W-3 well in Lower Congo Basin
The data shows TOC, major elements contents, minor elements contents and clay minerals contents form W-3 in Lower Congo Basin. The samples needed for element geochemical testing were taken from the debris samples of Lower Sendji, Upper Sendji, Likouala, Madingo and Paloukou Formations in W-3 Well, Lower Congo Basin. All samples were crushed by agate grinding bowl without pollution to more than 200 items. The major elements and trace elements (including rare earth elements) were tested by the State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Wuhan). Source rocks usually refer to the rocks buried in the ground that can generate oil and gas, which mainly include coal measures strata, mudstones, carbonate rocks and so on. The development of high-quality source rocks is mainly controlled by paleoproductivity and original preservation conditions. Both high productivity and good preservation conditions are indispensable. Nowadays, the analysis of paleoproductivity and preservation conditions includes qualitative and quantitative aspects. Quantitative analysis is usually carried out by micro-constant element analysis, such as P, which can be an evidence for upwelling. The relative content of P/Al can be used as an evaluation parameter for favorable exploration zones of source rocks. The mineralization degree of pyrite (the ratio of iron in pyrite to total active iron), V/Cr, Ni/Co, U/Th and so on are the most commonly used indicators for judging redox conditions and preservation environment of organic matter. Based on the geochemical indexes of related elements, the differences of terrigenous clastic influence, redox conditions and paleoproductivity can comprehensively compared, and the main factors controlling the organic matter enrichment of source rocks in the Lower Congo Basin are identified, which can provide reference for improving the identification and prediction accuracy of source rocks.