(743a) North Dakota Carbonsafe – Early Successes

As part of the U.S. Department of Energy’s (DOE’s) CarbonSAFE program, the Energy & Environmental Research Center (EERC) is conducting commercial-scale site characterization and permitting of up to two geologic horizons for the geologic storage of anthropogenic CO₂ emissions. These storage horizons would collectively and permanently store nearly 4 million metric tons (MMt) of CO₂ per year captured as part of Minnkota Power Cooperative’s (Minnkota’s) Project Tundra. Minnkota’s ambitious initiative to build the world’s largest postcombustion carbon capture and storage facility in central North Dakota demonstrates the existence of a business case for carbon capture, and storage (CCS). The EERC and project team is building upon the success, learnings, and momentum of the North Dakota CarbonSAFE Phase II feasibility study. Minnkota’s primary generating resource is the two-unit Milton R. Young Station (MRYS), a minemouth lignite coal-fired power plant. The mine which provides the lignite coal for MRYS is owned and operated by BNI Coal, Inc. (BNI) and is adjacent to the MRYS facility. The lignite used as the fuel for electrical generation also serves as the primary source of the captured CO₂ that will be securely stored by Tundra SGS. The storage project together with the carbon capture project are commonly referred to as Project Tundra.

The proposed Tundra SGS injection site in Oliver County, North Dakota, will include up to three injection wells, one dedicated monitoring well for the lowest USDW (underground source of drinking water), and associated surface facility infrastructure that will accept CO₂ transported via a CO₂ flowline. In addition, one deep subsurface monitoring well is proposed to be installed. Two wells are being evaluated for the injection of CO₂ into the Broom Creek Formation with the option of either a third Broom Creek well or a well for injection of CO₂ into the Black Island–Deadwood Formation. Project partners anticipate submitting applications and supporting documents for CO₂ storage facility permits to the North Dakota Department of Mineral Resources in 2021.

To acquire the necessary near-surface and subsurface information to fully characterize the site and meet the needs of the storage facility permits, two stratigraphic test wells were recently drilled, cored (>1300 feet of core), and logged. One of the wells was drilled outside of the CarbonSAFE project. In addition, approximately 21 miles of 2D seismic data and 12 square miles of 3D seismic data were acquired in the project area near MRYS and integrated into 6 square miles of existing 3D seismic data and the geophysical logs collected from the stratigraphic test wells.

Geophysical well logs were used to pick formation top depths and interpret lithology and petrophysical properties. The site-specific data collected were used to validate the presence of upper and lower seals and inform the construction of geologic models, reservoir simulations, geochemical modeling, and geomechanical analysis, with the goal of demonstrating the suitability of the formations for CO₂ storage and to complete the UIC (underground injection control) Class VI permitting assessments. Geologic modeling efforts incorporated the characterization data, and the resulting model was used in reservoir simulation to delineate the extent of the necessary pore space to store the CO₂ and support a risk-based area of review. Both large domain and small domain versions of these geomodels were created to accurately simulate small-scale CO₂ plume location and migration as well as large-scale pressure plume effects in each potential storage formation.

The EERC and the project team leveraged North Dakota’s Class VI Primacy status to prepare and submit applications for two storage facility permits and associated monitoring well and UIC Class VI injection wells. As such, the applications and their supporting documents were prepared in accordance with the North Dakota Century Code and the North Dakota Administrative Code and demonstrate that 1) the proposed Tundra SGS site comprises injection zones of sufficient areal extent, thickness, porosity, and permeability to receive up to 80 MMt of CO₂ over 20 years and
2) the confining and secondary confining zones are free of faults and transmissive fractures.