ZONING OF THE OIL ACCUMULATION DENSITY OF THE EAST-PAIDUGIN DEPRESSION JURASSIC RESERVOIRS (USING CALCULATED THERMODYNAMIC PARAMETERS OF THE OIL SOURCE TOGUR SUITE)

Abstract

The relevance of the study. The study and development of the unallocated subsoil fund of the Tomsk region east is being carried out to stabilize the falling level of oil production in the southeast of Western Siberia. The choice validity of the study area is determined by the prospects and underexploration of the Ob River right bank. The main aim of the research is to replenish the resource base of the Tomsk region fuel and energy complex at the stage of identifying promising areas and sites for predictive and exploratory research. The objects of the research are the Lower Jurassic oil source Togur suite, weathering crust and Paleozoic reservoirs of the East-Paidugin depression territory. The subjects of the research are the thermodynamic regime of Togur oil generation sources, the capacitive properties of pre-Jurassic reservoirs. The task of the research is to perform zonal zoning of the pre-Jurassic complex of the East-Paidugin megadepression and framing structures based on the integration of basement rock petrotype classifications, thermodynamic characteristics of the oil source Togur suite and the distribution of weathering crust thicknesses. Research methods. The study of the hydrocarbons generation density by the Togur suite is based on paleotemperature reconstructions of sedimentary rocks at each moment in the development of the basin at known temperatures on the surface (paleoclimate) and heat flow values given at the base of the sedimentary cover. The zoning of the weathering crust and Paleozoic reservoirs was carried out on the basis of a conditional classification of foundation rocks petrotypes, the integration of three digital parameters, namely, the weight coefficients of the potential for the formation of reservoirs by various petrotypes, the values of oil generation density and the values of weathering crust thicknesses. When ranking sites according to the density of primary oil accumulation, the weight coefficient of the basement rock petrotype potential was taken as the first important feature, the density of Togur oil generation was the second, and the thickness of the weathering crust was the third. Results. Areas of the Vladimirov megaprotrusion western cape and the Vargat mesotrough northeastern side is assigned to the zone with the maximum prospects for the Paleozoic reservoir. Highly promising areas include areas of the Belonogov mesouplift, the northern part of the East-Paidugin junction megadepression and the Vladimirov megauplift, and the Beloyar mesouplift northeastern slope. The zone with the highest potential for the weathering crust reservoir includes areas of the Vargat mesotrough northeastern side, the Vladimirov megadepression western cape, the northern part of the junction of the East-Paidugin megadepression and the Vladimirov megadepression, and the area of the junction of the Vladimirov megadepression northwestern slope and the East-Paidugin megadepression northeastern edge. The zone with high prospects includes areas of the Vargat mesoprotrusion northern part and the Beloyar mesoprotrusion southeastern slope, the Beloyar mesoprotrusion eastern slope and the Vargat mesoprotrusion southwestern slope, the Belonogov mesouplift western and eastern parts. Conclusions. The zones of maximum and high predictive prospects for weathering crust and Paleozoic reservoirs are recommended to be taken into account when planning the search for pre-Jurassic oil deposits in the Tomsk region northeast. Along with that, research results visibly promote development of the methodology and the theory of Geothermics as of Exploration Geophysics method.

Keywords

• oil source suite paleotemperature reconstruction
• weathering crust and paleozoic reservoirs
• conditional classification of foundation rocks petrotypes
• digital zoning and ranking
• northeast of tomsk region