Print this pageProterozoic-Early Palaeozoic Carbonate Reservoirs in East Siberia, Russia
ROBERTSON, GARY
A Proterozoic to early Palaeozoic petroleum system is defined in the Siberian Platform, East Siberia, Russia. Riphean and Cambrian carbonate reservoirs, Riphean carbonate source rocks and Cambrian evaporite seals are important elements of the petroleum system.
The Siberian Platform is a large, stable and ancient craton. Archaean igneous and metamorphic basement is overlain by 3,000-8,000m thick unmetamorphosed Proterozoic to Mesozoic sediments. The sedimentary cover comprises thick Riphean carbonates, Vendian clastics and Cambrian carbonates and evaporites, locally overlain by Ordovician to Cretaceous clastics and Triassic volcanics. Broad regional folds and re-activated basement faults provide structure in the sedimentary cover, complicated by Cambrian salt movement and Triassic igneous activity.
Three hydrocarbon plays are identified: i) Riphean carbonates in structural-stratigraphic traps, ii) Vendian clastics in stratigraphic traps, and iii) Vendian clastics and Cambrian carbonates in structural-stratigraphic traps. Riphean and Cambrian carbonate reservoirs are predominantly dolomitic, with karst and vugular secondary porosity connected by permeable fractures. Vendian clastics are fine to medium-grained quartz-rich argillaceous sandstones. Organic-rich Riphean and Vendian sediments are the petroleum source. Hydrocarbon generation and migration commenced in the Proterozoic and continued through the early Palaeozoic. Entrapment has been preserved by an efficient Cambrian evaporite seal and stable tectonic conditions.
Oil and gas was first discovered in the Proterozoic to early Palaeozoic petroleum province in 1962. Around fifty fields have been discovered to date and discovered recoverable reserves are estimated at 40 Tcf gas and 6 Bbbl oil and condensate. Full commercial development of the East Siberian region has been limited by geographic remoteness. Undiscovered hydrocarbon potential is anticipated to be high.