Microfacies Analysis and Stratigraphic Framework of Yamama Formation in Sindbad, Halfaya and Ad'daimah Oil Fields, Southern Iraq

The Yamama Formation represents a part of the Late Berriasian-Aptian sequence, deposited during Early Cretaceous period within main shallow marine depositional environment. studied area covers three oil fields; Sindbad field, Halfaya and Ad'daimah located in southeastern Iraq. Six major microfacies were recognized succession represented by to determine recognize paleoenvironments. These are; Peloidal Packstone, Algal Wackestone Bioclastic – Foraminiferal Wackstone, Oolitic Grainstone Mudstone Microfacies. are classified into standard Facies Zones MFS-18/FZ- 8, SMF 15/FZ-6 SMF-10/FZ-7, representing restricted marine, shoal open associations facies, respectively. is divided cycles stages highstand system tracts. characterized shallowing upward mode where they with semi-restricted facies for each cycle. To northeast study near Halfya-5 well, association appeared lower middle succession, Da-1 Sn-2 cycles. This case suggests that paleo high was developed north area, while extended southern part. presence between Sulaiy successions refers continuous deposition same stage all wells. It may mark end maximum flooding surface (MFS). first started underlain then association. repetition this cycle sections symmetrically indicates harmonic oscillation sea level second third sequence. field Mesopotamian Block fields Basra Blok explain significant variation thickness other fields. suggest occurrence subsidence uplifting stages. fact distinguished cycles, albeit roughly, lifting sit-down processes synchronized sedimentation.