Investigation of geochemical interactions of carbon dioxide and carbonate formation in the Northwest McGregor oil field after enhanced oil recovery and CO2 storage

Abstract The Plains CO 2 Reduction Partnership, one of the seven U.S. Department of Energy National Energy Technology Laboratory Regional Carbon Sequestration Partnerships, is conducting a carbon dioxide (CO 2 ) huff ‘n’ puff (HnP) project in the Northwest McGregor oil field in North Dakota to determine the effects CO 2 has on the productivity of the reservoir, wellbore integrity, and the carbonate formation into which the CO 2 was injected. This paper outlines the approach and current observations derived from numerical modeling and laboratory simulations of potential geochemical reactions to evaluate the short-term risks for operations (e.g., porosity and permeability decrease) and long-term implications for CO 2 storage via mineralization. The integration of data obtained during mineralogical analyses, fluid sampling, and laboratory experiments proved to be a key for the better understanding of the dynamic geochemical processes that happen in the reservoir after CO 2 injection and was necessary for successful completion of the numerical modeling. Results of the numerical modeling suggest that the already acidic and highly saline environment (pH 2 injection, especially in the near term, which correlates with the postinjection field geochemical analyses.