Reservoir Evaluation of Carbonate Rocks Using Well-Log Data in the Eastern Sirte Sedimentary Basin, Libya

Abstract

This study aims to investigate the petrophysical properties of the Lidam Formation in Well X3, located in the eastern Sirte Sedimentary Basin, Libya. These properties include effective porosity and permeability, which are influenced by mineral composition and shale content and play a significant role in determining the storage capacity and productivity of reservoir fluids (oil, gas, and water). Therefore, evaluating these properties is essential for assessing the production potential of hydrocarbon reservoirs. The study utilized well-log data for reservoir evaluation using Schlumberger equations and interpretation charts, in conjunction with FlexInLog software, to achieve an optimal assessment of the Lidam Formation. The results demonstrated a strong agreement between the petrophysical parameters derived from well-log analysis and those obtained from core sample data. Reservoir evaluation revealed that the formation is composed mainly of limestone and dolomite, with minor amounts of anhydrite and a shale content not exceeding 30%. The formation exhibits an average effective porosity of 6% and an average secondary porosity of 0.71%. Oil saturation exceeds 65%, with more than 60% of this value representing movable oil saturation. These findings indicate that the carbonate reservoir interval constitutes a highly productive oil-bearing zone. Furthermore, the established zone parameters can serve as a valuable reference for evaluating neighboring areas containing rocks with similar petrophysical characteristics.