The article presents the results of studying the role of rocks fracturing in the formation and spatial distribution of hydrocarbon deposits in the North-Western Caspian Sea. A comprehensive study of the features of the rocks internal structure, their spatial oil saturation and the relationships between them has been carried out. As a source data, a large amount of core material and the latest information on the geological structure, oil and gas content and geodynamic development of the territory at the final stage of geological history were used.
The leading role of differently oriented zones of increased early age fracturing (two young generations) in the formation and spatial distribution of hydrocarbon deposits in this water area has been established. It is noted that a special role is played by a horizontally oriented complex (multi-stage) zone of increased fracturing, regionally developed in the earth's crust in the interval of thicknesses of rocks of the Middle Jurassic-Early Cretaceous age. It is established that this large zone of low-amplitude disjunctive dislocations controls the range of regional oil and gas content of the Middle Jurassic-Lower Cretaceous sediments, as well as the selective (through the section) oil saturation of rocks within productive layers. It is determined that the non-uniform (up to thin-layered) character of the oil saturation of contemporaneous rocks within the limits of one productive horizon (layer) does not have a direct connection with the lithologic-petrophysical characteristics of rocks, and is always associated with the presence of a horizontal oil-saturated fracture network in them.
The early age and the ongoing two-stage formation of hydrocarbon deposits within the water area of the North-Western Caspian are justified. Conclusions and results are valid for all deposits in the North-Western Caspian Sea. The obtained results can also be used for carrying out of prospecting and exploration in other regions (onshore and offshore), where zones of high fracturing are the primary exploration targets.
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