Microfacies Analysis of the Mishrif and Kifil Formations of Amara Oil field/South of Iraq

Abstract

The lithologic and petrographic studies of the Mishrif and Kifil formations in Amara oil field in wells AM11,AM9, AM5 was revealed that the Mishrif formation consists of limestone and dolomitic limestone. While the Kifil formation is consist of the anhydrite and mud-dominated limestone. The skeletal grains of Mishrif formation includes variety of benthos foraminifera, bivalves (Rudist) ,corals , stromatolite, algae, ostracods, gastropods, echinoderms. Non-skeletal grains are rare and authegenic minerals of pyrite and iron oxide are present. The rocks of the formation are affected by diagenesis such as dolomitization ,dissolution and recrystallization. The Kifil formation rocks do not have any skeletal grains and affected by recrystallization only .The microfacies analysis of Mishrif formation reveals that the formation consists of: mudstone, wackestone, packstone, grainstone and boundstone deposed in the fore environments extend from for reef, back reef to: open marine, reef, shoals platform margin, restricted environment. The Kifil formation divided into tow lithological facies these are limestone and evaporite and we recognized mudstone microfacies only deposited in restricted environment and represents the Mishrif reservoir cap rocks . The research illustrated that the upper contact of Mishrif formation is gradational and conformable with Kifl formation with evidence from a gradual changes from limestone to anhydrite. In this study was considered the evaporites and limestone to Kifil formation. The Kifil formation is presence by thickness (7m) in the Amara Oilfield .