Abstract

The offshore of the United Arab Emirates (U.A.E.) contains eight diapiric islands; Dalma, Zirkouh, Qarnain, Das, Sir Bani Yas, Arzana, Sir Abu Nuwair and Abu Musa. These islands and Jebel Dhanna Peninsula owe their relief to the diapiric movement of salt which has pierced and deformed the overlying strata. These diapiric islands have similar shapes, stratigraphic sequences, areal distribution of the identified stratigraphic units and general tectonic framework. With the exception of Das Island, the stratigraphic sequence on the surface of all the diapiric islands consists, in ascending order, of: 1) Infracambrian to Cambrian (Hormuz Group) composed of igneous and metamorphic rocks, salt, anhydrite, carbonate and clastic interbeds; 2) Miocene composed of sandstone, siltstone, shale, carbonate and evaporite interbeds; and, 3) Pliocene to Recent sediments composed of mixed facies of clastics, carbonates and evaporites. The structural configuration and the tectonic development of the Arabian Gulf Basin played an important role in the salt movement, which enhanced the formation and distribution of the islands, the timing of hydrocarbon generation, migration, and entrapment in the surrounding fields. The U.A.E., one of the world's richest in oil reserves, has almost 200 billion barrels (Bbbl) of oil and 275 trillion cubic feet (TCF) of gas that is sourced mainly from the Upper Jurassic and Lower to Middle Cretaceous formations and accumulated in carbonate reservoirs that range in age from upper Paleozoic to Oligo-Miocene. The geophysical and the geological data revealed three trap geneses in the U.A.E.: 1) Salt-related; 2) basement-related; and, 3) fold belt (collision) traps. Salt-related oil fields of the U.A.E. offshore area are characterized by: (a) dome-shaped structures; (b) independent closures; (c) radial faults within the structures; and, (d) multi-step structural growth histories. Subtle turtle structures exist between the diapiric islands of the U.A.E.. These structures form fields at Hair Dalma and Dalma, near Dalma Island, Mandous field, near Sir Abu Nuwair Island, and Mubarek field near the Abu Musa Island. The quality of the carbonate reservoir in the salt related oil fields is attributed to the effects of the diapiric salt movement.

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