Most of small oil fields in the South of Russia have complex unconventional fractured clay reservoirs in geological section. To justify the effectiveness of prospecting and exploration, it is necessary to characterize the petrophysical model of the reservoir properties in the productive Khadum-Batalpashinsk deposits. During certain processes, clay Oligocene rocks acquire effective porosity, become reservoirs with necessary filtration-capacitive properties, and are one of the reserves for expanding the mineral resource base. The study found that the thin pores of the matrix and the thin inter-plate and inter-sheet voids are filled with film, capillary and free water disconnected and immobile. Oil content in clays is in the form of films and lenses along lithogenetic cracks that develop along the planes of bedding of clays of various compositions. Oil mobility is provided by cracks with increased openness. The results of study of the paleogeographic conditions of sedimentation show that the productive stratum consists of two clay reservoir rocks different in reservoir properties. There is a tendency to form first, primarily, clay strata in the Khadum and then the Batalpashinsk strata with improved reservoir properties. A study of the lithological characteristics of Lower Maikop sediments allowed to conclude that there is a wide siderite formation of rocks, including clay, previously rated as ‘non-carbonate’. It was revealed that if the contrast of petrophysical parameters can serve as a criterion for the oil content of a section in a particular well, then the uniformity of the rocks composing it can serve as a criterion for determining the productivity of a particular interval. This feature confirms the fact of the influence of secondary physical and chemical processes, under the influence of which the leveling of the petrophysical parameters of the rocks occurs in accordance with the new thermodynamic conditions. The considered complex of geological, geophysical, and laboratory methods of searching for oil in clay deposits enables to increase the efficiency of exploration.
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