Depositional Architecture and Stratigraphic Framework of Albian Succession in Balad and Nasiyia Oil Fields

The Albian Carbonate-clastic succession in the present study is represented by Mauddud and Nahr Umr formations were deposited during stage within Wasia Group More than 200 thin sections of cores cuttings addition to well logs data for from 4 boreholes two oil fields (Ba-4, Ba-8, Ns-2 Ns-4) used interpret different associations facies as architectures describe sedimentary framework basin development petrophysical properties. Seven major microfacies diagnosed carbonate Formation, while Nar Formation includes five lithofacies; their grain types characteristic depositional textures enabled recognize paleoenvironments. These restricted, shallow open marine, back-reef, slope deep marine succession. While Umr, lithofacies bay fill, back-shore distributary channel. studied Balad field which represents 3rd order four 4th cycles (A1, A2, A3 A4). are asymmetrical starts with cycle A1 where Backshore Lower transgressive systems tract then appear hightstand bounded below a surface coinside unconformable underlying Shuaiba Formation. In Nasyria three A2 A4) absence cycle. channel lower part highstand reflected shallowing upward channel, fill back-sore This relatively thick parasequence reflect time sea level stillstand tectonic subsidence controlling factor on producing necessary accommodation aggregational progradation clastic deposit.