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Evolution of nC16H34-water–mineral systems in thermal capsules and geological implications for deeply-buried hydrocarbon reservoirs

Yuan, Guang-Hui; Jin, Zi-Hao; Cao, Ying-Chang; Liu, Ke-Yu; Gluyas, Jon; Wang, Yan-Zhong; Xi, Ke-Lai

Evolution of nC16H34-water–mineral systems in thermal capsules and geological implications for deeply-buried hydrocarbon reservoirs Thumbnail


Guang-Hui Yuan

Zi-Hao Jin

Ying-Chang Cao

Ke-Yu Liu

Yan-Zhong Wang

Ke-Lai Xi


Organic-inorganic interactions between hydrocarbons and most minerals in deeply buried reservoirs remain unclear. In this study, gold capsules and fused silica capillary capsules (FSCCs) with different combinations of nC16H34, water (distilled water, CaCl2 water) and minerals (quartz, feldspar, calcite, kaolinite, smectite, and illite) were heated at 340 °C for 3–10 d, to investigate the evolution and reaction pathways of the organic–inorganic interactions in different hot systems. After heating, minerals exhibited little alteration in the anhydrous systems. Mineral alterations, however, occurred obviously in the hydrous systems. Different inorganic components affected nC16H34 degradation differently. Overall, water promoted the free-radical thermal-cracking reaction and step oxidation reaction but suppressed the free-radical cross-linking reaction. The impact of CaCl2 water on the nC16H34 degradation was weaker than the distilled water as high Ca2+ concentration suppressed the formation of free radicals. The presence of different waters also affects the impact of different minerals on nC16H34 degradation, via its impact on mineral alterations. In the anhydrous nC16H34-mineral systems, calcite and clays catalyzed generation of low-molecular-weight (LMW) alkanes, particularly the clays. Quartz, feldspar, and calcite catalyzed generation of high-molecular-weight (HMW) alkanes and PAHs, whereas clays catalyzed the generation of LMW alkanes and mono-bicyclic aromatic hydrocarbons (M-BAHs). In the hydrous nC16H34-distilled water–mineral systems, all minerals but quartz promoted nC16H34 degradation to generate more LMW alkanes, less HMW alkanes and PAHs. In the nC16H34-CaCl2 water–mineral systems, the promotion impact of minerals was weaker than that in the systems with distilled water. This study demonstrated the generation of different hydrocarbons with different fluorescence colors in the different nC16H34-water–mineral systems after heating for the same time, implying that fluorescence colors need to be interpreted carefully in investigation of hydrocarbon charging histories and oil origins in deeply buried reservoirs. Besides, the organic–inorganic interactions in different nC16H34-water–mineral systems proceeded in different pathways at different rates, which likely led to preservation of liquid hydrocarbons at different depth (temperature). Thus, quantitative investigations of the reaction kinetics in different hydrocarbon-water-rock systems are required to improve the prediction of hydrocarbon evolution in deeply buried hydrocarbon reservoirs. Graphical abstract


Yuan, G., Jin, Z., Cao, Y., Liu, K., Gluyas, J., Wang, Y., & Xi, K. (2022). Evolution of nC16H34-water–mineral systems in thermal capsules and geological implications for deeply-buried hydrocarbon reservoirs. Geoscience Frontiers, 13(2), Article 101322.

Journal Article Type Article
Acceptance Date Oct 23, 2021
Online Publication Date Jan 24, 2022
Publication Date 2022-03
Deposit Date Feb 16, 2022
Publicly Available Date Feb 17, 2022
Journal Geoscience Frontiers
Print ISSN 1674-9871
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 13
Issue 2
Article Number 101322


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This is an open access article distributed under the terms of the Creative Commons CC-BY license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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