The Precambrian succession of Oman from Platform to Basin: Predicting reservoir and source rock distribution

Abstract

Summary Based on recent multidisciplinary studies of the Precambrian succession of Oman, both in PDO cores and in outcrops, a new correlation from type sections in outcrops to the subsurface is proposed. The results have implications for source and reservoir rock distribution, stratigraphy, and Precambrian tectonic setting and evolution of Oman. The type Precambrian Nafun Group sections are found in the Huqf outcrops of central Oman, and represent a proximal, continental to shallow marine sequence up to ~2000 m thick. The succession studied in the subsurface is ~800 m thick and dominated by deeper water, basinal deposits with numerous source rock intervals and poor potential as conventional reservoirs, more alike the Precambrian succession exposed in north Oman. Reservoir rocks are proven in shallow water carbonate deposits of the Khufai and Buah Formations, and are possible in clastic deposits of the Masirah Bay Formation. The best source rocks are found in basinal deposits of the Masirah Bay, Khufai and Buah Formations, and were deposited during transgressive system tracks. Paleofacies maps and regional distribution support Ediacaran deposition controlled by regional thermal subsidence along a passive margin on the eastern side of the Mozambique Ocean.