Our multiscale approach probes the physical, chemical, and transport processes for hydrogen geostorage & carbon dioxide utilization/geostorage in unconventional organic-rich shale, from the molecular-scale (i.e., Å) to the core-scale (i.e., cm), 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.
MD 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
Thermodynamics
Example of our novel thermodynamic computations mDFT and iSAFT used to predict the percentage of dissolved natural gas (for each gas component) in kerogen (as a function of maturity). The results highlight the competitive sorption of CO2 over hydrocarbons in kerogen.
Inputs into the kerogen composite model include kerogen (black) and nanopores (white) whose properties (3 nm and 15 vol%) are derived from our novel NMR measurements and MD simulations; red squares show the size of nanopores before the kerogen is swollen by the dissolved fluids.
Our novel mDFT (molecular density function theory) and iSAFT (interfacial statistical associating fluid theory) can predict the phase behavior based on pore-size distribution and kerogen maturity, as well as predict how kerogen properties influence the competitive sorption of methane versus hydrogen. Our thermodynamic computations provide an efficient computation of complex hydrocarbon mixtures confined by highly heterogeneous solids under a wide range of pressure and temperature conditions not readily achievable in the laboratory.
Adapted from: Jinlu Liu et al. 2019
Geostorage Workflows
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 carbon dioxide geostorage, hydrogen geostorage & recovery, or 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”.