冀中地区凝析油、轻质油油源的判别

IDENTIFICATION OF THE SOURCE OF THE CONDENSATE AND VOLATILE OIL IN JIZHONG REGION

本文依据凝析油、轻质油和生油岩、煤的轻烃分析及Ⅰ、Ⅱ、Ⅲ类干酪根和煤的热解气相色谱分析资料,进行了油/油、油/岩对比。对比结果表明,苏桥—文安地区石炭-二叠系和奥陶系的凝析油、轻质油中芳烃和环烷烃含量高,正构烷烃相对含量低,石蜡指数和庚烷值低,甲苯与正庚烷比值大于1.0,与煤系有机质特征相似,主要来自石炭-二叠纪煤系地层。根据庚烷值及饱和烃碳同位素推断,它们的生成和排出期为R_o=0.80—1.20％。其它地区的凝析油、轻质油轻烃组成特征与此相反,与下第三系Ⅰ、Ⅱ类生油母质特征相似,主要来自下第三系成熟度较高的生油岩。

Based upon the data from an analysis of the light hydrocarbons from the condensate, volatile oil and source rocks and those from the Py-GC analysis of type Ⅰ, Ⅱ and Ⅲ kerogen and coal, this paper gives a correlation between oil/oil and oil/source rocks. Correlation results show that condensate oil and light oil in Carboniferous-Permian and Ordovician formations in Suqiao-Wenan region is characterized by high content of aromatics and naphthenes, low content of normal aliphatic hydrocarbons, low paraffin index and heptane value, and with a toluene/n-heptane ratio>1. These features are similar to those of coaliferous formations, and therefore they should mainly come from C-P coaliferous formations. It is predicted from the heptane value and C-isotopes that their generation and expulsion occured at a time when R_o=0.8-1.20%. The condensate oil in other regions has a features just on the contrary, with a toluene/n-heptane<1.0, and is similar to those of the type Ⅰ, Ⅱ source materials. They should come from the relatively highly matured source rocks in the Lower Tertiary formations.