Microfacies Analysis of Bajawan and Baba Formations in Selected wells of Bai Hassan Oil Field, North Iraq

The current study aims to analyze the microfacies, diagenetic processes, and depositional environments of the Baba and Bajawan formations in three wells of the Bai Hassan oil field, located in the northwest of Kirkuk Governorate in northern Iraq, namely BH-80, BH-193, and BH-194. The study involved the analysis of 60 rock thin sections from well BH-80, 23 thin sections from well BH-193, and 22 thin sections from well BH-194, which led to determining the microfacies and the associated depositional environments. The results showed that the rocks of both formations contain many benthic foraminifera shells, such as Nummulites, Lepidocyclina, and Miliolid, in addition to a low percentage of echinoderms, algae, corals, and rock fragments, all embedded in a matrix composed of micrite and microspar. Five main types of microfacies were identified: homogeneous non-fossiliferous lime mudstone, wackestone, packstone, grainstone, and coralline boundstone, in addition to secondary facies types. The depositional environments were also determined, with the Bajawan Formation being deposited in shallow marine waters within a lagoonal environment of normal salinity, characterized by moderate energy and semi-restricted conditions near a tidal flat, within a lagoon-back reef environment. In contrast, the Baba Formation was deposited in calm, low-energy, deep waters with normal salinity, within environments such as back-reef (shallow lagoon), reef, and fore-reef. The observed diagenetic processes include cementation, dissolution, compaction, dolomitization, and micritization.