DETERMINATION OF SEDIMENTARY THICKNESS FOR ASSESSING THE HYDROCARBON SOURCE ROCK POTENTIAL USING GRAVIMETRY: CASE OF MOUNT BANGU IN THE WEST CONGOLESE SUB-BASIN (DRC)

This study focuses on determining sedimentary thickness to evaluate the hydrocarbon source rock potential using the gravimetric method, applied at Mount Bangu in the West Congolese sub-basin of the Democratic Republic of Congo (DRC). The main objective is to accurately estimate the thickness of sedimentary formations and their burial depth, parameters that are essential for understanding the thermal maturation conditions of potential source rocks. To achieve this objective, we applied the method developed by J. Goguel, whose approach is well adapted to environments composed of fine-grained rocks, typical of our study area. The gravimetric data were processed using a gravity profile superimposed on the topography of Mount Bangu, which is considered, from a geophysical perspective, as a graben-like collapse structure. The classical steps of gravimetric processing were carried out: calculation of the Bouguer anomaly, separation of residual and regional anomalies, and derivations along the X, Y, and Z axes. The results obtained show a sedimentary thickness of approximately 5 km, with a lateral extension estimated at 13 km. Considering the regional geothermal gradient as studied in the Central Cuvette – to which the West Congolese sub-basin is attached – this depth places the sediments within the window of full maturity for liquid hydrocarbons. This suggests significant petroleum potential, further supported by surface hydrocarbon indicators such as dysmigration phenomena observed in nearby regions including Kimpese, Kisantu, and their surroundings. Thus, the gravimetric results reinforce the hypothesis of an active petroleum system within the West Congolese sub-basin and open perspectives for more detailed geological and geophysical investigations.