Linking sedimentary properties to mechanical characteristics of carbonate reservoir rock: An example from central Persian Gulf

Abstract

A comprehensive understanding of mechanical properties of reservoir rocks can help in all stages of hydrocarbon and geothermal exploration, field development, and Carbon Capture Storage (CCS). In this study, the sedimentological properties of a carbonate reservior have been studied and the effect these properties have on mechanical parameters such as Uniaxial Compressive Strength (UCS), Young's modulus (E), Cohesion (C) and Internal friction angle (φ) of the rock at ambient (20 °C) and reservoir (90 °C) temperature conditions. These carbonates were grouped in three units (A, B, and C) based on a statistical analysis of petrophysical logs and core analysis. The results show that changes in mechanical properties are mainly influenced by diagenetic processes. The two main influencing overprints in the studied samples are dolomitization and anhydrite cementation, which strongly affect porosity, the dominant pore type and mineralogy which in turn are the most important influencing factors on mechanical properties. Although samples with 25–35% anhydrite (Unit A) show the highest strength, this parameter strongly reduces under high temperature conditions. The effect of dolomitization on rock texture and on porosity as the main strength-controlling factor is also very apparent. Therefore, samples with crystalline carbonate texture (Unit C) show the lowest UCS, E, C and φ values.