Characterizing Mineral and Textural Heterogeneity in Carbonates: Insights from Complex Conductivity and Acoustic Response

Spectral Induced Polarization (SIP) has been widely applied to carbonate rocks but remains challenging due to its sensitivity to factors such as mineralogy, pore size distribution, aspect ratio, dissolution, reprecipitation, and cementation, all varying throughout a reservoir’s life. Isolated SIP measurements often fail to accurately decipher these intertwined phenomena, potentially leading to misinterpretation. To address this, our study combines SIP-based complex conductivity measurements with other laboratory techniques, including acoustic measurements, mercury intrusion porosimetery (MIP), and SEM imaging, to investigate the influence of mineralogical and textural heterogeneity in clay-inundated carbonate rocks. Using 21 carbonate cores from Miocene-age formations in the Indian Western Offshore, we observe a pronounced sensitivity of SIP to textural heterogeneity across homogeneous, intermediate, and heterogeneous facies. In-phase conductivity variations of 60–80% and quadrature conductivity variations of 80–90% were linked to transitions in dominant pore sizes, with homogeneous samples (< 1 μm pores) and heterogeneous samples (> 1 μm pores) confirmed via MIP. A clear relationship between formation factor (F) and cementation factor (m) emerges when pore-size-driven dissolution dominates; however, this change when followed by reprecipitation and cementation. Additionally, correlations between electrical and acoustic parameters provide further insights. Our novel approach integrates SIP with multiple characterization techniques, revealing the overlooked sensitivity of SIP to carbonate textural variations. This comprehensive analysis advances understanding of heterogeneity’s impact on petrophysical properties in complex carbonate formations, refining methods for their intricate characterization.