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Oil shale of the Middle Volga region: composition, structure, energy properties

The article presents the results of the Volga oil shale study in the territory of Tatarstan and the Ulyanovsk region. It is shown that shales are polymineral rocks of complex composition. The main valuable component is organic matter (kerogen), formed from the products of aquabionts fossilization. Ash components are represented by clay minerals, clastic fragments of mineral grains, calcareous fragments of organic residues, and diagenetic pyrite. Organic matter has a complex structure. The predominant fractions are light and medium hydrocarbons boiling out in the temperature range 150-560°C. In smaller amounts, heavy fractions are present, which are released at temperatures of 560-620°C. The heat capacitance of oil shale ranges from 1607 to 9052 J/g. Loss of shale mass can range from 18.0 to 25.0% of the original sample. According to the summary valuable and genetic indicators, the Volga oil shale belongs to the humus-sapropel type; low-calorie in heat of combustion terms; polysulphide in terms of sulfur content; aluminosilicate-carbonate in terms of the prevalence of oxides in ash.