Reforming of deposits in ancient oil and gas basins (on the example of deposits of the Baikit anteclise eastern slope of the Siberian Platform)

Abstract

The paper considers the stages of formation of modern deposits within the south-western part of the LenaTungussky oil-bearing basin. The main oil and gas source strata capable of generating hydrocarbons are described, the structure of the terrigenous reservoir is considered, a model of deposits formation is developed. The secondary transformation of the reservoir in the zone of development of paleo water-oil contacts, which completely seal the void space, are revealed. The presence of several paleo water-oil contacts is evidence of multi-stage reshaping of deposits. After changing the structural plan in the Paleozoic-Mesozoic time, these zones operate as lithologic impermeable beds. Accordingly, most of the generated hydrocarbons are distributed on the migration path within the slopes of modern large structures and in the reformed non-anticlinal traps. The study of the migration paths of hydrocarbons from generation to accumulation and features of secondary transformations made it possible to establish the presence of a complex multi-stage re-formation of paleodeposits and identify the mechanisms of their formation.