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Интеллектуальная Система Тематического Исследования НАукометрических данных |
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The Barents Sea shelf is assumed to contain considerable oil and gas resources in Mesozoic reservoirs both in Russian and Norwegian sectors as confirmed by discoveries of the gas fields Murmanskoe, Severo-Kidinskoe, Shtokmanovskoye, Ledovoe, Snohvit. Shales of Triassic succession in this region are of a great interest for scientists as potential source rocks for the hydrocarbons. The present work is devoted to composition, characteristics and depositional environments of Triassic sediments of the Barents Sea shelf and their hydrocarbon generation potential. The main goal was to evaluate a connection between type and quantity of organic matter and paleogeographic settings. Our geochemical studies of the Triassic oil and gas source rocks in the Barents Sea are based on 20 Triassic rock samples with presumably high TOC from the outcrops at the Franz Josef Land and Svalbard Archipelagos. Studies of paleogeographic environments were based on field-trip, literature and well data. Macro- and micro descriptions have been done to identify lithological properties of the samples. Complex of geochemical methods was used to characterize quality and quantity of organic matter, its genetic type, composition and maturity: Rock Eval pyrolysis, extraction, liquid adsorption and gas chromatography. Paleogeographic maps of the Barents Sea region for Early, Middle and Upper Triassic epochs have been constructed on bases of litho-stratigraphic columns. Comparison of sedimentary facies zones was made according to lithology, biostratigraphy, thicknesses, and geochemical data of organic matter. The Barents Sea in Triassic time provided an example of a vast extensional basin, where sedimentary environments changed from fluvial to deltaic, coastal and marine ones. Quality of the Triassic source rocks is strongly correlated with depositional environments. The best source rocks with highest content of humic-sapropelic organic matter (TOC=0,5-7%) and high oil and gas generation potential were deposited during Early and Middle Triassic in intrashelf basins at Svalbard and Norwegian shelf. Contemporaneous source rocks with humic type and high to average content of OM (TOC=0,4-1,2%) are related to shallow and near-shore marine environments at Franz Josef Land. The basin underwent general shallowing in Late Triassic, thus the source rocks of this age in the north, north-west and south-west of the region contain humic type of OM and have gas generation potential. At the south of the Barents Sea and in Pechora Sea, the Triassic rocks have low OM content and generation potential due to prevailing fluvial and deltaic oxidizing depositional environments.