辽西-冀北坳陷中-上元古界油源及成藏期分析

Study on the Origin and Accumulation Stage of Hydrocarbon Distributed in the Middle-Upper Proterozoic System in the Liaoxi-Jibei Depression

利用有机地球化学分析技术,研究了辽西-冀北坳陷中-上元古界沥青、油苗显示相对集中的地层(雾迷山组、铁岭组和下马岭组)油气的来源、成熟程度与成藏期次。研究表明,区内中-上元古界部分地层有机质丰度较高,具备油气生成的物质基础,源岩多达到成熟-高成熟的演化阶段,是中-上元古界油气的主要贡献者。中-上元古界储层中存在大量类型各异的油气包裹体,根据油气包裹体的产状与光学特征可以判定它们分属不同地质时期储层流体活动的产物,指出中-上元古界经历了三到四期的油气成藏过程,中晚期油气成藏意义较大。

Advanced analytical methods of organic geochemistry are adopted to analyze the source rock and accumulation stages of hydrocarbon distributed in the Middle-Upper Proterozoic Wumishan, Tieling and Xiamaling formations in the Liaoxi-Jibei Depression. The result shows that the parts of the Middle-Upper Proterozoic formations have high organic abundance with high hydrocarbon maturity. They are the main source rocks of the investigated oil. There are many kinds of organic inclusions distributed in the Middle-Upper Proterozoic formations. The types, colors, fluorescence, distribution characteristics and homogenization temperatures of fluid inclusions are used to judge the various forming stages. It is believed that the Middle-Upper Proterozoic formations had experienced three or four stages of oil-gas migration and accumulation. The oil-gas accumulation in the mid-late stage is more favorable for forming oil-gas reservoirs.