective with increased oil production. Thus, the paper examines different CO2-EOR development options that could greatly increase the amount of CO2 injected, and ultimately stored, to recover incremental oil via the application of CO2-EOR, and speculates on how even greater storage efficiencies with CO2-EOR can be realized.Assuming historically-based values for CO2 utilization, most life cycle analyses of CO2 storage in association with CO2-EOR show that the emissions associated with producing, processing, transporting and/or utilizing the incremental oil produced are greater than the CO2 injected and stored in association with CO2-EOR. However, current CO2-EOR operations are achieving much higher utilization values, and assuming the wide-scale application of “next generation” technologies applied to existing and potential new resource targets, even larger utilization values are realizable.Recent work by Advanced Resources, for example, shows that “next generation” CO2-EOR applied to the main pay zone (MPZ) of oil reservoirs uses, on average, about 0.45 metric tons per barrel of oil produced, while CO2-EOR applied to the residual oil zone (ROZ) underlying and in between existing oil fields uses, on average, about 0.50 metric tons per barrel of oil produced. Many projects are likely to achieve even higher values of CO2 utilization for CO2-EOR. These utilization values are over double that assumed in most traditional LCA analyses applied to CO2-EOR operations. And even greater utilization values are realizable. For comparison, emissions associated with the production, transport, refining, and ultimate combustion of the incremental oil produced are estimated to be on the order of 0,42 to 0.43 metric tons per barrel.Given these values for CO2 utilization with CO2-EOR, accounting for emissions associated with CO2-EOR operations, with activities downstream of CO2-EOR operations (i.e., crude oil transport and refining), and even accounting for the combustion of fuels created from the barrel of crude, the amount of CO2 injected and stored in the reservoir during CO2-EOR can generally be greater than that associated with the emissions associated with the incremental oil produced.Going forward, it will be important that legal and regulatory frameworks for verifying and accounting for GHG emissions reductions acknowledge the importance of CO2 storage with CO2-EOR in achieving GHG emissions goals.