Home – Home – Jornals – Russian Geology and Geophysics 2024 number 1

This issue of the journal is dedicated to the 90th birthday of Academician of the RAS A.E. Kontorovich. This introductory article reviews the included materials. The topics of the articles are closely connected to the scientific interests of Aleksei Emilievich, even though they are not fully represented. This anniversary issue includes articles concerning topical questions of geology, tectonics, stratigraphy, petroleum potential, as well as various aspects and characteristics of oil and organic matter geochemistry in oil-and-gas source formations of sedimentary basins of Siberia and the Arctic. Among the many lines of research A.E. Kontorovich pursued was the geology and geochemistry of concentrated forms of subsoil organic matter - coal. Therefore, this issue logically ends with an article on the study of the most ancient Devonian coals.

The estimation results of the initial total unconventional resources of hydrocarbon in Domanik type sediments, the Khadum and Bazhenov formations are provided. The reasonability of estimating hydrocarbon resources in these deposits by the volumetric method is substantiated. The stratigraphic interval of their distribution is given. The technique of oil and gas geological zoning based on the mapping of structural and facies zones, the degree of catagenetic transformation of organic matter, and the boundary values of the thickness of carbonaceous rocks in the section is described. The criteria for the allocation of pay intervals that make up the effective part of the section are determined. The choice of parameters such as porosity coefficient, oil recovery coefficient, oil saturation coefficient, correction factor and oil density is justified. For each complex of deposits, adjustments related to the features of the geological structure of the estimation targets, the conditions of their occurrence and the degree of geological and geophysical study have been introduced into the estimation of total geological resources. The volumes of total geological and recoverable resources of unconventional hydrocarbon sources for the Volga-Ural, Timan-Pechora, Black Sea-North Caucasus, West Siberian and Lena-Tunguska oil and gas provinces are given. The conducted research has rationalized extensive resources, the recovery of which can compensate for the decrease in oil volumes from traditional deposits.

This article presents the latest state of exploration and development of shale oil of continental lacustrine formations in the main basins of China, summarizes the main theoretical considerations and key technologies for exploration and development, and suggests prospects for exploration and development of shale oil in China. It is believed that the exploration and development of oil in shale formations rich in organic matter of types I and II of medium and high maturity are key to the breakthrough of production of 10 million tons in China. This will play an important role in China’s stable oil production at the level of 200 million tons per year in the future. The efficient development of medium- and low- maturity shale oil resources can be significantly improved and lead to serious changes in oil production only after new breakthroughs in the theory and technology of shale deposits.

The results of regional geological exploration over the past 18 years within the Aldan-Maya potential petroleum area were used as the basis for the refinement of the geological structure of the study area. The study considers the key structural features of the sedimentary cover of the Aldan-Maya region and major tectonic events that affected its structure. The generalization and interpretation of regional seismic survey data provided the basis for building a series of geoseismic sections and structure maps, which, in turn, were used in structural tectonic zoning of the study area. The map showing outcrops of Riphean formations and groups on the pre-Vendian erosion surface was complied. Tectonic schemes for three structural levels (upper Karelian-Lower Riphean, Middle-Upper Riphean and Vendian-Cambrian) confirmed their fundamental difference. In particular, the large Maya inclined swell was detected only in the topography of the Lower Riphean and is absent in the overlying structures of Middle Riphean-Vendian age, which are represented by weakly differentiated monoclines. The parameters of the major tectonic elements were determined.

The Vendian oil and gas complex (OGC) consists of the Vilyuchan, Nepa, and Tira stratigraphic horizons. The horizons are divided into correlation layers, stratigraphic charts are refined, cyclometric stratigraphic charts of oil and gas-bearing areas of the southern part of the Lena-Tunguska province are constructed. The lower boundary of the Vendian oil and gas complex and the base of the Vendian system are established in the Nuj zone of the Nepa-Botuoba and Irkutsk zones of the Angara-Lena oil and gas region (OGR) at the end of the pre-Vendian break in sedimentation. In the Angara-Lena OGR, the Typta Formation lies after a break both on different formations of the Baikalian system, and on the basement, and it is covered by sandstones of the Vendian Nepa horizon. The Typta Formation is assigned to the Vendian system, to the Vilyuchan horizon. In the Nepa-Botuoba OGR, a long pre-Vendian break divided the Talakan Formation into an upper Vendian and a lower Riphean parts. The name Talakan is left for the Vendian strata, the lower part is divided into three strata of the Baikalian system. The cyclometric stratigraphic scale is based on repetitions of cyclically constructed sections of horizons and their parts. Repetitions are considered as the result of oscillatory movements of the Earth, which take place at different intervals of time. The ranks of movements are planetary (40 Myr), long-period (20 Myr), and regional. In these ranks of time, nexacylites, horizons and regocyclites were formed. The horizons linked the regional and cyclometric stratigraphic scales. Breaks in the sedimentation of the Vendian OGC are divided by duration into short-term separating regocyclites, long-term separating horizons and two breaks - pre-Vendian and pre-Danilovo, the duration of which reaches 10-20 Myr.

In this paper we analyze the geological structure and prospects of hydrocarbon potential of the Paleozoic deposits in southeastern regions of West Siberia, including the Tomsk, Novosibirsk, Omsk regions and the southwest of the Krasnoyarsk Territory in the left-bank part of the Yenisei River. In the process of our studies, we analyzed the tectonic structure of the basement and made a conclusion that most of the studied area is occupied by the Central West Siberian zone of Late Hercynides. In the northeast of the Tomsk region and the adjacent area of the Krasnoyarsk Territory, the cis-Yenisei Upper Protezoic-Paleozoic sedimentary subbasin, lying on the pre-Baikal basement, developed. We constructed regional-zonal models of the Riphean-Cambrian deposits of the cis-Yenisei subprovince and Paleozoic deposits in the area of distribution of Hercynides and analyzed the material composition and age of the rocks of the pre-Jurassic basement. We assessed hydrocarbon potential of the Upper Proterozoic-Paleozoic deposits, identified prospective blocks and objects, developed seismogeological criteria to identify and map in detail the Paleozoic oil and gas prospective reservoirs and constructed seismogeological models of reference fields.

The Bazhenov horizon is the main source rock stratum of the West Siberian petroleum province, which possesses significant resources of hard-to-recover hydrocarbons, making it a unique exploration target. The study summarizes geochemical data on crude oils (39 samples) collected from pools within the Bazhenov and Tutleima formations. A comparative analysis of the carbon isotope composition and geochemical parameters calculated from the composition of the identified saturated and aromatic compounds (pristane/phytane, C₂₉/C₂₇ steranes, C₃₅/C₃₄ homohopanes, tricyclane index, relative concentrations of dibenzothiophenes) confirm a common aquatic genotype of the studied oils and their genetic affinity to the organic matter of the same age. At the same time, significant variations in the main physical and chemical characteristics of the studied Bazhenov oils may be caused their fractionation during migration processes.

A complex of laboratory studies of Riphean rocks and oils was carried out by the organic-geochemistry methods to construct a basin model for the Kamo arch of the Baikit anteclise of the Siberian craton. We compared the parameters of the organic matter (OM) and oils of the Upper Riphean Iremeken carbonaceous member by biomarker hydrocarbons. Analysis of the obtained chromatography-mass spectrometry data showed an unordinary group hydrocarbon composition of extracts from the OM and oils and low contents of cheilanthanes and steranes in them. Within the Kamo arch, the Upper Riphean Iremeken OM-enriched deposits with a high petroleum potential might have reached the peak of petroleum generation only in the deepest part of the Madra trough; thus, the traps could not be completely filled with oil. The distribution of tricyclic terpanes in the rock bitumens from the studied wells testifies to immature OM in the Iremeken Formation. However, in the most submerged zones of the Kamo arch and in the adjacent areas, oil was generated from the OM of the Iremeken Formation. This is evidenced by the oils of the Upper Iremeken Subformation in the Kuyumbinskoe field and the Ter’-Kamo license area.

The kinetic characteristics of kerogen (activation energy and frequency factor distributions of the initial generative potential) determine the dynamics of naphthide generation during catagenesis. In the previous studies on quantitative modeling of naphthidogenesis in the Kuonamka source rocks, the kinetic characteristics were taken by analogy with the known kerogens from other complexes and provinces. It seems relevant to determine the effective kinetic characteristics of the kerogen from the Kuonamka source rocks from experimental data. To estimate the kinetic parameters, specialized multi-rate pyrolysis studies were performed. The variations in pyrolysis data was reported to be presumably associated with the conditions of kerogen and source rock formation during accumulation and diagenesis of organic matter. The effect of carbonate and organic carbon contents on the temperature range of the second pyrolysis peak is recorded. Reconstruction of the average (effective) kinetic characteristics of kerogens from the Kuonamka source rock, was conducted using data on kerogens from Serkinsky-5 and 10 and Tit-Ebya-6 wells, which are less degraded than kerogens from Ust’-Maiskaya-366 well and probably attained the early mesocatagenesis grades. The current average effective kinetic characteristics of kerogen were estimated and corrected for the possible partial degradation of reference samples. The obtained effective kinetic models of kerogen are compared with models of kerogens of various genetic types known from the literature. The estimated effective kinetic characteristics of kerogens or Menil-1 and Type B kerogens with similar characteristics are to be taken, as a first approximation, in regional historical-genetic (basin) modeling of naphthide generation in the Kuonamka source rock.

We have studied biostratigraphy, lithology and geochemistry of drill cores from the Kyulenke River basin. The study of fossil remains and rock compositions, the analysis of trilobite distributions and changes in the lithological and geochemical characteristics of the sediments made it possible to identify structural features of the marker horizons, to correlate borehole sections and outcrops, to compare individual Cambrian intervals and the regional zones of the Yudoma-Olenek facies region of the Siberian Platform. The study has shown rocks of the Kuonamka Fomation to be enriched in uranium (U) and revealed a direct relationship between the contents of U and organic carbon (C_org) in the analyzed rocks, typical for the lower and middle Cambrian black shale deposits sampled from the outcrops in the eastern parts of the Siberian Platform. For the first time, a relationship of rock radioactivity by gamma-ray logging with the contents of U and C_org in Cambrian rocks was established.

The composition of the oldest coals of the Timan-northern Urals region has been studied comprehensively, and their hydrocarbon and microcomponent characteristics are given. The relationship between different types of coals and Late Devonian plant communities of the North Timan is revealed. It is also determined that some samples contain microspores, megaspores, and plant remains belonging mainly to the lycopod Helenia . The most probable source of jet coals is identified as the wood of the progymnosperm Callixylon . The values of vitrinite reflectance and T_max and the data on the distribution of polycyclic biomarkers and methylphenanthrenes indicate the low maturation of the coal organic matter. The coal bitumen investigated here is characterized by the dominance of steranes and diaster-13(17)-enes of compositions С₂₈ and С₂₉. The following diterpanes are identified: beyerane, 16α(H)-kaurane, 16β(H)-kaurane, and 16α(H)-atisane. At the same time, phyllocladane is absent.