Abstract
Adsorption is an important phenomenon in surface chemistry, especially for nano-porous shales. In the shale gas-in-place, adsorbed gas could contribute up to 85%. However, adsorption is hard to quantitatively characterize due to different adsorption mechanisms, patterns, surfaces, and pore sizes. Moreover, key thermodynamic parameters, such as the enthalpy of adsorption, are challenging to determine due to uncertainties in adsorbed gas densities used in constructing absolute isotherms. In this paper, we revisit the Brunauer, Emmett, and Teller (BET) model, analytically simplify Ono-Kondo (OK) models for subsurface shales, and compare commonly used mono- and multilayer adsorption models (e.g., Langmuir, supercritical Dubinin-Radushkevich (SDR), supercritical BET (SBET), and simplified OK (OKs) models) with recently proposed pressure-dependent adsorption densities to develop a practical and reliable methodology that can be used in the supercritical state, typical for subsurface black shale conditions. Three independent data sets were used for nitrogen and methane adsorption isotherms at different temperatures. We demonstrate that adsorption predicted by the SDR model is comparable or lower than that predicted by the SBET model, but higher than the amounts predicted by Langmuir and OK models. The nitrogen BET method tends to underestimate the accessible SSA for methane. Measurement of isosteric heat of adsorption is suggested instead of the experimental fitting method, due to the significant difference between the calculated results by two commonly used methods. Experimental fitting and simulation methods are also briefly reviewed to guide future research on shale gas adsorption.
Original language | English |
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Article number | 119454 |
Journal | Fuel |
Volume | 287 |
DOIs | |
State | Published - Mar 1 2021 |
Funding
We acknowledge the financial support of Center for Energy Research, Training, and Innovation (CERTAIN Seed Grant), Friends of Orton Hall (FOH) Grants, AAPG Grant-in-Aid, Ohio Department of Natural Resources, Division of Geological Survey Grant (ONDR Rock Grant), Alumni Grants for Graduate Research and Scholarship at The Ohio State University, American Chemical Society Petroleum Research Funding. This work was supported in part by The Ohio State University Office of Energy and Environment. Special thanks are given to the Shaanxi Yanchang Petroleum (Group) Co. Ltd. for providing drilling cores used in our previous work. Contributions to previous measurements of experimental data and manuscript preparation by G.R. were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences and Biosciences Division. We acknowledge the financial support of Center for Energy Research, Training, and Innovation (CERTAIN Seed Grant), Friends of Orton Hall (FOH) Grants, AAPG Grant-in-Aid, Ohio Department of Natural Resources, Division of Geological Survey Grant (ONDR Rock Grant), Alumni Grants for Graduate Research and Scholarship at The Ohio State University, American Chemical Society Petroleum Research Funding. This work was supported in part by The Ohio State University Office of Energy and Environment. Special thanks are given to the Shaanxi Yanchang Petroleum (Group) Co., Ltd. for providing drilling cores used in our previous work. Contributions to previous measurements of experimental data and manuscript preparation by G.R. were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences and Biosciences Division.
Funders | Funder number |
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Division of Geological Survey | |
Friends of Orton Hall | |
Office of Basic Energy Sciences | |
Ohio Department of Natural Resources | |
Ohio State University Office of Energy and Environment | |
Shaanxi Yanchang Petroleum (Group) Co. Ltd. | |
U.S. Department of Energy | |
Department of Natural Resources | |
Office of Science | |
Basic Energy Sciences | |
American Chemical Society Petroleum Research Fund | |
Ohio State University | |
American Association of Petroleum Geologists | |
Chemical Sciences, Geosciences, and Biosciences Division |
Keywords
- Langmuir
- Ono-Kondo
- Shale gas
- Supercritical BET
- Supercritical Dubinin-Radushkevich
- Supercritical adsorption