-
Date submitted2023-12-07
-
Date accepted2024-11-07
-
Date published2025-04-25
Determination of the tangential component of cutting resistance during frozen sedimentary rock cutting using blocked, deeply blocked and cell cutting methods
Due to the insufficient accuracy of existing studies of frozen sedimentary rock cutting process for practical calculations, the article solves the problem of determining the tangential component cutting resistance for blocked, deep blocked and cell cutting, which are currently the most commonly used methods in earthmoving equipment. The cutting tool and rock mass force interaction is considered from the point of view of the emerging stresses, which act on the separated chip element. The analytical dependences for determining the tangential component of cutting resistance were obtained. The numerical explanation of the choice of cell cutting in relation to blocked and deeply blocked cutting is given. For all three methods of cutting, under equal geometrical parameters of the cutting tool and the physical and mechanical properties of the frozen rock, the numerical value of the tangential component of cutting resistance is obtained. The comparison of the cutting resistance estimated values has shown that cell cutting requires relatively less energy and is preferred during the process of frozen sedimentary rock excavation. During field and laboratory investigations with the use of a multi-purpose cutting stand, a sufficient convergence of the analytical statements with the physics of frozen sedimentary rock cutting process was established. The results of the research allow a more reasonable approach to the adjustment of existing methods for determining the required tractive force and power for the drive of an excavation machine, and, therefore, to the actual efficiency and profitability of work.
-
Date submitted2024-05-30
-
Date accepted2024-10-14
-
Date published2024-11-12
Thermodynamic modelling as a basis for forecasting phase states of hydrocarbon fluids at great and super-great depths
The possibility of discovering oil and gas occurrences at great (more than 5 km) and super-great (more than 6 km) depths is considered in two aspects. The first one is the preservation conditions of large hydrocarbon accumulations forming at depths to 4 km and caused by different geological and tectonic processes occurring at great and super-great depths with partial oil-to-gas transformation. It was ascertained that among the factors controlling preservation of liquid and gaseous hydrocarbons are the temperature, pressure, subsidence rate (rate of temperature and pressure increase), time spent under ultrahigh thermobaric conditions, and initial composition of organic matter. The possibility of existence of liquid components of oil at great and super-great depths is characteristic of sedimentary basins of China, the Gulf of Mexico, the Santos and Campos basins on the Brazilian shelf, and in the Russian Federation it is most probable for the Caspian Depression, some submontane troughs and zones of intense accumulation of young sediments. Determination of critical temperatures and pressures of phase transitions and the onset of cracking is possible using the approach considered in the article, based on estimation of organic matter transformation degree, kinetic and thermobaric models taking into account the composition of hydrocarbon fluid. The second aspect is the estimation of composition of hydrocarbons associated with rocks forming at great depths or rocks transformed under conditions of critical temperatures and pressures. This aspect of considerable science intensity can hardly be considered as practically significant. The study focuses on the investigation of the possibilities of thermodynamic modelling and the use of alternative methods for studying the transformation degree of liquid formation fluid into components of the associated gas through the example of two areas with identified oil, condensate and gas accumulations.
-
Date submitted2024-10-29
-
Date accepted2024-10-29
-
Date published2024-11-12
Study of thermodynamic processes of the Earth from the position of the genesis of hydrocarbons at great depths
In the context of significant depletion of traditional proven oil reserves in the Russian Federation and the inevitability of searching for new directions of study and expansion of the raw material base of hydrocarbon raw materials in hard-to-reach regions and on the Arctic shelf, a scientific search is underway for accumulations in complex geological conditions and in manifestations that differ significantly from traditional ones, which include the processes of oil and gas formation and preservation of oil and gas in low-permeability “shale” strata and in heterogeneous reservoirs at great and super-great depths. Within the oil and gas provinces of the world, drilling of a number of deep and super-deep wells has revealed deposits at great depths, established connections between hydrocarbon deposits and “traces” of hydrocarbon migration left in the core of deep wells, which has made it possible to significantly re-evaluate theoretical ideas on the issue of oil and gas formation conditions and the search for technologies aimed at solving applied problems. Modern geochemical, chromatographic, bituminological, coal petrographic and pyrolytic methods of studying oil and bitumoids extracted from the host rocks of deep well cores give a hope for identifying correlations in the oil-source system, revealing processes that determine the possibility of hydrocarbon formation and accumulation, and defining predictive criteria for oil and gas potential at great depths.
-
Date submitted2024-05-13
-
Date accepted2024-09-05
-
Date published2024-11-12
Potential trace element markers of naphthogenesis processes: modeling and experimentation
With the growing demand for hydrocarbon energy resources, there is a need to involve oil fields at deeper horizons in processing and increase the profitability of their development. Reduction of expenses on prospecting works is possible at revealing and substantiation of physicochemical markers of the naphthogenesis processes. One of the key markers is the transition metals content, which are both a measure of oil age and markers of potential associated processes in the migration and formation of hydrocarbons in the Earth's strata. The elemental composition of samples of oil and reservoir rocks of the Timan-Pechora field was studied. Based on the results of thermodynamic modeling, plausible processes of contact rock minerals transformation were proposed. Based on the results of molecular modeling the probable structure of vanadium and nickel host molecules in the heavy fraction of oils is proposed. The ratios of transition metal and sulfur contents were experimentally established, and assumptions about possible mechanisms of formation of deep hydrocarbon reservoirs were made. Analysis of the obtained ratios of transition metal contents in reservoir rocks and oil samples allowed to suggest possible processes of mantle fluids contact with the host rock and subsequent accumulation of hydrocarbons on sorption active rocks. According to the combined results of experimental and theoretical studies it was found that polymers of heavy fraction more selectively capture vanadium, which indicates the predominance of vanadium content in oil-bearing rocks in relation to the content of nickel. In this case, oil acts as a transport of transition metals, leaching them from the bedrock.
-
Date submitted2023-08-14
-
Date accepted2023-12-27
-
Date published2024-12-25
Modelling of compositional gradient for reservoir fluid in a gas condensate deposit with account for scattered liquid hydrocarbons
In oil and gas reservoirs with significant hydrocarbon columns the dependency of the initial hydrocarbon composition on depth – the compositional gradient – is an important factor in assessing the initial amounts of components in place, the position of the gas-oil contact, and variations of fluid properties throughout the reservoir volume. Known models of the compositional gradient are based on thermodynamic relations assuming a quasi-equilibrium state of a multi-component hydrodynamically connected hydrocarbon system in the gravity field, taking into account the influence of the natural geothermal gradient. The corresponding algorithms allow for calculation of changes in pressure and hydrocarbon fluid composition with depth, including determination of the gas-oil contact (GOC) position. Above and below the GOC, the fluid state is considered single-phase. Many oil-gas-condensate reservoirs typically have a small initial fraction of the liquid hydrocarbon phase (LHC) – scattered oil – within the gas-saturated part of the reservoir. To account for this phenomenon, a special modification of the thermodynamic model has been proposed, and an algorithm for calculating the compositional gradient in a gas condensate reservoir with the presence of LHC has been implemented. Simulation cases modelling the characteristic compositions and conditions of three real oil-gas-condensate fields are considered. The results of the calculations using the proposed algorithm show peculiarities of variations of the LHC content and its impact on the distribution of gas condensate mixture composition with depth. The presence of LHC leads to an increase in the level and possible change in the type of the fluid contact. The character of the LHC fraction dependency on depth can be different and is governed by the dissolution of light components in the saturated liquid phase. The composition of the LHC in the gas condensate part of the reservoir changes with depth differently than in the oil zone, where the liquid phase is undersaturated with light hydrocarbons. The results of the study are significant for assessing initial amounts of hydrocarbon components and potential efficiency of their recovery in gas condensate and oil-gas-condensate reservoirs with large hydrocarbon columns.
-
Date submitted2023-02-10
-
Date accepted2023-09-20
-
Date published2024-04-25
Depth distribution of radiation defects in irradiated diamonds by confocal Raman spectroscopy
Five colored diamonds were investigated. According to the results of the study by FTIR, UV-Vis-NIR and Photoluminescence spectroscopy, they are natural type Ia diamonds. The depth distribution of the color intensity was carried out by measuring the intensity of the PL peak at 741 nm (GR1 center) upon excitation by a laser with a wavelength of 633 nm of Raman Confocal microscope. To minimise the perturbation due to geometrical effects, defect distribution profiles were normalised with respect to diamond Raman peak intensity (691 nm) point by point. For two diamonds, the intensity of the GR1 peak (741 nm) sharply decreased to a depth of 10 µm, and then became equal to the background level, which is typical for irradiation with alpha particles from natural sources like uranium. In other diamonds, the profiles vary slightly with depth, and the color intensity is close to uniform, which is for irradiation with accelerated electrons or neutrons. The source of radiation has not been determined. However, long duration radioactivity measurements of the diamonds suggested that neutrons were not used for colour centers production in the diamonds studied.
-
Date submitted2022-08-10
-
Date accepted2023-02-28
-
Date published2024-02-29
Selection of the required number of circulating subs in a special assembly and investigation of their performance during drilling of radial branching channels by sectional positive displacement motors
The task of sludge removal to the surface during construction of directional and horizontal wells and strongly curved radial channels is relevant. For stable operation of technical system “Perfobore”, it is proposed to use a circulating sub that ensures efficient cleaning of channel wellbore from the drilled rock. Two schemes of technical system “Perfobore” are considered, consisting of two seven-meter coiled tubing, a positive displacement motor, a bit and one circulating sub in the first scheme and two subs in the second scheme. For each of the schemes CFD modeling was implemented to determine values of pressure and speed. It was found out that the use of two circulating subs in the assembly is more efficient. In order to confirm the numerical experiment, bench tests were carried out. It was determined that the designed circulating sub can eject up to 25 % of pumped drilling fluid. The bench tests of full-size technical system “Perfobore” for drilling 14-meter channels with two circulating subs showed that the axial load on positive displacement motor produced by hydraulic loader was 3000 N and pressure drop depending on flow rate was 1.5-2.0 MPa. This allows the motor to operate at maximum power.
-
Date submitted2022-06-09
-
Date accepted2022-11-17
-
Date published2022-12-29
Drilling of deep and ultra-deep wells for prospecting and exploration of new raw mineral fields
Scientific and technological progress over the last century has led to an enormous increase in the consumption of minerals, including energy resources. Most of the exploited oil and gas fields are already considerably depleted, so it is necessary to search for new hydrocarbon resources, particularly at great depths. Deep drilling plays a special role in solving this problem. The article considers the world and Russian experience of ultra-deep wells drilling. The methods and technologies used in the construction of wells, as well as complications and accidents occurring during their drilling were analyzed. The analysis revealed that the existing limitations for drilling parameters of deep and ultra-deep wells are caused by the technical characteristics of surface and bottomhole drilling equipment, which do not meet the extreme drilling conditions. The directions for development of deep and ultra-deep well drilling machinery and technologies are suggested. The notion of extreme rock and geological drilling conditions is introduced, which describes drilling in conditions of hydrostatic pressure of flushing fluid column and high bottomhole temperature both at stable and unstable wellbore conditions, coming close to the upper limit of operating technical characteristics of bottomhole assembly, the drill string and flushing fluid.
-
Date submitted2021-05-19
-
Date accepted2022-04-07
-
Date published2022-04-29
On the possibility of reducing man-made burden on benthic biotic communities when mining solid minerals using technical means of various designs
The paper analyses features of the species composition and diversity of biotic communities living within the ferromanganese nodule fields (the Clarion-Clipperton field), cobalt-manganese crusts (the Magellan Seamounts) and deep-sea polymetallic sulphides (the Ashadze-1, Ashadze-2, Logatchev and Krasnov fields) in the Russian exploration areas of the Pacific and Atlantic Oceans. Prospects of mining solid minerals of the world’s oceans with the least possible damage to the marine ecosystems are considered that cover formation of the sediment plumes and roiling of significant volumes of water as a result of collecting the minerals as well as conservation of the hydrothermal fauna and microbiota, including in the impact zone of high temperature hydrothermal vents. Different concepts and layout options for deep-water mining complexes (the Indian and Japanese concepts as well as those of the Nautilus Minerals and Saint Petersburg Mining University) are examined with respect to their operational efficiency. The main types of mechanisms that are part of the complexes are identified and assessed based on the defined priorities that include the ecological aspect, i.e. the impact on the seabed environment; manufacturing and operating costs; and specific energy consumption, i.e. the technical and economic indicators. The presented morphological analysis gave grounds to justify the layout of a deep-sea minerals collecting unit, i.e. a device with suction chambers and a grip arm walking gear, selected based on the environmental key priority. Pilot experimental studies of physical and mechanical properties of cobalt-manganese crust samples were performed through application of bilateral axial force using spherical balls (indenters) and producing a rock strength passport to assess further results of the experimental studies. Experimental destructive tests of the cobalt-manganese crust by impact and cutting were carried out to determine the impact load and axial cutting force required for implementation of the collecting system that uses a clamshell-type effector with a built-in impactor.
-
Date submitted2021-03-30
-
Date accepted2021-07-27
-
Date published2021-10-21
Integrated development of iron ore deposits based on competitive underground geotechnologies
- Authors:
- Vladimir L. Trushko
- Olga V. Trushko
The article presents an analytical review of the current state of the iron ore base of the ferrous metallurgy of Russia and the world, identifies the largest iron ore provinces and iron ore producers. The promising directions of development and improvement of the quality of the iron ore base of Russia and the features of the development of new deposits of rich iron ores are identified. Effective technologies for the development of rich iron ores deposits that ensure an increase in production volumes are proposed. The geomechanical justification of rational technological parameters that are easily adapted to changes in mining and geological conditions has been performed. Based on the results of field studies, the use of an elastic-plastic model with the Coulomb – Mohr strength criterion for modeling changes in the stress-strain state of an ore rock mass during mining operations is justified and recommendations for ensuring the stability of mine workings are developed. Effective engineering and technical solutions for the complex development and deep processing of rich iron ores with the production of fractionated sinter ore, which increases the efficiency of metallurgical processes, the production of high-grade iron oxide pigments and iron ore briquettes, which increase the competitiveness of iron ore companies and the full use of the resource potential of deposits, are presented.
-
Date submitted2019-07-10
-
Date accepted2019-08-30
-
Date published2019-12-24
Methodology for calculating technical efficiency of power sections in small-sized screw downhole motors for the «Perfobur» system
With an increase in the share of old and low-yield wells and for the efficient exploitation of fields, it is necessary to include low-capacity formations into production. There are many wells where sidetracking and hydraulic fracturing are difficult due to the close proximity of the gas cap and underlying water caused by geological and technological reasons, and the use of existing secondary drilling-in technologies is not effective due to the extensive colmatated zone or annular circulation. Relevance of radial drilling technologies is growing, which allows drilling-in of the formation with a network of extended channels to establish high-quality hydraulic communication between the formation and the well without affecting the permeability of the formation. In contrast to radial drilling technologies using hydraulic washing, technical system (TS) «Perfobur» uses small-sized screw downhole motors (SDM) and rock cutting tools for channel construction. For efficient milling of production casing and destruction of rock, the hydraulic downhole motor must have high torque, and for the possibility of drilling with a high rate of angle gain, it must have short power section. Existing Russian and foreign SDM have limited number of standard sizes and do not meet the requirements specified for the development of the downhole module of TS «Perfobur». The paper discusses the development of universal small-sized sectional screw downhole motors for milling casing strings and drilling a network of branched channels of super-small diameter and radius of curvature as a part of the TS «Perfobur». Methodology proposed in the article for selecting optimal configuration of the SDM power sections allows constructing small-sized sectional downhole motor that meets the technical requirements and has improved characteristics compared to standard SDM.
-
Date submitted2019-06-29
-
Date accepted2019-08-25
-
Date published2019-12-24
New technical solutions for ventilation in deep quarries
- Authors:
- S. G. Shakhrai
- G. S. Kurchin
- A. G. Sorokin
The paper discusses the issues of ventilating in deep quarries caused by the intensification of blasting operations at great depths, the increased distance of ore truck transportation to the daylight area, constant change in the geometrical parameters of the quarry, its microrelief and direction of mining, and increased isolation of the mined space from the environment. We provide a brief analysis of the current tools for forced airflow in deep quarries, which showed that the use of forced ventilation is often challenging since it leads to high energy consumption, high level of noise exceeding the permissible parameters, and high speeds of forced air flows may blow the dust off the quarry surfaces. The article presents methods and tools developed at the Siberian Federal University for intensifying the natural airflow in deep quarries by changing the air density at the entrance and exit points of the pit, as well as heating the shady areas using mirrors and solar energy, which do not interfere with mining and blasting operations.
-
Date submitted2018-11-03
-
Date accepted2019-01-21
-
Date published2019-04-23
Estimation of critical depth of deposits by rock bump hazard condition
- Authors:
- V. N. Tyupin
During the development of minerals by the underground method, dynamic manifestations of rock pressure occur at a certain depth, which significantly reduces the safety of mining operations. Regulatory documents prescribe at the exploration and design stages to establish the critical depth for classifying a deposit as liable to rock bumps. Currently, there are a number, mainly instrumental, methods for determining the liability of rock mass to rock bumps and methods based on the determination of physical and technical properties and the stress-strain state of rock massifs. The paper proposes a theoretical method for determining the critical depth for classifying a deposit as liable to rock bumps. A formula for determining the critical depth of the rock bump hazard condition is obtained. A mathematical analysis of the influence of the physical and technical parameters of the formula on the critical depth is carried out. Its physical and mathematical validity is substantiated. The numerical calculations of the critical depth for 17 developed fields were carried out using a simplified formula. It also provides a comparison of calculated and actual critical depth values. It is established that the variation of the actual and calculated critical depth is due to the lack of actual data on the value of the friction coefficient and parameters of fracturing of the rock mass in the simplified formula. A simplified calculation formula can be used to estimate the critical depth of a field at the survey and design stages. More accurate results can be obtained if there are actual data on fracture parameters, friction coefficients and stress concentration near the working areas.
-
Date submitted2018-01-15
-
Date accepted2018-02-28
-
Date published2018-06-22
About the role of hydrafed calcium carboaluminates in improving the technology of complex processing of nephelines
- Authors:
- V. M. Sizyakov
- V. N. Brichkin
The scientific justification and development of the method for industrial synthesis of complex aluminates of alkaline earth metals is an innovative solution that determined several directions in the development of technology for complex processing of nepheline raw materials. It ensures the production of high-quality metallurgical alumina, the effective utilization of nepheline sludge and production of new types of multipurpose by-products. The modern development of these technical solutions is associated with ensuring the energy efficiency of the synthesis of hydrafed calcium carboaluminates (HCCA) and increasing the level of purification of aluminate solutions. The conditions for synthesizing HCCA with the use of calcareous materials of natural and technogenic origin have been experimentally determined, which makes it possible to isolate the average particle diameter as one of the determining factors of this process. The effect of the turnover of the hydrogarnet sludge on the removal of kinetic limitations in the process of deep desalination of aluminous solutions is theoretically justified. The conditions of a two-stage dosage of HCCA are experimentally determined. It is shown that the optimum ratio of the amount of the reagent supplied in the first and second stages is about 3: 2. At the same time, the maximum degree of precipitation of silica provides the production of aluminate solutions with a silicon module at the level of 95,000, which is achieved by using a HCCA synthesized based on chemically precipitated calcium carbonate in the processing of wastes from the production of mineral fertilizers.
-
Date submitted2016-11-18
-
Date accepted2016-12-28
-
Date published2017-04-14
Frequency electromagnetic sounding with industrial power lines on Karelia-Kola geotraverse
The paper describes theory, method and first experimental results of research on the interaction between electromagnetic waves of extremely low and ultra low frequency (0.1-200 Hz), the Earth crust and ionosphere in the field of two mutually orthogonal industrial power lines, 109 and 120 km long, in the course of FENICS experiment (Fennoscandian Electrical conductivity from Natural and Induction Control Source soundings). The main focus was on the observation results along the line of Karelia-Kola geotraverse over a distance of 700 km from the source. High horizontal homogeneity of geoelectrical lithosphere section has been detected in the eastern part of the Baltic shield at depth range from 10-15 to 50-70 km. Parameters of «regular» lithosphere section have been specified to the depth of 60-70 km. As a result of inverse problem solution for the western part of Karelia and Central Finland, a zone of decreased transverse resistivity has been detected at the depth of 50-60 km, corresponding to the area, detected by seismic methods, where Moho boundary reaches the same depth.
-
Date submitted2016-09-04
-
Date accepted2016-11-14
-
Date published2017-02-22
Methodology of reducing rock bump hazard during room and rillar mining of North Ural deep bauxite deposits
- Authors:
- D. V. Sidorov
The article describes practical experience of using room and pillar mining (RAPM) under conditions of deep horizons and dynamic overburden pressure. It was identified that methods of rock pressure control efficient at high horizons do not meet safety requirements when working at existing depths, that is explained by changes in geodynamic processes during mining. With deeper depth, the geodynamic processes become more intensive and number of pillar and roof failures increase. When working at 800 m the breakage of mine structures became massive and unpredictable, which paused a question of development and implementation of tools for compliance assessment of used elements of RAPM and mining, geological, technical and geodynamic conditions of North Ural bauxite deposits and further development of guidelines for safe mining under conditions of deep horizons and dynamic rock pressure. It describes reasons of mine structure failures in workings depending on natural and man-caused factors, determines possible hazards and objects of geomechanic support. It also includes compliance assessment of tools used for calculations of RAPM structures, forecast and measures for rock tectonic bursts at mines of OAO “Sevuralboksitruda” (SUBR). It describes modernization and development of new geomechanic support of RAPM considering natural and technogenic hazards. The article presents results of experimental testing of new parameters of RAPM construction elements of SUBR mines. It has data on industrial implementation of developed regulatory and guideline documents at these mines for identification of valid parameters of RAPM elements at deep depths.
-
Date submitted2014-12-25
-
Date accepted2015-02-01
-
Date published2015-12-25
Deep structure and composition characteristics of the continental earth's crust geostructures on the Russian Federation territory
- Authors:
- A. S. Egorov
Principal features of deep structure and composition of the lithosphere geostructures of the continental part of the Russian Federation territory are characterized within the radial-zonal model of the Earth’s crust. The principal units of the model are megablocks (paleoplites) with ancient layered continental crust and interblock megazones (structures of tension, compression and shear), separating them. The results of the geological-geophysical modeling are presented in the form of layer by layer deep structure schemes – of consolidated basement and of the platform cover and accompanied by a set of the earth's crust sections, carried out along regional profiles, performed with the application of a deep seismic sounding (DSS) method and reflected waves of common depth point (CDP) method.
-
Date submitted2014-09-01
-
Date accepted2014-11-21
-
Date published2015-06-26
Determenation of the bolting parameters under conditions of the zonal disintegration of rocks around underground workings
- Authors:
- M. A. Rozenbaum
- B. P. Badtiev
Recently the phenomenon of zonal disintegration of rocks had discovered at around underground workings at great depths. The main element of this fault concentric system that paralleled working profile. The paper presents the method and formula determination of the bolted mine workings developed on stress-deformed rock massif at great depths at zonal disintegration of rocks around un-derground workings.
-
Date submitted2013-07-23
-
Date accepted2013-09-11
-
Date published2014-03-17
Use of coefficient of output at pit delimitation
- Authors:
- G. A. Kholodnyakov
- N. S. Vainonen
In work it is settled an invoice the final depth of a pit of the conditional complex occurrence presented by three minerals. It is shown that when developing complex occurrence it is more expedient to use coefficient of output, instead of overburden ratio.
-
Date submitted2010-07-01
-
Date accepted2010-09-12
-
Date published2011-03-21
Usage modern computer techniques for validation of actions guaranteeing opening strength of pit edge
- Authors:
- S. N. Kotlov
In this article is described an example of using program Modflow for the issues of oreation geofiltration processes numerical simulation on procedure of horizontal drainage well simulation. Also is estimated stability of pit edges in case of using system horizontal drains.
-
Date submitted2009-10-08
-
Date accepted2009-12-10
-
Date published2010-09-22
Control of dynamic rock pressure manifestations in mining the «Antey» deposit
The article considers the conditions and pattern of dynamic rock pressure manifestations in mining the «Antey» deposit of uranium ores. Data on geological, technological and geomechanical conditions of the deposit mining are given. The methods and means for rock pressure control are described as well as the results of their application at deep horizons of ore mine are given.
-
Date submitted2009-07-17
-
Date accepted2009-09-18
-
Date published2010-04-22
Transformation of the form and angular parameters of rock movement processes with depth at ore deposits
- Authors:
- A. G. Shadrin
- M. A. Shadrin
It was established the increase of movement angles with mining depth and the mechanism of forming the stable natural arching in underground mining of ore deposits. The conditions and parameters of forming the stable natural arching were determined, under which the zone of dangerous deformations localizes inside the ore mass and does not manifest itself on the earth surface. The nomogram for analytical determination of the rock movement angles was developed, and the table was drawn up of the natural arching conditions with due account of main mining-and-geological factors of ore deposit occurrence and its mining.