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The geothermal field of the platform cover within the Grodno region is considered. The cover rests on a crystalline basement of Precambrian rocks. Temperature distribution maps for depths of 100; 200 and 300 m below ground level were compiled based on thermograms recorded in boreholes and were supplemented by the heat flow map. These reveal geothermal anomalies both of temperature and heat flow density distribution within the region. The temperature in the region monotonously increases with depth, while preserving the general features of the thermal field. The anomalies identified on the 100 m map persist for depths of 200 and 300 m. The main role in the formation of temperature anomalies is played by near-surface factors, such as groundwater circulation, and the influence of paleoclimatic changes on the Earth’s surface in the past. A low heat flow (< 30 mW/m2) in the eastern part of the region gradually increases up to 50 mW/m2 in the vicinity of Grodno. Its areal variation relates to the distribution of granitoid and blastomylonite rocks in the crystalline basement. Increased heat flow is typical of silicic rock massifs with elevated concentrations of long-living radioactive isotopes of uranium, thorium and potassium. Their decay creates an additional radiogenic component of heat flow.

Link for citation: Krutenko D.S., Isaev V.I., Isaev S.G. Density of hydrocarbons and deep heat flow of the territory (southeast of Western Siberia). Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 148-163. In Rus. The relevance. According to the ruling theory for organic origin of petroleum, geothermal regime is considered to be the main factor, which is responsible for realization of potential for oil generation. Therefore, it is not irrelevant to develop geothermics as a method of exploration geophysics for forecasting and evaluating oil and gas potential. Forecast tasks are reduced to detection local geothermal anomalies and establishing its relation to hydrocarbon deposits. This method may make a good showing while supplementary exploration in the territories with well-developed infrastructure and a large amount of wells as it is based on modelling and analysing of available data and does not propose additional field works. The main aim: establishing qualitative and quantitative relations between deep heat flow and oil and gas potential, also between gradient zones of heat flow and localization of hydrocarbon fields in the west of Tomsk Region. Objects: thermal field and oil and gas potential in the west of Tomsk Region. Subjects. The thermal field is described with such parameters as deep heat flow density and horizontal gradient of heat flow. Hydrocarbon fields are divided depending on fluid type into oil, oil-gas-condensate and gas-condensate. Methods. The deep heat flow was determined through paleotemperature modelling. The grid with cells of 20×20 km was set on study territory in increments of 10 km. Heat flow values were determined in the centers of each cell using Kriging interpolation method. The absolute horizontal gradient of heat flow was calculated on the same grid using five spot formula. Quantitative parameter of oil and gas potential – hydrocarbon density – was determined on the same grid. Quantitative relations were investigated by correlation and regression analysis. Relationships of heat flow density and horizontal gradient of heat flow with localization of hydrocarbon fields of different fluid type were detected by one-way ANOVA test. Results. The main results of this study are established distribution patterns for deposits of different fluid type in thermal field. Correlation analysis showed highly significant correlation coefficients. The conclusion. Oil and oil-gas-condensate fields tend to the average heat flow values (52 mW/m2), while gas-condensate are associated with high heat flow values (57 mW/m2). The value of the absolute horizontal gradient of heat flow increases in row oil fields – oil-gas-condensate fields – gas-condensate fields. The difference between average values of gradient for all of field types is statistically significant. Therefore, we indicate appearance of geothermal quantitative criterion for forecasting fluid type of deposits in areas of high potential for hydrocarbons. Quantitative relation of high significance (r=0,53) between heat flow density and hydrocarbon density is established for high heat flow values (>56 mW/m2). Weak correlation (r=0,3) was indicated between horizontal gradient of heat flow and hydrocarbon density.

A mathematical model of the temperature field was constructed and the temperature values for hypsometric levels of 1000, 2000 and 3000 m were calculated. for these hypsometric levels, as well as a map of the isothermal surface +50 ºC. Working with this program involves the construction of digital models of the surface, ancillary operations with them and visualization of surfaces. The digital model of the surface has the form of values in the nodes of a rectangular regular grid, the dimension of which depends on the specific problem to be solved. The efficiency of the program of interpolation of two-dimensional functions is determined by the following aspects: a set of various interpolation methods; the ability of the researcher to control the various parameters of these methods; availability of means of an estimation of accuracy and reliability of the constructed surface; the opportunity to clarify the result based on the personal experience of the expert in view of various additional factors that could not be depicted as source data. It is confirmed that the patterns of distribution of the natural thermal field in the upper part of the earth’s crust are due to a number of reasons, the main of which are the lithological composition of rocks, features of tectonic structure and the nature of groundwater movement. As a result of the analysis of graphic constructions, a sharp decrease in the subsoil warming towards the Carpathian folded structure was witnessed. It has been scientifically proven that the subsoil warming within the Mukachevo basin is much higher than within the Solotvyno basin. The confinement of geothermal anomalies to zones of intensive development of deep faults has been confirmed mathematically and experimentally. Based on this feature, it can be argued that the presence of positive geothermal anomalies is a criterion of gas bearing capacity for predicting deposits within local defiection objects.