**3. Materials and Methods**

The study methodology consisted of a number of sequential steps [16–19], including:


The Kingdom and TEMIS 3D software systems (VNIGRI licenses) were used to process seismic survey data and build a basin model. To calculate the hydrocarbon potential of the oil and gas system, balance equations were used, obtained on the basis of numerous experimental data from VNIGRI [25,26] and linked to the degree of transformation of organic matter (catagenesis) [27–32].

The greatest contribution to the clarification of the hydrocarbon potential of the studied area was made by such parts of this study as:

Refinement of the structural model (a series of structural maps) based on the interpretation and linking of the profile seismic survey on the land part of the site, in the transitional shallow water zone (depths less than 25 m), on Kolguev Island, and in the relatively deep water zone (more than 25 m).

Clarification of the boundaries of the development and thickness of the Lower Paleozoic part of the section (separately the Lower-Middle Ordovician terrigenous strata, Lower Silurian carbonate strata, Lower Devonian terrigenous-carbonate strata, Middle Devonian-Lower Frasnian terrigenous strata, and Middle-Upper Frasnian (so-called "Domanik") carbonate-siliceous-clay strata).

Identification of characteristic features inherent in oil and gas source deposits (organic carbon content of more than 0.5% per rock), with an emphasis on the Lower Paleozoic part of the section.

Identification of lithological and facies features and boundaries of the distribution of the oil and gas system, traditional for the Timan–Pechora OGP—the Domanik oil and gas source formation.

Conduction of a laboratory study by pyrolysis of core samples from the Ordovician, Lower Silurian, and Middle Frasnian parts of the section.

Determination of the stratigraphic interval of the distribution of Lower Silurian sediments enriched with organic matter and tracing their distribution within the studied area.

Determination of the lithological composition (microscopic and petrographic study of samples) and lithotypes, typical for sediments enriched with organic matter.

Study of the petrophysical features of Ordovician and Middle Frasnian terrigenous deposits in order to identify reservoirs.

Paleotectonic reconstructions along the lines of individual seismic profiles in order to determine the time of immersion of the source sediments to the depths of the "oil window".

Mapping the current concentration of organic carbon and the catagenetic maturity of organic matter.

Recalculation of the amount of organic carbon in Silurian and Upper Devonian rocks at the beginning of catagenesis.

Clarification of possible ways of hydrocarbon migration through the transit terrigenous strata of the Lower and Middle Devonian.

Construction of a basin model in the TEMIS and assessment of the hydrocarbon potential of the studied area.

To assess the residual oil and gas potential of the Silurian strata, an integrated approach was applied using quantitative models of oil and gas generation developed by Neruchev S.G. [25,26] for the main genetic types of organic matter, which can be used as a basis for assessing the oil and gas formation of any potential oil and gas source strata.

Sapropel OM is characterized by the highest oil-producing potential (I-II types of kerogen according to international terminology).

Based on these models, in which the weight percentage of generated liquid and gaseous hydrocarbons in the mass of the initial substance is calculated.

In this study, the technology of TEMIS for basin modeling is used. The essence of modeling is to restore the geological processes that determine oil and gas formation [27–32].

The resource assessment by the volume-genetic method is based on the capabilities of a rock enriched with organic matter to generate hydrocarbons. This method evaluates the generation potential of the oil and gas source strata and the degree of its realization. The method of calculating the generated hydrocarbons by the oil-producing stratum located in the center of an oil and gas formation includes the calculation of the current content (mass) of organic carbon (Cc) in oil and gas-producing rocks, an estimate of the mass of generated hydrocarbons per unit mass of Cc, and an estimate of the total amount of generated hydrocarbons by the oil and gas-producing rock [25,26].

The theories and technologies of basin modeling have been successfully tested for a number of other regions [31,33–39].
