Characterization of kerogen nanopores using 2D NMR relaxation and MD simulations

Philip M. Singer; Yunke Liu; Xinglin Wang; George J. Hirasaki; Arjun Valiya Parambathu; Walter G. Chapman; Dilipkumar N. Asthagiri; Eva G. Vinegar; Harold J. Vinegar

doi:10.1016/j.mrl.2025.200220

Characterization of kerogen nanopores using 2D NMR relaxation and MD simulations

Philip M. Singer
, Yunke Liu
, Xinglin Wang
, George J. Hirasaki
, Arjun Valiya Parambathu
, Walter G. Chapman
, Dilipkumar N. Asthagiri
, Eva G. Vinegar
, Harold J. Vinegar

Advanced Computing for Life Sciences and

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

The characterization of kerogen nanopores is crucial for predicting the geostorage capacity and recoverability of natural gas in unconventional gas shale reservoirs. Towards this end, a powerful technique is presented which integrates 2D NMR T ₁- T ₂ relaxation measurements with molecular dynamics (MD) simulations of hydrocarbons confined in the nanopores of kerogen. The integrated NMR-MD technique is demonstrated using T ₁- T ₂ measurements of kerogen isolates and organic-rich chalks saturated with heptane, together with MD simulations of heptane completely dissolved in a realistic kerogen model. The NMR-MD results are used to extract the swelling ratio and nanopore size distribution of kerogen as a function of depth in the reservoir. The effects of organic nanoconfinement on the T ₁ relaxation dispersion and T ₂ residual dipolar coupling of heptane are investigated, as well as the effect of downhole effective stress on the kerogen nanopore size as a function of depth and compaction. Potential applications in partially depleted gas shale reservoirs are discussed, including CO₂ utilization/geostorage, geostorage of green H₂, and integration of the NMR-MD technique with thermodynamic models for predicting the competitive sorption of gas mixtures in kerogen.

Original language	English
Article number	200220
Journal	Magnetic Resonance Letters
Volume	5
Issue number	4
DOIs	https://doi.org/10.1016/j.mrl.2025.200220
State	Published - Nov 2025

Funding

The authors wish to thank Vinegar Technologies LLC , Chevron Energy Technology Company , Rice University Consortium for Processes in Porous Media , and the American Chemical Society Petroleum Research Fund (No. ACS PRF 58859-ND6 ) for their financial support. The authors wish to thank Thiago J. Pinheiro dos Santos for the insightful discussions on the simulations. The authors are grateful to Core Laboratories for the Rock-Eval analysis and bitumen extraction, to Zealax Inc. for their technical support on the Bruker minispec, to the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy (No. DE-AC02-05CH11231), and to the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for high-performance computer time and support. Research at Oak Ridge National Laboratory is supported under contract DE-AC05-00OR22725 from the U.S. Department of Energy to UT-Battelle, LLC. This research used resources of National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract # DE-AC02-05CH11231. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).

Keywords

Compaction
Effective stress
Nanoconfinement
Relaxation dispersion
Residual dipolar coupling
T-T mapping

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10.1016/j.mrl.2025.200220

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title = "Characterization of kerogen nanopores using 2D NMR relaxation and MD simulations",

abstract = "The characterization of kerogen nanopores is crucial for predicting the geostorage capacity and recoverability of natural gas in unconventional gas shale reservoirs. Towards this end, a powerful technique is presented which integrates 2D NMR T 1- T 2 relaxation measurements with molecular dynamics (MD) simulations of hydrocarbons confined in the nanopores of kerogen. The integrated NMR-MD technique is demonstrated using T 1- T 2 measurements of kerogen isolates and organic-rich chalks saturated with heptane, together with MD simulations of heptane completely dissolved in a realistic kerogen model. The NMR-MD results are used to extract the swelling ratio and nanopore size distribution of kerogen as a function of depth in the reservoir. The effects of organic nanoconfinement on the T 1 relaxation dispersion and T 2 residual dipolar coupling of heptane are investigated, as well as the effect of downhole effective stress on the kerogen nanopore size as a function of depth and compaction. Potential applications in partially depleted gas shale reservoirs are discussed, including CO2 utilization/geostorage, geostorage of green H2, and integration of the NMR-MD technique with thermodynamic models for predicting the competitive sorption of gas mixtures in kerogen.",

keywords = "Compaction, Effective stress, Nanoconfinement, Relaxation dispersion, Residual dipolar coupling, T-T mapping",

author = "Singer, \{Philip M.\} and Yunke Liu and Xinglin Wang and Hirasaki, \{George J.\} and \{Valiya Parambathu\}, Arjun and Chapman, \{Walter G.\} and Asthagiri, \{Dilipkumar N.\} and Vinegar, \{Eva G.\} and Vinegar, \{Harold J.\}",

note = "Publisher Copyright: {\textcopyright} 2025 The Authors.",

year = "2025",

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doi = "10.1016/j.mrl.2025.200220",

language = "English",

volume = "5",

journal = "Magnetic Resonance Letters",

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AU - Singer, Philip M.

AU - Liu, Yunke

AU - Wang, Xinglin

AU - Hirasaki, George J.

AU - Valiya Parambathu, Arjun

AU - Chapman, Walter G.

AU - Asthagiri, Dilipkumar N.

AU - Vinegar, Eva G.

AU - Vinegar, Harold J.

PY - 2025/11

Y1 - 2025/11

N2 - The characterization of kerogen nanopores is crucial for predicting the geostorage capacity and recoverability of natural gas in unconventional gas shale reservoirs. Towards this end, a powerful technique is presented which integrates 2D NMR T 1- T 2 relaxation measurements with molecular dynamics (MD) simulations of hydrocarbons confined in the nanopores of kerogen. The integrated NMR-MD technique is demonstrated using T 1- T 2 measurements of kerogen isolates and organic-rich chalks saturated with heptane, together with MD simulations of heptane completely dissolved in a realistic kerogen model. The NMR-MD results are used to extract the swelling ratio and nanopore size distribution of kerogen as a function of depth in the reservoir. The effects of organic nanoconfinement on the T 1 relaxation dispersion and T 2 residual dipolar coupling of heptane are investigated, as well as the effect of downhole effective stress on the kerogen nanopore size as a function of depth and compaction. Potential applications in partially depleted gas shale reservoirs are discussed, including CO2 utilization/geostorage, geostorage of green H2, and integration of the NMR-MD technique with thermodynamic models for predicting the competitive sorption of gas mixtures in kerogen.

AB - The characterization of kerogen nanopores is crucial for predicting the geostorage capacity and recoverability of natural gas in unconventional gas shale reservoirs. Towards this end, a powerful technique is presented which integrates 2D NMR T 1- T 2 relaxation measurements with molecular dynamics (MD) simulations of hydrocarbons confined in the nanopores of kerogen. The integrated NMR-MD technique is demonstrated using T 1- T 2 measurements of kerogen isolates and organic-rich chalks saturated with heptane, together with MD simulations of heptane completely dissolved in a realistic kerogen model. The NMR-MD results are used to extract the swelling ratio and nanopore size distribution of kerogen as a function of depth in the reservoir. The effects of organic nanoconfinement on the T 1 relaxation dispersion and T 2 residual dipolar coupling of heptane are investigated, as well as the effect of downhole effective stress on the kerogen nanopore size as a function of depth and compaction. Potential applications in partially depleted gas shale reservoirs are discussed, including CO2 utilization/geostorage, geostorage of green H2, and integration of the NMR-MD technique with thermodynamic models for predicting the competitive sorption of gas mixtures in kerogen.

KW - Compaction

KW - Effective stress

KW - Nanoconfinement

KW - Relaxation dispersion

KW - Residual dipolar coupling

KW - T-T mapping

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DO - 10.1016/j.mrl.2025.200220

M3 - Article

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JO - Magnetic Resonance Letters

JF - Magnetic Resonance Letters

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M1 - 200220

ER -

Characterization of kerogen nanopores using 2D NMR relaxation and MD simulations

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Keywords

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