张强凹陷七家子洼陷沙海组烃源岩地球化学特征

Geochemical characteristics of hydrocarbon source rocks from Shahai formation of Qijiazi sag in the Zhangqiang depression

七家子洼陷是张强凹陷南部地区的生油洼陷,其主要生油层位是沙海组,分为Ⅰ、Ⅱ油组,七家子洼陷沙海组烃源岩主要是暗色泥岩,厚度大、质地纯、分布面积广。有机质类型主要为腐殖–腐泥型、腐泥–腐殖型。通过对烃源岩样品的有机碳、氯仿沥青"A"、总烃、生烃潜量及烃转化率等丰度指标进行分析,表明该区烃源岩有机质丰度高,是品质较好的生油岩,为南部地区的各类圈闭提供了充足的油源。

Qijiazi sag is an oil sag in the north of Zhangqiang depression, the main oil-bearing beds are from Xiasha formation, which can be divided into Ⅰ and Ⅱ oil groups, both belonging to self-generating and self-preserving type. The hydrocarbon source rocks of the Qijiazi sag are mainly of dark mudstone, with a large thickness, pure mass and wide distribution area. Organic type is mainly of humic substances to sapropel type and sapropel to humic substances type. Based on the analysis of hydrocarbon source rocks of organic carbon, chloroform bitumen ‘A', total hydrocarbon, potential hydrocarbon generation and hydrocarbon conversion rate, hydrocarbon source rocks have high abundance of organic matter and belong to good oil source rock, which provides adequate oil for all kinds of traps in the south area.