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Date submitted2024-05-17
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Date accepted2025-03-27
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Date published2025-03-27
Determination of impact hazard potential of rocks in the Norilsk Industrial Region
The deeper the mineral deposits developments are, the worse the mining and geological conditions become. Significant growth of stress level in the rock mass contributes to possible manifestation of rock pressure in dynamic form. The resulting task of assessment of rock impact hazard is closely related to the task of obtaining more accurate results of compression tests of samples in rigid or servohydraulic test presses using graphs of their full deformation. This approach requires special expensive equipment, considerable time resources, and sufficient core material. Therefore, it is important to have an approach that allows to assess the propensity of rocks to brittle fracture with research methods simple enough not to result in the loss of quality and reliability of the obtained results. This paper presents the results of laboratory tests of rocks from the Norilsk Industrial Region to determine their tensile and compressive strengths. Test methods involved both domestic and foreign standards for determining the value of the brittleness coefficient. The impact hazard potential of rocks was determined using the Kaiser criterion. It is found that the tested lithological types (rich sulfide ores, hornblende, disseminated ores, and gabbro-dolerite rocks), with the exception of anhydrite, have a low impact hazard potential.
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Date submitted2024-03-29
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Date accepted2024-11-07
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Date published2025-02-26
Well killing with absorption control
The development of new fields with low-permeability reservoirs required the introduction of new production technologies, of which the most significant for well killing and underground repair were multi-ton hydraulic fracturing, the simultaneous operation of two or three development sites by one well grid, and an increase in the rate of fluid extraction. These global decisions in field development have led to the need to search for new effective materials and technologies for well killing. The article is devoted to the analysis of problems associated with the process of killing production wells in fields characterized by increased fracturing, both natural and artificial (due to hydraulic fracturing), with reduced reservoir pressure and a high gas factor. The relevance of the analysis is due to the increase in the number of development sites where complications arise when wells are killed. Particular attention is paid to technical solutions aimed at preserving the filtration and capacity properties of the bottomhole formation zone, preventing the absorption of process fluid, and blocking the manifestation of gas. The classification of block-packs used in killing is given, based on the nature of the process fluid. Suspension thickened water-salt solutions are considered, forming a waterproof crust on the surface of the rock, which prevents the penetration of water and aqueous solutions into the formation. This approach ensures the safety and efficiency of killing operations, especially when working with formations in which maintaining water saturation and preventing the ingress of the water phase are of critical importance. Modern trends in the development of technology are revealed, and promising areas for further improvement of well killing with absorption control are outlined.
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Date submitted2024-06-17
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Date accepted2024-07-17
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Date published2024-10-03
Justification on the safe exploitation of closed coal warehouse by gas factor
The annual increase of coal production and its demand lead to the necessity in temporary storage places (warehouses) organization to accommodate raw coal materials before the shipment. It is noted that at the open method of coal storing the dust emission from loading/unloading operations and from the pile surface effects negatively the health of the warehouse workers and adjacent territories. An alternative solution is closed-type warehouses . One of the main hazards of such coal storage can be the release of residual methane from coal segregates into the air after degassing processes during mining and extraction to the surface, as well as transportation to the place of temporary storage. The study carries the analysis of methane content change in coal during the processes of extraction, transportation and storage. Physical and chemical bases of mass transfer during the interaction between gas-saturated coal mass and air are studied. It is determined that the intensity of methane emission depends on: the coal seam natural gas content, parameters of mass transfer between coal, and air and the ambient temperature. The dynamics of coal mass gas exchange with atmospheric air is evaluated by approximate approach, which is based on two interrelated iterations. The first one considers the formation of methane concentration fields in the air space of the bulk volume and the second accounts the methane emission from the pile surface to the outside air. It is determined that safety of closed coal warehouses exploitation by gas factor can be ensured by means of artificial ventilation providing volumetric methane concentration in the air less than 1 %. The flow rate sufficient to achieve this methane concentration was obtained as a result of computer modeling of methane concentration fields formation in the air medium at theoretically calculated methane emission from the pile surface.
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Date submitted2021-01-21
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Date accepted2023-09-20
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Date published2023-12-25
Adaptation of transient well test results
Transient well tests are a tool for monitoring oil recovery processes. Research technologies implemented in pumping wells provide for a preliminary conversion of measured parameters to bottomhole pressure, which leads to errors in determining the filtration parameters. An adaptive interpretation of the results of well tests performed in pumping wells is proposed. Based on the original method of mathematical processing of a large volume of field data for the geological and geophysical conditions of developed pays in oil field, multidimensional models of well flow rates were constructed including the filtration parameters determined during the interpretation of tests. It is proposed to consider the maximum convergence of the flow rate calculated using a multidimensional model and the value obtained during well testing as a sign of reliability of the filtration parameter. It is proposed to use the analysis of the developed multidimensional models to assess the filtration conditions and determine the individual characteristics of oil flow to wells within the pays. For the Bashkirian-Serpukhovian and the Tournaisian-Famennian carbonate deposits, the influence of bottomhole pressure on the well flow rates has been established, which confirms the well-known assumption about possible deformations of carbonate reservoirs in the bottomhole areas and is a sign of physicality of the developed multidimensional models. The advantage of the proposed approach is a possibility of using it to adapt the results of any research technology and interpretation method.
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Date submitted2022-06-27
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Date accepted2023-06-20
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Date published2023-12-25
Analysis of the problems of high-quality drinking water extraction from underground water intakes on Vysotsky Island in the Vyborg district of the Leningrad region
This article presents the results of drilling, experimental filtration work and laboratory studies aimed at assessing the resources and quality of groundwater in the licensed area of Vysotsky Island located in the Leningrad region, in the Gulf of Finland in accordance with the requirements of regulatory documents. Analysis of the results of hydrochemical studies and their comparison with data on water intakes in adjacent areas gives the right to conclude that it is possible to classify a hydrogeological unit as a different type of resource formation than those located in the surrounding areas. Groundwater in this area is confined to an unexplored deep fractured regional high-pressure zone. According to the received data, the explored water intake can be attributed to a unique groundwater deposit, which has an uncharacteristic composition of groundwater in the north of the Leningrad region, which may be due to the mixing of modern sediments and relict waters of the Baltic glacial lake. The stability of groundwater characteristics is confirmed by long-term monitoring.
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Date submitted2023-03-16
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Date accepted2023-06-20
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Date published2023-07-19
Energy efficiency of the linear rack drive for sucker rod pumping units
- Authors:
- Oksana Yu. Ganzulenko
- Ani P. Petkova
At present, in order to increase oil production and reduce economic costs in the development of marginal fields, the development of a cluster method using compact mobile drives of sucker rod pumping units (SRPU) is relevant. The aim of the work is to analyze the ways to improve the energy efficiency of the SRPU by reducing the loss of mechanical and electrical energy, to select the most energy-efficient compact drive for the development of marginal fields in the cluster method, to carry out the kinematic and strength calculations of the drive of the selected size, to develop an adaptive control system for a group of drives in the cluster development of drillings. According to the results of the performed calculations, the linear rack-and-gear drive has the highest efficiency of the drive mechanism. The kinematic and strength calculations of a linear rack-and-gear drive with a stroke length of 1120 mm and a load of up to 8 tons are presented. It was shown that the usage of a direct torque control system and a kinetic energy storage system for the SRPU drive elements and a rod string is an effective means of reducing energy costs in oil production from marginal fields. The use of the developed system for storing and redistributing the potential energy of the rods between the SRPUs that lift oil made it possible to eliminate fluctuations in the power consumption, reduce the power peak value by three times, the peak value of the current consumed from the electric network by two times, and reduce losses in the input converter and cables by three times.
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Date submitted2023-01-27
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Date accepted2023-03-04
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Date published2023-04-25
Use of the UNIFAC model in the calculation of physicochemical properties of ecotoxicants for technological and ecoanalytical purposes
- Authors:
- Vladimir G. Povarov
- Ignatyi I. Efimov
Modern development vector of environmental monitoring leads to elaboration of analytical methods for qualitative and quantitative analysis of different ecotoxicants. Many studies face the lack of information on isomers and homologues of already studied compounds. This problem cannot always be solved experimentally due to the difficulty of separating or synthesizing certain compounds; the use of group theories of solutions will help partly; using them, solubility in water or partition coefficient between two immiscible solvents is calculated for ecotoxicants. These parameters are important for solving the analytical and ecological problems. The partition coefficient in the octanol – water system is associated with a possibility of accumulation of different compounds in living organisms; the partition coefficient in the hexane – acetonitrile system can be used in gas chromatographic analysis. Solubility in water is closely associated with accumulation of ecotoxicants in water bodies, as well as with their ability to be transferred. This paper presents the capabilities of the UNIFAC model for solving physicochemical problems using the example of calculating the properties of real ecotoxicants on the basis of the available thermodynamic data. All the obtained calculated values were compared with those determined experimentally. In the case of pyrene derivatives, solubility data were obtained for the first time using a correlation group model to calculate the heat of fusion and melting temperature.
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Date submitted2022-05-06
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Date accepted2022-11-17
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Date published2023-02-27
Comprehensive study of filtration properties of pelletized sandy clay ores and filtration modes in the heap leaching stack
There are the results of a study of the factors determining the formation and changes in the filtration properties of a heap leaching stack formed from pelletized poor sandy-clay ores. An analysis of methods of investigation of filtration properties of ore material for different stages of heap leaching plots functioning is carried out. Influence of segregation process during stack dumping on formation of zones with very different permeability parameters of ore has been established by experimental and filtration works. The construction and application of a numerical model of filtration processes in pelletized ores based on laboratory experiments is shown. By means of solution percolation simulation at different irrigation intensities the justification of optimal stack parameters is provided in terms of the geomechanical stability and prevention of solution level rise above the drainage layer.
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Date submitted2021-05-13
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Date accepted2022-11-28
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Date published2022-12-29
Reproduction of reservoir pressure by machine learning methods and study of its influence on the cracks formation process in hydraulic fracturing
Hydraulic fracturing is an effective way to stimulate oil production, which is currently widely used in various conditions, including complex carbonate reservoirs. In the conditions of the considered field, hydraulic fracturing leads to a significant differentiation of technological efficiency indicators, which makes it expedient to study in detail the crack formation patterns. For all affected wells, the assessment of the resulting fractures spatial orientation was performed using the developed indirect technique, the reliability of which was confirmed by geophysical methods. In the course of the analysis, it was found that in all cases the fracture is oriented in the direction of the development system element area, which is characterized by the maximum reservoir pressure. At the same time, reservoir pressure values for all wells were determined at one point in time (at the beginning of hydraulic fracturing) using machine learning methods. The reliability of the used machine learning methods is confirmed by high convergence with the actual (historical) reservoir pressures obtained during hydrodynamic studies of wells. The obtained conclusion about the influence of the formation pressure on the patterns of fracturing should be taken into account when planning hydraulic fracturing in the considered conditions.
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Date submitted2022-01-31
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Date accepted2022-09-06
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Date published2022-11-10
Filtration studies on cores and sand packed tubes from the Urengoy field for determining the efficiency of simultaneous water and gas injection on formation when extracting condensate from low-pressure reservoirs and oil from oil rims
- Authors:
- Nikolay A. Drozdov
Oil rims as well as gas condensate reservoirs of Russia's largest Urengoy field are developed by depletion drive without formation pressure maintenance, which has led to serious complications in production of oil, gas and condensate. In addition, field development by depletion drive results in low values of oil and condensate recovery. These problems are also relevant for other oil and gas condensate fields. One of the possible solutions is simultaneous water and gas injection. Rational values of gas content in the mixture for affecting gas condensate fields and oil rims of oil and gas condensate fields should be selected using the data of filtration studies on core models. The article presents the results of filtration experiments on displacement of condensate and oil by water, gas and water-gas mixtures when simulating the conditions of the Urengoy field. Simultaneous water and gas injection showed good results in the experiments on displacement of condensate, residual gas and oil. It has been ascertained that water-gas mixtures with low gas content (10-20 %) have a better oil-displacement ability (9.5-13.5 % higher) than water. An experiment using a composite linear reservoir model from cemented core material, as regards the main characteristics of oil displacement, gave the same results as filtration experiments with sand packed tubes and demonstrated a high efficiency of simultaneous water and gas injection as a method of increasing oil recovery at oil and gas condensate fields.
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Date submitted2020-10-26
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Date accepted2021-07-28
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Date published2021-10-21
Investigation of the influence of the geodynamic position of coal-bearing dumps on their endogenous fire hazard
The paper investigates the hypothesis according to which one of the factors influencing the spontaneous combustion of coal-bearing dumps is its geodynamic position, i.e. its location in the geodynamically dangerous zone (GDZ) at the boundary of the Earth crust blocks. This hypothesis is put forward on the basis of scientific ideas about the block structure of the Earth crust and the available statistical data on the location of burning dumps and is studied using computer modeling. A dump located in the area of Eastern Donbass was chosen as the object of research. The simulation results show that the penetration of air into the dump body from the mine through the GDZ, which crosses the mining zone, is possible at an excess pressure of 1000 Pa created by the main ventilation fans. The fire source appearance in the dump body causes an increase in the temperature of the dump mass and becomes a kind of trigger that "turns on" the aerodynamic connection between the dump and the environment, carried out through the GDZ. It is concluded that the establishment of an aerodynamic connection between the mine workings and the dump through the GDZ can be an important factor contributing to the endogenous fire hazard of coal-bearing dumps. The simulation results can be used in the development of projects for monitoring coal-bearing dumps and measures to combat their spontaneous combustion.
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Date submitted2021-02-05
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Date accepted2021-03-30
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Date published2021-04-26
Assessment of negative infrastructural externalities when determining the land value
- Authors:
- Elena N. Bykova
The work forms and substantiates the concept of land value, based on a new institutional theory. The infrastructural component of the cost of land in the presented concept determines, on the one hand, the efficiency of the use of natural resources, properties, demand for land on the market, on the other hand, the costs, which are determined not only by capital investments in construction of engineering infrastructure, but also by losses associated with restrictions on activities within zones with special conditions for territory use, creation of unfavorable conditions for economic activity, small contours, irregularities and others on a specific land plot, which are external negative infrastructural externalities that create losses of rights holders of land plots that are not compensated by the market, falling within the boundaries of these zones. Methods for assessing the impact of such negative infrastructural externalities on the cost of land encumbered by zones in different conditions of land market activity have been developed and tested, based on an expert-analytical approach (depressed market); the ratio of market values of land plots encumbered and unencumbered by a specific zone, and qualimetric modeling (inactive market); modeling by introducing into the model the factor of presence of zones with special conditions for territory use, based on the grouping of zones according to similar regulations for use, or by introducing the parameters of this factor (active market). Methods for taking into account spatial deficiencies and compensating for restrictions and prohibitions on activities on the territory of land plots with an individual market assessment are proposed.
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Date submitted2021-01-25
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Date accepted2021-02-22
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Date published2021-04-26
Conducting industrial explosions near gas pipelines
The problem to ensure the safety of objects which are in the area of blasting operations, ensuring the destruction of hard rocks, remains relevant. The article presents the results of a large-scale experiment to determine the safe conditions for conducting drilling and blasting operations near the active gas pipeline. The simplest and most reliable way to ensure the safety of the protected object from seismic impact is to reduce the intensity of the seismic wave, which is achieved by changing the parameters of drilling and blasting operations. This requires research to determine the impact of blasting operations on the parameters of seismic waves and the development of methods for measuring these parameters. The paper presents a detailed analysis of the seismic blast wave impact on the displacement of the ground and the model gas pipeline. The features of seismic monitoring during blasting operations near the active gas pipeline are shown. The seismic coefficients and attenuation coefficient of seismic waves are determined. It is proved that the readings of the seismic receivers on the surface and in the depth of the massive differ by two or more times.
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Date submitted2020-05-18
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Date accepted2020-06-16
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Date published2021-04-26
Traction asynchronous electric drive of mine electric locomotivesimulation model structure improvement
The article discusses the solution to the problem of underground railway transport slipping in dynamic modes, which occurs when there is a significant difference in the speeds of the driving and driven pairs of wheels. The state of the rail surfaces largely determines the coefficient of adhesion, therefore, using a mathematical model, the condition for the dependence of the magnitude of slipping and tractive effort is selected. For effective acceleration and deceleration of an electric locomotive, it is necessary to control the coefficient of adhesion at a certain level. A simulation model of rolling stock has been created, which for the first time takes into account a mechanical system with distributed parameters. In the structural diagram of the automatic control system of traction electric drives with frequency regulation, such factors as the volume of goods being moved, rolling friction, slope (rise) levels and the state of the rail track are taken into account. The simulation results show the features of the movement and stops of the freight train not only by the diagrams of speed and forces in the modes of acceleration-deceleration and uniform movement, but also the positions of the plungers and tractive forces on the couplings of the electric locomotive and all trolleys involved in the movement of goods. The practical application of the proposed method lies in the possibility of starting a heavily laden train from its place on the ascent section in conditions of insufficient adhesion coefficient with contaminated roads.
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Date submitted2020-05-05
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Date accepted2020-10-05
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Date published2020-11-24
Assessment of the Influence of Water Saturation and Capillary Pressure Gradients on Size Formation of Two-Phase Filtration Zone in Compressed Low-Permeable Reservoir
The paper examines the influence of capillary pressure and water saturation ratio gradients on the size of the two-phase filtration zone during flooding of a low-permeable reservoir. Variations of water saturation ratio s in the zone of two-phase filtration are associated with the pressure variation of water injected into the reservoir; moreover the law of variation of water saturation ratio s ( r , t ) must correspond to the variation of injection pressure, i.e. it must be described by the same functions, as the functions of water pressure variation, but be subject to its own boundary conditions. The paper considers five options of s ( r , t ) dependency on time and coordinates. In order to estimate the influence of formation and fluid compressibility, the authors examine Rapoport – Lis model for incompressible media with a violated lower limit for Darcy’s law application and a time-dependent radius of oil displacement by water. When the lower limit for Darcy’s law application is violated, the radius of the displacement front depends on the value of capillary pressure gradient and the assignment of s function. It is shown that displacement front radii contain coefficients that carry information about physical properties of the reservoir and the displacement fluid. A comparison of two-phase filtration radii for incompressible and compressible reservoirs is performed. The influence of capillary pressure gradient and functional dependencies of water saturation ratio on oil displacement in low-permeable reservoirs is assessed. It is identified that capillary pressure gradient has practically no effect on the size of the two-phase filtration zone and the share of water in the arbitrary point of the formation, whereas the variation of water saturation ratio and reservoir compressibility exert a significant influence thereupon.
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Date submitted2020-06-15
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Date accepted2020-06-15
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Date published2020-06-30
Description of steady inflow of fluid to wells with different configurations and various partial drilling-in
- Authors:
- Valery A. Iktissanov
There are many equations of steady inflow of fluid to the wells depending on the type of well, presence or absence of artificial or natural fractures passing through the well, different degrees of drilling-in of the wellbores. For some complex cases, analytical solutions describing the inflow of fluid to the well have not yet been obtained. An alternative to many equations is the use of numerical methods, but this approach has a significant disadvantage – a considerable counting time. In this regard, it is important to develop a more general analytical approach to describe different types of wells with different formation drilling-in and presence or absence of fractures. Creation of this method is possible during modeling of fractures by a set of nodes-vertical wells passing from a roof to floor, and modeling of a wellbore (wellbores, perforation) by a set of nodes – spheres close to each other. As a result, based on this approach, a calculation algorithm was developed and widely tested, in which total inflow to the well consists of the flow rate of each node taking into account the interference between the nodes and considering the impermeable roof and floor of the formation. Performed modeling confirmed a number of known patterns for horizontal wells, perforation, partial drilling-in of a formation, and also allowed solving a number of problems.
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Date submitted2019-02-01
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Date accepted2019-09-16
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Date published2020-02-25
Priority parameters of physical processes in a rock mass when determining the safety of radioactive waste disposal
- Authors:
- V. S. Gupalo
Consideration of geodynamic, hydrogeochemical, erosion and other quantitative characteristics describing evolutionary processes in a rock mass is carried out when choosing a geological formation for the disposal of radioactive waste. However, the role of various process parameters is not equal for safety ensuring and additional percentages of measurement accuracy are far from always being of fundamental importance. This makes it necessary to identify various types of indicators of the geological environment that determine the safety of radioactive waste disposal for their detailed study in the conditions of the burial site. An approach is proposed to determine the priority indicators of physical processes in the rock mass that determine the safety of disposal of various types of radio active waste and require increased attention (accuracy, frequency of measurements) when determining in - situ conditions. To identify such factors, we used the sensitivity analysis method that is a system change in the limits of variable values during securty modeling in order to assess their impact on the final result and determine the role of various physical processes in ensuring safety.
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Date submitted2019-01-31
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Date accepted2022-12-02
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Date published2020-02-25
The relationship of fracture toughness coefficients and geophysical characteristics of rocks of hydrocarbon deposits
This paper contains the results of laboratory tests to determine the fracture toughness coefficient K IC of rocks for terrigenous and carbonate objects by three methods. The tests were carried out by different methods due to the lack of a standard method for determining the fracture toughness characteristics of rocks in Russia. We used the following methods for determining the K IC coefficient: the extension of core specimens with an annular fracture, the action of a concentrated load on a beam specimen with a fracture and the method of bending semi-circular samples with a fracture according to ISRM recommendations. The paper presents the relationship of the fracture toughness coefficients with the P-wave velocity and porosity. The obtained dependencies characterize the general trend of changing for the studied parameter and can be used in the design of hydraulic fracturing in the fields for which tests were conducted.
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Date submitted2019-05-30
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Date accepted2019-09-03
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Date published2020-02-25
Study on influence of two-phase filtration transformation on formation of zones of undeveloped oil reserves
- Authors:
- S. I. Grachev
- V. A. Korotenko
- N. P. Kushakova
In order to study the process of fluid filtration during flooding of an oil field, article uses Rapoport – Lis model of non-piston oil displacement by water. During plane-radial filtration in a homogeneous formation, radii of disturbance zones are determined with and without taking into account the end effect. Influence of changes in value of capillary pressure gradient on distribution of water saturation coefficient in the non-piston displacement zone for high and low permeability reservoirs is revealed. Application of an element model for a five-point injection and production well placement system showed that, using traditional flooding technology, flat-radial fluid filtration is transformed into rectilinear-parallel. At solving equation of water saturation, Barenblatt method of integral relations was used, which allows determining the transformation time. By solving the saturation equation for rectilinear-parallel filtration, change in the value of water saturation coefficient at bottomhole of production well for an unlimited and closed deposit is determined. It is shown that an increase in water cut coefficient of a production well is possible only for a closed formation. To determine coefficient of water saturation in a closed deposit, a differential equation with variable coefficients is obtained, an iterative solution method is proposed. In the element of the five-point system, oil-saturated zones not covered by development were identified. For channels of low filtration resistance, conditions for their location in horizontal and vertical planes are established. It is shown that, at maintaining formation pressure, there is an isobar line in formation, corresponding to initial formation pressure, location of which determines direction of fluid crossflow rates. Intensity of crossflows affects application efficiency of hydrodynamic, physical and chemical, thermal and other methods of enhanced oil recovery.
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Date submitted2019-08-08
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Date accepted2019-09-16
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Date published2020-02-25
Testing of preformed particles polymer gel technology on core filtration models to limit water inflows
In order to reduce watering of wells and equalize their injectivity profiles, the prospects of introducing PPG technology in Russian fields are considered, in which preformed particles polymer gel are pumped into the injection well. These particles, being a supersorbent based on polyacrylamide, absorb water, become elastic, which allows them to shrink and tear in narrow filtration channels. When the polymer is filtered along permeable layers saturated with water, polymer particles accumulate in waterlogged intervals and thus they form a polymer plug, which redistributes the filtration flows and increases the coverage of the formation by the process of oil displacement. More than 4000 downhole operations have been carried out in the fields of China and the USA using PPG technology by now. In domestic fields in Western Siberia, there is limited experience in applying a similar technology in high-temperature formations with low mineralization of formation water. Due to the absence of hydrolytic processes in polyacrylamide, well-known domestic compositions are not applicable due to the low absorption capacity in the conditions of low-temperature deposits with increased mineralization of formation water. The authors synthesized a polymer based on polyacrylamide by block polymerization, which allows to obtain a high absorption capacity, including for low-temperature formations with high mineralization of formation water, which is typical for Perm Territory fields. Filtration experiments were carried out on core models with the composition developed by the authors, this composition focused on low formation temperatures and high mineralization of formation water. As a result of the experiments, it was found that the swollen particles of the gel are able to pass into fractures with a diameter less than their own size at least 20 times. With a significant increase in the viscosity of the dispersion medium, the stability of the suspension increases. Particles of polymer gel have the necessary strength for injection in the field conditions. The fracture permeability during polymer injection decreases by several times and becomes comparable with the permeability of pore collectors.
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Date submitted2019-04-27
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Date accepted2019-07-10
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Date published2019-10-23
Estimation of Rock Mass Strength in Open-Pit Mining
The paper presents results of an experimental study on strength characteristics of the rock mass as applied to the assessment of open-pit slope stability. Formulas have been obtained that describe a correlation between ultimate and residual strength of rock samples and residual shear strength along the weakening surface. A new method has been developed to calculate residual interface strength of the rock mass basing on data from the examination of small-scale monolith samples with opposing spherical indentors. A method has been proposed to estimate strength characteristics (structural weakening coefficients and internal friction angles) of the fractured near-slope rock mass. The method relies on test data from shattering small-scale monolith samples with spherical indentors, taking into ac- count contact conditions along the weakening surface, and can be applied in the field conditions. It is acceptable to use irregular-shaped samples in thetests.
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Date submitted2018-11-03
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Date accepted2019-01-16
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Date published2019-04-23
Interpretation of the tracer investigation results considering convective mass transfer
- Authors:
- V. A. Korotenko
- S. I. Grachev
- A. B. Kryakvin
The paper discusses the results of interpreting well tracer studies. It is shown that from the law of mass conservation it follows that when filtering a volume of an indicator, part of the injected tracer flows into the matrix. With the flow of fluid containing the indicator from the low-filtration resistance channel (LFR) into the surrounding matrix, the linear dimensions of the flow area depend on the permeability and porosity properties of the high-permeability channel and the matrix. While another part of the tracer moves toward the production well, its mass is lost due to diffusion processes. From the solution of the diffusion equation, it follows that the initial concentration of the tracer decreases in the course of filtration along the LFR channel. To interpret the results of the tracer studies, different cases of the LFR channels' location in the volume of the productive formation are considered. The varied parameter w allows characterizing the presence of several peaks in the concentration of the indicator and calculation the filtration parameters of the LFR channels. Depending on the known technological indices, several methods for determining pore volumes in the LFR channels have been proposed. To reduce the water cut in producing wells and to apply the technology of changing or aligning the injectivity profiles, calculations of the pore channels' radii in the mass of highly permeable seams are presented. It is shown that the volume of the chemical reagent pumped into the injection well to isolate the LFR channel is affected by the linear dimensions of the drainage area for the aqueous solution of indicator. Examples of the calculation for the permeability and porosity parameters of the LFR, the volume of pore channels necessary to isolate water inflow, and the radii of pore filtration channels, which influence the selection of the size of chemical reagent molecules, are given.
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Date submitted2018-07-12
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Date accepted2018-09-09
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Date published2018-12-21
Application of the theory of wavelets for compression and filtration of geoinformation
- Authors:
- A. S. Yarmolenko
- O. V. Skobenko
The purpose of the article is to develop a detailed and accessible technology for the application of wavelets in the processing of geo-information, the subject of research is wavelet-based filtering and compression of geo-information. The research methodology is based on the modern theory of wavelets in the light of linear algebra. Research methods involve study and generalization, abstraction, formalization, mathematical modeling using computer programs compiled by the authors. After the introduction and formulation of the problem, the basic positions of linear algebra are presented, on which the content of the article is based when constructing orthonormal bases in one- and two-dimensional cases. First, the application of the general theory to the decomposition of the vector of initial data in the Haar and Shannon bases is given. Further, on the basis of the Haar basis, orthonormal bases of wavelet transforms and filtering information are constructed. The procedure for creating wavelet filters by a sequence of convolutions, the use of MSA analysis for constructing an orthonormal basis of the wavelet transform is considered. Implemented the practical possibility of wavelet filtering based on specific programs for modeling geo-information data fields and images, data compression and filtering. The result of the work is the methods of constructing orthonormal bases by various methods of wavelet transform, based on which algorithms and corresponding computer programs for geoinformation compression are compiled using the example of terrain and photographic images. The efficiency of geoinformation compression and noise filtering using wavelets was investigated. A method has been developed for determining the value of a filter depending on the accuracy of the initial geo-information, illustrated by the example of calculating the filter value for compressing information about the heights of the terrain. The same technique is recommended for image filtering.
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Date submitted2017-12-29
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Date accepted2018-03-06
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Date published2018-06-22
Evaluation of signal properties when searching for cavities in soil under concrete slabs by radio detection stations of subsurface investigation
- Authors:
- G. V. Rudianov
- E. I. Krapivskii
- S. M. Danilev
A method of localization of concealed cavities on the basis of studying of the reflected electromagnetic impulses is considered in the paper. An issue of early detecting of concealed cavities in engineering facilities is a critical one due to a significant influence on further serviceability of a structure. Problems of localization of concealed cavities in the soil body under the concrete slabs of hydropower stations were studied; the results of ground radar detecting investigations of the cavities, physical simulation of a cavity as well as a mathematical modeling of a reflected signal are presented. Modern subsurface radar detection provides methods which allow to reliably detect concealed cavities in the soil. However, it is possible only in case of a clear boundary between the adjacent layers that conditions a jump of dielectric permeability. In the result of an abrupt change of dielectric permeability a reflected wave occurred; the existence of subsurface heterogeneity is conditioned by the properties of this wave. Moreover, the greater is the difference between the values of dielectric permeability in the adjacent layers, the larger amplitude the reflected wave will have. If the cavity is at the stage of forming, i.e. it is filled with the soil of reduced density, then there is no clear boundary at the border of the layers which will condition a gradual change of dielectric permeability with depth. In this case an amplitude of a reflected wave will be minimal and a formation signal will be masked out by jamming signals reflected from various heterogeneities. In such case to determine a cavity at the stage of forming seems to be impossible. To determine poor signals an analysis of a phase of a reflected signal may be used; phase alters in compliance with the reflection coefficient change pattern. The article contains information about signals reflected from the heterogeneities and a conclusion regarding a possibility of detecting cavities in the soil on the basis of a method of coherent processing of signals is made.
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Date submitted2017-09-17
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Date accepted2017-11-06
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Date published2018-02-22
Collaborative interpretation of the data obtained by resistivity and ground penetrating radar methods for assessing the permeability of sandy clay soils
- Authors:
- D. A. Lalomov
- V. V. Glazunov
A method for estimating the filtration factor of sandy clay soils is considered on the basis of a joint interpretation of the data of a set of methods of engineering electrical exploration, including electrical resistivity tomography and ground penetrating radar studies. The solution of this problem is based on the use of known empirical connections between the imaginary and real parts of the complex dielectric permittivity, specific electrical resistance, and Q factor. An example of the effective joint use of the ground penetrating radar and non-contact electrical resistivity tomography shows how to obtain qualitative and quantitative estimates of a changing filtration factor in a draining road layer. It is necessary to use precise engineering geological information in order to provide the required estimates. The proposed approach makes it possible to describe continuous profiles of a pavement and underlying layers by ground penetrating radar and electrical resistivity tomography, as well as to assess soil properties when conducting an electrical survey from the surface of asphalt concrete pavement. Recommendations for the implementation of the developed methods of complex engineering and geophysical research are given for solving issues of repair work design, supervision, and quality control of road construction.