CAREER: Shales as Barriers for Fluid Flow in Geoenergy Projects

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This Faculty Early Career Development (CAREER) award will blend methods from rock mechanics, soil mechanics, geology, and materials science to tackle the challenges in characterization of shales’ behavior from laboratory to field scales. Shale formations are abundant in the subsurface and are key for successfully reaching the net-zero emission target to mitigate climate change by storing heat, CO2, and H2 deep underground. The large sensitivity of these low-permeable nanoporous clay-rich materials to changes in degree of saturation, mechanical loading, pore pressure, and temperature, convert shale characterization into a very challenging task. Overcoming this challenge is a required step to reliably predict and model the short- and long-term response of shales in assessing the safety of low-carbon geoenergy projects. The research developments will be integrated in the educational program by training engineering students on approaching the design of energy geotechnics projects, guiding students to apply their knowledge to create video education modules and engage them in public deliberation, contributing to the nation’s effort to increase diversity in the STEM workforce and worldwide effort to mitigate climate change.The goal of this research is to substantially advance the understanding and measurement of the physical processes governing the response of partially or fully saturated shale-like materials subjected to thermo-hydro-mechanical (THM) loading. Despite the long duration of the characterization of coupled processes in shales (weeks to months at the laboratory scale and months to years at the field scale), this project will undertake these tasks enabling the development of realistic models to obtain accurate predictions for geoenergy projects. Experimental methods and standards will be developed to characterize the short- and long-term effect of THM loading on shales and control their degree of saturation. These deliverables will bring first-ever measurements of the poromechanical and two-phase flow parameters associated with the controlled partially saturated response of stiff clay-rich rock and provide data to benchmark material models. Field experiments will involve monitoring a long-term cool fluid injection in a shale formation and a geothermal field to evaluate the upscaling of laboratory data to the field scale achieved by a combination of high-performance finite element modeling and machine learning. The developed experimental and numerical tools will allow for prediction of long-term mechanical and transport response of shale-like materials and evaluation of subsurface projects within them, making designs feasible and safe.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.