Petroleum System in the Southeastern Siberia: From Proterozoic Sources to Cambrian Traps

Abstract

Southeastern Siberia is the most explored part of the vast Lena-Tunguska petroleum province. It consists of three basic structures: PredPatom trough, Nepa-Botuobin anteclise, and Angara-Lene terrace. Main potential source rocks are largely upper Proterozoic within the PredPatom trough. Other Lower Cambrian source rocks are scattered to make up only 7-9% of the regional petroleum potential. Over 90% of oil and gas discovered to date is reservoired in the Riphean-Cambrian subsalt section on the Nepa-Botuobin and Angara-Lena regional highs. A thick Cambrian salt-bearing section provides a good seal. The main stage of hydrocarbon migration occurs in Vendian - Cambrian time out of the PredPatom trough. Traps are combining stratigraphic wedging out with structural features and reefs. Many of those were affected by late Paleozoic-early Mesozoic volcanic traps, sills, and/or overthrust tectonics. There are over 25 discoveries (mostly gas and condensate) in the region. About two of these are considered giant fields. Math modeling of hydrocarbon generation processes shows that significant petroleum potential is yet to be discovered, particularly in the PredPatom trough.