Microfacies and depositional analysis of the mishrif Formation in selected wells of zubair oilfield, Southern iraq

Abstract

This research includes evaluating  the microfacies of the Mishrif limestone  formation in wells of the Zubair field (Zb-199, Zb-43, Zb-47,Zb-114).  This study is depending on the biological content by analyzing the thin slices, six major facies and ninteen secondary facies were identified (Wackstonemicrofacies,Wackstone-packstone Microfacies,packston Microfacies,packston-Grainstone Microfacies, Grainstone Microfacies) The main skeletal grains of the Mishrif formation include coral, Rudist, large and small benthonic Foraminifera & planktonic Foraminifera (Planktonic Foraminifera are common in the lower part of the Mishrif Formation), ostracods, echinoderms, and molluscs. The Rudist were found in small to large fragments The Non-skeletal grains included peloids.

The most important diagenetic processes affecting on the Mishrif Formation are dolomitization,dissolution,cementation,micritization,recrystallization and compaction.Mishrif succession comprises six paleoenvironments which, shallow open marine, rudist biostrome, shoal, back shoal, and lagoon.The dominant pore types are vuggy, interparticle , intercrystal and moldic.