RETRACTED ARTICLE: Microfacies and environmental study of the Mishrif Formation in Noor Field

Abstract

Mishrif Formation is one of the most important formations in Iraq, both economically and geologically, which was deposited during the Cretaceous period in the secondary sedimentary cycle (Cenomanian–Early Turonian) and is regarded as the principal carbonate reservoir in central and southern Iraq. A petrographic and microfacies study has been carried out by examining available thin sections for well nos. 1 and 2 as well as well log data for environmental subdivision. The microfacies analysis shows that the Mishrif succession comprises six paleoenvironments which are deep marine, shallow open marine, rudist biostrome, shoal, back shoal, and lagoon. Petrographic study from thin-section examination shows that the skeletal grains included rudist, coral Foraminifera (benthonic, planktonic), echinoderms, ostracods, and molluscs. The rudists are very important contributors in building the Mishrif carbonate platform, and the corals are very common in the Mishrif succession and along with the rudists. Non-skeletal grains included pellets, micrite, and intraclasts. Six digenetic processes affected Mishrif Formation, and the most effective is dolomitization and dissolution. The lateral extension of these microfacies has been identified by integrating the thin-section data and well log character variation with similar characteristic for microfacies.