Effect of Nanoconfinement on NMR Relaxation of Heptane in Kerogen from Molecular Simulations and Measurements

Kerogen-rich shale reservoirs will play a key role during the energy transition, yet the effects of nanoconfinement on the NMR relaxation of hydrocarbons in kerogen are poorly understood. We use atomistic MD simulations to investigate the effects of nanoconfinement on the 1H NMR relaxation times T 1...

Full description

Saved in:
Bibliographic Details
Published in:The journal of physical chemistry letters 2023-02, Vol.14 (4), p.1059-1065
Main Authors: Valiya Parambathu, Arjun, Chapman, Walter G., Hirasaki, George J., Asthagiri, Dilipkumar, Singer, Philip M.
Format: Article
Language:English
Subjects:
Colloids
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Nanopores
Nuclear magnetic resonance spectroscopy
Physical Insights into Materials and Molecular Properties
Quantum confinement
Shale
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Kerogen-rich shale reservoirs will play a key role during the energy transition, yet the effects of nanoconfinement on the NMR relaxation of hydrocarbons in kerogen are poorly understood. We use atomistic MD simulations to investigate the effects of nanoconfinement on the 1H NMR relaxation times T 1 and T 2 of heptane in kerogen. In the case of T 1, we discover the important role of confinement in reducing T 1 by ∼3 orders of magnitude from that of bulk heptane, in agreement with measurements of heptane dissolved in kerogen from the Kimmeridge Shale, without any models or free parameters. In the case of T 2, we discover that confinement breaks spatial isotropy and gives rise to residual dipolar coupling which reduces T 2 by ∼5 orders of magnitude from the value for bulk heptane. We use the simulated T 2 to calibrate the surface relaxivity and thence predict the pore-size distribution of the organic nanopores in kerogen, without additional experimental data.
ISSN:1948-7185
1948-7185
DOI:10.1021/acs.jpclett.2c03699