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Title: Model representations of kerogen structures: An insight from density functional theory calculations and spectroscopic measurements

Molecular structures of kerogen control hydrocarbon production in unconventional reservoirs. Significant progress has been made in developing model representations of various kerogen structures. These models have been widely used for the prediction of gas adsorption and migration in shale matrix. However, using density functional perturbation theory (DFPT) calculations and vibrational spectroscopic measurements, we here show that a large gap may still remain between the existing model representations and actual kerogen structures, therefore calling for new model development. Using DFPT, we calculated Fourier transform infrared (FTIR) spectra for six most widely used kerogen structure models. The computed spectra were then systematically compared to the FTIR absorption spectra collected for kerogen samples isolated from Mancos, Woodford and Marcellus formations representing a wide range of kerogen origin and maturation conditions. Limited agreement between the model predictions and the measurements highlights that the existing kerogen models may still miss some key features in structural representation. A combination of DFPT calculations with spectroscopic measurements may provide a useful diagnostic tool for assessing the adequacy of a proposed structural model as well as for future model development. This approach may eventually help develop comprehensive infrared (IR)-fingerprints for tracing kerogen evolution.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [3]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Univ. of Nevada, Las Vegas, NV (United States). Dept. of Physics and Astronomy
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). MultiScale Materials Science for Energy and Environment (MSE2), The Joint CNRS-MIT Lab. Dept. of Civil and Environmental Engineering; Aix-Marseille Univ., Marseille (France). Interdisciplinary Center of Nanoscience of Marseille (CINaM)
Publication Date:
Report Number(s):
SAND2017-0775J
Journal ID: ISSN 2045-2322; 650701
Grant/Contract Number:
AC04-94AL85000; ANR-11-LABX-0053; ANR-11-IDEX-0001-02
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); SNL Laboratory Directed Research and Development (LDRD) Program; National Research Agency (ANR) (France)
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS
OSTI Identifier:
1399488

Weck, Philippe F., Kim, Eunja, Wang, Yifeng, Kruichak, Jessica N., Mills, Melissa M., Matteo, Edward N., and Pellenq, Roland J. -M.. Model representations of kerogen structures: An insight from density functional theory calculations and spectroscopic measurements. United States: N. p., Web. doi:10.1038/s41598-017-07310-9.
Weck, Philippe F., Kim, Eunja, Wang, Yifeng, Kruichak, Jessica N., Mills, Melissa M., Matteo, Edward N., & Pellenq, Roland J. -M.. Model representations of kerogen structures: An insight from density functional theory calculations and spectroscopic measurements. United States. doi:10.1038/s41598-017-07310-9.
Weck, Philippe F., Kim, Eunja, Wang, Yifeng, Kruichak, Jessica N., Mills, Melissa M., Matteo, Edward N., and Pellenq, Roland J. -M.. 2017. "Model representations of kerogen structures: An insight from density functional theory calculations and spectroscopic measurements". United States. doi:10.1038/s41598-017-07310-9. https://www.osti.gov/servlets/purl/1399488.
@article{osti_1399488,
title = {Model representations of kerogen structures: An insight from density functional theory calculations and spectroscopic measurements},
author = {Weck, Philippe F. and Kim, Eunja and Wang, Yifeng and Kruichak, Jessica N. and Mills, Melissa M. and Matteo, Edward N. and Pellenq, Roland J. -M.},
abstractNote = {Molecular structures of kerogen control hydrocarbon production in unconventional reservoirs. Significant progress has been made in developing model representations of various kerogen structures. These models have been widely used for the prediction of gas adsorption and migration in shale matrix. However, using density functional perturbation theory (DFPT) calculations and vibrational spectroscopic measurements, we here show that a large gap may still remain between the existing model representations and actual kerogen structures, therefore calling for new model development. Using DFPT, we calculated Fourier transform infrared (FTIR) spectra for six most widely used kerogen structure models. The computed spectra were then systematically compared to the FTIR absorption spectra collected for kerogen samples isolated from Mancos, Woodford and Marcellus formations representing a wide range of kerogen origin and maturation conditions. Limited agreement between the model predictions and the measurements highlights that the existing kerogen models may still miss some key features in structural representation. A combination of DFPT calculations with spectroscopic measurements may provide a useful diagnostic tool for assessing the adequacy of a proposed structural model as well as for future model development. This approach may eventually help develop comprehensive infrared (IR)-fingerprints for tracing kerogen evolution.},
doi = {10.1038/s41598-017-07310-9},
journal = {Scientific Reports},
number = ,
volume = 7,
place = {United States},
year = {2017},
month = {8}
}