Microfacies and Diageneses Associated Mishrif Formation in X Oilfield Southeast Iraq

Abstract

     The fractal fifteen thin section showed that the deposition of the Mishrif Formation is gradual upwards. It was deposited in a period that suffered from several marine fluctuations. It began as a cycle of marine retreat that led to the sedimentation of reefs, followed by a short-term marine advance, and then a widespread marine retreat that led to the emergence of sedimentary facies and various Rudist assemblies. Through scrutiny and analysis of the slides, the presence of five main facies (basin facies, slope facies, shallow open marine, shoal, and rudist biostrom environment) was observed. The results showed that the morphological processes re-crystallization, decomposition, and dolomitization have the greatest role in improving the porosity, in addition that the Rudist biostrom and shoal facies environment have good reservoir properties in units MA, MB2, and MB2. The modulation processes affecting the development of the reservoir properties of the different units were identified, with an indication of the severity of their impact and their role in the growth and destruction of porous systems. These processes are micritization, dissolution dolomitization, cementation, recrystallization, stylolitization, and compaction.