多元热流体下油页岩干酪根演化行为的反应分子动力学研究

doi:10.3969/j.issn.2096-1693.2026.03.031

摘要/Abstract

摘要：

在油页岩原位转化过程中，干酪根结构高度交联、反应路径复杂，导致轻质产物生成受限，并易伴随碳骨架重排和重质组分积累。针对单一对流介质难以同时实现高效传热与化学改质的问题，本文构建了由60% 水蒸气(H₂O)、30%氧气(O₂)和10%二氧化碳(CO₂)组成的多元热流体体系，并基于ReaxFF反应分子动力学方法研究其对抚顺油页岩干酪根非等温演化行为的影响。结果表明，多元热流体显著促进产物轻质化，气态烃(C₁-C₄)和轻质油(C₅-C₁₃)产率分别由29.7%、26.3%提高至35.7%、30.5%；同时，重质组分C₁₄-C₄₀产率由29.5%降至26.5%，半焦C₄₀₊产率由12.6%降至5.9%。反应位点和化学键断裂分析表明，多元热流体能够促进桥连醚键和脂肪族C-C键等弱键提前断裂，使裂解路径由侧链断裂主导转变为骨架与侧链协同断裂。反应网络进一步表明，乙烯位于干酪根演化过程的反应网络核心枢纽，且多元热流体中H₂O与O₂位于反应网络核心区域附近，CO₂则主要发挥外围调控作用，整体体现出“氧化-供氢-调控”的协同机制。本研究从分子尺度系统揭示了多元热流体中各组分的协同作用机制及其对干酪根演化行为与产物分布的调控规律，为油页岩原位转化高效改质提供了理论参考。

关键词: 油页岩干酪根, 多元热流体, ReaxFF反应力场, 协同机制, 演化行为

Abstract:

During the in situ conversion of oil shale, the highly cross-linked structure and complex reaction pathways of kerogen restrict the formation of light products and are often accompanied by carbon skeleton rearrangement and the accumulation of heavy components. To address the difficulty of achieving both efficient heat transfer and chemical upgrading using the single convective medium, this study constructed the multi-component thermal fluid system composed of 60% steam (H₂O), 30% oxygen (O₂), and 10% carbon dioxide (CO₂), and investigated its influence on the non-isothermal evolution behavior of Fushun oil shale kerogen using ReaxFF reactive molecular dynamics simulations. The results show that the multi-component thermal fluid significantly promotes the formation of lighter products. The yields of gaseous hydrocarbons (C₁-C₄) and light oil (C₅-C₁₃) increased from 29.7% and 26.3% to 35.7% and 30.5%, respectively, while the yields of heavy components (C₁₄-C₄₀) and semi-coke (C₄₀₊) decreased from 29.5% and 12.6% to 26.5% and 5.9%, respectively. Reaction site and bond-breaking analyses indicate that the multi-component thermal fluid promotes the early cleavage of weak bonds such as bridged ether bonds and aliphatic C-C bonds, shifting the cracking pathway from side-chain-dominated cleavage to the synergistic cleavage of both the carbon skeleton and side chains. Reaction network analysis further shows that ethylene serves as a core hub in the reaction network during kerogen evolution. In the multi-component thermal fluid system, steam and oxygen are located near the core region of the reaction network, whereas CO₂ mainly plays a peripheral regulatory role, reflecting an overall synergistic mechanism of “oxidation-hydrogen donation-regulation.” This study systematically reveals, at the molecular scale, the synergistic roles of different components in the multi-component thermal fluid and their regulatory effects on kerogen evolution behavior and product distribution, providing theoretical guidance for efficient upgrading during oil shale in situ conversion.

Key words: oil shale kerogen, multi-component thermal fluid, ReaxFF reactive force field, synergistic mechanism, evolution behavior

中图分类号:

娄旭, 王敬, 颜若凡, 徐智远, 刘慧卿. 多元热流体下油页岩干酪根演化行为的反应分子动力学研究[J]. 石油科学通报, 2026, 11(5): 1685-1702.

LOU Xu, WANG Jing, YAN Ruofan, XU Zhiyuan, LIU Huiqing. Reactive molecular dynamics study on the evolution behavior of oil shale kerogen under multi-component thermal fluid[J]. Petroleum Science Bulletin, 2026, 11(5): 1685-1702.

https://sykxtb.cup.edu.cn/CN/Y2026/V11/I5/1685

图/表 18

图1 抚顺干酪根分子结构(C₂₂₈H₃₅₀N₆O₁₀S₃)

Fig. 1 Molecular structure of Fushun kerogen (C₂₂₈H₃₅₀N₆O₁₀S₃)

图2 反应分子动力学模拟过程中干酪根基质密度变化

Fig. 2 Density evolution of the kerogen matrix during reactive molecular dynamics simulations

图3 干酪根基质孔隙结构(浅蓝色为孔隙表面)

Fig. 3 Pore structure of the kerogen matrix (light blue represents the pore surface)

图4 不同反应氛围下油页岩热重实验

Fig. 4 Thermogravimetric experiments of oil shale under different reaction atmospheres

图5 非等温ReaxFF热解模拟干酪根失重特性与热重实验结果对比

Fig. 5 Comparison of mass loss characteristics of kerogen during non-isothermal ReaxFF pyrolysis simulation with thermogravimetric (TG) experimental results

图6 不同升温速率下干酪根裂解产物质量百分比

Fig. 6 Mass percentage of kerogen pyrolysis products at different heating rates

图7 典型烃类产物分子数量随温度变化

Fig. 7 Variation of molecular number of typical hydrocarbon products with temperature

图8 典型含氧化合物分子数量随温度变化

Fig. 8 Variation of molecular number of typical oxygenated compounds with temperature

图9 氢自由基数量随温度变化

Fig. 9 Variation of hydrogen free radical number with temperature

图10 含氧自由基数量随温度变化

Fig. 10 Variation of oxygen free radical with temperature

图11 不同反应条件下干酪根反应位点(蓝色箭头为初始反应位点，绿色箭头为二次反应位点)

Fig. 11 Kerogen reaction sites under different reaction conditions (the blue arrow is the initial reaction site, and the green arrow is the secondary reaction site)

图12 直接热解下干酪根演化过程反应网络及关键反应频次分布

Fig. 12 Reaction network and key reaction frequency distribution of kerogen evolution process under direct pyrolysis

图13 多元热流体热解下干酪根演化过程反应网络及关键反应频次分布

Fig. 13 Reaction network and key reaction frequency distribution of kerogen evolution process under multi-component thermal fluid pyrolysis

图14 多元热流体作用下干酪根典型产物生成路径及贡献比例示意图

Fig. 14 Schematic diagram of typical product formation path and contribution ratio of kerogen under the action of multi-component thermal fluids

图15 直接热解下乙烯分子化学键断裂过程图

Fig. 15 Bond cleavage process of ethylene formation under direct pyrolysis

图16 多元热流体热解下乙烯分子化学键断裂过程图

Fig. 16 Bond cleavage process of ethylene formation under multi-component thermal fluid pyrolysis

图17 直接热解下甲烷分子化学键断裂过程图

Fig. 17 Bond cleavage process of methane formation under direct pyrolysis

图18 多元热流体热解下甲烷分子生成图

Fig. 18 Methane formation pathway under multi-component thermal fluid pyrolysis

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