Petrophysical characterization of Jurassic and Triassic rocks of the Morskoye field and Ogayskoye block based on core analysis

Boranbay Ratov, Володимир Львович Хоменко, A. O Zhailiyev, Aigul Gusmanova, Shalala Huseynova

2026

Closed access Metadata (CSL-JSON)
DOI 10.5510/ogp20260101148
Data confidence 70 medium
How this score is calculated

It is built from checkable properties of the record itself: whether the article has a DOI, how many independent sources confirmed its data, whether the required fields are filled in, and how recent the latest confirmation is. Disagreement between sources and a missing identifier lower it. A value of 80 or above means the record was published without further checking; 60 to 79 means it is published at reduced confidence, with a manual check advisable. A record verified by an editor by hand is never pushed below 90 by a recalculation. This scores our data about the article, not the article itself.

Abstract

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.