Optimal and sustainable oil extraction is made possible by an excellent understanding of the reservoir in which it is trapped. The Cenomanian reservoir of the Makelekese field is subdivided into eleven distinct sequences (ranging from A to K) consisting essentially of carbonates (calcite and dolomite), silts and clays (smectite, illite, kaolinite, chlorite, mica). This lithological heterogeneity, characterized by significant clayey, is the basis of the degradation of the permeability of the reservoir and influences the flow of fluids, and therefore the productivity of the wells. An oil reservoir is an invisible and complex physical system that we want to know as well as possible from the information obtained by geologists and geophysicists. Some data provide direct knowledge of the subsoil, localized to areas where drilling has been carried out, for example lithological parameters taken from logs. In addition, given the unsuitability of the Cenomanian reservoir (due to its high argillosity), a study of the three-dimensional distribution of the clay facies with quantification of the estimation uncertainties by geostatistical methods allowed us to subdivide the Cenomanian reservoir into four zones, including the most clayey would be located in the southwest of the reservoir, with a clay content exceeding 57.4206% and the least clayey in the southeast, with a clay content below 41.867%. The approach used in the context of this study therefore showed the influence of clays on the daily production (in barrels) of four wells in the Makelekese field and made it possible to identify the target areas for a planned intervention technique such as Hydraulic fracking.

The possibility of existence of viable petroleum systems in west Congolien Basin has been subject to controversies over the last decade, given the extreme Tectonical events that underwent this sedimentary basin. Some studies have reported interesting results regarding potential source rocks and the organic matter input. Here, we report the petrophysical investigation of geological formations outcropping around Sekelolo and Kwilu/Snel, of which lithological units are likely to bear fluids, thus playing the role of oil and gas reservoir. The porosity and the permeability obtained from Laboratory analyses, range within 10-15% and >250 millidarcy respectively. Petrophysical results suggest the existence of very good reservoirs, while further studies are necessary to elucidate the maturation and preservation of organic matter from secondary alteration during the evolution of the basin.