The article discusses the structural features of the void space of the rocks of the volcanic-sedimentary sequence of the central zone of the north-eastern framing of the Krasnoleninsky arch. Presented ways of separating rocks by type of void space and quantifying the fracture, pore, and cavern volcanic capacities based on a standard complex of well logging methods. It has been established that the features of the void space of the rocks of the volcanic-sedimentary sequence differ depending on the petrotypes. A combination of a fissure and a cavernous type of voids is characteristic of lava formations - effusive rocks, clastolavas, and lavoclastites. The structure of the void space of pyroclastic formations - tuffs depends on the size of the fragments of their constituents. Agglomerate tuffs differences are characterized by a fissure-cavernous-granular type of voids, ash - granular (pore). The pore type represents the void space of volcanic-sedimentary and sedimentary rocks. According to the data of acoustic, density and neutron logs, based on the relationship between the interval time of longitudinal waves and the density of non-porous minerals, a method for identifying intervals is proposed. The method is adapted for the types of rocks found in the section of the volcanic-sedimentary sequence. The quantitative determination of the fraction of voids types in volcanic rocks is carried out according to the method of V.M. Dobrynin As a result of the petrophysical adjustment using the results of special core investigations for deposits of the volcanic-sedimentary sequence, the theoretical dependences of the interval times of the longitudinal and transverse elastic waves on the coefficient of total porosity are calculated. The selection of tuning factors was made taking into account the structural features of the void space of rocks. It has been established that the effusive differences of volcanic rocks differ from volcaniclastic ones — tuffs, clastolavs, and lavoclastites in terms of the compressibility coefficients of intergranular pores and cavernous voids. An example of separation of rocks from a section of a volcanic-sedimentary sequence according to the type of void space according to a standard complex well logging methods is given. The fracture, intergranular and cavern reservoirs were calculated. The results are confirmed by the data of logging, geological and technological studies of wells and test results. It is shown that the use of the results allows to increase the reliability of the identification of productive intervals of the volcanic-sedimentary sequence.
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