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.
Exploration & Appraisal
United has access to almost 5000 km of 2D Seismic data, including 174 km acquired in 2014, as well as 203 km² of recently acquired 3D Seismic data on the blocks.
United has identified 222 closures (greater than 1 km2) on the blocks and has evaluated 26 prospects in both the Upper Cretaceous and Lower Cretaceous zones.
Ranking of prospects includes criteria such as prospective resource value, quality of seismic data, surface accessibility and proximity to roads and proposed CPF location, number of stacked closures, chance of success and capital requirements.
The current exploration portfolio accesses a total of 375 MMbbls of Unrisked Prospective Resources (McDaniel estimates) and 650 MMbbls of Unrisked Prospective Resources (internal estimates).
DISCOVERIES & PROSPECTS
There are four Upper Cretateous discoveries on the Doba blocks (Belanga-Campanian, Belanga-YO, Lara-YO & M’Biku-M) to date with 12.6 MMbbls of associated 2C Contingent Resource.
Using historical 2D Seismic and United acquired 2D and 3D Seismic, closures and prospects have been identified by United and validated by 3rd party evaluators GEOSEIS and McDaniels and Associates.
In total, 381 closure objects were identified with risking and volumetric screening resulting in 222 undrilled lead candidates, many of which are stacked.
United analysis of lead drill candidates indicate 1,015 MMbbls of Unrisked Mean Recoverable oil and 213 MMbbls of Risked Mean Recoverable oil on the Blocks.
3rd Party (McDaniel) analysis of the top 24 prospects indicate a total Unrisked Mean Prospective Resource of 471 MMbbls on the blocks.
CONTINGENT & PROSPECTIVE RESOURCE
United has completed multiple independent Contingent and Prospective Resource reports for DOC & DOD (Doba) blocks.
