The article considers the structural peculiarities of the void space, affecting the filtration properties of volcanogenic-sedimentary rocks of the central zone of the northeastern framework of the Krasnoleninsky arch. A method for permeability coefficient determination is proposed based on standard well logging complex data. The volcanogenic-sedimentary strata are characterized by a complicated composition (presence of cracks, caverns, intergranular pores) and the structural peculiarities (distribution of voids by size of the void space of rocks). These peculiarities reduce the reliability of permeability coefficient determination in interaction with the porosity coefficient. With a constant porosity coefficient value, variations in the permeability coefficient range greatly. The connections between capacitive and filtration properties should be used for more accurate permeability estimation, taking into account the peculiarities of the internal structure of the void space of rocks. Such connections are based on different structural models of void space. The permeability estimation of rocks of the studied strata is made according to the dumbbell model, which describes the void space of rocks as an interconnected system of voids (macrocapillaries) and channels (microcapillaries) connecting them. The model takes into account the differences in equivalent sections (capacitive, filtration, electric) of macro- and microcapillaries, interconnected due to electrohydrodynamic analogy. The ratio of sections is determined by the electric tortuosity of the void space meaning expansion of current electric lines in large voids and narrowing in connecting channels. The values of the permeability coefficients calculated using the dumbbell model approximate the results of the core sample studies well enough. The exception is intensively fractured samples, in which the calculated values of the permeability coefficient are significantly lower than those measured in the core samples.
This permeability coefficient calculation model is applicable to rocks with increased capacitive properties. The properties of the matrix have a decisive effect on the filtration characteristics of such rocks, the void space of which is of crack-cavern-granular type. The main effective capacity in rocks with reduced capacitive properties is represented by cracks and cavities; the matrix is characterized by low filtration and capacitive properties. Open cracks have a decisive effect on the filtration properties of such rocks. Evaluation of their filtration properties was made using the dependence of the permeability coefficient established by hydrodynamic studies on the coefficient of fractured voids determined by well logging.
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