A quantitative assessment of diagenetic controls in the lower Sarvak reservoir of an Iranian oil field, Zagros Basin

This study investigates the heterogeneity of geomechanical parameters such as pore pressure, uniaxial compressive strength (UCS) and Young’s modulus utilizing the coefficient of variation index in the Lower part of Sarvak Formation, a key reservoir within an oilfield in the Dezful Embayment. The main objective of this study is to establish a genetically based understanding of geomechanical heterogeneity by (1) identifying a representative geomechanical heterogeneity index (CVG), (2) characterizing the controlling mechanisms within each geomechanical facies, and (3) explaining the spatial distribution of geomechanical heterogeneity. Therefore, the effect of main diagenetic parameters such as cementation, dissolution, compaction and dolomitization along with shaliness and fracture intensity on geomechanical parameters variation were investigated. Electrofacies analysis of the reservoir led to the definition of five geomechanical electrofacies, characterized by their individual geomechanical and diagenetic properties. Based on this assessment, diagenetic parameters and shale volume can influence the geomechanical heterogeneity. In addition, in order to distinct the effect of each diagenesis processes on different facies, geomechanical electrofacies analysis can assist. According to this analysis, the effect of diagenesis modifications on heterogeneity in geomechanical facies are different based on its inherent geomechanical properties. In addition, fracture intensity developing can be varied in each geomechanical facies. As a result, this study introduces a new geomechanical coefficient of variation (CVG) heterogeneity index based on CV of three geomechanical properties to evaluate the diagenetic processes and shaliness effects on geomechanical properties which can be used for heteronomous carbonate geomechanical models.