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THE UPPER LENA ARCHED UPLIFT IS THE MAIN OBJECT OF PREPARING A RESOURCE BASE OF HYDROCARBONS IN THE SOUTH OF THE SIBERIAN PLATFORM

A. G. Vakhromeev 1,2, A. S. Smirnov 3,5, A. M. Mazukabzov 1, I. V. Gorlov 1,3, N. V. Misyurkeeva 1,4, G. Yа. Shutov 6, V. V. Ogibenin 3

1 Institute of the Earth’s Crust SB RAS, Irkutsk, Russia; 2 Institute of the Subsoil Use, Irkutsk National Research Technical University, Irkutsk, Russia; 3 Gazprom Geologorazvedka, Tyumen, Russia; 4 Sigma-geo, Irkutsk, Russia; 5 Tyumen Industrial University, Tyumen, Russia; 6 O. Yu. Schmidt Institute of Physics of the Earth RAS, Moscow, Russia

The current results of geological exploration at the unique Kovyktinskoye gas condensate field (GCF) in the Irkutsk Region are considered as a result of the development of conceptual ideas about the prospects of oil and gas potential in the south of the Siberian Platform. At the initial stage of oil and gas exploration, this area was called the Irkutsk Amphitheater, oil-and-gas-bearing, sedimentary basin. Later, most of it was included in the Angara-Lena Petroleum Region. The authors worked out in detail the well-known ideas of different years about the geological position of the unique Kovyktinskoye gas condensate field, whose localized reserves today amount to more than 2.7 trillion m3. A considerable volume of accumulated data of deep drilling and field geophysics on the structure of the sedimentary cover and the crystalline basement surface of the southern and southeastern part of the craton, including the latest geological and geophysical data, was taken into account. It is concluded that the most correct results of more than 70-year exploration for oil and gas fit into a geological model of the major Upper Lena neotectonic arched uplift proposed by geologists of the USSR MINGEO VostSibNIIGGiMS in the 1980s. The inherited uplift from the Lower Paleozoic to the present time is formed by a “skew” bed of sedimentary cover of the platform part of the amphitheater and irregular vertical movements of the fore deeps – the Angara-Lena and Angara-Sayan ones – as a result of tectonic movements differing in amplitude. Contours of the Angara-Kovykta oil and gas accumulation zone, the object of highpriority geological exploration, with the aim of increasing the resource base of natural gas in the south of the Irkutsk Region, were outlined and justified.

Keywords: Kovyktinsloye gas condensate field, Angara-Kovykta oil and gas accumulation zone, Upper Lena uplift, marginal (Riphean) depressions, overthrust tectonics, virgations of linear folding.

DOI 10.20403/2078-0575-2019-3-38-56