富油煤有机地球化学特征及其地质指示意义

Organic geochemical characteristics and geological indicative significance of tar-rich coal

  • 摘要: 富油煤作为集煤基燃料、液态油气、气态能源三位一体的战略性矿产资源,其高效勘探与分级利用对于保障国家能源安全和实现煤炭资源价值最大化具有重要意义。针对当前富油煤有机地球化学特征认识不足及其评价中焦油产率单一指标的局限性,采用煤岩显微分析、可溶有机质族组分分离与生物标志化合物测试相结合的方法,系统分析了不同含油性煤的煤岩学特征、可溶有机质族组分组成及生物标志化合物分布规律,并探讨了焦油产率与煤岩−地球化学参数的关联性。研究结果表明,镜质体和类脂体与焦油产率呈显著正相关,惰质体与焦油产率呈显著负相关关系。富油煤(含高油煤)的氯仿沥青“A”质量分数(均值0.73%)显著高于含油煤(均值0.44%),且氯仿沥青“A”与焦油产率呈显著的正相关关系。富油煤(含高油煤)的饱和烃质量分数(均值21.99%)显著高于含油煤(均值10.22%),富油煤(含高油煤)的芳香烃质量分数(均值25.65%)显著低于含油煤(均值41.33%)。基于煤岩显微组分和生物标志化合物数据分析,建立了包含煤的显微组分、族组成及诸多分子标志物在内的3+3+9项综合评价指标体系。沉积环境分析表明,富油煤和高油煤形成于还原环境,其有机质来源以高等植物(如柏科、杉科)及浮游植物为主。研究成果能够科学、全面地预测和评价煤岩的含油性,有效弥补了焦油产率单一指标的局限性,为煤岩含油性预测提供了新的量化指标,对煤炭资源分级利用和高效开发具有重要指导意义。

     

    Abstract: As a strategic mineral resource that integrates coal-based fuel, liquid oil, and gaseous energy, the efficient exploration and tiered utilization of tar-rich coal are of great significance for ensuring national energy security and maximizing the value of coal resources. To address the current limitations in understanding the organic geochemical properties of tar-rich coal and the overreliance on tar yield as a sole evaluation criterion, this study integrates coal petrographic analysis, fractionation of soluble organic matter, and biomarker compound analysis to systematically investigate the petrographic features of coals with varying tar-bearing characteristics, the compositional profiles of soluble organic fractions, and the distribution patterns of biomarker compounds. The study further examines the correlation between tar yield and coal petrology–geochemical parameters. Results indicate that vitrinite and liptinite exhibit a significant positive correlation with tar yield, whereas inertinite shows a significant negative correlation. The chloroform asphalt “A” mass fraction (average 0.73%) in tar-rich coal (include tar-high coal) is significantly higher than that of tar-containing coal (average 0.44%), and demonstrates a strong positive correlation with tar yield. Additionally, the saturated hydrocarbon content in tar-rich coal (including tar-high coal) averages 21.99%, significantly exceeding the 10.22% observed in tar-containing coal; in contrast, the aromatic hydrocarbon mass fraction in tar-rich coal (average 25.65%) is considerably lower than that in tar-containing coal (average 41.33%). Based on these findings, a comprehensive classification system comprising three categories each for maceral composition, group components, and biomarker parameters was established. Sedimentary environment analysis reveals that tar-rich and tar-high coals formed under reducing conditions, with organic matter predominantly derived from higher plants (e.g., Cupressaceae, Pinaceae) and phytoplankton. The research findings enable a more scientific and comprehensive prediction and evaluation of the oil-bearing capacity of coal seams. They effectively address the limitations of relying solely on tar yield as an indicator, providing new quantitative metrics for predicting coal tar content. This holds significant guiding value for the tiered utilization and efficient development of coal resources.

     

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