F. N. Sadooni*
*Dept of Geology, UAE University, PO Box 17551, Al-Ain, United Arab Emirates.
Middle Turonian-lower Campanian carbonates in central Iraq may represent a significant oil play. The Turonian Khasib Formation is an important reservoir unit in the giant East Baghdad and Balad oilfields with estimated cumulative reserves of around 9 billion brl. The formation is present in other fields in central and southern Iraq and may constitute an important reservoir there.
The Khasib Formation consists of limestones and marlstones containing planktonic foraminifera and calcispheres together with extensively bioturbated chalks. These sediments were laid down in a basinal to sub-basinal setting which evolved into a shallow- marine shelf or coastal lagoon.
The best porosity (around 20%) occurs in the intensively bioturbated middle part of the formation, in which chalky matrix porosity is enhanced by an extensive network of micro-fractures. The Tithonian-Berriasian Chia Gara and the Valanginian-Campanian Balambo Formations are potential source rocks for this oil. Organic matter is mostly marine Type II kerogen or mixed marine-continental.
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