A. G. Kalmykov

Experimental investigations of hydrocarbon fluid recovery from hydrothermally treated rocks of the Bazhenov Formation

The results of experimental shale-oil recovery from hydrothermally treated rocks of the Bazhenov Formation are discussed. It is shown that the yield depends on the duration of an experiment: the longer the hydrothermal impact is, the higher the oil yield is. The potential of oil recovery from hydrothermally treated rocks of the Bazhenov Formation is as high as 25 mg/g or 2.5 wt %. The addition of reducing agents such as aluminum or oxalic acid provides no increase in the coefficient of oil recovery. It is established that the yield of the oil fraction at 250°C is insignificant; at 300°C, it amounts to 25 mg/g, while at 350°C, it decreases up to 15 mg/g. This means that a temperature of 300°C is preferable, since it provides a higher yield of oil products and oil fractions are largely represented by normal alkanes, while chromatograms that were obtained at 350°C indicate the development of complex processes, including graphitization of kerogen.

Geochemical technique of organic matter research in deposits enrich in kerogene (the Bazhenov Formation, West Siberia)

The international interest in shale oil has recently provoked special attention to the Russian unconventional oil-source formations, including the Bazhenov Formation of West Siberia, domanik deposits in the Volga–Ural region, and the lower Maikop Group of the Cis-Caucasus. High contents of para-autochthonous soluble organic matter (bitumen) in clayey–carbonate, clayey–siliceous, carbonate–clayey–siliceous rocks with low filtration–capacity properties results in significant uncertainties in the identification of the generation potential of organic matter (OM). Examination of a large database on the OM of the Bazhenov Formation allowed us to propose an optimum complex technique for study of the source rock potential and assessment of the amount of produced hydrocarbons in the kerogen-rich sediments. The investigations include a combination of Rock Eval pyrolysis prior to and after extraction with different solvents, the comparison of bituminological and pyrolytic characteristics, and the determination of the group composition of soluble organic matter, as well as chromatography and chromato-mass spectrometry.

The geochemical patterns of rocks of the Bazhenov and Abalak formations (Western Siberia)

The composition of rocks of the Bazhenov and Abalak formations in Western Siberia is described. Correlations of the concentrations of the major and minor components in rocks with the concentrations of minor elements and organic material are shown. Study of the concentration of minor elements allows us to determine the conditions of sedimentation: redox potential, hydrogen sulfide contamination, and the source of sedimentary material. The results show that rocks of the Bazhenov Formation were formed under the conditions of low fluxes of clastic material, a reduced environment, and a periodically occurring hydrogen sulfide mode.

The Composition and Reservoir Properties of the Deposits of the Bazhenov Formation in the Central Part of the Tundrin Depression

The section structure was characterized according to the lithological and petrophysical studies of the core from the Bazhenov Formation that has been uncovered in the central part of the Tundrin Depression. The productive oil intervals where the reservoirs of the pore and fissure-pore types occur were identified.

An Experimental Study of the Oil Production from Domanik Formation Rocks Under Hydrothermal Conditions

The experimental results on synthetic oil production from rocks of the Domanik Formation under hydrothermal conditions are reported. The potential for oil-product extraction from the oil fractions of the rocks under a hydrothermal impact was up to 60 mg/g or 6.0 wt %. The injection of inorganic additives (sodium carbonate or silica gel) did not increase the oil-recovery factor. As well, the amount of the recoverable oil products directly depended on the mineral composition of the rocks. The relationship between the percentage of hydrocarbon yield and the mineral composition of the rocks was determined. Clay minerals and silica increased the yield of synthetic oil; carbonates, conversely, inhibit the process.

Estimation of the heat-impact potential for stimulating the development of the deposits of the Bazhenov Formation according to the results of experimental studies

The influence of temperature on rock samples of the Bazhenov Formation is shown. The samples underwent pyrolysis at 300–480°C, as well as in closed autoclaves in the presence of water under formation pressure. The temperature impact at 400°C resulted in a decrease in the S2 pyrolytic peak by 90–95% and almost complete formation of the generation potential of the rocks. Microtomographic studies of samples combined with raster electron microscopy revealed a correlation between the variable reservoir properties of the rocks. At 350°C, the rocks are characterized by a system of fractures; as a result of impacts, the porosity and permeability can increase from several to several tens of times. Our results will allow more precise modeling of the influence of tertiary processes on the rocks of the Bazhenov Formation in order to increase the final oil recovery of the bed.

The phosphate-containing interlayers of the Bazhenov Formation as potential reservoirs

The possible reservoir type of the Bazhenov Formation relative to the intervals enriched in phosphates (apatite varieties) is described in this work. The phosphate rocks are characterized by a highly developed pore space; their porosity can reach up to 14%. Along with this, these rocks have explicit geochemical characteristics of oil-reservoir rocks in comparison with other rock samples in the well. As an example, the productivity index and oil-saturation index for phosphates are twice as high as the background values. The composition of such rocks can slightly vary: fluorine can be observed in phosphate minerals, while the rock is always enriched in organic matter (>8 wt %).