Geology and Petrophysics of the Ozouri Group, Central Gabon

The Ozouri Group in Gabon is comprised of finely textured siliceous dolomitic and calcareous claystones, shales, limestones, dolomites, porcellanite and cherts. It was deposited during the Late Paleocene and Early Eocene on a transgressive continental margin. It is highly siliceous and organically rich, with affinities to the Miocene Monterey Formation of California. It is often fractured by deeper structural movement of the underlying Ezanga salt. Economic oil production from the Ozouri is dependent on the most effective combination of matrix (storage) and fracture (deliverability) porosity. The most efficient combination can be related to variations in the lithologic and petrophysical characteristics of the formation. Horizontal drilling techniques can be utilized to fully exploit production from the Ozouri Group.