Microfacies evaluation of mauddud formation in Ratawi field, South Iraq

Abstract EN

This paper includes studying the microfacies evalution of Mauddud Formaion in four wells(Rt-2, Rt-5, Rt17 and Rt-19).

Seventy-seven(77) sampels were collected of above mentioned wells.

Based on fossil content of the samples under study, four main microfacies were identified: packstone , wakestone , grainstone and lime mudstone microfacies ,which deposited in shallow open marine and restricted marine environments.

Petrographic examination of thin section indicated that diagenesis vary in intensity from one site to another, such as dissolution, cementation, compaction, dolomitization and micritization, which led to the improvement and deterioration of porosity.

The dominant pore types are vuggy, interparticle and intercrystal.The lithology, mineralogy and the matrix were determined by using crossplot method, which showed that the predominant lithology of the formation is limestone with the presence of dolomite in very few percentages and the mineralogy is calcite.

Based on the relationship between porosity and permeability the resevoir performance of the microfacies classified into four types: bad, fair, good and very good.

Based on petrophysical properties and core description of well study Mauddud Formation was divided into four rock units A,B,C and D , in terms of reservoir, units A and C are considered good ,while B and D are bad.