Investigating the Effects of Reservoir Properties and Diagenetic Features on Carbonates Velocity Variations: A Case Study

Abstract

Summary Carbonate rocks are extremely heterogeneous due to their complex forming processes. As a result of this complexity, sonic velocities within carbonate rocks exhibit a scattering pattern on their velocity-porosity cross plot. In order to make an accurate interpretation of seismic data, it is crucial to understand the reason for such velocity changes. This research investigates all of the possible diagenetic features and reservoir factors that might affect the seismic velocities of a carbonate field. For this purpose, we studied thin-section data, SEM images, XRD analysis, and well log data in two wells penetrated in this carbonate reservoir. Then, these data were analyzed for the most dominant diagenetic features controlling velocities. Finally, reservoir properties and their relationship with these diagenetic features were evaluated to determine their impact on sonic velocities. Our Results illustrate that increasing dominance of micritization, bioturbation, silicification, and compaction cause sonic wave velocities to increase while recrystallization decreases the sonic wave velocities. On the other hand, porosity and pore types are the most important reservoir properties that affect sonic velocities in the given wells. Increasing stiff pores’ dominancy causes sonic wave velocities to increase while raising porosity, reference pores, and crack pore volume percentage decrease the seismic velocities.