Investigations on geological aspects of capillary transition zones of carbonate reservoirs by applied imaging techniques

This study focuses on the petrographic analysis of thin sections of the rock composites such as grain and cement, pore types and geometry, diagenetic events like dissolution and compaction, their modifications on the pore systems, factors that decide wettability and rock-fluid interaction, which has an impact on relative permeability. An imaging technique such as computerised tomography (CT) scan has been used to find out more information on the geometry, texture, and distribution of the pore systems of the transition zone samples which control petrophysical properties of 17 rock samples. Thin section and petrophysical study were conducted to examine the diagenesis of the samples. It has been found that five major diagenetic processes have affected this transition zone including micritisation, dissolution, cementation, dolomitisation, and compaction. Medical CT scan confirmed the presence of three types of heterogeneities varying from low to medium to high in the rock samples of the transition zones. [Received: May 22, 2017; Accepted: June 19, 2018]