This study has been conducted on 73 feet of cores of Etel carbonate with full package of composite wire line logs to model lateral and vertical extent and regional connectivity within Etel formation. The main objective of the study is to Recognize and define the different environmental lithofacies distribution and establish diageneses process that effecting on reservoir quality within different lithofacies types at each core level to construct a regional variation. A detailed Petrographic study by thin-sections & XRD test compiled with detailed log analysis showed three main depositional facies have been recognized in Etel formation which have been subdivided into nine Microfacies. The Etel Formation in UU pool comprises of Carbonate/ Evaporates sequence. It is typically Limestone, Dolomite and Anhydrite. The diagenetic processes of this formation that have been distinguished are; Micritization, Recrystallization, Dolomitization, replacive Anhydrite, Dissolution, and Cementation with late burial diagenesis as compaction, Fracture and late Cementation. The highest measured porosity and permeability values are recorded in the Dolomitized Bioclastic Wackestone facies. ...................... Keywords:............... Petrophysical properties, petrography, diagenesis process, lithology facies., reservoir quality