Vol 276 Iss. 1

Specific features of deep structure and tectonics of the Magadan and West Kamchatka shelves in the Sea of Okhotsk and adjacent area of the Kamchatka Peninsula were verified by geological and geophysical modelling. The investigations aimed at studying the localization pattern of hydrocarbon fields on the northern flank of the Okhotsk oil and gas province are based on results of regional and medium-scale geological surveys and prognostic and prospecting studies, geophysical survey data (gravity anomaly field Δg in the Bouguer reduction with an intermediate layer density 2.67 g/cm3, anomalous magnetic field ΔTа, regional seismic lines and the results of their generalizations), and petrophysical well survey materials. Different algorithms for solving the direct and inverse problems as well as pattern recognition with and without training were used in processing and interpretation of potential geophysical fields. The studies showed that the specific features of deep structure and tectonics of the region are determined by the sequence and nature of manifestation of Mesozoic and Cenozoic orogenic processes at the boundaries of the Eurasian and Okhotsk Sea lithospheric paleoplates. The study of regional shear zones developing along the Okhotsk-Chukotka suture zone and the Okhotsk-West Kamchatka Block demonstrated their vital influence on the morphology of sedimentary basins. Thus, the tectonic activity in the Okhotsk-Chukotka shear zone extending subparallel to the Eurasian coast, led to formation of an extensive network of feather dislocations and basins of two types: large longitudinal shear depressions (sedimentary basins that form due to extersion along strike-slip faults) and shear-pull-apart basins oriented at an angle to the axis of the main shear. Mapping of horst uplifts makes it possible to confirm the position of oil and gas formations prioritized for exploration according to the structural criterion.

In the current mine surveying practice, when assessing the harmful impact of underground construction on the earth's surface and undermined objects, the geotechnical system underground structure – rock mass is traditionally considered, which does not include the surface infrastructure. Such an approach can lead to distorted estimates of load levels, impacts and potential deformations for both buildings and the earth's surface. In order to determine the influence of the building and assess the interaction of elements of the geotechnical system tunnel – rock mass – building, the study analyses the undermining of the historical stage building of the Mariinskii Theatre by a complex of workings in Saint Petersburg metro station Teatralnaya. Numerical simulation by the finite element method in the PLAXIS 3D software package is used, the geotechnical model is calibrated in accordance with data of the field mine surveying and geodetic measurements. The models show that during undermining of buildings, their heterogeneous structure, weight and spatial rigidity significantly affect the distribution of deformations in the base of the construction, which is confirmed by localization of cracks in load-carrying structures that appeared after the start of mining operations. When assessing and predicting deformations by numerical methods, it is not always sufficient to simulate the rock mass – tunnel system, since this can lead to overestimated predicted values of the earth’s surface deformations, underestimated values of subsidence, and an incorrect assessment of the harmful effect on the undermined object. It was concluded that only an integrated approach using simulation, field measurements and survey data can ensure a correct analysis of the interaction of the rock mass, underground structures and above-ground infrastructure facilities with complex spatial geometry and allow a reliable assessment of the harmful effect on the undermined object with reference to structural damage. This contributes to adoption of adequate and timely protection measures for buildings and structures.

The results of experiments aimed at studying the influence of various nanomaterials on the key properties of drilling emulsions based on diesel fuel are presented. The nanomaterials used included spherical SiO2 nanoparticles with sizes of 5 and 80 nm, single-walled and multi-walled carbon nanotubes, as well as Al2O3 nanofibers. The nanomaterials were incorporated into standard formulations of drilling fluids containing a hydrocarbon phase of 65 %, with a mass concentration of nanomaterials in the emulsions reaching up to 2 %. The study examined the rheological, filtration, and antifriction properties, as well as the colloidal stability and inhibiting capacity of the modified drilling emulsions. It was demonstrated that even at low concentrations, the nanomaterials significantly affect the properties of drilling emulsions, indicating their potential for practical applications. Furthermore, the use of nanotubes exhibits effectiveness at lower concentrations (0.1 wt.%) compared to spherical nanoparticles.

Quarry wastewater from open-pit iron ore mining enterprises is a source of contamination of surface water bodies and groundwater with chemical compounds used during development, including the products of decomposition and incomplete consumption of ammonium nitrate during blasting operations in mines – nitrate, nitrite, and ammonium nitrogen. Such characteristics of mining wastewater as high tonnage, organic matter deficiency, and sparse microbiome must be considered when selecting neutralization methods. Biological and physicochemical methods are used to treat wastewater contaminated with nitrogen compounds. Some methods are economically infeasible due to the significant volumes of wastewater generated. An important task is to find an economically viable and highly effective method for treating quarry water from nitrogen compounds. The article presents the results of theoretical and experimental studies of the possibility of using a permeable geochemical barrier based on a redox system consisting of iron scrap and carbon-containing material (screenings from the production of birch activated charcoal) for treating quarry waters from nitrate ions. Thermodynamic analysis allowed us to determine the chemistry of nitrate ion reduction by the Fe0-C redox system in a neutral and slightly alkaline medium typical of quarry waters. The study of the kinetic patterns of nitrate ion reduction showed that the process rate is described by a first-order equation. It was found that the rate constant for nitrate ion reduction increases with reaction mixture temperature rise: at 278 K – 0.0365 min–1, 283 K – 0.0416 min–1, 288 K – 0.0809 min–1, 293 K – 0.0901 min–1. The data obtained will allow substantiating the choice of the reactive barrier or reactor design for the treatment. Experimental studies on the treatment of real and model quarry waters in a laboratory setup simulating a geochemical barrier proved the high efficiency of nitrate ion reduction (more than 97 %). The treated water meets the requirements for water discharge into fishery water bodies.

For years attempts have been made in the drilling industry to increase the drilling efficiency and decrease the associated costs. The drilling efficiency can be evaluated by comparing applied energy, i.e., mechanical specific energy, with rock strength. The mechanical specific energy is defined as the energy required to destroy a unit volume of the rock. Over the years, this concept has been refined, and researchers proposed various models. Mechanical specific energy directly affects drilling efficiency, as excessive energy can lead to drill string vibrations and bit wear. In this study, a database was established by collecting drilling and log data from the Asmari formation in one of the oil fields of Iran. Various forms of specific energy were examined to develop the appropriate model based on operational conditions and the formation being drilled. Additionally, the confined compressive strength of the rock in the studied well was calculated. The results showed that the developed specific energy model provides a realistic energy value, as it includes all relevant parameters with an output close to the rock strength. Based on the comparison of mechanical specific energy with confined compressive strength, the optimal drilling parameters were determined: weight on bit ranges from 22.24 to 44.48 kN, flow rate ranges from 0.027 to 0.029 m³/s, torque ranges from 2522 to 3091 N·m, and rotational speed ranges from 160 to 180 rpm. Also, an inefficient drilling zone was identified in the studied well, where excessive applied energy compared to rock strength led to the drill bit damage and a significant reduction in penetration rate. The results highlighted the importance of drilling efficiency estimation in the drilling process, where an economic and technically feasible decision can be made by comparing the surface input energy with the rock strength.

This article outlines the key principles and assumptions that form the basis of the filtration consolidation model for water-saturated clay soils described by K.Terzaghi in 1925 for calculating the settlement of structures. One of the main assumptions that requires revision is the notion that the pore water in clay soils has properties identical to those of bulk water. In the modern context, pore water should be considered in terms of its structuredness under the influence of the active centers of solid particles, ions, and other factors. The results of experimental studies on the effect of active centers of the solid surface, primarily clay particles, on the change in water structure via nuclear magnetic resonance relaxometers of various generations are presented. The patterns of changes in the structure of pore water in water-saturated clay soils of different granulometric and mineral compositions in the range of changes in their conditional physical state by moisture are shown. The structuredness of pore water in soils contributes to its inertness to the perception of external pressure and to the need to revise the concepts of filtration consolidation in favour of the rheological model for predicting the development of settlements as the main criterion for their stability.

An experimental study has been conducted on natural materials such as sandstone and andesite, which are commonly used in the mining, oil and gas industries, as well as in road construction. Cylindrical samples were tested under quasi-static and dynamic loads in fragment preservation conditions. X-ray tomography was used to determine the stages and mechanisms of destruction and the spread of cracks in the material before and after testing. The quasi-static uniaxial compression tests were performed, in which the deformation fields were measured, in situ, by using the digital image correlation method and acoustic emission signals. Analysis of the results revealed the specific features of fracture of andesite and sandstone samples. The destruction of andesite, which consists of hard and soft phases, follows a quasi-brittle scenario in the soft phase, with the size of the resulting fragments corresponding to the solid phase. When main vertical cracks spread throughout the entire volume of sandstone, which is a homogeneous material and consists of strong, loosely interconnected grains of sand, there was no sharp drop in its bearing capacity because friction forces between sand grains contribute significantly to holding them together, especially under compression conditions. Once the load was taken off, the sample broke up into pieces. The destruction of the tested samples subjected to quasi-static loading proceeds in two steps. The first step involves the accumulation of damages in the form of multiple main cracks coinciding with the direction of the maximum stress. During the second step, multiple daughter cracks are formed, which promotes the failure of the sample. In the case of dynamic compression, complete fragmentation of the sample occurred when the energy of the loading pulse was sufficient, and this was accompanied by the separation of the formed fragments. The results of this study are promising for the development of numerical fracture models intended to investigate the kinetics of defect nucleation and growth in rocks. These models can also be used to optimize the drilling processes.

A comprehensive study of the evolutionary history of the Marun-Keu complex in the Polar Urals is presented. Utilizing both original data and published earlier information, this work establishes the temperature and pressure ranges corresponding to the magmatic and metamorphic stages of rock evolution, as well as estimates the geothermal gradient and continental crust thickness. Thermobarometric calculations for the magmatic stage were performed using machine learning techniques, specifically the “random forest” algorithm, based on experimental datasets and require minimal petrochemical input regarding rock composition. The pressure-temperature (PT) conditions of the metamorphic stage were evaluated using the THERIAK-DOMINO software package. The host rocks of the eclogites are interpreted as products of partial melting of continental crust induced by interaction with heated basic-ultramafic melts. Peak metamorphic pressures for the eclogites are estimated not to have exceeded approximately 21 kbar, with corresponding temperatures ranging 730-750 °C. Subsequent retrograde metamorphism within the Marun-Keu eclogites was constrained to temperatures below 640 °C and pressures above 5 kbar. The geothermal gradient during protolith formation of the eclogites was calculated to be approximately 13 °C/km, consistent with contemporary estimates for continental crustal settings. Furthermore, the subduction parameters were inferred, yielding an estimated slab dip angle of 6-8°, and a subduction velocity between 2.2 and 2.9 cm/year, which does not contradict the hypothesis of continental subduction.

The paper presents the results of geological, geochemical and isotope geochronological studies of Early-Middle Devonian volcanogenic-sedimentary strata of the NW Rudny Altai, which host Devonian VMS-type (volcanogenic massive sulphide) deposits. The study provides a solution to the problems of identification and correlation of volcanic formations, study of their structural and lithological-facial features, which is traditionally a necessary element in the reconstruction of ore-magmatic systems. The aim of the study is to reconstruct the volcanic sequence in the Early-Middle Devonian and to evaluate the contribution of volcanogenic formations of riftogenic and supra-subduction nature to which VMS-type deposits are genetically related. Isotopic U-Pb dating of zircons from representative tuffs is consistent with an age of ~390 Ma. The formation of the volcanogenic strata occurred in a tectonic setting associated with the opening of the sea basin, corresponding to the initial stage of riftogenesis in the Rudny Altai. In terms of geochemical characteristics, the rocks of the lower section are similar to those of the ensialic arcs. The petrogenesis of such magmas should be associated with fluid-saturated conditions of partial melting of crustal substrates and under the control of dehydration of the subducting plate. In the upper section, the volcanic rocks are geochemically similar to bimodal formations from riftogenic settings behind the ensialic arc. This is confirmed by analyses of the genetic type of the formation community (magmatic, sedimentary and ore-bearing) and is consistent with the geochemical type of the volcanic rocks, which is similar to that of riftogenic settings. The conceptual geodynamic scenario corresponds to the formation of the Rudny Altai ore deposits in the transition zone between the island-arc and the back-arc basin, similar to the riftogenic settings of the Eastern Asian margin.

Changes in the business conditions of gas industry enterprises and the regulatory framework for the creation and operation of energy facilities require the development of the energy infrastructure of production facilities. The diversity and a large number of existing energy facilities, as well as the use of a risk-oriented approach to the gas industry management lead to the need to create decision support systems for the strategic development of the energy infrastructure of production facilities on an industry-wide scale. The purpose of the study is to develop a set of mathematical models for calculating the index of the technical condition of energy complexes of production facilities used to prepare structured information as a part of a decision support system creation for the strategic development of the system, which will allow us making a decision on the minimum required volume and timing of reconstruction of the energy infrastructure of a production facility under modern conditions with restrictions on the reconstruction budget. The solution of such a multi-criteria problem required: justification of a set of admissible solution alternatives, risk assessment when making specific decisions, development of a system and mathematical dependencies for assessing the criterion indicators that make up the technical condition index taking into account preferences and decision rules, as well as the rules for calculating the weight of the assessment components in the value of the integral indicator. Based on the developed mathematical models, an algorithm for the technical condition index determination of a single energy complex of a production facility was formulated, which is an integral part of the generalized algorithm for applying the mathematical support of the decision-making system for the strategic development of the energy infrastructure of gas industry enterprises.

A new model of an integrated economic system is investigated which consists of two markets – raw materials and products interconnected by selling and processing raw materials into products. When the markets reach an equilibrium state, this model allows estimating the commodity flows and the economic efficiency of each producer of raw materials or products taking into account the market conditions. With such a structure of interconnected commodity markets, producers in the raw materials market are buyers of raw materials, and in the products market – sellers. Due to this feature of the market system the demand function for raw materials is set implicitly, and the standard methods for searching the equilibrium seem ineffective for this problem. In order to find an equilibrium state for the presented structure of interconnected commodity markets, an algorithm for searching the Nash equilibrium was developed, which takes into account the desire of each market player to maximize profits considering the market conditions and the behaviour of competitors. By applying the methods of game theory and economic modelling, this research provides insight into competitive dynamics and strategic interactions both between players within a single commodity market in terms of competition, and between the markets proper in terms of formation of interconnected pricing. The results have practical significance for developing the market and investment strategies for the companies from real sectors of economy, production modernization programs, and optimization of government subsidy programs.

Monitoring of the stability of technogenic objects is a critical aspect of ensuring safety and preventing emergencies caused by mining and geological processes. The integrated use of various monitoring methods allows obtaining comprehensive information on the dynamics of deformation processes. The complex system of geotechnical monitoring of technogenic objects on the basis of geospatial data was developed, which was tested in the conditions of the “Edelweiss +” open-pit coal mine (Republic of Kazakhstan). The system was based on the step-by-step integration of Earth remote sensing methods, satellite radar interferometry, aerial photography with the use of unmanned aerial vehicles (UAVs), as well as modern instrumental methods – electronic tacheometry and GNSS measurements. The first stage – analysis of archive satellite images to identify areas of significant surface displacements. The second stage is aerial photography using UAVs to create detailed 3D models of surface areas with deformations. The third stage includes the creation of a geomechanical monitoring system based on instrumental observation methods in areas with critical changes. The final stage is the creation and updating of a geospatial database that provides continuous monitoring of the object’s condition. As a result of testing of the geotechnical monitoring system based on Sentinel-1 and TerraSAR-X/TanDEM-X satellite images, surface subsidence of up to 25 mm was detected on the northern side of the “Edelweiss +” open-pit mine. Aerial photography of the open-pit mine allowed us to construct digital 3D models of the terrain, the comparison of which confirmed deformation processes at the +556 m horizon. Instrumental observations using modern geodetic methods clarified the type and dynamics of deformations of the rock mass. Integration of geospatial data in the geotechnical monitoring system ensures prompt detection of deformations, their analysis and forecast, which allows us to minimize the risks of destruction and increase the safety of operation of technogenic objects.

The article reports on the presence of minerals of the crichtonite group (MCG) in ooids of mineralized volcaniclastic rocks of the Rudnogorskoe iron deposit (Eastern Siberia). The ooids are characterized by a concentric-zoned structure of detrital component, expressed in a sequential change of hematite-smectite core → smectite-chlorite → chlorite-garnet → apatite-chlorite zones, which are rimmed by thin-layered magnetite. Rare crystalline MCG aggregates in ooids are found in the peripheral apatite-chlorite zone. Based on the chemical composition and Raman spectra, the MCG are identified as crichtonite and davidite-Ce. The following components are determined in the composition of crichtonite, wt.%: TiO2 63.73-70.69, FeO 18.03-23.58, SrO 2.24-4.03, CaO 2.22-4.10, MgO 0.33-1.02, Al2O3 up to 2.01, MnO up to 0.54 and Ce2O3 up to 1.88. Davidite-Ce typically occurs along the edges of crichtonite and contains, wt.%: TiO2 60.54-62.28, FeO 22.67-25.77, Ce2O3 3.18-5.0, La2O3 2.47-2.74 and SrO 0.58-0.64. The MCG also contain up to 4.69 wt.% UO2. Complex processes of breakdown of MCG and their replacement by anatase are accompanied by the formation of REE (anzaite-Ce) and U (uraninite) minerals and subsequent transformation of anatase to rutile. A sequence of mineral formation of the ooids indicates that the formation and growth of the MCG crystals is a result of lithification of accumulated Ti and trace elements during smectitization of basaltic clasts. Further processes of mineral transformation are associated with the transformation of crichtonite to simple Ti oxides and the precipitation of REE and U minerals. Titanite is a product of the final skarn stages of ore formation.

Groundwater is one of the key natural resources, so maintaining its high quality is one of the main problems in mining. The aim of the article is to study the dynamics of the level and hydrochemical regime of groundwater in the influence zone of apatite-nepheline ore mining in the southeastern part of the Khibiny alkaline mountain massif. Over the 10-year history of the Oleniy Ruchey Mining and Processing Plant of North-West Phosphorous Company JSC, significant changes in the chemical composition of the studied groundwater of the aquifers of the Upper Quaternary Ostashkov fluvioglacial horizon f,lgQIIIos and Paleozoic intrusions yPz have occurred. The content of the main ions in groundwater increased from 2 to 20 times, nitrates up to 50 times (exceeding the maximum permissible concentrations of 45 mg/l), and NO^–₃ entered the category of the main ions of groundwater. The source of the main ions and the increase in mineralization in groundwater is the weathering and leaching of the main ore minerals – apatite and its varieties, nepheline, sulphide minerals, as well as the use of explosives containing nitrogen compounds. As a result of this hydrochemical evolution of groundwater, the ratio of the main ions has changed – natural water of hydrocarbonate-sodium composition with neutral pH values has now become hydrocarbonate-calcium, NO^–₃ are in the second place among anions, and Na+– among cations. In the hydrodynamic regime of groundwater at the Oleniy Ruchey deposit, spring and autumn maximums of groundwater levels are clearly expressed. During a decrease in the level, contaminated more mineralized mine waters are drawn to the wells, and during an increase in the level, low-mineralized waters of atmospheric precipitation infiltrate into the aquifers. A decrease in average annual groundwater levels has been established, which is associated with an increase in the quarry depth and the water intake of groundwater for water supply to the mine.