Аңдатпа
This study presents the results of an integrated study of the petrophysical and lithological properties of Jurassic and Triassic rocks in the Morskoye field and the Ogayskoye block, within the Caspian Basin. The research aims to refine reservoir evaluation parameters through detailed laboratory analyses of core samples with geophysical well log interpretation. Core material from 23 wells (1980 samples) was analyzed using mineralogical, granulometric, and petrophysical methods, with additional verification from seismic data and well test results. Mineralogical studies based on X-ray diffraction confirmed the predominance of quartz, carbonates, and clay minerals, while granulometric analysis revealed the dominance of fine-grained and pelitic fractions, explaining the generally low filtration capacity of the studied reservoirs. The laboratory experiments established robust empirical relationships between porosity, permeability, and saturation parameters. Strong statistical reliability was achieved, particularly for the K₁al–K₁nc stratigraphic intervals, where reservoir properties demonstrated stability and consistency. A clear linear correlation between bulk density and porosity was identified, allowing accurate determination of the matrix density (2.69 g/cm³) used in quantitative well log interpretation. Special attention was given to the recognition of thin coal interbeds within Jurassic deposits. These intervals showed distinctive geophysical responses, including abnormally high neutron porosity and low bulk density, and were systematically excluded from reservoir classification to avoid misinterpretation. Phase permeability tests demonstrated the significant influence of residual oil and water saturations on multiphase flow behavior, offering insights into displacement efficiency and fluid mobility within pore networks. The study also determined lithology- and depth-specific threshold values of porosity and permeability, which enhance the accuracy of identifying and delineating productive intervals. The results provide a reliable methodological foundation for improving reservoir characterization, refining hydrocarbon reserve estimation, and supporting exploration and development strategies in geologically complex settings. Keywords: reservoir; filtration; saturation; core; porosity; permeability.