Taking bio-induced precipitation to the field for sustainable geo-energy storage: Experimental and numerical studies of leakage mitigation

There is a consensus that geologic hydrogen and CO₂ storage as critical geo-energy technologies will play a significant role in meeting the 2050 net-zero global carbon emission target. However, the potential leakage of stored CO₂ and hydrogen from the subsurface to shallower rocks or atmosphere through the faults/fractures expected in most subsurface rocks poses significant environmental and safety concerns. We propose reducing the permeability along these faults/fractures to curtail the gas leakage. This work presents the first-of-a-kind development of experimentally validated core-to-field-scale numerical models for studying the application of a biologically induced mineral precipitation (BIMP) technology to mitigate the leakage of the stored CO₂ and hydrogen from these subsurface rocks. Further, we proposed a novel approach for estimating the field-scale CO₂ and hydrogen gas storage efficiencies of applied BIMP technology for sealing the fractures/faults that serve as the leakage pathways. Relative to the core-scale experiments, our numerical model showed an accuracy of 95 % in the permeability reduction. We quantified CO₂ and hydrogen leakage through natural fractures at the field scale and observed a natural fracture permeability reduction of up to 100 % after the BIMP treatment for the fractures closest to the horizontal treatment well. Finally, the results after the BIMP treatment indicate an increase in the long-term CO₂ storage efficiency from 50 % to 77 % over 1100 years relative to pre-treatment, while the BIMP treatment increases the efficiency from 65 % to 87 % for 25-year cyclic storage and production of hydrogen. In conclusion, this work presents the first experimentally validated core-to-field-scale model for the application of BIMP to improve storage efficiency.