Mishrif Formation is one the main oil reservoirs in southern Iraq. This study analyze the microfacies and depositional environment for Mishrif Formation in North Rumaila oilfield. The study was based on the analysis of 17 wells core. The Mishrif Formation represents deposition in a carbonate platform ramp system, with scattered patch reefs and shoals developed across the ramp margin and the platform top. It is characterize by skeletal grains (bioclasts) which are dominated such as Foraminifera, Rudist, Calcareous Algae and other skeletal grains included molluscs shell fragments with Chondrodonta sometimes, and Echinoderms while non-skeletal grains are less abundant which are represented by Peloids and Ooids. The sedimentological and stratigraphic analysis of Mishrif Formation core led to identification of 16 facies association, 7 of which are found in the mB unit (lower part of the Formation) whereas they are deposited in outer ramp, mid ramp, ramp margin and lagoon, while 9 in the mA unit (upper part of the formation) which are deposited in intra plate basin, mid ramp, inner ramp, ramp margin and lagoonal supra tidal.

According to the petrography analysis of Mishrif Formation, the foraminifera fossils is dominated in the formation, by the study there are 4 foraminiferal group / microfacies association (Oligosteginid/planktonic foraminiferal, Alveolinid association, Dicyclina/high diversity foraminiferal and Miliolid / low diversity foraminiferal) can be identified and build the sedimentary model with microfacies which are applicable to the Mishrif Formation.