The Doba basin is part of the Central African Rift system located in the southwest portion of Chad.

The basin, about 300 km long and 150 km wide, includes a succession of fluvial deltaic and lacustrine sediments up to 7,500 meters thick that range in age from Neocomian to present day.

The Doba basin is marked by extensive folding and faulting related to stresses caused by continental break-up and the formation of the Atlantic Ocean.  It is a failed rift basin formed in the early Cretaceous (144-100 Ma), during the break-up of Gondwana and the opening of the South Atlantic Ocean.

Upper and Lower Cretaceous fluvial-deltaic sediments have resulted in the formation of multiple reservoirs in the Basin.  The succession of continental shales and sandstones provide stacked reservoirs, seals and hydrocarbons source rocks throughout the section.

The Lower Cretaceous is stratigraphically and informally subdivided, from bottom to top, into F, E, D, C, Mangara Formations and B stratigraphic units throughout the Doba Basin. There are oil shows in the E and oil production from the C and D formations.  The E and D formations are all very good candidates for hydrocarbon sources.  In the deepest part of the basin on block DOD, the Lower Cretaceous is section is approximately 5000 m thick.

The Upper Cretaceous is stratigraphically and informally subdivided, from bottom to top, into the A, M, Miandoum Formations and the Campanian zone throughout the Doba Basin.  Oil is produced from stacked sands within each of these formations. United’s discoveries are in sands with the M, Miandoum and Campanian zones.  The Upper Cretaceous reaches up to 3000 m in thickness.