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Date submitted2024-04-16
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Date accepted2024-09-24
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Date published2024-11-12
Deep-buried Lower Paleozoic oil and gas systems in eastern Siberian Platform: geological and geophysical characteristics, estimation of hydrocarbon resources
The study of deep-buried oil and gas systems is a promising trend in the preparation of hydrocarbon resources. The study of the factors determining oil and gas potential is extremely important. The Lena-Vilyui sedimentary basin in the eastern Siberian Platform has a potential for the discovery of large oil and gas fields in deep-buried Cambrian deposits. The use of original methodological approaches to the analysis of black shale and overlying deposits, generalization of the results of lithological, biostratigraphic and geochemical studies of Cambrian deposits in territories adjoining the study area, modern interpretation of geophysical data showed that siliceous, carbonate, mixed rocks (kerogen-mixtite) of the Kuonamka complex and clastic clinoform-built Mayan deposits are most interesting in terms of oil and gas potential. Oil and gas producing rocks of the Lower and Middle Cambrian Kuonamka complex subsided to the depths of 14 km. The interpretation of modern seismic surveying data confirms the hypothesis of a limited occurrence of the Upper Devonian Vilyui rift system. Based on generalization of geological, geophysical and geochemical archival and new materials on the Lower Paleozoic deposits of the eastern Siberian Platform, a probabilistic estimation of geological hydrocarbon resources of the Cambrian and younger Paleozoic complexes in the Lena-Vilyui sedimentary basin was performed. Based on basin modelling results it was concluded that the resources were mainly represented by gas. It is presumed that oil resources can be discovered in traps of the barrier reef system as well as on the Anabar and Aldan slopes of the Vilyui Hemisyneclise. With a confidence probability of 0.9, it can be stated that total initial resources of oil and gas (within the boundaries of the Vilyui Hemisyneclise) exceed 5 billion t of conventional hydrocarbons. The recommended extremely cautious estimate of resources of the pre-Permian complexes is 2.2 billion t of conventional hydrocarbons. In the study area, it is necessary to implement a program of deep and super-deep parametric drilling without which it is impossible to determine the oil and gas potential of the Lower Paleozoic.
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Date submitted2022-09-26
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Date accepted2023-03-23
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Date published2023-12-25
A new diamond find and primary diamond potential of the Chetlas uplift (Middle Timan)
In the previously poorly studied southeastern part of the Chetlas uplift in the Middle Timan, a new occurrence of diamond satellite minerals and a diamond grain were found in the modern channel sediments of the Uvuy River basin. In order to assess the prospects of the area under consideration for identification of diamondiferous objects of practical interest, a characteristic of chromium-bearing pyropes and chromospinelides as the main kimberlite of diamond satellite minerals are given and the diamond grain itself is described. The material for the research was 16 schlich samples, each with a volume of 8 to 15 l. The minerals were studied using optical and scanning electron microscopy, Raman spectroscopy, laser luminescence and X-ray diffraction (Debye – Sherrer method). It is shown that among the pyropes, most of which correspond in composition to minerals of the lherzolite paragenesis, there are varieties belonging to the dunite-harzburgite paragenesis, including those belonging to diamond phase stability regions. Among the studied chromospinelides, chrompicotites and aluminochromites similar in composition to those found in rocks such as lherzolites and harzburgites, as well as in kimberlites, were identified. A diamond grain found in one of the samples has the form of a flattened intergrowth with distinct octahedron faces, complicated by co-growth surfaces with other mineral grains that have not been preserved to date. The discovery of the diamond and the established signs the formation of aureoles of the diamond satellites minerals in the channel sediments of the studied area open up the prospects for discovering their primary sources here.
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Date submitted2021-12-16
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Date accepted2022-04-07
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Date published2022-07-13
The Upper Kotlin clays of the Saint Petersburg region as a foundation and medium for unique facilities: an engineering-geological and geotechnical analysis
- Authors:
- Regina E. Dashko
- Georgiy A. Lokhmatikov
The article reviews the issues concerned with correctness of the engineering-geological and hydrogeological assessment of the Upper Kotlin clays, which serve as the foundation or host medium for facilities of various applications. It is claimed that the Upper Kotlin clays should be regarded as a fissured-block medium and, consequently, their assessment as an absolutely impermeablestratum should be totally excluded. Presence of a high-pressure Vendian aquifer in the lower part of the geological profile of the Vendian sediments causes inflow of these saline waters through the fissured clay strata, which promotes upheaval of tunnels as well as corrosion of their lining. The nature of the corrosion processes is defined not only by the chemical composition and physical and chemical features of these waters, but also by the biochemical factor, i.e. the availability of a rich microbial community. For the first time ever, the effect of saline water inflow into the Vendian complex on negative transformation of the clay blocks was studied. Experimental results revealed a decrease in the clay shear resistance caused by transformation of the structural bonds and microbial activity with the clay’s physical state being unchanged. Typification of the Upper Kotlin clay section has been performed for the region of Saint Petersburg in terms of the complexity of surface and underground building conditions. Fissuring of the bedclays, the possibility of confined groundwater inflow through the fissured strata and the consequent reduction of the block strength as well as the active corrosion of underground load-bearing structures must be taken into account in designing unique and typical surface and underground facilities and have to be incorporated into the normative documents.
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Date submitted2020-12-08
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Date accepted2021-10-18
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Date published2021-12-16
Prospects for the oil and gas content of the Upper Permian deposits of the southwestern part of the Vilyui syneclise based on the analysis of sedimentary environments and geochemical conditions of oil and gas content
The article discusses the prospects for the oil and gas content of the Upper Permian deposits in the southwestern marginal part of the Vilyui syneclise. In this margin, the Permian terrigenous complex with proven oil and gas productivity in the central part of the syneclise, pinches out. The study area, represented by the monoclinal slopes of the Vilyui syneclise, is considered a promising area for the exploration of non-structural hydrocarbon traps in the Upper Paleozoic sediments. The objectives of the study include identifying general patterns of sediment formation, associated mainly with the development of the alluvial complex, and substantiating the potential opportunities of migration and accumulation of hydrocarbons in the predicted traps. The research is based on the interpretation of the latest seismic surveys and prior-years geological and geophysical data. Authors carried out structural and paleo-structural analysis, identified lithofacies in the well log, generalized and analyzed the geochemical conditions of the oil and gas content of the Upper Permian deposits, traced the pinching out of the Upper Permian deposits on the southwestern margin of the syneclise, and also outlined areas of river valleys development that form zones of advanced reservoirs. The results of the studies have validated promising oil and gas accumulation zones on the southwestern slopes of the syneclise associated with non-anticlinal hydrocarbon traps. Authors also drew up a diagram of the oil and gas potential of the Upper Permian deposits. The obtained results are of interest for prospecting for oil and gas in the area under study.
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Date submitted2018-11-20
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Date accepted2018-12-28
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Date published2019-04-23
Refined assessment of seismic microzonation with a priori data optimisation
- Authors:
- I. B. Movchan
- A. A. Yakovleva
The work is devoted to the issues of seismic microzonation representativeness, which is amongst the mandatory assessments that precedes civil and industrial construction. In addition to the practical approach and in accordance with the normative documentation, the authors propose parametric interpretation of the remote basis by means of tracing geodynamic zones and elements of the geoblock structure, where the leading marker of seismogenic risk zones is the anomaly of spatial variability of the geofield, coinciding with the discordant intersection of localised land structures. Verification of this marker is achieved by displaying a cartographic distribution image within the range of the seismic point increment, detailed on the basis of approximation dependencies.
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Date submitted2009-08-17
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Date accepted2009-10-18
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Date published2010-02-01
Geotechnical engineering and hydrogeological specifics of estimate high-rise buildings construction and operation conditions (in terms of local zone on the right bank of Neva river)
- Authors:
- A. M. Zhukova
In the paper specificity of geotechnical engineering conditions in the local zone of the right river Neva bank are considered. The influence of underground topographies of Pre-Quaternary soils roof formed by paleovalleys on the specificity of engineering geological profile is analyzed. Influence of tectonic faults on physical and mechanical properties of Upper Kotlin clays (Upper Vendian) which it is planned to use as the basis for high-rise constructions is considered. Negative influence of Low Kotlin (Upper Vendian) pressure water-bearing horizon on clay properties in the construction foundation and structural materials is investigated.
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Date submitted2009-08-19
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Date accepted2009-10-02
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Date published2010-02-01
The estimation features of vulnerability and desintegration оf subway construction materials in Saint Petersburg
- Authors:
- P. V. Kotyukov
In this paper the features of subway construction materials degradation depending on engineering-geological, hydro-geological and geoecological conditions of Saint Petersburg underground space are considered. The basic types of subway construction placing and their destruction specificity depending on influence of water-bearing horizons hydrodynamic and hydro chemical conditions, natural and natural-technogenic gas bio-production and microbial activity are analyzed. The examples of the disintegrated materials and new growths (salt efflorescence, stalactites and others) chemical compound features depending on the content of ground waters basic components affecting on tunnels lining are resulted.
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Date submitted2008-10-05
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Date accepted2008-12-18
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Date published2009-12-11
A new regional stratigraphical scheme of the upper palaeozoic of Taimir
- Authors:
- S. B. Shishlov
The structural-genetic analysis of the Upper Palaeozoic sections of Taimir allowed us to distinguish seven geoformations – regional geological bodies, which had been formed as a result of transgression-regression cycles in the palaeobasin. The geoformations are considered as the regional stratigraphic units (Horizont in Russian usage). Lithologically uniform parts of the geoformations (gradations), which resulted from lateral differentiation of landscapes during the regional sedimentation cycle, are used as local stratigraphical units. The developed stratigraphical scheme based on the geoformations and gradations is the geohistorical model of the Late Palaeozoic of Taimir.