Nanoscale Study of CO2-induced Geo-chemo-mechanical Alterations for Geological Carbon Sequestration: Case Study of the Illinois Basin Decatur Project
CEE 298 Winter Seminar Series
Ange Akono, Northwestern University
Tuesday, January 16, 2018 - 4:30 pm
Geological carbon sequestration (GCS) is the process of capturing man-made CO2 emissions and injecting them into underground storage repositories. GCS is considered a viable defense mechanism to climate change and the approach is being explored in many regions around the world including but not limited to Algeria, Canada, Australia, Norway, China, and the United States of America. However, a major concern of GCS is the presence of microseismicity recorded at carbon dioxide injection sites. An example is the Illinois Basin Decatur Project, a pilot project funded by the U. S. Department of Energy. One million tonnes of CO2 was injected from November 2011 until November 2014. During the three years of injections, a significant number of microseismic events was recorded. The presence of microseismicity fuels concern that widespread GCS might result in felt seismicity and infrastructure damage. Therefore, a fundamental understanding of fluid-rock interactions and their effect on the host rock mechanical constitutive behavior is necessary to ensure the structural integrity of geological carbon sequestration systems.
We focus on understanding the failure and fracture of Mt Simon sandstone, host rock in the Illinois Basin Decatur Project, as a result of incubation in fluids such as deionized water, brine, and CO2-saturated brine. Thanks to unique geomechanical characterization tools such as microscopic scratch testing, the changes in fracture resistance can be investigated at the pore level as a function of the rock geochemistry, the fluid chemistry, and the surrounding temperature. Rigorous and physics-based multi-scale approaches such as nonlinear micromechanics or microporomechanics are combined with high-resolution nanoscale depth-sensing methods such as statistical nanoindentation. This wide array of interdisciplinary techniques enables to probe the local constitutive behavior (elasto-plastic response, creep response, dynamic behavior, etc.) and predict the macroscopic mechanical response based on fluid-induced local changes in mineralogy, morphology, and composition. The research methodology and findings are important to guide future regulations and policies on carbon dioxide capture and storage.
Dr. Ange-Therese Akono is an Assistant Professor and Louis Berger Junior professor in the Department of Civil and Environmental Engineering at Northwestern University. Dr. Akono holds a PhD (2013) and an MSc (2011) from the Massachusetts Institute of Technology (United States), along with an MSc (2009) from the École Polytechnique (France). Dr. Akono’s honors include the NCSA faculty fellowship (2016-2017), the ASCE New Faces of Civil Engineering Professionals Award (UIUC, 2016), the ASCE nomination for the DiscoverE New Faces of Engineering Award (UIUC, 2016), the Academy for Excellence in Engineering Education Collins Fellowship (UIUC, 2015), and the MIT Energy Initiative Fellowship (MIT, 2009). Dr. Akono’s laboratory investigates fracture and failure mechanisms in complex materials systems from the molecular level up to the macroscopic scale. This research is articulated over three main thrusts: environment-friendly and high-performance structural materials, natural and nano-engineered biomaterials, and geological materials such as organic-rich shale or reservoir host rock. Dr. Akono’s areas of expertise include nano-mechanics, fracture analysis, nanotechnology, advanced experimental testing, and multiscale modeling.