Rock typing and reservoir zonation based on the NMR logging and geological attributes in the mixed carbonate-siliciclastic Asmari Reservoir

Abstract

Rock typing is known as the best way in heterogeneous reservoirs characterization. The rock typing methods confine to various aspects of the rocks such as multi-scale and multi-modal pore types and size, rock texture, diagenetic modifications and integration of static/dynamic data. Integration of static and dynamic behavior of rocks and their sedimentary features are practiced in this study. Porosity, permeability and pore size distributions are investigated as the static and capillary pressure, water saturation and irreducible water saturation as dynamic behavior of the rocks. Results from core data analysis in some intervals and continuously NMR data through the whole well are also involved. Initially, based on Flow Zone Index method, while considering geological attributes, 7 rock types are determined. The petrophysical properties of the rock types including Pc, SW and SWir are combined into the rock types. Afterward, pore types, facies characteristics, texture and diagenetic overprints are involved in the rock type's classification to capture spatial trends and relationships. Eventually, the rock types are defined in the cored intervals by these parameters and predicted in non-cored intervals by NMR. The rock types are established to provide a clue on the high and low permeable zones and accurate reservoir zonation