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Interfacial Adsorption Kinetics of Methane in Microporous Kerogen
Runxi Wang,
Saikat Datta,
Jun Li,
Saad F. K. Al-Afnan 
,
Livio Gibelli,
Matthew K. Borg
,
Livio Gibelli,
Matthew K. Borg
Langmuir, Volume: 39, Issue: 10, Pages: 3742 - 3751
Swansea University Author: Saikat Datta
DOI (Published version): 10.1021/acs.langmuir.2c03485
Abstract
Rapid declines in unconventional shale production arise from the poorly understood interplay between gas transport and adsorption processes in microporous organic rock. Here, we use high-fidelity molecular dynamics (MD) simulations to resolve the time-varying adsorption of methane gas in realistic o...
| Published in: | Langmuir |
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| ISSN: | 0743-7463 1520-5827 |
| Published: |
American Chemical Society (ACS)
2023
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| Online Access: |
Check full text
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa69379 |
| Abstract: |
Rapid declines in unconventional shale production arise from the poorly understood interplay between gas transport and adsorption processes in microporous organic rock. Here, we use high-fidelity molecular dynamics (MD) simulations to resolve the time-varying adsorption of methane gas in realistic organic rock samples, known as kerogen. The kerogen samples derive from various geological shale fields with porosities ranging between 20% and 50%. We propose a kinetics sorption model based on a generalized solution of diffusive transport inside a nanopore to describe the adsorption kinetics in kerogen, which gives excellent fits with all our MD results, and we demonstrate it scales with the square of the length of kerogen. The MD adsorption time constants for all samples are compared with a simplified theoretical model, which we derive from the Langmuir isotherm for adsorption capacitance and the free-volume theory for steady, highly confined bulk transport. While the agreement with the MD results is qualitatively very good, it reveals that, in the limit of low porosity, the diffusive transport term dominates the characteristic time scale of adsorption, while the adsorption capacitance becomes important for higher pressures. This work provides the first data set for adsorption kinetics of methane in kerogen, a validated model to accurately describe this process, and a qualitative model that links adsorption capacitance and transport with the adsorption kinetics. Furthermore, this work paves the way to upscale interfacial adsorption processes to the next scale of gas transport simulations in mesopores and macropores of shale reservoirs. |
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| College: |
Faculty of Science and Engineering |
| Funders: |
The authors would like to thank Colin Bousige (and co-workers) for providing us the kerogen structures used in this work. This work was financial supported by King Fahd University of Petroleum and Minerals (KFUPM), Saudi Arabia. All MD simulations were run on ARCHER2, the UK’s national supercomputing service. M.K.B. and L.G. are thankful for the support from the Engineering and Physical Sciences Research Council (EP/N016602/1, EP/R007438/1, and EP/V012002/1). For the purpose of open access, the author has applied a CC BY public copyright license to any Author Accepted Manuscript version arising from this submission. |
| Issue: |
10 |
| Start Page: |
3742 |
| End Page: |
3751 |