Abstract

The Albian–Cenomanian Mauddud Formation extends over most parts of the Arabian basin including north Iraq. The formation consists mainly of Orbitolina-bearing limestone with local basin margin rudist buildups in the offshore North field of Qatar and northeast Iraq. Extensive dolomitization, with wide variations in both extent and texture, has been reported from both outcrops and wells. The Jurassic–Cretaceous pelagic strata are probably the possible source for the Mauddud Formation oil in northern Iraq, whereas indigenous sources in the Mauddud strata and Nahr Umr shales, as well as the Upper Jurassic rocks, are probably the source rocks in the southern parts in the basin. Porosity of 10–35% and permeability of 10–110 md have been reported from different fields of the basin. This porosity is attributed to a combination of dolomitization, fracturing, and dissolution. There are two main oil provinces where the Mauddud Formation is a major oil-producing reservoir. The northern province includes Iraq's oil fields such as Ain Zalah, Bai Hassan, and Jambur. The southern province includes the Ratawi field in southern Iraq, Raudhatain, Sabriya, and Bahra fields in Kuwait, Bahrain (Awali) field in Bahrain, and Fahud and Natih fields in Oman. The formation has high oil potential in the southern and southeastern fields of Iraq and the offshore areas of Qatar and Saudi Arabia.

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