In this paper we study the ability of logs to make an appreciable contribution in the search for complementary geological information by interpreting the data recorded during the prospecting of wells by nuclear probe. We focused on nuclear logs such as gamma-gamma (or density logs), neutron-neutron and natural radioactivity logs (gamma ray) used in the Mibale-18 well surveys located in the city of Muanda in Kongo Central a western province of Democratic Republic of Congo. It is much more a pedagogical and methodological approach of the subject intending to show that the logs are based on the measurements of some physical parameters which allow a horizontal and vertical follow-up of the lithological units with a correlation between the variations of the stratigraphic units between the drill holes of different logs.The different recordings in the Mibale-18 wellhave led to a qualitative differentiation of the various lithological units thereby confirming the restructuring of a stratigraphic log from the logs. The results obtained were coherent in the synthesis characterizing the oil reservoirs of the Mibale field in Muanda coastal basin in the Upper Pinda. In the drilling of the Mibale-18 well; it was possible to identify oil indices well marked by the stratigraphic recordings and correlations of the different measurements made by different probes. This allowed us to identify and limit the potential of our well.

Keywords : Logs, lithology, Mibale-18, Upper Pinda.