Geological Characterisation and Depositional Settings of Hydrocarbon Reservoirs in the Doba Basin in Chad: Implications for Exploration and Production

Abstract

This study investigates the lithostratigraphic architecture and depositional environment of petroleum reservoirs in the Doba oil field, located in the Lake Chad Basin. Scientific research that exhibits the important geological and geophysical settings of this basin is lacking. The sedimentary fill of the Doba Basin spans from the Early Cretaceous to the Late Cretaceous, with some sequences extending into the Cenozoic. Hydrocarbon production in Doba Basin, particularly the northern boundary, for instance, has not yet succeeded due to the unawareness of its depositional environment. Understanding these geological characteristics is crucial for optimising the exploration and exploitation of petroleum resources. The research involves analysing geological, well log, core sample and petrophysical data from the oil wells to identify and correlate lithostratigraphic units across the oil field. The results show that the architecture, chronostratigraphic interval, lithostratigraphic units, and depositional environment are limited to the clay, sand, anhydrite, coal, sandstone, and limestone deposits from the base of the Cretaceous. These deposits exhibit spatio-temporal dispersion across the study area, influenced by local and/or regional tectonic controls. The identified reservoirs exhibit excellent porosity characteristics, ranging from 25% - 29.5%, and permeability generally is greater than 600 millidarcies (md). The results of this study will serve for the future prospector on the neighboring oil and gas fields of our study area. Significant advances have been made to ensure future exploration success.