海相页岩芳烃演化规律及成熟度指示意义——来自西加拿大盆地二白斑组自然演化与热模拟样品的对比研究

Aromatic hydrocarbon evolution patterns and maturity indication significance of marine shale: a comparative study of naturally evolved and thermally simulated samples from the Second White Specks Formation of Cretaceous Colorado Group, Western Canada Basin

葛祝时 左兆喜 肖七林 郑伦举 黄海平

GE Zhushi ZUO Zhaoxi XIAO Qilin ZHENG Lunju HUANG Haiping

1. 长江大学 资源与环境学院, 武汉 430100; 2. 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; 3. 中国地质大学(北京) 能源学院, 北京 100083

1. College of Resources and Environment, Yangtze University, Wuhan, Hubei 430100, China; 2. Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China; 3. School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China

选取西加拿大盆地白垩系科罗拉多群二白斑组低成熟海相页岩进行地层孔隙热解生烃模拟实验，利用GC-MS对自然演化系列样品和热模拟系列样品内的芳烃进行了定量分析，系统对比自然演化与热模拟样品芳烃地球化学特征。结果表明：(1)自然系列页岩三甲基萘和四甲基萘、菲和甲基菲绝对含量相对较高，且随着演化程度的增加而增加；热模拟系列页岩内菲和甲基菲绝对含量和变化趋势在较高的热演化程度下依然保持与自然系列相同，而三甲基萘和四甲基萘绝对含量相对较低且变化趋势不同，随成熟度增加表现为先增加后减少。(2)自然系列页岩三甲基萘指数(TMNR)值随埋深增加逐渐增大，而热模拟系列页岩TMNR值表现为先减小后增大；自然系列和热模拟系列页岩四甲基萘指数(TeMNR)值、甲基菲指数(MPI)值变化具有协同性，TeMNR值随成熟度的增加呈先减小后增大，MPI值随成熟度的增加而增加，表明菲系列化合物可有效指示热模拟和自然演化条件下页岩的成熟度。(3)热模拟实验在一定温度内能够较好地反演芳烃热演化历程，即：350 ℃之前热模拟页岩TMNR值与自然演化页岩的规律不同，350 ℃之后相同；425 ℃之前烷基菲相关参数与自然演化页岩的规律相同，超过425 ℃后与自然演化不同，这主要受温度达到临界值而导致芳烃演化机理改变以及升温速率和有机质赋存状态等因素的影响。

A pyrolysis hydrocarbon generation experiment was conducted on low-maturity marine shale from the Second White Specks (2WS) Formation of the Cretaceous Colorado Group in the Western Canada Basin. Using GC-MS, quantitative analysis of aromatics in naturally evolved and thermally simulated samples was performed to systematically compare the geochemical characteristics of aromatics in both sets of samples. The results indicated that: (1) In the naturally evolved series of 2WS shale, the absolute contents of trimethylnaphthalene (TMN), tetramethylnaphthalene (TeMN), phenanthrene (P) and methylphenanthrene (MP) were relatively higher andincreased with the degree of evolution. In the thermally simulated series, the absolute contents and trends of P and MP remained consistent with those of naturally evolved series at higher thermal evolution levels, whereas the absolute contents of TMN and TeMN were relatively lower and showed different trends, increasing initially and then decreasing with maturity. (2) The trimethylnaphthalene ratio (TMNR) values of the naturally evolved series increased gradually with burial depth, while the TMNR values of the thermally simulated series decreased initially and then increased. The tetramethylnaphthalene ratio (TeMNR) and methylphenanthrene index (MPI) values of both series showed a consistent pattern: TeMNR values decreased initially and then increased with maturity, while MPI values increased with maturity, suggesting that phenanthrene series compounds effectively indicated shale maturity under both thermal simulation and natural evolution conditions. (3) The thermal simulation experiment was capable of effectively replicating the thermal evolution process of aromatics within a certain temperature range. Specifically, TMNR values of the simulated shale deviated from the naturally evolved shale before 350 ℃ but became consistent after 350 ℃. Similarly, alkyl phenanthrenes-related parameters aligned with those of the naturally evolved shale before 425 ℃ but diverged significantly beyond 425 ℃. This divergence was primarily influenced by the change in aromatic evolution mechanisms when the temperature reached a critical value, as well as by factors such as heating rate and the state of organic matter.

国家自然科学基金企业创新发展联合基金“海相深层油气富集机理与关键工程技术基础研究”(U19B6003)资助。

https://doi.org/10.11781/sysydz202403590