Perpustakaan Digital ITB

This study conducts a comprehensive evaluation of water saturation (Sw), a critical factor in reservoir characterization, particularly in complex low resistivity reservoirs (LRR), where conductive clay minerals and bound water significantly complicate resistivity log interpretation. Four established methods for estimating water saturation—Archie, Simandoux, Waxman-Smits, and the Difference Method—are systematically compared, focusing on their accuracy, applicability, and robustness in low resistivity reservoirs characterized by heterogeneous lithology and complex mineralogy. The Difference Method isolates the contribution of clay-bound water by utilizing effective porosity and dry clay volume parameters derived from neutron and density logs, thereby mitigating the bias introduced by conductive bound water that affects conventional models. Results demonstrate that Archie’s method consistently overestimates Sw, often producing values greater than 1.0, which are physically unrealistic, while Simandoux and Waxman-Smits models provide more moderate but still somewhat inflated Sw estimates in certain intervals. The Difference Method yields the lowest and most physically plausible Sw values, aligning more closely with actual reservoir conditions. Validation was performed through fractional flow analysis to determine Sw values in the reservoir and permeability correlation, revealing an inverse relationship between Sw and permeability that supports the reliability of the Difference Method in addressing the challenges posed by LRR. This study underscores the critical importance of selecting appropriate Sw estimation techniques, highlighting the Difference Method as a superior approach for enhancing petrophysical evaluation accuracy and optimizing hydrocarbon production management in low resistivity reservoirs.