Carbonate deposition and hydrocarbon reservoir development at the Precambrian-Cambrian boundary: The Ara Group in South Oman

The transgressive carbonate laminites are the main reservoir facies and thus represent a relatively unusual reservoir unit. The presence of organic material and the relative scarcity of carbonate mud influenced diagenesis and reservoir properties. Distribution of organic material and carbonate mud can be linked to specific environmental conditions (low physical and biogenic disturbance of sediment and stratified water mass) and the sequence stratigraphic position (low flux of fine-grained carbonate during TST). In contrast, diagenetic evaporite formation has largely degraded reservoir quality in porous shallow-water facies near the top of the A4C.