The overall jump in global demand for gas, and especially oil, gives rise to particular concern regarding mankind’s energy future. In the middle and late 21st century, the crucial role in securing oil and gas supply of mankind will be played by sedimentary basins in the Arctic Ocean deep-water area, including those of the continental shelf in Russia’s Arctic seas. There is a 0.90 probability that the initial in-place resources of hydrocarbons in the Arctic Ocean will be greater than 90 Btoe. The estimates predict the rise of oil and gas industries on the Arctic shelves in the near future.
The evolutionary-genetic method, whereby modern sedimentary basins are interpreted as end-products of a long geological evolution of a system of conjugate palaeo-basins, enables the assessment of the petroleum potential of the Western sector of the Russian Arctic. Modern basins in this region contain relics of palaeo-basins of a certain tectonotype formed in varying geodynamic regimes. Petroleum potential estimates of the Western Arctic vary broadly—from 34.7 to more than 100 billion tons of oil equivalent with the share of liquid hydrocarbons from 5.3 to 13.4 billion tons of oil equivalent. At each stage of the development of palaeo-basins, favourable geological, geochemical and thermobaric conditions have emerged and determined the processes of oil and gas formation, migration, accumulation, and subsequent redistribution between different complexes. The most recent stage of basin formation is of crucial importance for the modern distribution of hydrocarbon accumulations. The primary evolutionary-genetic sequence associated with the oil and gas formation regime of a certain type is crucial for the assessment of petroleum potential. Tectonic schemes of individual crustal layers of the Western sector of the Russian Arctic have been compiled based on the interpretation of several seismic data sets. These schemes are accompanied by cross-sections of the Earth’s crust alongside reference geophysical profiles (geo-traverses). A tectonic scheme of the consolidated basement shows the location and nature of tectonic boundaries of cratons and platform plates with Grenvillian basement as well as Baikalian, Caledonian, Hercynian, and Early Cimmerian fold areas. Four groups of sedimentary basins are distinguished on the tectonic scheme of the platform cover according to the age of its formation: (1) Riphean-Mesozoic on the Early Precambrian basement; (2) Paleozoic-Cenozoic on the Baikalian and Grenvillian basements; (3) Late Paleozoic-Cenozoic on the Caledonian basement; (4) Mesozoic-Cenozoic, overlying a consolidated basement of different ages. Fragments of reference sections along geo-traverses illustrate features of the deep structure of the main geo-structures of the Arctic shelf and continental regions of polar Russia.
The study of the hydrocarbon potential of the Arctic is being considered in Russia as the most crucial direction of preparing a new raw material base of oil and gas, which will replace the extracted reserves in traditional areas of development during the second third of this century. The sharp fall in global hydrocarbon prices has led to a reduction in research and exploration costs, especially in hard-to-reach areas and hard-to-recover reserves as well as the need to determine the contribution to the country's fuel and energy balance from the hydrocarbons development of the Arctic zone, including the shelf, without which it is impossible to plan and develop new expensive projects. A fair assessment of oil and gas potential, based on a set of ideas about the processes of formation of sedimentary basins and oil and gas generation processes, contributed to obtaining new geophysical information on the results of seismic work executed in the Arctic zone of the Russian Federation between 2010 and 2020. A quantitative assessment of oil and gas resources was performed using geological analogies (for wellstudied geological and geophysical areas) and the volume-genetic method (for less studied basins). It showed significant differences from the most well-known assessments of the Arctic, both in terms of the total volume of hydrocarbons and their phase composition. It was concluded that there is ambiguity in assessing the potential of deepwater zones of the Arctic seas. Because of that, it is important to study coastal and shallow areas, especially oil content.
The sedimentary cover of the Timan–Pechora petroleum basin records several phases of tectonic activity in the area: rifting and incipient ocean opening; a passive margin setting with intracontinental rifts and aulacogen, an intrashelf depression and inversion swells; collisional orogeny with the development of a foredeep; vertical isostatic movements associated with the development of a late syneclise and renewed orogenic movements. The deposition of source and reservoir facies occurred during the divergent phases of the tectogenesis (Ordovician–Tournaisain). The formations that accumulated during a convergent tectonic regime (Visean–Triassic) comprise mostly reservoir rocks. Because of thermal maturity of organic matter, the sedimentary rocks in the area span the broad range of oil and gas generation zones. The identified hydrocarbon kitchen areas were developed in different geodynamic settings: in the east of a passive margin, within rift-related troughs, and in the Ural foredeep. The first two were more liquids-prone fairways, with predominant oil and condensate generation, whereas the latter was largely a gas- and gas-condensate-generative source. The change of structural settings, the extension of oil and gas kitchens, variation of the regional dip, and recurrent faulting caused both the formation of new play fairways and the destruction of existing ones. The new oil-prone fairways that formed synchronously with the onset of intense oil generation might have later evolved into oil- and gas-prone fairways or even oil-, gas-, condensate-prone fairways at the expense of the gas component of petroleum systems, which is thought to increase as a source rock generating mostly oil became capable of generating oil, gas, and condensate. In addition, tectonically active zones may provide the most favorable conditions for the formation of gas and gas-condensate accumulations due to a decrease in formation pressure and expulsion of a free gas phase or due to its updip migration from great depths. Analysis of hydrocarbon generation and accumulation conditions provided insights into the evolution of a petroleum system of each play and transformation of a sedimentary basin into a petroleum basin. The study revealed the areal distribution patterns for oil and gas plays. The long-lived oil-prone plays are confined to a series of paleouplifts within the Izhma–Pechora and Khoreiver tectonically stable blocks. Oil-, gas-, and condensate-prone plays are associated with a tectonically active setting (Pechora–Kolva aulacogen and Timan block), whereas mostly gas- and condensate-prone plays are found within the Ural foredeep.
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