Study On Distribution Characteristics Of Main Source Rocks In Lower Congo Basin

Lower Congo Basin is not only one of the series of salt bearing basins in West African passive continental margin,but also one of the most abundant basins of oil and gas resources in West African.There are five sets of hydrocarbon source rocks in the basin: Bucomazi group in Neocomian-Lower Aptian,Moita Seca group in Albian,Iabe group in Upper Cretaceous,Landana group in Paleocene-Oligocene,and Malembo group in Oligocene-Miocene.Through the sequence stratigraphic division of the target horizon,comprehensive identification of sedimentary facies,and comprehensive evaluation of source rocks,the following understandings have been drawn: The sequence stratigraphy of the Lower Congo Basin is divided into nine second-order sequences.Source rocks in SSQ1 and SSQ5-SSQ8 can be subdivided into 3,3,2,4,and 7 three-level sequences;four types of seismic facies can be identified in the Lower Congo Basin,At the same time,it is clear that the basin develops rift-phase lacustrine carbonate platform,transitional salt rocks,and marine turbidite facies in the passive continental margin from bottom to top.Based on this,the marine sedimentary model and salt-lake sedimentary model of the Lower Congo Basin were summarized;By studying the Bucomazi and Iabe formations of the main source rock in the Lower Congo Basin,it is believed that the longitudinal fault controlling of the two formations leads to poor lateral continuity and two formations are generally distributed along the direction of the basin trend on the plane;Based on the analysis of the main controlling factors about the production and preservation mechanisms in the Lower Congo Basin.,the main source rock development model in the Lower Congo Basin rift period and passive continental margin period was established.