Our multiscale approach probes the physical, chemical, and transport processes for hydrogen geostorage and recovery & carbon dioxide utilization and geostorage in unconventional organic-rich shale, from the molecular scale (nm), to the core scale (cm), and to the reservoir scale (km), using our unique combination of:
NMR Measurements
Example of a 2D T1–T2 map using our novel 2D NMR pulse sequence to quantify signal from both the solid phases (kerogen, bitumen, clay hydroxyls) and fluid phases (micro-macro pore heptane, heptane dissolved in kerogen, clay-bound water) in a heptane-saturated core from a Type II-S organic-rich chalk reservoir.
Adapted from : Yunke Liu et al. 2023
SEM image shows how the organic matter (O/M, i.e., kerogen and bitumen) resides in the macro-pore space by coating the carbonate grains (Ca), which corroborates the NMR interpretation.
Adapted from : Zeliang Chen et al. 2019
Our novel NMR (nuclear magnetic resonance) approach can quantify and monitor methane vs hydrogen recovery from each pore type (e.g., micro-fractures, inorganic meso-macro pores, and organic nanopores) using 2D T1–T2 maps on gas shale cores, as a function of methane draw-down pressure, hydrogen injection pressure, and rock properties including mineralogy, permeability, total organic content, and thermal maturity.
Molecular Simulations
MD simulations of 1H-1H dipole-dipole relaxation of heptane completely dissolved in a realistic Type-II kerogen model (left) using our novel concept of “molecular modes of NMR relaxation”, without any free parameters. Our simulations predict T1 dispersion (i.e., frequency dependence), residual dipolar coupling in T2 , and NMR surface relaxivity.
Measurement of NMR nanopore size distribution in kerogen using the surface relaxivity from MD simulations, without requiring additional experimental data such as gas-adsorption isotherms.
Our novel MD (molecular dynamics) simulations and GCMC (grand canonical Monte Carlo) simulations can extrapolate the NMR response at reservoir pressure and temperature conditions, which is not readily achievable in the laboratory. Our molecular simulations can also provide information on storage and transport of hydrogen and methane in kerogen.
Adapted from: Arjun Valiya Parambathu et al. 2023
Geostorage Workflows
Reservoir simulations are then used to upscale the results from the core scale (cm) to the reservoir scale (km) for planning pilot tests. Some of the geostorage workflows under investigation include:
Current research on hydrogen geostorage focuses on the use of salt caverns, saline aquifers, and depleted sandstone gas reservoirs. One alternative is to store green hydrogen (i.e., hydrogen produced from renewable energy sources) in partially depleted gas shale reservoirs, for their vast existing geostorage capacity, their access to pipelines and other infrastructure, and their proximity to green hydrogen production from renewable energy sources, all in one centralized location.
Another alternative is to produce blue hydrogen (i.e., hydrogen produced from steam methane reforming and carbon dioxide geostorage), all in one centralized location.
Multi-well super pads have 24 horizontal wells, or more. Each horizontal well could be selected for either carbon dioxide geostorage, blue hydrogen geostorage & recovery, or, green hydrogen geostorage & recovery, all in one centralized location.
Furthermore, while one well is being pressurized with hydrogen for geostorage, an adjacent well can be depressurized for hydrogen recovery, thereby providing a continuous source of hydrogen; i.e., a continuous “hydrogen battery”.