Microfacies Analysis and Depositional Environment of Baba Formation in Selected Wells from Kirkuk Oil Field, Northeastern Iraq

Abstract

Abstract: The Baba Formation succession (Middle-Late Oligocene) were studied within the wells (K-1) and (K-2) in the Kirkuk oil field, North-eastern Iraq. As the formation thickness in the first well is about (45) meters and the second well is about (65) meters, respectively. The formation consists of hard limestone, brown in color and dolomitic limestone. Petrography The formation rocks consist of many benthic foraminifera as (Miliolid) and planktonic foraminifera as (Globigerina aselli, Globigerina ampliapertura, Globigerina praebulloides, Catapsydrax dissimilis, Chilogumbelina sp. , Globigerina ciperoensis , Paragloborota liaopima), In addition to Nummulites fichteli, Nummulites vascus and a few of Lepidocyclina sp., echinoderms, bryozoa, and algae, and their fragments. The Microfacies appear to be highly affected by many diagenesis processes such as dolomitization, compaction, cementation, dissolution and recrystallization. The formation composed of three main microfacies, which in turn were divided into (11) secondary microfacies whose general characteristics were similar to the characteristics of the microfacies proposed by Flugel, namely (RMF-2, RMF-3, RMF-5, RMF-7, RMF-13, RMF-16). Based on the results of the microfacies analysis, it was found that the sedimentary environment of the Baba Formation is the carbonate ramp environment, as the facies of the Baba Formation spread within the restricted environment of the inner ramp, which was characterized by the spread of the millolid fossils to the middle ramp environment with the spread of Nummulites shells, and towards the outer ramp with the presence of planktonic foraminifera.