The geochemical study of the sequences of 3rd order of the East of the margin of Abidjan permitted to identify the source rocks of the albian deposits. The pyrolytic methods applied to 30 samples of cuttings, from the drillings Freedom 1 and 2, revealed three types of organic matter at the early of maturity, the types III, II/III and II in the sequences. The variation of the origin of the organic matter in the systems tracts of the sequences testifies a change in the environment of deposit in phase with the eustatic fluctuations. The passage from the type III or II/III to the type II, eventually coupled with a rise of the values of the TOC and/or S2, in this study, evokes a rise in the marine level which would support the good conditions of safeguarding of the organic matter. The albian source rocks in the drilling Freedom 1 are bad source rocks whereas those in the drilling Freedom 2 are good producing source rocks of oil and/or gas hydrocarbon.

This work presents the results of palynological analysis of the Albo-Cenomanian interval of two wells located on the Abidjan margin in the offshore sedimentary basin of Côte d'Ivoire. It aims to reconstruct deposition environments during this interval coinciding with the oceanic anoxic event (EAO1) recorded in the Atlantic. After classical chemical attacks with strong acids, the palynomorphs extracted from 114 cuttings samples were identified and counted. The results show that out of 9786 registered palynomorphs 5108 belong to the Y-3M well and 4678 to the Y-4M well. Quantitative analysis of spore groups, pollen grains (Classopollis, Ephedripites, Araucariacites), elateres and dinocysts revealed a predominantly continental (littoro-deltaic) depositional environment with marine incursions. This sedimentation occurred under a predominantly arid to semi-arid palaeoclimate under relatively humid conditions in some places. These palynological quantitative approaches will help to refine the deposit environment of the Albian in Ivory Coast.

This paper presents the results of the detailed petrographical analysis of sandstone samples from three wells from the offshore Ivorian Basin. The study reveals the presence of three types of sandstones in the Albian – Cenomanian succession, namely subarkoses, arkoses and lithic arenites, with dominant detrital minerals comprising quartz, feldspar and lithic fragments. The main authigenic minerals comprise calcite, siderite, silica, kaolinite and pyrite, while the key diagenetic events include compaction, dissolution and recrystallization of feldspar, neoformation and replacement of feldspar, and finally cementation. Primary pore spaces are reduced or occluded by calcite, silica, siderite and pyrite. Secondary porosity was created locally from the dissolution of feldspars but has been partly reduced by authigenic kaolinite. The presence of illitized kaolinite overgrowths and dissolved feldspars, together with significant quartz and the mainly concavo-convex and stylolithic contacts between quartz grains, suggest that the Albian-Cenomanian sandstones of the Ivorian Basin have reached an advanced stage of diagenesis. These diagenetic processes affect petrophysical values which varied as a function of depth.