Microfacies Analysis and Depositional Environment of the Mishrif Formation at Selected Wells in E Oilfield, Southren Iraq

Abstract

The Mishrif Formation is an important succession that was deposited during the Cenomanian–Early Turonian. More than 79 thin sections of core in addition to well log data for the Mishrif Formation from 2 boreholes within the E oilfield (E-1, and E- 2) were used to determine the different associations facies to interpret the depositional environment of the Mishrif Formation. Six major microfacies were diagnosed the Mishrif Formation, Mudstone, Wackestone, Packstone, Grainstone, Boundstone, and Rudstone and ten submicrofacies include: Bioclastic Packstone submicrofacies with rich Echinodermat, Coral and Rudist fragment and high Dolomitization, Rudstone submicrofacies with large Rudist fragment and vug porosity , Boundstone submicrofacies with very large coral, Plankton Foraminiferal Packstone submicrofacies withe Globigerinelloides and Calcispheres, Bioclastic Wackestone to Packstone submicrofacies with dolomite and calcareous algae, Peloidal Packstone with coral, pillites, pieces of Rudist and Separate-Vug pore, Bioclastic Packstone to Grainstone submicrofacies, Peloidal to Bioclastic Packstone submicrofacies, Benthonic Foraminiferal Mudstone submicrofacies, Rudist fragmented Mudstone. These microfacies were deposited in restricted, shoal, shallow open marine, rudist bioherm, and deep marine environments.