Abstract

• The area under investigation lies in Ngape Township, western part of Minbu, Magway Region. In the study area, the Cretaceous to Pliocene Formations are exposed. The main structure of the study area is monocline. The present research aimed to conduct reservoir potential of Okhmintaung Formation. Stratigraphically, the Okhmintaung Formation (Late Oligocene) is mainly made up of thin- to medium-bedded sandstone with bluish gray shale. Petrographically, the sandstone of Okhmintaung Formation is arkose and lithic arkose.By the facies analysis, in Okhmintaung Formation, from top to bottom, Thick- bedded to massive sandstone facies, sand with gypsum intercalation facies, bioturbated sandstone facies, nodular gray shale facies, and sand-shale alternation facies were observed. By the petrographic texture, porosity, and diagenetic features enhancing or destroying the potential porosity of the sand body are also started in Okhmintaung Formation. Some of the sand bodies do not favor the potential of good reservoir because of the size, textural features and diagenetic imprints. Some of the reservoir cannot regard as medium potential due to the petrographic fabric forming lesser potential. By studying the diagenetic features, some of the Okhmintaung sandstone possesses pore-filling clays and very thin grain coating. These authigenesis can destroy reservoir potential and cannot regard as medium potential due to the petrographic fabric forming lesser potential. The textural features suggest that Okhmintaung sandstones are fair reservoir.