摘要：Graphical abstractDisplay OmittedHighlights•Organic-inorganic interactions occur differently innC16H34-water–mineral systems.•Different waters and minerals affectednC16H34degradation.•Different interactions generate different hydrocarbons.•Chemical diagenesis does not cease in hot reservoirs with the presence of water.AbstractOrganic-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 ofnC16H34, water (distilled water, CaCl2water) 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 affectednC16H34degradation 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 CaCl2water on thenC16H34degradation 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 onnC16H34degradation, via its impact on mineral alterations. In the anhydrousnC16H34-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 hydrousnC16H34-distilled water–mineral systems, all minerals but quartz promotednC16H34degradation to generate more LMW alkanes, less HMW alkanes and PAHs. In thenC16H34-CaCl2water–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 differentnC16H34-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 differentnC16H34-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.
关键词：KeywordsennC16H34-water–mineral systemsOrganic-inorganic interactionsHydrocarbon degradationMineral alterationDeeply buried hot reservoirs
