三塘湖盆地条湖组烃源岩地化特征及致密油油源对比

Geochemical Characteristics of Hydrocarbon Source Rock and Oilsource Correlation of Tight Oil in Tiaohu Formation,Santanghu Basin

通过对三塘湖盆地马朗-条湖凹陷条湖组二段烃源岩有机地球化学分析,认为条湖组二段上部泥岩和底部沉凝灰岩烃源岩有机质类型以Ⅱ_2型和Ⅲ型为主,总体处于低熟-成熟早期阶段;马朗凹陷条湖组泥质烃源岩TOC较高,但氯仿沥青"A"低,为中等-差烃源岩;条湖凹陷条湖组泥质烃源岩有机质丰度低,为差烃源岩。对马朗凹陷条二段沉凝灰岩烃源岩进行热压模拟实验,结果表明:马朗凹陷条二段含有机质凝灰岩产油率低于芦草沟组灰质泥岩产油率,经估算条湖组致密油自源比例不超过20%,主要以外来烃为主。通过原油与烃源岩生标等因素及碳同位素特征对比,认为条湖组致密油与芦草沟组二段源岩亲缘关系最近;与条湖组自身烃源岩存在差异;马朗凹陷条湖组致密油原油主要来自芦草沟组二段。

According to the geochemical analysis of hydrocarbon source rock in the second member of Tiaohu formation in Malang-Tiaohu depression of Santanghu basin,it is considered that organic matter type of source rock from the sedimentary tuff and mudstone of Tiaohu formation are mainly type Ⅱ2 and type Ⅲ ,are in the early stage of Low maturemature;In Tiaohu formation, Malang depression,the content of TOC in the argillaceous source rocks was high,but the content of the chloroform asphalt ＂A＂ was relatively low, belongs to middle to poor grading;In Tiaohu formation of Tiaohu depression,he abundance of organic matter in the argillaceous source rocks was low,belongs to poor grading.Based on the thermal pressure simulation experiments in the source rock from the sedimentary tuffin Tiaohu formation,Malang de- pression,the result shows that the oil productivity in the tuff from Tiaohu formation are lower than lime mudstone in the Lucaogou formation,it is verified that the source of tight oil in Tiaohu formation is mainly from the hydrocarbon in the other place.According to the characteristic contrast of the carbon isotope, crude oil and the biomarkers,it is considered that relationship between tight oil from Tiaohu formation and Source rock from Lucaogou formation are closest,the crude oil in Tiaohu formation of Malang depression is mainly from the second member of Tiaohu formation.