The Precaspian depression is located within the southeastern margin of the East European Platform. This is one of the largest and deepest depressions of ancient platforms and one of the largest salt dome areas in the world. The article considers the problems associated with the reconstruction of the conditions of the unique Precaspian depression formation, peculiarities of applicability of geological and geophysical data for the analysis of different in age and depth parts of the geological section, provides a brief review of existing concepts of the formation of the depression. The dependence of formation and development of petroleum systems on the peculiarities of the considered concept is considered separately. All data for the analysis of hydrocarbon systems, as well as the results of any other studies of the Precaspian basin, are characterized by poor age and area distribution. In this regard, reconstructions of the conditions of the formation of the depression become of great importance, since they allow evaluation of the missing data, and therefore make forecasts more targeted. First of all, this relates to the restoration of sedimentation conditions, retrospective forecast of thermobaric conditions, etc. An important aspect of the study is the type of hydrocarbon systems. The authors consider drainless or autoclave systems, i.e. systems where hydrocarbons remain in situ - directly in oil and gas source rocks or in an adjacent reservoir without the possibility of long-distance migration. Deposits with such conditions could, for example, form in the Lower Permian alluvial fans in the central part of the depression. However, it is worth noting that deep-sea fans are found not only in the Permian, but also in the Carboniferous and Devonian complexes. Such conditions lead to a further stretching of the catagenesis scale, and also have a positive effect on the preservation of reservoirs, which, under conditions of the early arrival of hydrocarbons, become significantly less compacted as they sink. Thus, based on the considered concept of the formation of the Precaspian depression, the forecast for the oil and gas potential of the entire territory, including the most submerged Central Precaspian depression, and the entire Phanerozoic section is favorable.
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