Sedimentological study of the Lower-Middle Miocene Sequences at Selected Wells in Jambur and Khabaz oilfields, NE Iraq

Abstract

The study includes petrographic and stratigraphical chraractrstic of the lower-middle Miocene sequence at selected wells from Jambur and Khabaz oilfields. Four hundred and sixty thin section from Jeribe, Serikagni, Euphrates, Dhiban, Anah and Azkand formations in four wells from Jambur and Khabaz oilfields are studied. The stratigraphic study indicates that contact between Jeribe and Faꞌtha formations, Jeribe and Dhiban formations are unconformable in all wells under study, while the contact between Jeribe and Anah, Anah and Azkand, Euphrates and Serikagni formations are conformable.
 The petrographic study reveals that most of the studied formations are limestone rich in benthonic foraminifera especially in Jeribe and Anah formations, with low percentage of planktonic foraminifera such as Globigerina species in Serikagni and Azkand formations. Additionally, echinoids, coral algae, ostracoda and intraclast remains are present. Non-skeletal component such as, pellets and ooids are rare in Euphrates Formation. Microfacies analysis shows the presence of several microfacies distributed in the studied formations.
 The environments of lower-Middle Miocene formations have been concluded from petrography and microfacies studies. Jeribe Formation was deposited in lagoonal or semi lagoonal environment, while Serikagni and Euphrates formations were deposited in deep marine environment and shallow open lagoon environment respectively. Closed lagoonal environment is assigned for deposition of Dhiban Formation, while slope and reef environment is recognized for the Azkand Formation and tidal and supratidal with reef marine tropical environment for the Anah Formation.