上古生界煤系烃源岩显微组分组成及生烃特征——以渤海湾盆地石炭-二叠系烃源岩为例

The composition of maceral and the hydrocarbon-generation characteristics of upper Paleozoic coal-bearing source rocks:Taking Carboniferous-Permian source rocks in Bohai Bay Basin as an example

上古生界煤系烃源岩在渤海湾盆地广泛发育,是我国东部深层油气的主要贡献者之一。综合前人对该套烃源岩分布、地球化学特征及生烃演化特征研究成果,应用显微傅里叶红外光谱、激光热解-气相色谱、核磁共振等测试数据分析不同有机显微组分的化学成分及其结构差异,探讨煤系地层有机显微组分与倾油性、倾气性之间的关系;综合多个地区的煤系烃源岩和有机显微组分特征进行分析,明确黄骅坳陷各地区上古生界煤系烃源岩生烃潜力,为合理评价研究区上古生界煤系地层油气勘探前景提供参考。结果表明渤海湾盆地黄骅坳陷上古生界煤系烃源岩厚度大,有机显微组分以镜质组为主,富氢组分含量较高,壳质组+腐泥组含量为2.8%~54%,基质镜质体含量为2.68%~32.4%,生油能力最强的组分为角质体、树脂体和孢子体;由于区域构造活动的频繁及差异,导致复杂多样的构造热演化史,存在多种热演化生烃史类型,持续深埋型和稳定埋深型是探区内主要的生烃演化史类型,有利于二次生烃的形成以及油气保存,区域内孔西-王官屯、乌马营一带,以及歧北-张巨河地区是寻找上古生界煤成油气的有利地区。

The coal-bearing source rocks of upper Paleozoic are widely developed in the Bohai Bay Basin,which is one of the major contributors to deep oil and gas in eastern China.Based on the previous research results on the distribution,the geochemical characteristics and the hydrocarbon generation evolution characteristics of this set of source rocks,the analysis of chemical components and chemical structure differences about different organic maceral was carried out by using the test data from Micro-FTIR,laser pyrolysis-gas chromatography and NMR,the relationship between the organic maceral with the oil-prone and gas-prone of coal measure strata is discussed.According to the comprehensive analysis about the characteristics of coal-bearing source rocks and organic maceral in many areas,the hydrocarbon-generation potential of coal-bearing source rocks of upper Paleozoic in different areas of Huanghua depression is determined,it provides a reference for the reasonable evaluation about the prospect of oil and gas exploration of upper Paleozoic coal measure strata in the study.The results indicated that the coal-bearing source rocks of the upper Paleozoic in the Bohai Bay Basin are thick.The organic maceral was dominated by the vitrinite,the content of the rich hydrogen is higher,the percentage of exinite+sapropelinite is 2.8%-54%,the percentage of the desmocollinite is 2.68%-32.4%,the most powerful component of oil-generation is the cutinite,resinite and sporophyte.Due to the frequent and different regional tectonic activities,there are complex and diverse history of tectonic-thermal evolution and many kinds of thermal-evolution and hydrocarbon generation history,the continuous deep burial type and stable buried type are the main hydrocarbon generation evolution history types in the exploration area,it is beneficial to the formation of secondary hydrocarbon generation and the preservation of oil and gas.The belts of Kongxi-Wang Guantun,Wu Maying and Qibei-Zhang Juhe become the favorable areas to find the coal-formed oil(gas)of the upper Paleozoic within the region.