Petrophysical characteristics of carbonate rocks of organogenic structures of late devonian age (Voronezh horizon) in Orenburg region

Background. The carbonate rocks represented by organogenic structures of the Voronezh horizon (D₃vr) at the Volostnovsky, Vostochno-Volostnovsky and Yuzhno-Volostnovsky fields in the northern part of the East-Orenburg oil and gas bearing region of the Volga-Ural oil and gas bearing province are studied.

Aim. To establish a connection between the structures of lithological types of carbonate rocks and their reservoir properties within the organogenic structures of the Voronezh horizon at the Volostnovsky, Vostochno-Volostnovsky and Yuzhno-Volostnovsky deposits.

Materials and methods. Stock materials on the geological structure of the northern part of the Vostochno-Orenburg district were used. Histograms of the distribution of porosity and permeability values were constructed. A petrophysical model was proposed followed by its verification and analysis.

Results. Data on the filtration-capacitance properties of carbonate rocks were analyzed. Histograms reflecting changes in porosity and permeability for individual zones of organogenic structures were constructed. A petrophysical model describing the relationship between the lithological characteristics of rocks of the selected zones and their reservoir properties was proposed. The model was verified based on the data on the Volostnovsky site and neighboring deposits.

Conclusion. The carbonate reservoirs of the Voronezh horizon are characterized by a complex structure with degraded reservoir properties. This information should be taken into account when developing deposits to ensure an increase in geological oil reserves and an extended service life of wells.

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