Determination of electrical facies using MRGC and ANN clustering methods

Abstract

The present research was performed on Iran's most crucial reservoir formation (Asmari Formation) in the Mansouri oil field in southwest Iran. This Formation is generally composed of carbonate lithologic, but it has sandstone layers in some zones. It is also the youngest reservoir rock in Iran. In the first step, the lithology of the Asmari Formation was determined by cross-lithology diagrams, and a combination of lime, dolomite, anhydrite, and sandstone with shaley layers was estimated. Also, in the sequence of this geological/reservoir zoning formation, five zones were identified with different geological/reservoir conditions, and the average of each of these petrophysical parameters was calculated in each zone, with the best reservoir quality in zones 3 and 5 with sandstone/shale lithology. Also, this study determines facies clustering methods MRGC and ANN and reading of gamma, neutron, density, acoustic and resistivity diagrams, facies having common geological/reservoir conditions in different subdivisions. For this purpose, the combined log readings of DT, RHOB, GR, Sw, NPHI, and PHIE were used. After applying the software (Geolog) method, an optimal model with 8 clusters (facies) was obtained. The reservoir features and plots in the software for better separation of rock species studied. Finally, five facies with different lithological compositions and reservoir conditions were identified in this study. The information obtained from determining electrical facies by clustering method determines the reservoir zone from non-reservoir and qualitatively (good, medium, and poor) of Mansouri oilfield were achieved.