Reservoirs of the Augila oil field consist of a carbonate and clastic unit and the underlying fractured and weathered granitic basement rock. The Upper Cretaceous sedimentary reservoir rocks were deposited along the crest of a paleohigh composed of lower Paleozoic or upper Precambrian granitic rocks. The regional high extended over an area greater than 1,000 sq mi (2,580+ sq km), had more than 2,000 ft (610 m) of topographic relief, and was intensely fractured and weathered prior to burial.

A diachronous basal clastic unit, composed of basement-derived material deposited as the sea advanced across the high, grades upward and laterally into carbonate rocks forming a single sedimentary reservoir. Petrographic and ecologic studies indicate that porosity and permeability in the sedimentary reservoir are the result of the environments of deposition and diagenesis. The Augila field is divided into the following environmental sectors: (1) low energy--well protected from the open sea; (2) low to moderate energy--shallow marine and slightly protected; (3) low to moderate energy--shallow open-marine shelf; and (4) low energy--open marine. These depositional environments were controlled by granitic ridges which existed along the crest of the regional uplift and formed barrier islan s during deposition of the sedimentary reservoir.