Geochemical studies of organic matter in Jurossic-Triassic record (378
2-6038 m) of Tjumen' boring hole (SG-6) were carried out. It was found
that the Koltogory-Urengoy graben-rift structure should be considered
as a linear site of the intensive and persistent generation and migra
tion of hydrocarbons at the Western Siberian plate. The hydrocarbons c
ould exist in liquid state up to the depth of 4.7 km, at higher depths
(4.7-6.0 km) the hydrocarbons could be present in gaseous or gas-cond
ensate state.