Petrophysical Characterization and Lithology of the Mishrif Formation in Ratawi Oil Field, Southern Iraq

The Ratawi Oil Field (ROF) is one of Iraq's most important oil fields because of its significant economic oil reserves. The major oil reserves of ROF are in the Mishrif Formation. The main objective of this paper is to assess the petrophysical properties, lithology identification, and hydrocarbon potential of the Mishrif Formation using interpreting data from five open-hole logs of wells RT-2, RT-4, RT-5, RT-6, and RT-42. Understanding reservoir properties allows for a more accurate assessment of recoverable oil reserves. The rock type (limestone) and permeability variations help tailor oil extraction methods, extraction methods and improving recovery techniques. The petrophysical properties were calculated using Interactive Petrophysics software (version 4.5), employing various methods such as density (RHOB), neutron porosity (NPHI), sonic, gamma-ray, resistivity, and caliper logs. The well logs were evaluated and adjusted based on the environmental conditions. The lithology of the formations was identified through Neutron-Density cross plots, which revealing a composition primarily of limestone. The optimum approach for calculating clay volume was the gamma-ray method, which indicated approximately 10% clay content. For calibrating effective porosity with core data, the NeutronDensity method proved to be the most accurate, showed values between 12% and 14% in the MB unit. The Archie technique was selected for its compatibility with limestone. Formation water resistivity was estimated from analogies of the southern field of the Mishrif reservoir (RW=0.021). Permeability was calculated using the flow zone indicator method (FZI) with an average between 0.2 and 0.35 md. According to the petrophysical analysis conducted at Mishrif, the formation consists of four units: MA, MB1, MB2, and MC. The most significant hydrocarbon-bearing unit in the formation is MB1.The insights gained from this study not only enhance the understanding of the Mishrif Formation but also contribute to the development of more efficient extraction techniques and improved reservoir management strategies. By optimizing recovery methods based on precise petrophysical and lithological data, the study supports the sustainable and economically viable exploitation of hydrocarbon resources in the ROF and similar reservoirs worldwide. These findings are significant in the broader context of petroleum engineering and reservoir management, as they provide a foundation for improved recovery techniques and sustainable resource management.