Geological Characteristics Of Heavy Oil And Accumulation Advantage Areas Prediction In Volga-Ural Basin

Heavy oil is an unconventional energy becoming more and more important in the process of industrialization, which has great potential of production.The Volga-Ural basin is one of the most important petroliferous basins in Russia,which is located in the central region of Volga-Ural piedmont zone, it is one of the four major metallogenic belt of the global oil sands with a large number of heavy oil resources.The heavy oil in the basin is mainly concentrated in Devonian and Carboniferous, and in this paper we focus on these two strata as the main research target.The existing data of the heavy oil reservoirs in the basin are relatively fragmented and lack systematic research.There remains some problems, the Main controlling factor and the formation law of heavy oil is not clear.Therefore, on the basis of structural geology, petroleum geology, sedimentology, geochemistry of oil and gas theory, combined with some typical characteristics of heavy oil field, this paper discussed the geological characteristics of heavy oil,and analysis the distribution characteristics and main control factors of heavy oil, further summarized the law of heavy oil accumulation.Prediction of the heavy oil favorable area in Volga-Ural basin is based on such reserch.Through analysis of hydrocarbon source rock lithology, thickness, distribution and relative geochemical indicators(including analysis of organic carbon content,organic content,Chloroform Bitumen "A" content,and reflectance of vitrinite), the paper draws the conclusion that the oil source of heavy oil fields mainly comes from Domanik group, followed by the Visean stage;Comparing the sealing characteristics of cap rock and the lithology and properties of reservoir in various regions,we found favorable scope of heavy oil `s reservoir and cap rock.According to the summarize of characteristics of heavy oil reservoir, we draw the conclusion that the main types of reservoir traps are stratigraphic-structure compound.The migration, thickening and accumulation of oil mainly depend on the tectonism, the characteristics of the structural units and the combination of source reservoir caprock assemblage.Through the analysis of reservoir trap types and distribution characteristics in the Volga-Ural basin,we conclude that the main controlling factors of the distribution of heavy oil reservoirs in the Volga-Urals basin is hydrocarbon source rocks, tectonic factors, and cap rock. Secondly, established the heavy oil reservoir accumulation model of Volga-Urals basin, the preliminary summary is that the pattern of heavy oil reservoir is slope degradation type. Finally, based on the above analysis results, the predicted favorable areas of heavy oil are Tatar uplift connected with Melekess depression,edge of Zhiguli-Pugachev uplift and Bashkir uplift.