Paleotemperature research of coals in the Volga-Ural oil and gas province (Russian Federation) in connection with forecasting of non-traditional hydrocarbon sources

Abstract

© Published under licence by IOP Publishing Ltd. Using of thermal methods of influence on the formation allows engaging in the extraction unconventional sources of hydrocarbons. One of the most important unconventional oil and gas objects are highly carbonaceous deposits. On the territory of the Volga-Ural oil and gas province, such objects is the Domanik Formation, which are clayey-siliceous-carbonate shale rocks with a high content of organic matter (OM). To identify and clarify the mechanisms of formation of oil and gas fields, as well as forecast and search for promising areas in the area of distribution of shale strata, the method of measuring the reflectivity of vitrinite is used. However, the absence of residues of plant organic matter in the Domanikites creates difficulties in applying the method. To assess the prospects of individual sections of the Domanik Formation, it is possible to use the paleotemperatures of the field of adjacent and overlying sediments, where coal seams and inclusions of plant organic matter are present. The basis of this approach is the paragenetic association of oil, coal and shale sediments. The formation of shale and coal-bearing formations is due to the primary conditions of sedimentation, and the formation of oil and gas deposits is associated with deep thermal effects during periods of tectonic activation on the territory. The structure of modern thermal fields, due to changes in temperature values, is controlled by the location of zones of deep faults in the crystalline basement of the platforms. Paleotemperatures are determined quite accurately by the degree of catagenetic transformation of organic matter (OM), which can be used to reconstruct the structure of ancient thermal fields in sedimentary formations and identify areas of maximum warming. Regional patterns of change in the degree of coal metamorphism can be used as a basis for forecasting and identifying promising areas of oil and gas shale raw materials.