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选取济阳坳陷东营凹陷古近系不同埋深的11块烃源岩样品,粉碎后提取粒径小于2μm黏粒级组分,分3个温度段(<300℃、300~500℃、500~650℃)进行全岩和黏粒级组分样品的热解—色谱检测,探讨不同温度段释放烃的特征和意义,以及黏粒级组分对于烃源岩生烃的贡献。结果表明:在不同温度段,不管是烃源岩全岩还是黏粒级组分,轻质油(C_5—C_(14))组分在所有组分中含量高,在300℃以前和300~500℃段轻质油组分含量超过50%,而在500~650℃段气态烃(C_1—C_4)(特别是甲烷)含量明显增加,而轻质油含量有所下降。在300~500℃段,不论是烃源岩全岩,还是黏粒级组分,生烃产率和产烃量的值都是最高的,其次是500~650℃段,最低的是300℃以前。通过不同温度段特征的比较,发现全岩和黏粒级组分的热解特征有相似之处,轻质油组分是烃源岩热解生烃的主要组分,且300~500℃是烃源岩生烃高峰温度段。对300~500℃段热解—色谱特征进一步研究发现,黏粒级组分的轻烃(C_1—C_(14))百分含量高于全岩,重烃组分(C_(15+))则相反,而且黏粒级组分总烃产量占全岩的平均值高达72.57%,这些特征表明黏粒级组分是烃源岩生烃的主要贡献者,且黏土吸附的有机质在有机质生烃过程中对轻烃组分(C_1—C_(14))的贡献显著。对烃源岩和黏粒级组分开展热解—色谱特征研究,可获取不同温度段释放烃或烃赋存等特征,这对开展有机质生烃和资源评价以及非常规油气赋存特征的研究都具有重要意义。
Eleven hydrocarbon source rock samples of different depths in the Paleogene of Dongying Sag, Jiyang Depression were selected. After crushing, the samples with the size of less than 2μm were fractionated into three temperature sections (<300 ℃, 300 ~ 500 ℃, 500 ~ 650 ℃), pyrolysis and chromatographic detection of whole rock and clay fraction samples were carried out to investigate the characteristics and significance of hydrocarbon release in different temperature ranges and the contribution of clay fraction to the hydrocarbon generation of source rocks. The results show that the content of light oil (C_5-C_ (14)) is high in all components at 300 ℃ and before at 300 ℃, The content of light oil in 500 ℃ is more than 50%, while the content of C 1 -C 4 (especially methane) in 500 ~ 650 ℃ is obviously increased while the content of light oil is decreased. At 300 ~ 500 ℃, the values of hydrocarbon generation rate and hydrocarbon production are the highest among the whole rock and clay-bearing fractions of source rocks, followed by 500 ~ 650 ℃, the lowest is 300 ℃ before. Through the comparison of the characteristics of different temperature sections, it is found that the pyrolysis characteristics of the whole rock and the clay fraction are similar. The light oil component is the major component of pyrolysis hydrocarbon generation in the source rock, and 300 ~ 500 ℃ is Hydrocarbon generation peak temperature of source rocks. Further study on the pyrolysis-chromatographic characteristics of 300-500 ℃ showed that the percentage of light hydrocarbon (C 1 -C 14) in the clay fraction was higher than that of the whole rock and heavy hydrocarbon (C 15+) On the contrary, the total hydrocarbon production of the clay-fractioned components accounts for 72.57% of the total rock mass. These characteristics indicate that clay-grade components are the major contributors to the hydrocarbon generation of hydrocarbon source rocks. In the light hydrocarbon component (C_1-C_ (14)) contribution is significant. The pyrolysis and chromatographic characterization of source rocks and clay fractions can be used to obtain the characteristics of hydrocarbon release and hydrocarbon occurrence in different temperature ranges, which is of great significance for organic hydrocarbon generation and resource assessment and unconventional hydrocarbon occurrence All have important meaning.