Correlation of filtration and capacitance properties and structure of hollow space of tournaisian reservoirs

The paper discusses the relationship between the reservoir properties of the Tournaisian carbonate reservoirs and the structural features of their void space. The purpose of the study was to determine the factors that determine differences in rock permeability at similar porosity values based on a comprehensive core analysis. The object of study was the carbonate deposits of the Tournaisian stage of the Volga-Ural region, represented mainly by wackestones and packstones. A set of methods was used, including standard laboratory determinations of porosity, permeability and associated water saturation, a study of anisotropy of permeability on cubic samples, petrographic study of thin sections and analysis of the structure of the void space according to NMR data. It has been established that the highest filtration and capacitance properties are characterized by packstones, for which a combination of intergranular and intragranular pores connected by capillary channels is typical. Wackestones are characterized by a predominance of microand small-pore space, weak connectivity of pores and, as a result, reduced permeability values, even with comparable porosity. It has been shown that secondary leaching pores play the main role in the formation of reservoir properties of the studied rocks, while cracks have a subordinate value. No pronounced permeability anisotropy was detected in the studied sample. When typing Tournaisian carbonate reservoirs and interpreting well logs, it is necessary to take into account not only the quantitative parameters of porosity, but also the morphology, dimension and hydrodynamic connectivity of the elements of the void space

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