科特迪瓦盆地下白垩统阿尔布阶烃源岩地球化学特征及分布规律

Geochemical characteristics and distribution of Lower Cretaceous Albian stage source rocks in Côte d’Ivoire Basin

科特迪瓦盆地是非洲重要的石油生产地之一,基于钻井、测井及地球化学资料综合分析,对区内白垩系湖相烃源岩进行了综合评价,利用有机碳法建立白垩系烃源岩总有机碳(total organic carbon,TOC)定量预测模型,厘定了烃源岩地震反射特征与地化特征的关系,并对主力烃源岩横向分布特征进行了研究。结果表明:下白垩统阿尔布阶烃源岩TOC均值为2.63%,以Ⅱ型干酪根为主,镜质体反射率(Ro)为0.3%~0.9%,主要处于低成熟-成熟阶段,整体属于好-优质烃源岩。优质烃源岩主要分布在盆地东部凹陷的中心区域,TOC值为4.00%~5.00%,发育厚度较大,连续性较好。

The Côte d’Ivoire Basin is one of the important oil production areas in Africa.Based on the comprehensive analysis of drilling,logging,and geochemical data in Côte d’Ivoire Basin,this paper comprehensively evaluated the Cretaceous lacustrine source rocks in the study area,established the total organic carbon(TOC)quantitative prediction model of the Cretaceous source rocks in the study area by using the organic carbon method,determined the relationship between seismic reflection characteristics and geochemical characteristics of the source rocks,and tracked the main source rocks horizontally.The results show that the TOC of the Lower Cretaceous Albian source rocks is 2.63%,the kerogen type II is dominant,and the Ro is 0.3%-0.9%.Source rocks are mainly in the low-mature to mature stage,and generally of good and premium quality.Premium quality source rocks are mainly distributed in the central area of the eastern depression of the basin,TOC values is ranging from 4.00%to 5.00%,thickness is large,and continuity is good.