The article shows that sections of volcanogenic deposits are characterized by a high degree of variability due to a variety of rock types, the development of tectonic dislocations, post-magmatic transformations characterized by uneven spatial distribution. These factors cause significant variations in the material composition and petrophysical characteristics of the rocks, the structure of the void space, which leads to ambiguous changes in geophysical parameters and complicates their geological interpretation. It has been shown that it is recommended to take into account the influence of the above factors on geophysical parameters to increase the accuracy of geologic interpretation of log data. According to the results of description of petrographic features and determination of chemical composition of core samples, 11 petrological rock types were identified. It was shown that 10 out of 11 can be identified according to the data of the standard log complex, including gamma, neutron, gamma-gamma density, acoustic, lateral logs. The dependence was obtained to determine the porosity coefficient of volcanogenic rocks through hydrogen content and acoustic impedance by combining acoustic, neutron, gamma-gamma density logs. In comparison with the use of separate logging methods, the calculation of the dependence makes it possible to significantly increase the accuracy of determining the porosity of rocks. The features of reservoir isolation are considered using direct qualitative features – narrowing of the well diameter as a result of formation of clay crust and radial gradient of electrical resistance recorded by probes of different depth. It has been shown that direct qualitative features are characterized by variable stability and can be used to isolate reservoirs in combination with quantitative criteria. It is proposed to determine the oil saturation factor based on the dependence of electrical resistance on the volume water saturation of rocks, determined from core samples with preserved saturation, selected using insulating technology. The need to take into account the influence of the type of void space and secondary transformations on the readings of electrical (electromagnetic) methods is shown. Quantitative criteria are proposed for determination, which represent the dependence of critical values of water saturation on porosity obtained for different groups of petrotypes. At the same time, critical values of water saturation were obtained from the results of processing relative phase permeability curves.
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