Actual studies of petroleum-series hydrocarbon formation and preservation within East Barents Basin

The authors discuss the aspects of petroleum-series hydrocarbon formation and preservation in Triassic-Cretaceous deposits within East Barents Basin. The results of exploratory drilling are indicative of the predominant gas bearing capacity of the regions; although, despite this fact, the presence of bitumen shows and petroleum-series hydrocarbons having undetermined genesis is revealed on the islands of Franz Josef Land Archipelago framing this region, and in the seafloor sediments of the northern part of the Barents Sea waters. In order to determine their sources, reconstruction of hydrocarbon system evolution was carried out using 3D basin modelling technologies taking into account main tectonic and sedimentary features of the region development from Later Devonian rift stage up to the current syneclise stage. To account for major structural rearrangements, reconstruction the thicknesses of sediments removed during major upwarping phases in Triassic-Cenozoic time was carried out. Thermal history takes into account the Mesozoic magmatism and Quaternary glaciation events. Reliability of the results obtained was tested on the actual kinetic spectra of Mesozoic source rock samples, and calibrated with the density of heat flow and vitrinite reflectance measurements. As a result, it was found that Upper - Middle Triassic deposits have partially left the main oil and gas generation zones by the time of main structures formation, which in some way responds to emplacement of intrusions that caused thermal destruction of Organic Matter and resulted in generation of gaseous fluid. The Jurassic source rocks remained mainly immature. The modelling results are tested using combined gas chromatography mass-spectrometry of bitumen samples taken in 2022 during a surveying company on the Franz Josef Land Archipelago. According to biomarkers, bitumen sources are rocks containing Organic Matter of continental and coastal marine genesis, which corresponds to the Middle Triassic interval; however, no direct oil-Organic Matter correlations could be revealed. Physical methods and digital simulators have supported the fact of liquid hydrocarbons presence in the region. Substantiation of their sources and assessment of generation amount remain among the priority tasks for future studies