塔斯马尼亚油页岩生烃模拟排出油与滞留油地球化学对比Ⅰ：族组分及同位素组成

A comparative study on the geochemical characteristics of expelled and retained oil from hydrocarbon generation simulation of Australian Tasmanian oil shale Ⅰ: fraction and isotopic compositions

林静文 谢小敏 文志刚 吴芬婷 许锦 马中良 张雷

LIN Jingwen XIE Xiaomin WEN Zhigang WU Fenting XU Jin MA Zhongliang ZHANG Lei

油气地球化学与环境湖北省重点实验室, 武汉 430100 油气资源与勘探技术教育部重点实验室, 武汉 430100 长江大学 资源与环境学院, 武汉 430100 中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126

Hubei Key Laboratory of Petroleum Geochemistry and Environment, Wuhan, Hubei 430100, China Key Laboratory of Exploration Technologies for Oil and Gas Resources of Ministry of Education, Wuhan, Hubei 430100, China College of Resources and Environment, Yangtze University, Wuhan, Hubei 430100, China Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China

澳大利亚塔斯马尼亚下二叠统油页岩富含有机质，有机质的生物来源相对单一，主要为塔斯马尼亚藻，且成熟度较低，是热模拟实验的理想样品。为研究排出油与滞留油的地球化学特征和热演化特征，对其进行了生排烃模拟实验。结果表明，该油页岩的生油高峰为340℃；各温度点排出油与滞留油的族组分相对含量对比结果显示，以生油高峰温度点340℃为界，饱和烃和芳烃含量在此温度之前随着温度升高而减少，而生油高峰之后，则随着温度升高而增加；非烃与沥青质的含量则与饱和烃、芳烃的变化趋势相反。排出油中的饱和烃含量比滞留油高，滞留油中的芳烃含量明显大于排出油。排出油与滞留油的族组分稳定碳同位素都发生了倒转，芳烃具有最重的同位素，饱和烃和非烃次之，沥青质一般具有最轻的同位素。在整个模拟过程中，滞留油碳同位素皆重于排出油，芳烃碳同位素最为稳定，表明其可能是油源对比的有效指标。如将模拟生烃后高压釜内含滞留烃的页岩作为页岩油系统，热模拟后高压釜内页岩样品的含油饱和指数（OSI）值在生油高峰附近最高，从一定程度上指示成熟度是影响页岩油勘探的重要因素之一。

Australian Lower Permian Tasmanian oil shale is rich in organic matter with relatively lower maturity, and the bio-precursor of organic matter is dominated by Tasmanite. Thus it is an ideal sample for thermal simulation experiment. In order to study the compositional characteristics and thermal evolution characteristics of expelled and retained oil, artificial simulation experiments were carried out. Results show that the peak temperature for oil generation of Tasmanian oil shale is ~340 ℃. Taking the peak temperature of 340 ℃ as a boundary, the relative content of oil fractions at each temperature showed that, the content of saturated hydrocarbon and aromatic hydrocarbon decreased with the increase of temperature before 340 ℃, but increased with the increase of temperature after the peak point. The content of polar fraction and asphaltene is opposite to that of saturated aromatic fractions. The content of saturated hydrocarbon in expelled oil is higher than that in retained oil, and the content of aromatic hydrocarbon in retained oil is obviously higher than that in expelled oil. Stable carbon isotopes of the fractions of both expelled oil and retained oil have been reversed. Aromatics appeared to have the heaviest isotope, followed by saturated hydrocarbons and non-hydrocarbons. Asphaltenes generally have the lightest isotopic values. In the whole simulation process, the carbon isotope composition of retained oil is heavier than that of expelled oil, and the aromatic carbon isotope is the most stable, indicating that it is an effective indicator of oil source comparison. If the residual hydrocarbon shale in autoclave is taken as a shale oil system after hydrocarbon generation simulation, the oil saturation index (OSI) value of the shale samples in the autoclave after thermal simulation is the highest near the peak of oil generation, suggesting that maturity is one of the important factors affecting the exploration of shale oil.

国家自然科学基金面上项目 41972163;国家自然科学基金面上项目 42072154

https://doi.org/10.11781/sysydz202201150