Authors
1
Department of Earth Sciences. Institute for Advanced Studies in Basic Sciences (IASBS). Zanjan. Iran
2
Department of Computer Science and Information Technology. Institute for Advanced Studies in Basic Sciences (IASBS). Zanjan. Iran
3
Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
4
Assistant professor, Institute for Advanced Studies in Basic Science, 45195-1159 Zanjan, Iran
Abstract
This research aims to accurately identify and describe the reservoir units of the Asmari Formation in the Cheshmehkhosh field using two unsupervised clustering methods: single-linkage hierarchical clustering and k-means clustering, applied to petrophysical log data alongside petrographic and sedimentological data. The Asmari Formation is the most important hydrocarbon reservoir in Iran, containing over 90% of the country's recoverable oil reserves. This formation was deposited in a shallow marine environment during the Oligocene-Miocene period. The results of this study indicate that the Asmari Formation in the Cheshmehkhosh field can be divided into three distinct lithologies: carbonate, siliciclastic, and evaporite. The carbonate lithology, which is the most prevalent in this field, is represented by 10 different dolomitic and limestone microfacies. Using the clustering methods, 12 reservoir units were identified in this formation, among which zones EZ10, EZ12, EZ11, EZ9, and EZ8, in descending order, have the best reservoir quality and are the speed zones. The results show that units with sandstone siliciclastic facies, dolomitic facies, and high intergranular or vuggy porosity have the best production potential. Sedimentological factors such as the abundance of high-quality sedimentary facies including PF-1, MF-6, MF-2, MF-7, and MF-9, and quality-enhancing diagenetic processes like dolomitization and dissolution, play significant roles in determining the reservoir quality of the identified units. The results of the clustering have greater accuracy compared to previous petrophysical zonations in this field.
Keywords
)