Online Journal for E&P Geoscientists

As-Saruri, Mustafa A.^*1
(1) Petroleum Exploration, Ministry of Oil & Minerals, San'a, Yemen.

The Mesozoic rift basins of Yemen formed due to the breakup of Gondwana and separation of India/Madagascar from Africa-Arabia during the Late Jurassic/Early Cretaceous. The five Mesozoic sedimentary rift basins reflect in their orientation an inheritance from deep-seated, reactivated NW-SE trending Infracambrian Najd fault system.

The Sab’atayn and Say’un-Masilah basins are the only ones producing oil and gas so far, separated by Jahi-Mukalla high from each other, are both filled with syn- and post-rift sediments and display many similarities in source rocks and reservoir rocks, although the Tithonian evaporite is absent in the latter. Petroleum reservoirs in both basins have been charged from bituminous shale of Upper Jurassic Madbi Formation. The main reservoirs in the Sab’atayn basin include sandstone units of the Alif Member of the Sab’atayn Formation (Tithonian), the turbiditic sandstones of the Lam Member of the Madbi Formation (Tithonian) and the Proterozoic fractured basement (upthrown fault block), while the main reservoirs in the Say’un-Masilah basin are sandstones of the Qishn Clastics Member of the Qishn Formation (Hauterivian/Barremian) and the Ghayl Member of the Sa’ar Formation (Berriasian/Valanginian), and the Proterozoic metamorphic fractured basement. The Balhaf and Jiza’-Qamar basins, located respectively in central and eastern Yemen, contain a thick succession of post-rift Cretaceous sediments, although their depositional environments change from the continental in the west to the fully marine conditions to the east.

Cenozoic rift basins of Yemen developed and formed along major ENE/WSW transform faults mostly in the offshore area along the northern side of the Gulf of Aden and along NNW/SSE fault system parallel to the main Red Sea and are related to the Oligocene/Miocene rifting phases of the Gulf of Aden (the Mukalla-Sayhut, Hawrah-Ahwar and Aden-Abyan basins) and the Red Sea (the Tihamah basin) and were filled with a thick sedimentary succession displaying continental, evaporate, and shallow to deep marine facies.