«Bulletin of Perm University. Geology» (Vestnik Permskogo universiteta. Geologiya) is the peer-reviewed academic journal publishing the scientific papers covering all fundamental and applied aspects of modern geology, including general geology, geotectonics, petrology, mineralogy, lithology, hydrogeology, geoengineering, geochemistry, geophysics, mineral exploration, oil & gas geology, and geoecology. The journal publishes the papers in Russian and English.
ФГАОУ ВО «Пермский государственный национальный исследовательский университет» (ПГНИУ)
Composition and Framework of the Yaksha Formation of the Lower Permian of the Upper Pechora Salt Deposit (the Example of Well № 04 Section)
The paper presents he results of the composition study of the Yakshinskaya Formation overlying sediments above salt member of the Upper Pechora salt deposits. In the framework of the Yaksha Fm., four series are separated: 1) argillaceous-siltstone, 2) silt-argillaceous-gypsum-dolomite, 3) silt-argillaceous-dolomite, and 4) siltargillaceous. The studied interval of the Yaksha Fm. in the section of well № 4 shows a tendency in rocks composition to change from predominantly gypsum-dolomite to silty argillites and argillaceous siltstones. It is proposed to use the base of packet four, represented exclusively by terrigenous sediments, as a marker for drawing the controversial upper boundary of the Yaksha Fm.
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Experience in the Application of Cross-Dipole Acoustic Logging for the Separation of Gas-Bearing Deposits in Terrigenous and Carbonate Sections of Russian Deposits
Problem of identification of gas-saturated reservoirs in complex sections, where standard geophysical well surveys (GIS) are ineffective, remains important for oil industry. The technique of cross-dipole acoustic logging (CDA) is based on the analysis of the ratio of the normalized travel times of longitudinal (DTCO) and transverse (DTSH_XX) waves. The results of the CDA were compared with data from the standard GIS complex and nuclear magnetic logging (NMR). The purpose of the work is to evaluate the effectiveness of CDA for the diagnosis of gas saturation in reservoirs in Russia. It has been established that the excess of DTCO over DTSH_XX is a reliable sign of gas saturation. The modular dynamic testing (MDT) showed high sensitivity in terrigenous and carbonate reservoirs. CDA is recommended for inclusion in the GIS complex for searching for gas deposits.
Paleogeological Models of Permian Evaporite Basin within Caspian Region
The research is devoted to the structure and history of development of the Caspian salt-bearing province during the Kungurian time of the Early Permian. The preceding and following the formation of the thick salt-bearing stratum paleogeographic settings are considered. The sedimentary thickness of the evaporite stratum is reconstructed based on two possible scenarios of the development of the Caspian marine basin. In the first option, salt accumulation occurred in a shallow sea, but in a deep topodepression with almost no water layer. The second option considers an evaporite basin with a thick water layer equal to the depth of the topodepression. The results of the computer model are compared with paleo reconstructions based on the seismostratigraphic structure of the Kungurian salt-bearing stratum.
GENERAL AND REGIONAL GEOLOGY. GEOTECTONICS AND GEODYNAMICS
Salt Tectonics of the Northern Part of the West Siberian Basin and the Enisey-Khatanga Trough
Regional interpretation of modern geodata suggests the presence of up to 15 km-thick Paleozoic section in the sedimentary fill of the northern part of the West Siberian Basin and the Enisey-Khatanga Trough. The Paleozoic section comprises the evaporitic succession most likely of Ordovician age, which were deposited in troughs formed during the Early Paleozoic Uralian rifting. Study of salt structures indicate that salt diapirism has been a significant tectonic process contributing to the subsurface architecture and petroleum potential of these regions.
Structural and Formation Features of the Salt and Supra-Salt Parts of the Sedimentary Cover of the South-West of the Precaspian Basin
The aim of the work was to develop a tectonic model of the Kungurian-Quaternary complex of the sedimentary cover of the southwestern part at the junction of the Caspian Basin and the Karpinsky Ridge for the reconstruction of the formation and transformation of the Kungurian evaporite strata. In the course of the research, the main structural elements of the study area were identified for different stages of geological development. An assessment of the influence of regional tectonic elements on the bedding conditions and structural features of the Kungurian halogen strata was made. Based on seismic stratigraphic analysis, the study area was divided into zones according to the structural features of potassium-magnesium salt deposits. A retrospective model of the history of sedimentation processes was constructed along the sub latitudinal geological profile.
Stages of Halokinesis of the Kungurian Evaporite Formation of the Southwestern Part of the Peri-Caspian Depression
The morphology of the structure and lithological composition of the evaporite formation of the Kungurian age and the suprasalt complex of deposits in the southwestern part of the Peri-Caspian depression are considered. The evolution of the halokinesis process is reconstructed using a local section of the Sarpinskiy Trough as an example. The authors established that the growth of the salt dome and the subsidence of the adjacent trough in the study area began in the middle Permian and continued until the end of the Jurassic. Their structure and subsequent stage development had a significant impact on the formation and evolution of the overlying MesozoicCenozoic deposits.
Clarification of the Tectonics of the Verkhnekamskoye Salt Deposit Based on Seismic Survey Data
In result of seismic survey studies in recent years, new information about the tectonics of the Verkhnekamskoye salt deposit has been obtained. The data relate to the western edge of the southern part of the deposit, which is characterized by complex geological structure. Here, signs of disjunctive dislocations, high-intensity plicative dislocations, areas of salt erosion, lithofacial transitions, and potassium beds thinning are found. The boundaries and positions of such regional structures as Kamsko-Visherskiy swell, Kamskiy trough have been updated.
Chloride Type Halogenesis in Pripyat Potassium Bearing Basin
The problem of the formation of chloride salt-bearing series lacking in the magnesium sulfate is one of the most complex in the theory of halogenesis. Is chloride halogenesis an independent process or it is still a branch of marine halogenesis? The presence of thick chloride layers of salts indicates a large initial source of water-salt mass. Only sea (ocean) water could be such a source that never lost its sulfate content throughout the entire Post Proterozoic Stage. The article discusses the processes of formation of red-colored and variegated hypersaline associations established for potash deposits of the Middle-Upper Famennian salt-bearing formation of the Pripyat potassium-bearing basin.
Evaporite Sulfate-Carbonate Deposits in the Mesoproterozoic (Typical Riphean Section) and the Relationship with Warm Climate Periods
The genesis of the largest magnesite, siderite, and fluorite deposits in the Riphean deposits of the Bashkir megaanticlinorium was governed by the migration of evaporite brines at the tectonic-thermal stages of development of the structure of the Urals supra-rift basin in the time interval of 1400-1000 million years. Largescale formation and burial of brines in the Mesoproterozoic is associated with the development of evaporite environments that differ from modern ones. Formation of terrigenous-carbonate shelf basins occurred under conditions of longterm existence of warm climate, wide development of supra-platform seas with prevalence of shallow stagnant conditions, which caused wide development of biosulfate reduction and dissolution of authigenic sulfates.
Lithological and Geochemical Characteristics of the Lower Permian Potash Salts of the Northwestern Border of the Caspian Basin
Lithological and geochemical studies of potassium salts from the Lower Permian salt-bearing formation within the Perelyubskaya area (Saratov Region) revealed three sylvinite varieties in the studied sections, characterizing the diversity of the halogenic process as follows: a) regular crystallization of sylvite from brine with an insignificant input of terrigenous material (including anhydrite); b) crystallization under conditions of a high degree of coastal hydrodynamics and a significant input of terrigenous material, several desalinated waters, and the predominance of sylvite formed during the replacement of carnallite; c) crystallization of sylvinite and sylvitecarnallite rocks under conditions of elevated brine concentrations.
Brines Composition and Sedimentation Conditions of the Salts at the Yakshinskoye Deposit
The results of a fluid inclusions study in halite and insoluble salt residues in the underlying rock salt of the Yakshinskoye deposit, located in the western part of the Upper Pechora potassium-magnesium salt basin, are presented. Individual inclusions in halite were studied using fluid inclusion homogenization and ultramicrochemical analysis. Insoluble salt residues were identified using X-ray diffraction analysis. The isotopic composition of sulfur has been studied for nodular anhydrite. It was established that salts stratum of the Yakshinskoye deposit accumulated in shallow-water conditions, and the concentration of brines during crystallization in the underlying rock salt was close to the beginning of the precipitation of potassium minerals. Likely, the erosion of old potassium salts in the surrounding area preceded beginning of salt deposition.
Halocontamination of Mantle Magmas: the Role of Salts in the Formation of Alkaline Complexes
Results of the analysis of material and spatial-temporal relationships between alkaline magmatic and saliferous complexes allowed us to identify and characterize the prerequisites and features of participation of deeply buried salts in alkaline magmatism. The main ones are: similarity of specific sets of macro- and microcomponents of saliferous (halophilic) and alkaline (foidaphilic) complexes and proximity of their distribution areas. Salt-alkaline associations are identified, their tectonic types and reference objects of each type are characterized. For the first time, a geological and genetic model of «halocontamination of magma» with participation of salts in alkaline magma genesis as a source of alkali metals and volatiles is substantiated. A comparative analysis of its basic provisions with other models of alkaline magmatism is given.
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Indication of Aquatic Landscapes Salinization Rate
The salinization of freshwater represents one of the most serious threats to global aquatic ecosystems and associated biodiversity. Particular attention in the context of aquic landscape salinization was paid to bottom sediments, which act not only as indicators but also as active accumulators of salts. Understanding the mechanisms of bottom sediment salinization under natural and anthropogenic impacts, their consequences, and potential recovery strategies is critical for development of the effective water resource management and conservation strategies. This review examines the problem of aquatic landscape salinization in the taiga zone, using the Upper Kama region (Perm Krai, Russia) as a case study. This is an area with developed mining industry, where one of the most important challenges is the reclamation of post-technogenic territories. The following data are presented: (1) global statistics on freshwater salinization; (2) salinization indicators; (3) regional characteristics of salt load; (4) multidisciplinary approach to characterize the salinization processes. This study demonstrates that the aquatic complexes of post-technogenic territories are the integrated dynamic systems requiring the innovative approaches for mitigating salt pollution and rehabilitation of these areas.
Evaluation of Sediment Pollution in an Abandoned Alkaline Slurry Pond and Its Stratification Using the Machine Learning Techniques
The aim of this study is to characterize the contamination of sediments accumulated in an abandoned sludge storage facility, to develop, and test an automated method for precipitation stratification. The assessment of pollution is based on the sludge chemical composition using integral heavy metal indices: the total pollution index (Zc), and the potential environmental risk index (RI). According to the calculations, high level of pond sediments pollution was revealed. An automated approach to sediments stratification has been implemented using machine learning algorithms. This paper describes the Python-based algorithm and presents the results of its testing on sediment samples from a man-made reservoir. During the clustering process, five distinct layers were identified, which differ significantly in their chemical composition. The constructed cross-sections display the heterogeneous structure of the sediment column, and are in good agreement with the sections based on values of integral indices obtained manually. The best results were achieved using the cubic interpolation method.
Experience of Identification of the Missed and Complex, Low-Permeable Carbonate Tournaisian Reservoirs
This work was carried out to identify the permeable oil-saturated interlayers in complex, low-permeability carbonate reservoirs. Experience of reinterpreting the geophysical well logging data at the Tournaisian hydrocarbon deposit in the Perm Region is described. A comprehensive analysis of the geological and geophysical information made it possible to identify missed oil-saturated layers in low-permeable carbonates.
GEOLOGY, EXPLORATION AND EXPLOITATION OF OIL AND GAS RESOURCES
Methodology for Studying the Transit Zones (Using the Example of the Perm Krai)
Based on experience obtained in the Perm Krai and other regions of the Kama River basin, the paper examine the specifics of seismic exploration in transition zones, which are the shallow waters inaccessible to study using just a river or land-based survey alone. Successful seismic exploration in these zones relies on the use of a number of new technologies, including the explosive source placed in boreholes below the silt zone of the river bottom, and a system of compact equipment, and drilling rigs that enables exploration in ice-covered waters.
The Possibilities of Using the Large Language Models in Geology and Geophysics
The prerequisites for the emergence of the Large Language Models and their main features are considered. The highlighted main areas of application of large language models for geography and geophysics are as follows: analysis of geological and geophysical texts; data analysis and construction of multifactorial relationships; spatial modeling; generation of program code based on its description. The problems are largely related to the fact that large language models are at an early stage of development. The paper describes the prospects related to both improving the performance of electronics and finding the possible other directions in organization of data processing systems.
Integration of LWD Spectral Gamma-Ray Logging and Advanced Cuttings Analysis: Results, Synergy, and Implications for Operative Geological Interpretation
Experimental verification conformed strong correlation between spectral gamma logging (SGL) and cuttings analysis data for clay composition study that confirms the reliability of both methods for clay content evaluation. The integration of SGL and cuttings analysis minimizes misinterpretation risks: cuttings provide the reference points for SGL calibration, and continuous SGL data ensures an accurate depth correlation. The combined technology of SGL-LWD with continuous cuttings analysis is under field trials. The key objective has been defined as enhancing algorithms for integrated processing of heterogeneous data using AI to achieve followings: realtime generation of continuous formation property models while drilling; identification of secondary reservoirs; reliable formation boundary mapping (particularly in horizontal wells); reservoir characterization; optimization of drilling operations (coring point selection, well completion).
Comparative Effectiveness Analysis of Wiener – Levinson Deconvolution and Radon Transform for Suppressing the Reverberation Noise in Shallow Water Environments
A study of the suppression of intense reverberation noise during onshore 3D CMP seismic surveys in areas with a developed hydrographic network was conducted. Using as an example an area with extensive river network, a comparative analysis of two noise suppression approaches was performed: predictive Wiener-Levinson deconvolution and high-resolution Radon transform. It is shown that the spatial non-stationarity of the waveguide in river conditions limits the effectiveness of predictive deconvolution. A two-step processing scheme for the highresolution Radon transform with adaptive parameterization of the signal/noise separation boundaries is proposed. The results of visual analysis demonstrate a significant attenuation of the reverberation noise while preserving useful wave components.
Assessment of the Distribution of Soils Sensitive to Dynamic Loads: a Case Study of a Site in Moscow
This article presents a methodology for assessing the portion of soils sensitive to dynamic loads within the nearsurface (to a depth of 50 meters). According to regulatory requirements these soils necessitate costly dynamic testing. The methodology was tested on an 11.56 km² site in Moscow, within which the zones of dynamic impact from transportation (with a total area of 4.09 km²) were identified. The approach is based on a comprehensive analysis of archival data from engineering-geological boreholes, followed by geostatistic and raster algebra processing. For each stratigraphic-genetic complex (SGC), presented by a group of deposits of similar age and origin, the proportion of soils sensitive to dynamic loads (loose and water-saturated sands, weak clayey soils) was calculated. Subsequently, a weighted average proportion of content was determined for the intervals of 10, 20, 30, 40, and 50 meters. The results showed that the proportion of the target soils does not exceed 0.5. It was established that as the investigation depth increases (from 20 to 50 meters), the area of dynamic impact zones with a low proportion of content (<0.2) increases from 74% to 94.6%. This is attributed to the inclusion of more stable pre-Quaternary deposits in the analysis. The developed methodology allows for minimizing the risks of costly errors during the planning stage of site characterization. It can be used to create maps of soil dynamic instability across the entire territory of Moscow and can be integrated into systems such as a "Digital Twin."
GEOLOGICAL ENGINEERING, GEOCRYOLOGY AND SOIL SCIENCE
Physical Properties and Quality Characteristics of the Gravel-Sand Mixture from the Kochebakhtinskoye Deposit
The research examines the geological structure and qualitative characteristics of the sand-gravel mixture from the Kochebakhtinskoye deposit. Data on the granulometric composition, physical-mechanical properties, and compliance of the mineral resource with GOST standards are presented. The studies revealed that the characteristics of the sand-gravel mixture partially meet regulatory requirements.
Vendian Deposits of the Kolchim Uplift: Composition and Paleoclimate
The article presents the results of study of the mineral composition, structural, and textural features of the Vendian deposits from the Kolchim uplift, as well as the material composition of their pelitic fraction. Petrographic and Xray phase and X-ray fluorescence analyses were used to study the rock samples. Based on the results of studies, the composition of the Vendian deposits from the Kolchim uplift was clarified and supplemented. For the first time, an attempt has been made at paleoclimatic reconstruction, which is based on the composition of clay material whith the main role assigned to illite. This allows concluding that the climate of the epoch is close to the nival type with a predominance of physical weathering over chemical. Rock studies also confirm that the Vendian deposits consist of the erosion products from the underlying sediments of the Upper Riphean formations, as well as granitoids, and gneisses, the source of which are uplifts of the Timan with outcrops of the crystalline basement of the Russian Plate.
Application of Thermal DSC/TG Analysis in Geological Research Practice
This article examines aspects of the application of thermal analysis using the differential scanning calorimetry (DSK) and thermogravimetry (TG) methods based on the literature review of the large number of publications of domestic and international research teams. The main modern applications of the method include research in mineralogy, lithology, and petrography (detection of impurities in test samples, quantitative assessment of water forms, etc.), studies of caustobioliths of oil and coal series (study of dispersed organic matter, fractional composition of hydrocarbons, assessment of raw material quality, its heat capacity, and spontaneous combustion potential), research in the field of mineral processing, industrial safety (assessment of production process parameters, including spontaneous combustion of ores), and ecology (forms of soil organic matter).
On the Problem of Conducting the Special Operations to Prevent and Eliminate Environmental Consequences from Natural and Man-Made Emergencies
The authors have identified a close relationship between environmental protection and the economic, social and energy issues. It was established that the peaceful nuclear tests carried out in the USSR had economic prerequisites and environmental consequences. The authors note that the environmental situation after special operations carried out in the Perm region through nuclear explosions forced people to leave their homes and households. At the same time, nuclear contamination of soils and waters has been continued until these days. The need to take measures to mitigate the environmental consequences of natural and man-made emergencies was noted.
Application of Tectonic-Physical Approach for Construction of Tectonic Model of the Deeply-Buried Complexes
Recent publications on oil and gas tectonics note the extreme “eclecticism” of the terminology used in the tectonic zoning of the sedimentary basin and surrounding structures, in describing the stage of formation, tectonic conditions, and typification of different-scale discontinuous and plicate structures. The existing situation makes it difficult for researchers to understand each other and leads to the lack of an unified approach in describing the regional tectonic models. Formation of a unified terminology and a common approach in describing tectonic processes is an important and urgent problem. At present, when studying and describing the prospects of oil and gas bearing capacity in the north of the Volga-Urals province, definitions as the Ural geosyncline, TimanPechora province, Pechora-Kolva avlacogen (palaeorift), deep faults and regmatic fault network may be used in one published work. The study of the history of tectonic elements formation in areas with complex geological structure is complicated by overlapping tectonic structures of different order and age. Based on the tectonicphysical approach, authors carried out the reconstruction of the history of tectonic transformations within the study area. When interpreting seismic data of the internal structure of the fault zone, reconstruction of evolution of the formation, tectonic-physical ideas about structural paragenesis were used as a methodological tool. From the tectonic-physical point of view, the fault zone is considered not only as the uniform displacement plane, but as the whole volume of the section, in which genetically related brittle and plastic deformations are manifested. The internal structure of the fault zone is considered as a set of structural elements that determine its kinematics, stage and duration of formation. Application of modern approaches to geological analysis of shear tectonics areas is illustrated by detail analysis of 3D seismic cube data obtained at the territory of the Pechoro-Kozhva megaval. As a result, a new tectonic model was developed. In the conditions of complex deformation history of shear zones, the structures were dated according to their belonging to different-age paragenesis.
Some Features of the Study of Secondary Minerals of Kimberlite Rocks
The conducted studies have shown that kimberlite diatremes are characterized by individual features of the composition of the main mass of the rocks that compose them. Sometimes composition differences are characteristic not only of specific pipes, but even of individual bodies and blocks. The processes of serpentinization, carbonatization, chloritization and brucitization also have their own specific features in each diatreme. Individual properties are also characteristic of the main mass of kimberlites of secondary formations, consisting of two or more minerals. The appearance of kimberlite rocks in diatremes is largely determined by the development of a complex of secondary minerals that arose after the consolidation of rocks because of their endo- and exogenous transformations. The analysis of distribution of serpentine, phlogopite, chlorite, talc, calcite, dolomite, pyroaurite, brucite and their associations in kimberlites of the Siberian platform allowed us to consider the conditions of formation of individual new formations and to assess their role in the formation of the individual appearance of these diamond-bearing rocks. The differences of the latter are due to the intensity of development and uneven distribution of the main secondary minerals and their varieties. It was established that kimberlites underwent repeated changes during their formation, the intensity of which at different stages of diatreme formation has an individual character and depends on the specific conditions of mineral formation.
GEOLOGY, MINERAL EXPLORATION AND MINERAGENY
Selection of Explosive Source Parameters for 3D Seismic Exploration in the Transit Zones in the North of the Perm Region
Transit zones (shallow water areas and low-lying wetlands on the shores of the Kama and Votkinsk reservoirs) in the Perm Region are currently promising areas for oil and gas exploration. Therefore, it is necessary to improve the methods of seismic exploration usage for such areas. It can be realized using the existing experience of PJSC Permneftegeofizika related to implementation of environmentally friendly options such as using small and ultrasmall explosive charges. The article presents the results of study of the influence of the explosive source parameters on the quality of the 3D seismic data obtained in the north of the Perm Region in the transit zone of the Vishera River.
Methods of High Level Noise Reducing in Gravity Surveys on the Example of On-Ice Measurements
The paper considers the specifics of field observations and data processing techniques for on-ice gravity surveys that help reduce the level of noise and achieve high accuracy of gravity measurements. The study systematizes recommendations for on-ice surveys, including red reducing base-to-base loop duration, using a variation station, using seismic sensors to account for interference in post-processing of data, etc. Experimental observations were carried out using modern high-precision relative digital gravity meters Scintrex CG-5 and CG-6, allowing to compare the effectiveness of various methods for combating interference associated with the instability of the ice cover on which the gravimeter is located. An original algorithm for time series processing of the Scintrex CG-5, Scintrex CG-6 gravity meters has been developed, including dividing data by pickets, sorting values from the gravity sensor by time, introducing corrections in mGals for temperature, tilt, and lunar-daily variation, subsequent data filtering and data export in *dat file format. Processing of gravity meter time series has significantly improved the accuracy of gravimetric observations.
Geomagnetic Activity Effects on Magnetic Inclinometry Accuracy in the Arctic
The paper examines the influence of geomagnetic activity parameters on the accuracy of magnetic inclinometry during drilling in high-latitude regions. A stable relationship between geomagnetic variations and additional measurement error has been established. It is shown that the deviations of the magnetic declination (ΔD) and inclination (ΔI) can exceed the permissible metrological standards. Diurnal and seasonal irregularities in geomagnetic field variations have been identified, which have a significant impact on the accuracy of inclinometry. For an operational assessment of the suitability of the measurement conditions, an integral tolerance index (IID) is proposed, taking into account the deviations ΔD, ΔI and the Kp index. Recommendations have been developed to limit the use of magnetic inclinometers during periods of extreme geomagnetic activity.
Gravity Anomaly Modeling with Equivalent Sources in Earth's Polar Regions
An improved method for gravity anomaly transformation, accounting for the Earth's spheroidal shape, has been developed based on modeling the field using equivalent sources (point masses). The values of the point masses are determined by solving a system of linear algebraic equations using the least squares method. A regularized singular value decomposition (SVD) method can also be applied for this purpose. Both approaches ensure stable computation of transforms in the Earth's high-latitude regions, as demonstrated by the presented results for the area with coordinates 54°–72° N, 84°–132° E, which includes the Siberian Platform and surrounding structures.