(204c) Confined Dynamics and Transport Properties of Organic Compounds

The production of oil and gas from unconventional shale reservoirs has increased significantly over the past ten years.¹ However, shale reservoirs have extremely low permeability, a few hundred nano-darcies (0.0001 md) to a few milli-darcies (1 md), due to the nanoscale pore sizes and complex pore structures.² Reservoir characterization and production forecasting are challenging, as organics in this environment have unusual storage mechanisms. A significant amount of storage in shale is due to fluid both adsorbed in the nanopores and absorbed/dissolved in the organic matrix.³ In this study, we will present DOSY NMR results of organic compounds in confined space (<4 nm pore size) to understand their transport and relaxation properties. The NMR approach is readily accessible at most universities and can rapidly collect data for transport (diffusion) and relaxation (T₂) of fluids in confined geometries for pure and multicomponent systems. The results uncovered complex relationships between molecular size and polarity with no simple trend able to explain the changes is transport characteristics as a result of nanoconfinement.

References:

1. Annual Energy Outlook, www.eia.gov/aeo, 2018.
2. EIA/ARI World Shale Gas and Shale Oil Resource Assessment, Shale gas and shale oil resource assessment methodology, 2013
3. Liu, J. and Chapman, W. Thermodynamic modeling of the equilibrium partitioning of hydrocarbons in nanoporous kerogen particles, Energy Fuels, 2019.