Petroleum Occurrences in Subsalt Deposits of the Caspian Depression and the Mid-European Basin

The high productivity of the subsalt deposits of the Caspian and Mid-European salt-bearing basins demonstrably results from features of their structure and development: long and intense downwarping, the presence of a thick salt-sulfate caprock, the distribution of petroleum-generating and reservoir sequences, etc. The distribution patterns of the major zones of petroleum accumulation are primarily determined by paleotectonic and tectonic factors and are controlled by major basement rises of ancient origin. The distribution of petroleum occurrences through the section within the zones of petroleum accumulation has been associated with the lithologic-facies composition of the rocks. The predominant gas or oil-and-gas capcity is determined by the original type of disseminated organic matter, the grade of its catagenic transformation, and the features of formation of the segregations.