苏北盆地溱潼凹陷古近系阜宁组二段页岩油基本特征及成因分析

Basic characteristics and genesis analysis of shale oil in the second member of Paleogene Funing Formation in Qintong Sag, Subei Basin

昝灵 白鸾羲 印燕铃 张琬璐

ZAN Ling BAI Luanxi YIN Yanling ZHANG Wanlu

中国石化 华东油气分公司, 南京 210019

East China Oil and Gas Company, SINOPEC, Nanjing, Jiangsu 210019, China

苏北盆地溱潼凹陷古近系阜宁组二段陆相页岩油具有高产、稳产特征，在剖析页岩油形成条件的基础上，通过原油物性和地化特征分析，揭示了阜二段页岩油的成因。溱潼凹陷阜二段泥页岩分布广、厚度大，有机质丰度和热演化程度适中，具备形成页岩油的良好物质基础。阜二段页岩油具有低气油比、高异常压力特征，为低含硫轻质—中质油，饱和烃和轻烃含量较高，原油伴生气以甲烷为主。页岩油β-胡萝卜烷、伽马蜡烷含量高，ααα-C29甾烷（20R）含量高于ααα-C27甾烷（20R），形成于咸水的还原环境。热演化程度是控制陆相页岩油品质的关键因素，深凹带阜二段处于生烃高峰，页岩油流动性较好。阜二段Ⅰ、Ⅱ亚段泥页岩普遍含有木栓质体（6.6%）和底栖藻无定型体（11.5%），在成熟阶段既生油又生气，有利于形成轻质组分。阜二段泥页岩具有相对适中的有机质丰度和矿物组成，吸附油能力较弱，滞留油以游离油（69%~96%）为主。

The continental shale oil in the second member of Paleogene Funing Formation in the Qintong Sag, Subei Basin has the characteristics of high and stable production. Based on the analysis of the formation conditions of shale oil, the genesis of shale oil is revealed according to crude oil geochemical characteristics and physical properties. Results show that the mud shale in the second member of Funing Formation in the Qintong Sag is widely distributed and thick, with medium organic matter abundance and moderate thermal evolution, which provides a good material basis for the formation of shale oil. The shale oil in the second member of Funing Formation has the characteristics of low gas/oil ratio and high pressure, which belongs to low sulfur and light to medium oil, with high content of saturated hydrocarbon and light hydrocarbon, and the associated gas of crude oil is mainly methane. The shale oil has high content of β-daucane and gammacerane, and its sterane content of ααα-C29 (20R) is higher than that of ααα-C27 (20R), indicating that it is formed in the reduction environment of salt water. Thermal evolution is the key factor controlling the quality of continental shale oil. The second member of Funing Formation in the deep sag zone is at the peak of hydrocarbon generation, and the shale oil has good fluidity. The mud shale in the Ⅰ and Ⅱ submembers of the second member of Funing Formation generally contains suberinite (6.6%) and amorphous body of benthic algal (11.5%), and can generate oil and gas at the mature stage, which is conducive to the formation of light components. The mud shale in the second member of Funing Formation has the characteristics of moderate organic matter abundance and mineral composition, and its oil adsorption capacity is poor, making the remaining oil mainly free oil (69%-96%).

中国石化科技部项目 P20049-3;中国石化科技部项目 P21112

https://doi.org/10.11781/sysydz202302356