Page 9 - CEGE Magazine Fall 2022

“We are excited about this project because it will set us up, we hope,
to make a significant impact on a critical societal issue: climate change,” said Emmanuel Detournay, project director and Bennett Professor of Rock Mechanics in the Department of Civil, Environmental, and Geo- Engineering.
Co-director Joseph Labuz noted, “It is appropriate for the Center to be housed at the University of Minnesota because of our expertise in geomechanics.”
These actions are very much in the realm of the unknowns. Although the researchers have an inkling of the elements that need to be characterized and adjusted to achieve feasible CO2 storage in this way, there are extensive areas where a complete knowledge of engineered CO2 mineralization process in mafic and ultramafic rock is lacking. One key knowledge gap revolves around creating a strong, fundamental understanding of fluid flow and reactive transport in a fractured, multi-scale system where the permeability, porosity, pore space geometry, and available surface area for CO2 reaction and storage are continually changing through time.
Tight coordination and integration are necessary for the researchers to answer three fundamental overarching questions:
» What are the key factors and
processes that determine the CO2 mineralization rates (mass/time) in mafic and ultramafic rock masses?
» How do these factors and processes depend on the host rock lithology: mafic rocks (e.g., basalt) vs. ultramafic rocks (e.g., peridotite)?
» Once these factors and processes are identified and understood, how can the resulting models be deployed to generate hypotheses that can be tested at the scale of field operations?
In fact, the operational problems
occur at three distinct levels:
» Fracture network scale (>1m) forming the main arteries for moving CO2-laden fluid through the subsurface rock mass
» Fracture-porous medium system scale (0.1–1m) targeting individual links within the network, from which the fluid can infiltrate into the rock mass
Porous medium scale (< 0.1m) in
the rock mass, where the bulk of the mineralization will need to occur The schematic illustrates the scales and processes involved in the research and the connections between them, with
a need to tightly coordinate research findings across multiple scales.
The threads of geomechanics, geochemistry, porous media transport, and sensing technology are tightly woven through each research theme.
A multi-disciplinary, multi-institutional Center is the best way to approach such a complex issue. Mineral carbon storage, the focus of the Center research, has great potential to outpace the anthropogenic emissions of CO2 and even reverse some effects of climate change. CEGE is thrilled to have such passionate faculty focused on addressing one of the most important societal problems of our time.
Other University of Minnesota faculty involved in the Center include Peter Kang from the Department of Earth and Environmental Sciences, and Bojan Guzina, Joseph Labuz, Jia-Liang Le, Sonia Mogilevskaya, and Vaughan Voller from the Department of Civil, Environmental, and Geo- Engineering.
To make CO mineralization 2
efficient requires
1. Maximizing the reaction kinetics
by dissolving CO2 in water and adjusting pressure and temperature.
2. Increasing the rock surface available for reaction by pumping (injecting) the CO2 mixture through the fracture networks (natural or engineered) in the subsurface rock mass.
3. Creating self-sustaining, reaction- driven cracking pathways by which the CO2 mixture can progressively advance from the fracture network into and through the bulk of the rock mass.
4. Monitoring the progress of the mineralization via remote sensing, for example, via seismic imaging.
University of Minnesota College of Science and Engineering | DEPARTMENT OF CIVIL, ENVIRONMENTAL, AND GEO- ENGINEERING 9