Lithologic-facies and paleogeographic conditions of formation of natural oil and gas reservoirs in the South Caspian Basin

To study the reservoirs of the South Caspian basin, models of the distribution of natural reservoirs, paleogeographic sedimentation settings, lithological and facies schemes, thickness maps, sedimentation velocity maps, and a scheme for determining the boundaries of sedimentation depocenters based on the results of lithological, paleogeographic, and sedimentary-facies studies were developed. Paleogeographic reconstructions have shown that fluvial-delta complexes played a significant role in the formation of sedimentary complexes in the South Caspian basin. The general geological background of the SKB is characterized by: sharp lithofacial and filtration-capacitive heterogeneity of the section, which was built up in separate Cenozoic intervals in an environment of nonequilibrium avalanche sedimentation; rhythmicity of the productive stratum-red-colored stratum (PT-CT), expressed in periodic vertical substitution of clay differences with sandy ones; lens-forming regionally consistent wedging of the stratigraphic components of the PT section. CT both in the direction of rising and sinking of general folding; Lithologicalpaleogeographic and lithological-facies studies indicate the existence of favorable conditions for the formation of lithological and stratigraphic traps of oil and gas in clinoform complexes in the South Caspian basin. The results of these studies are of key importance for practical applicationin the field ofin the planning of geological exploration. Reservoir maps and litho-facies schemes provide a reasonable choice of the location of project wells in the most promising areas of reservoir development. Models of paleogeographic settings make it possible to predict the distribution of sand bodies in ancient delta complexes, and sedimentation rate maps help to assess the degree of rock consolidation and predict abnormal reservoir pressures. Keywords: South Caspian basin; paleogeography; lithologic-facies schemes; sedimentation rates; depocenters; reservoirs; clinoforms.