Evolution of the formation of gaseous hydrocarbons in the Earth's history

This paper generalizes materials on the distribution of the initial explore d world gas reserves throughout the stratigraphic scale and describes cycli c recurrence in this distribution. It is shown that 52% of the world gas re serves migrated in the section. With account of this migration, the authors estimate the scales of gas formation in individual stratigraphic subunits and the gas formation intensity in thousands of m(3) per year. The maximum intensities have been established in the Late Carboniferous (1990), Late Pe rmian (2403), Middle Jurassic (1328), Early Cretaceous (746), and Miocene ( 692). The evolution of gas formation is intimately related to the evolution of oi l formation and depends primarily on global tectonics. But in the Early Car boniferous-Late Cretaceous, when 78% of gas and 88% of coal formed, the rol e of tectonics was reduced by the effect of another factor - expansion of g round plants deep into continents (Davitashvili's ecogenesis theory). In th is period, the intensity of gas formation intimately correlated with the in tensity of coal formation, and in the other periods it was closely related to the intensity of oil formation.