The article provides the petrological and petrophysical characteristics of rocks of the volcanic-sedimentary sequence of the north-eastern framing of the Krasnoleninsky arch. Information is given on the petrotypes of rocks, their oil saturation, and filtration and capacitive properties. According to the results of core studies, rocks are divided into ten petrological types: effusives of acid composition (dense constitution and with voids); volcano-clastic rocks of acid composition; volcanic rocks transformed under the influence of post-magmatic processes, including rocks with a high content of minerals with a high and low specific gravity; weathering crust rocks; volcano-sedimentary rocks; sedimentary rocks; alkaline effusives and their transformed types. The possibility of petrological separation of rocks of the volcanic-sedimentary sequence is shown by comparing the geophysical parameters of the standard complex of geophysical methods. Alkaline effusives, their hydrothermally transformed types and sedimentary rocks, characterized by low values of natural radioactivity and increased values of bulk density can be identified with high confidence. Acidic and alkaline-acidic effusives of dense constitution are characterized by increased values of bulk density and resistance and reduced interval time of elastic waves and hydrogen content. Low density effusives of acidic and alkaline-acidic composition are identified by a decrease in bulk density, electrical resistance, and an increase in the interval time of elastic waves and hydrogen content. The change in geophysical parameters occurs gradually from effusive rocks to volcaniclastic rocks due to changes in the void space and the nature of saturation. The possibility of separating reservoirs by combining indirect qualitative features and quantitative criteria of geophysical parameters obtained by matching data from well logging, testing and geological and technological studies is shown. The presence of reservoir rocks, in addition to using quantitative criteria, is established at a qualitative level by the dissonance between the values of the interval time and the attenuation coefficient of the Stoneley surface wave with the background readings of the parameters under consideration characteristic of impermeable rocks. To increase the reliability of the petrophysical interpretation and reservoir identification in the section of the volcanic-sedimentary sequence it is recommended to perform special methods of well logging.
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