Microfacies analysis and stratigraphic framework of the Albian succession in the low folded zone, Northern Iraq

The study area is located in the north part of Iraq and extends from the north of Baghdad Governorate to the south of Mosul Governorate. The petrographic examination of the thin section of the Albian succession, the microfacies were diagnosed and the sedimentary environments characteristic of this succession were identified in detail for the wells within Chemchamal, Kirkuk, Qara Chauq and Makhul oil fields. The Albian cycle in study area is defined according to microfacies analysis and stratigraphic framework as a sequence between two sequence boundaries type I. The lower surface separates the Lower Qamchuqa Formation and the sediments of the above cycle, while the upper surface separates the sediments of this cycle from the sediments of the Middle Cenomanian succession. The Albia cycle represents a period of time about 12.4 Ma, which identifies it as a second-order sequence (Second Order). The depositional discontinuity that occurred during the last Aptian age that covered the sediments of the Lower Qamchuqa Formation as a result of the exposure of the Arabian Plate by the extensional forces that contributed to the creation of stress basins within the plate (Intra-Shelf basin). Which were characterized by facies differences and their content of microfossils, indicating that this cycle of rocks formed different marine sedimentary environments. The Batiwah Formation is considered the deep basin equivalent of the Upper Qamchuqa Formation, which was deposited within the shallow marine environment. In Kirkuk-109 well penetrates the sediments of the edge of the platform, which turns into the sediments of the swamp environment as in the Chamchamal-2 well. The Jawan Evaporative Formation represents the final evaporative phase of the Lowstand System Tract during the Early Cenomanian, which penetrated into the Ain Zala-1 well from the north to the Samarra-1 well in the south. The dolomitization process is considered one of the most important diageneses processes, those effects when Albian succession was exposed, which added a good reservoir character to the Upper Qamchuqa Formation.