非洲乍得Bongor盆地西部凹陷烃源岩评价

Evaluation of Hydrocarbon Source Rocks in Western Sag of Chadian Bongor Basin in Africa

基于有机碳及岩石热解、干酪根碳同位素和干酪根镜检等地化资料,结合测井、录井及地质资料,从烃源岩的纵向分布、有机质丰度、类型和成熟度4个方面,对Bongor盆地西部凹陷下白垩统烃源岩的生烃潜力进行研究。研究结果表明,研究区烃源岩厚度大,分布范围广;有机质丰度高,大部分烃源岩为中等-好烃源岩,Prosopis和Mimosa层位烃源岩在有机质丰度上要优于上覆Kubla层位烃源岩;有机质类型较好,有机质类型主要为Ⅱ1-Ⅰ型,上覆的Kubla层位烃源岩相对Mimosa和Prosopis层位较差,其有机质类型主要为Ⅱ2;有机质基本都已经进入成熟演化阶段,部分烃源岩进入高成熟阶段。

Based on the geochemistry information of rock-eval,kerogen carbon isotope and kerogen microscope,in combination with the log,geological logging and geological information,the hydrocarbon generative potential of the lower Cretaceous source rocks in subdepression of the western is researched from four aspects of the vertical distribution of the source rock,oganic matter abundance,oganic matter type and the maturity.The research results indicate that the source rocks in the studied aera have large thickness and wide distribution;the abundance of the oganic matter is high,most of the source rocks belong to the middle-good source rocks,but the oganic matter abundance in deeper stratas of the Prosopis and Mimosa are better than that in the upper strata of Kubla;the oganic type is also good of TypeⅡ1andⅠ,but the shallow strata of Kubla is worse than the deep strata of Prosopis and Mimosa of TypeⅡ2;most source rocks in this area is in low mature level,and a small portion is over-mature.