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Date submitted2024-06-17
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Date accepted2024-07-17
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Date published2025-04-25
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 submitted2024-07-28
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Date accepted2024-11-26
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Date published2024-12-12
From import substitution to technological leadership: how local content policy accelerates the development of the oil and gas industry
- Authors:
- Oleg V. Zhdaneev
- Ivan R. Ovsyannikov
Achieving technological sovereignty implies accelerating innovation and reducing import dependence. An effective tool for addressing these challenges is local content policy (LCP). The purpose of this study is to assess the impact of LCP on innovation activity in oil and gas companies and to provide recommendations for enhancing the effectiveness of this policy in Russia. The paper analyzes the influence of LCP on innovation levels in the oil and gas sector, drawing on examples from 10 countries. A positive short-term impact of LCP on innovation was identified in Brazil, Malaysia, and Saudi Arabia, with long-term effects observed in China and South Africa. Recommendations for improving the effectiveness of LCP in Russia are supplemented with a methodology for calculating the level of technological sovereignty. A refinement of the method for solving the «responsiveness» problem, incorporating the level of localization, has been proposed.
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Date submitted2022-10-04
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Date accepted2024-03-05
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Date published2024-08-26
Localization and involvement in development of residual recoverable reserves of a multilayer oil field
During waterflooding of a multilayer oil field there is a constant deterioration of the structure and composition of residual reserves due to geological and technological reasons. The largest share of residual reserves is localized in pillars, which arise from uneven development of the production facility and are undrained or poorly drained zones. The results of a quantitative assessment of the distribution of residual oil reserves in the Middle and Upper Devonian deposits of the Romashkinskoe oil field of the Republic of Tatarstan are presented. A retrospective method is proposed to identify reserves by analyzing and summarizing historical exploration data and the long history of reservoir development, and a calculation algorithm is proposed to quantify them. It has been established that residual oil reserves are localized in rows of dividing and injection wells, as well as in the central rows of producing wells in a three-line drive, in abandoned and piezometric wells, in the areas adjacent to the zones of reservoir confluence, pinch-out, oil-bearing contours, distribution of reservoirs with deteriorated porosity and permeability properties. Depending on geological conditions, algorithms for selecting geological and technical measures to include localized reserves in development and forecasting production profiles were proposed. According to the proposed method, residual recoverable reserves were identified and a number of wells were recommended for experimental works on their additional recovery: in well 16 (hereinafter in the text, conventional well numbers are used) after isolation of overlying high-water-cut formations, the additional perforation was carried out and oil flow was obtained. Additional perforation in well 6 resulted in oil recovery during development as well. Thus, the developed approaches to identifying residual recoverable reserves and patterns of their spatial distribution can be recommended in other multilayer oil fields with a long history of development.
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Date submitted2022-08-05
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Date accepted2022-11-17
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Date published2023-02-27
Feasibility study of using cogeneration plants at Kuzbass coal mines
The paper considers the problem of reducing greenhouse gas emissions in the process of coal mining during the coal mine methane utilization in power supply systems. An algorithm to form recommendations for the implementation of CMM generation is presented. A simulation model for one of the Kuzbass coal mines was developed in the PowerFactory software application. The simulation model considers the uneven nature of the power consumption of mining equipment. As a result of modeling, daily power consumption profiles and voltage levels in the coal mine power supply system were determined before and after the implementation of the proposed measures. Based on the results, the technical and economic effects was estimated, which consisted in reducing the direct and indirect carbon footprint, electricity and capacity fees. It has been established that the cost of carbon dioxide emission quotas significantly affects the investment attractiveness of cogeneration projects. Based on the results, recommendations are given to stimulate the development of small generation in coal mines.
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Date submitted2022-03-09
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Date accepted2022-11-17
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Date published2023-02-27
Development of methodology for economic evaluation of land plots for the extraction and processing of solid minerals
The Russian economy has a pronounced resource specialization; in many regions, subsoil use is a backbone or one of the main areas of the economy. In these conditions, the improvement of the methodology for the economic evaluation of lands on which mining enterprises are located is of particular relevance. On the basis of the existing experience in assessing industrial land, the authors present a developed methodology for determining the cadastral value of land plots where mining enterprises are located, taking into account their industry characteristics and the specifics of production and commercial activities. At the same time, cadastral valuation is considered as a specific form of economic valuation. Particular emphasis is placed on the importance of taking into account the cost factors that have the greatest impact on the formation of the cost of land for the extraction and processing of solid minerals, and the method of assessment depending on the characteristics of the object. To carry out theoretical research, the methods of analysis and synthesis of legal and scientific and technical literature in the field of cadastral and market valuation of land were used in the work. The practical part is based on the application of expert methods, including the method of analysis of hierarchies, system and logical analysis. The method of M.A.Svitelskaya was chosen as the basis, which presents a combination of modified methods of statistical (regression) modeling and modeling based on specific indicators of cadastral value. The use of this technique in economic practice contributes to increasing the efficiency of cadastral valuation and the objectivity of its results.
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Date submitted2022-05-23
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Date accepted2022-07-21
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Date published2023-02-27
Alluvial tin mining by spray-suction borehole method: a case study on remaining alluvial tin reserves in Bangka Belitung, Indonesia
The area of the Bangka Belitung Islands, which is a potential area for alluvial tin deposits in Indonesia, has been affected by the destruction of tin reserves on the mainland due to rampant artisanal mining, which has left remnants of small-dimensional reserves. The remnants of these reserves can no longer be mined using the hydraulic mining of open pit method due to the small dimensions of the deposits. The hypothesis is that such sedimentary conditions can only be mined by the borehole method. This research aimed to design tools and perform test mining using the borehole method with a spray-suction mechanism. This research produced a novelty, namely, a method and parameters for alluvial tin deposits mining using borehole mining methods, such as the excavation capacity, excavation radius, mining recovery, and dilution factor. The benefit of this research is expected to provide an opportunity to increase the amount of onshore alluvial tin reserves to support tin production.
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Date submitted2021-07-05
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Date accepted2022-11-17
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Date published2022-12-29
Determination of suitable distance between methane drainage stations in Tabas mechanized coal mine (Iran) based on theoretical calculations and field investigation
A large amount of gas is emitted during underground mining processes, so mining productivity decreases and safety risks increase. Efficient methane drainage from the coal seam and surrounding rocks in underground mines not only improves safety but also leads to higher productivity. Methane drainage must be performed when the ventilation air cannot dilute the methane emissions in the mine to a level below the allowed limits. The cross-measure borehole method is one of the methane drainage methods that involves drilling boreholes from the tailgate roadway to an un-stressed zone in the roof or floor stratum of a mined seam. This is the main method used in Tabas coal mine N 1. One of the effective parameters in this method is the distance between methane drainage stations, which has a direct effect on the length of boreholes required for drainage. This study was based on the measurement of ventilation air methane by methane sensors and anemometers placed at the longwall panel as well as measuring the amount of methane drainage. Moreover, in this study, the obtained and analyzed data were used to determine the suitable distance between methane drainage stations based on the cross-measure borehole method. In a field test, three borehole arrangements with different station distances in Panel E4 of Tabas coal mine N 1 were investigated. Then, the amounts of gas drained from these arrangements were compared with each other. The highest methane drainage efficiency was achieved for distances in the range of 9-12 m between methane drainage stations.
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Date submitted2022-06-20
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Date accepted2022-09-06
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Date published2022-11-03
Adaptive approach formation using machine vision technology to determine the parameters of enrichment products deposition
In this paper, an adaptive approach has been developed for automatic initialization of the thickening curve using machine vision technology, which makes it possible to determine with high accuracy the material parameters necessary for the design of thickening and clarification apparatuses. Software has been developed that made it possible to search for the coordinates of the condensation critical point in automatic mode. Studies on two samples of materials (tailings of apatite-containing ores and gold-bearing concentrate) were carried out and made it possible to statistically prove the reproducibility of the results obtained using the parametric criteria of Fisher and Bartlett. It has been established that the deposition curves are approximated with high accuracy by the Weibull model, which, together with the piecewise linear approximation, makes it possible to formalize the method for determining the critical point coordinates. The empirical coefficients of the Weibull model for two samples are found, and the final liquefaction and settling rates of the studied materials are determined.
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Date submitted2021-04-20
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Date accepted2022-04-26
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Date published2022-07-13
Prediction of the stress-strain state and stability of the front of tunnel face at the intersection of disturbed zones of the soil mass
The article presents a numerical solution of the spatial elastic-plastic problem of determining the stability of the tunnel face soils at the intersection of disturbed zones of the soil mass. The relevance of the study is related to the need to take into account the zones of disturbed soils when assessing the face stability to calculate the parameters of the support. Based on the finite element method implemented in the PLAXIS 3D software package, the construction of a finite element system "soil mass-disturbance-face support" and modeling of the intersection of the disturbed zones of the soil mass were performed. To assess the condition of soils, deformation and strength criteria are taken. The deformation criterion is expressed by the value of the calculated displacement of the tunnel contour in the face, and the strength criterion - by the safety coefficient until the maximum values of the stress state are reached according to the Coulomb–Mohr criterion. The results of the study are presented in the form of histograms of the safety coefficient dependences on the distance to the disturbance at different bending stiffness of the face support structure, as well as the isofields of deformation development. The parameters of rockfall formation in the face zone at the intersection of zones of disturbed soils were determined. The local decrease in strength and deformation properties in the rock mass along the tunnel track should be taken into account when assessing the stability of the tunnel face and calculating the parameters of the support. Within the framework of the constructed closed system, a qualitative agreement of the simulation results with the case of a collapse in the face during the construction of the Vladimirskaya-2 station of the St. Petersburg Metro was obtained.
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Date submitted2021-09-17
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Date accepted2022-04-07
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Date published2022-12-29
Technique for calculating technological parameters of non-Newtonian liquids injection into oil well during workover
Technique for automated calculation of technological parameters for non-Newtonian liquids injection into a well during workover is presented. At the first stage the algorithm processes initial flow or viscosity curve in order to determine rheological parameters and coefficients included in equations of rheological models of non-Newtonian fluids. At the second stage, based on data from the previous stage, the program calculates well design and pump operation modes, permissible values of liquid flow rate and viscosity, to prevent possible hydraulic fracturing. Based on the results of calculations and dependencies, a decision is made on the necessity of changing the technological parameters of non-Newtonian liquid injection and/or its composition (components content, chemical base) in order to prevent the violation of the technological operation, such as unintentional formation of fractures due to hydraulic fracturing. Fracturing can lead to catastrophic absorptions and, consequently, to increased consumption of technological liquids pumped into the well during workover. Furthermore, there is an increased risk of uncontrolled gas breakthrough through highly conductive channels.
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Date submitted2021-02-28
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Date accepted2021-11-30
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Date published2021-12-27
Substantiation of analytical dependences for hydraulic calculation of high-viscosity oil transportation
- Authors:
- Alexander K. Nikolaev
- Natalia А. Zaripova
One of the development priorities in oil and gas industry is to maintain gas and oil pipeline networks and develop pipeline-connected gas and oil fields of the Arctic zone of the Russian Federation, a promising region the resource potential of which will not only meet a significant portion of internal and external demand for various types of raw materials and primary energy carriers, but will also bring great economic benefits to subsoil users and the state. The mineral and raw material centers of the Nadym-Purskiy and Pur-Tazovskskiy oil and gas bearing areas are among the most attractive regions of the Arctic zone. It is necessary to develop a scientifically substantiated approach to improve the methods of oil transportation from the field to the existing pipelines. As it is known, the task of increasing the efficiency of pipeline transportation of high-viscosity oil is inseparably connected with solving problems in the field of thermal and hydraulic calculation of pipeline system. The article presents the substantiation of dependencies for hydraulic calculation of pipelines transporting high-viscosity oil exhibiting complex rheological properties. Based on the laws of hydraulics for non-Newtonian fluids, the formulas for calculating head losses for fluids obeying Ostwald's law are proposed, their relationship to the classical equations of hydraulics is shown. The theoretical substantiation of looping installation for increasing the efficiency of pipeline transportation of high-viscosity oil taking into account the received dependences for power fluid is considered.
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Date submitted2021-07-07
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Date accepted2021-10-18
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Date published2021-12-16
Influence of hydraulic compression on porosity and permeability properties of reservoirs
Active development of hard-to-recover oil reserves causes the need for an innovative approach to methods of oil recovery and intensification of its production, based on taking into account the specifics of filtration processes in low-productive reservoirs and complex geological and physical conditions. Pilot works for studying the mechanism of changes in porosity and permeability properties of reservoirs during swabbing of wells are presented. Based on the hydrodynamic investigations performed, the results of the work are analyzed. The method of oil production intensification using hydraulic compression of formation has been developed. It has been shown that when using hydraulic compression technology in the pore space of the formation, the effect of capillary and gravitational forces is strongly reduced. The influence of these forces decreases when significant pressure gradients with changing direction are formed during well swabbing for depression impact on the bottomhole zone of the formation. Hydraulic compression induced an increase in well productivity and flow rate; insights into how how permeability and porosity properties change during well swabbing were clarified. The range of compressive durability (minimum and maximum values) was determined for the Verean deposits of the Melekeskaya Depression and the South Tatar arch. The impact of formation hydraulic compression caused changes in permeability and porosity properties of the reservoir in the bottomhole zone on a qualitative level. Piezo- and hydraulic conductivity increased by 20 %. Experimental work in well 1545 of Keremetyevskoe field showed an increase of piezo- and hydraulic conductivity coefficients, effective formation thickness, change of filtration flows character.
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Date submitted2021-02-24
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Date accepted2021-10-18
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Date published2021-12-16
A probabilistic approach to the dynamic cut-off grade assessment
Cut-off grade is an important conditioning parameter that determines the quantity and quality of recoverable reserves and development efficiency. Today, Russian mining companies operate with certified quality requirements. By setting permanent quality requirements, the government seeks to prevent depletion of reserves, reduced production during periods of falling prices, and decreased budget revenues, expressing the interests of all members of society. But to what extent do the permanent quality requirements protect the interests of the state? The answer to this question is ambiguous and does not lie on the surface. The State Commission for Reserves and domestic researchers are working to find a rational solution to the problem of quality requirements. One solution is dynamic quality requirements. The effectiveness of their application has been proven for individual mining companies, but it is incorrect to transfer these conclusions to the entire mineral resource base of the country. This article presents a new approach to determining the dynamic cut-off grade, which varies depending on the price of minerals. The dynamic cut-off grade is proposed to be determined based on the indicators of constant requirements to the quality of exploration work, using the maximum allowable costs in the region. The approach allows to calculate the effect of the introduction of dynamic cut-off grade in the practice of subsurface use for the state (in the form of the amount of taxes received) and for subsoil users (in the form of the amount of income). For a group of gold-bearing deposits with open-pit mining method, it was established that the development of reserves using dynamic values of the cut-off grade in periods of price changes ensures compliance with the interests of the state and subsoil users.
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Date submitted2020-12-24
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Date accepted2021-10-18
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Date published2021-12-16
Natural gas methane number and its influence on the gas engine working process efficiency
The natural gas usage as a vehicle fuel in the mining industry is one of the priority tasks of the state. The article pays special attention to the component composition of natural gas from the point of view of its thermal efficiency during combustion in the combustion chamber of a power plant on a heavy-duty vehicle in difficult quarry conditions. For this, domestic and foreign methods for determining the main indicator characterizing the knock resistance of fuel in the combustion process – the methane number – are considered. Improvement of technical and economic indicators will be carried out by changing the composition of the gas mixture based on methane to fit the design features of the gas power plant, the methane number will be the determining indicator. A theoretical analysis of the influence of the methane number on such engine parameters as the compression ratio and the maximum speed of the flame front propagation in the second phase of combustion in the engine cylinder, expressed through the angle of rotation of the crankshaft, is presented. Based on the results of theoretical and experimental studies, the dependences of the influence of the methane number on the efficiency of the working process of the engine and its external speed characteristic were obtained.
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Date submitted2021-06-01
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Date accepted2021-07-27
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Date published2021-10-21
Indicator assessment of the reliability of mine ventilation and degassing systems functioning
- Authors:
- Nina O. Kaledina
- Valentina A. Malashkina
The gas emission control in the mines is operated by ventilation and degassing systems that ensure the aerological safety of the mines or minimize the aerological risks. The ventilation system of the mine and its individual sites includes a significant number of technical devices and equipment, and the air tubes are mainly mining workings, the condition of which determines the quality of the ventilation network (its capacity) and depends on a number of mining factors. Similarly, one of the most important elements of the degassing system, which includes its own chain of technological equipment, are wells, and in some cases, mining workings. Thus, mine ventilation and degassing systems cannot be attributed to purely technical systems, since they include mining elements characterized by high variability of the determining parameters. To assess their reliability, it is necessary to use various combined methods that include additional characteristics in relation to the mining component. At the same time, the reliability of technical devices that ensure the functioning of mine ventilation and degassing systems largely determines the efficiency (stability and reliability) of these systems and, consequently, affects the level of aerological risks. The described approach to assessing the reliability of ventilation and degassing systems of coal mines when analyzing aerological risks is based on the developed system of risk indicators for the methane factor and will allow determining the risk dynamics in automatic mode based on monitoring the parameters of the ventilation and degassing system state.
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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 submitted2020-06-12
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Date accepted2020-10-28
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Date published2020-11-24
Spatial non-linearity of methane release dynamics in underground boreholes for sustainable mining
- Authors:
- Ada K. Dzhioeva
- Vladimir S. Brigida
The paper is devoted to the problem of increasing energy efficiency of coalmine methane utilization to provide sustainable development of geotechnologies in the context of transition to a clean resource-saving energy production. Its relevance results from the fact that the anthropogenic effect of coalmine methane emissions on the global climate change processes is 21 times higher than the impact of carbon dioxide. Suites of gassy coal seams and surrounding rocks should be classified as technogenic coal-gas deposits, while gas extracted from them should be treated as an alternative energy source. Existing practices and methods of controlling coalmine methane need to be improved, as the current “mine – longwall” concept does not fully take into account spatial and temporal specifics of production face advancement. Therefore, related issues are relevant for many areas of expertise, and especially so for green coal mining. The goal of this paper is to identify patterns that describe non-linear nature of methane release dynamics in the underground boreholes to provide sustainable development of geotechnologies due to quality improvement of the withdrawn methane-air mixture. For the first time in spatial-temporal studies (in the plane of CH 4 - S ) of methane concentration dynamics, according to the designed approach, the parameter of distance from the longwall ( L ) is introduced, which allows to create function space for the analyzed process (CH 4 of S-L ). Results of coalmine measurements are interpreted using the method of local polynomial regression (LOESS). The study is based on using non-linear variations of methane concentration in the underground boreholes and specific features of their implementation to perform vacuum pumping in the most productive areas of the undermined rock mass in order to maintain safe aerogas conditions of the extraction block during intensive mining of deep-lying gassy seams. Identification of patterns in the influence of situational geomechanical conditions of coal mining on the initiation of metastable gas-coal solution transformation and genesis of wave processes in the coal-rock mass allows to improve reliability of predicting methane release dynamics, as well as workflow manageability of mining operations. Presented results demonstrate that development of high-methane Donbass seams is associated with insufficient reliability of gas drainage system operation at distances over 40 m behind the longwall face. Obtained results confirm a working hypothesis about the presence of spatial migration of methane concentration waves in the underground gas drainage boreholes. It is necessary to continue research in the area of estimating deviation angles of “advance fracturing” zone boundaries from the face line direction. Practical significance of research results lies in the possibility to use them in the development of scientific foundation for 3D gas drainage of a man-made coal-methane reservoir, taking into account spatial and temporal advancement of the production face.
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Date submitted2020-06-15
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Date accepted2020-06-15
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Date published2020-06-30
Multi-terminal dc grid overall control with modular multilevel converters
This paper presents a control philosophy for multiterminal DC grids, which are embedded in the main AC grid. DC transmission lines maintain higher power flow at longer distances compared with AC lines. The voltage losses are also much lower. DC power transmission is good option for Russian north. Arctic seashore regions of Russia don't have well developed electrical infrastructure therefore power line lengths are significant there. Considering above it is possible to use DC grids for supply mining enterprises in Arctic regions (offshore drilling platforms for example). Three different control layers are presented in an hierarchical way: local, primary and secondary. This whole control strategy is verified in a scaled three-nodes DC grid. In one of these nodes, a modular multilevel converter (MMC) is implemented (five sub-modules per arm). A novel model-based optimization method to control AC and circulating currents is discussed. In the remaining nodes, three-level voltage source converters (VSC) are installed. For their local controllers, a new variant for classical PI controllers are used, which allow to adapt the values of the PI parameters with respect to the measured variables. Concerning the primary control, droop control technique has been chosen. Regarding secondary level, a new power flow technique is suggested. Unbalance conditions are also verified in order to show the robustness of the whole control strategy.
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Date submitted2020-06-11
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Date accepted2020-06-11
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Date published2020-06-30
Mathematical model of the liquefied methane phase transition in the cryogenic tank of a vehicle
In order to increase the efficiency of using vehicles (VEH) in mining and quarrying conditions, it is necessary to improve the components of gas equipment (cryogenic tank, gas nozzles, fuel supply cryogenic tubes, etc.) for supplying liquefied natural gas to the engine, as well as storage of liquid methane in a cryogenic tank with a long service life. For this, it is necessary to consider the process of heat and mass transfer of liquefied natural gas in a two-phase liquid-gas medium, taking into account the phase transition in the closed volume of the cryogenic tank under consideration. The article presents a model of unsteady heat and mass transfer of a two-phase liquefied methane medium in a developed two-tank cryogenic tank using a Cartesian coordinate system with fractional control volumes in space. The experimental data confirm the efficiency of using a cryogenic tank on the VEH platform, in which the run on liquefied methane compared to standard fuels is tripled, the shelf life of liquefied gas in the proposed cryogenic tank is 2-2.5 times longer than in the standard one.
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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 submitted2019-05-30
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Date accepted2019-09-04
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Date published2020-02-25
Prospects for industrial methane production in the mine n.a. V.M.Bazhanov using vertical surface wells
The estimated methane resources in the coal stratum of Donbass are 798.5 billion m 3 , including 119.5 billion m 3 in the Donetsk-Makeevsky area. Such significant potential implies that methane can be used not only for industrial production and energy purposes but also as a commodity for the chemical industry. However, in practice, commercial production of methane from coal seams, as is done in the fields of the USA, Canada, India, and China, is not carried out, and methane, obtained as a by-product, is utilized for ensuring the safety of the main technological processes for coal mining. The main reasons for this are the difficult mining and geological conditions of bedding, low thickness and permeability, which does not allow to separate methane production into an independent type of activity due to its low profitability, especially with the use of new technologies based on hydraulic fracturing of coal seams. The assessment of the possibility of industrial methane production in the mine n.a. V.M.Bazhanov in the Donetsk-Makeevsky area of Donbass, which reserves equal to 23.7 billion m 3 , showed that a significant part of the methane reserves is concentrated in coal seams and interlayers with a gas content of 18.5-20.7 m 3 /m 3 . Moreover, in the host rocks, methane is practically in a liberated state. This circumstance makes possible the commercial production of methane for its utilization from the unloaded rock mass by wells drilled from the surface, without the use of hydraulic fracturing technology. The paper discusses the technology of methane extraction by a degassing well drilled from the surface into a coal-bearing stratum unloaded from rock pressure in a mining field of the 4th eastern face of the m 3 seam of the mine n.a. V.M.Bazhanov and its subsequent use as the fuel of an electric generator. It is shown that over the entire period of operation of the pilot well, the volume of actually produced methane exceeded the design value by 23 %, and the cost of the gas produced amounted to 1535 rubles per 1000 m 3 , which is more than 3 times lower than the market price for natural gas for consumers in the Russian Federation. This made it possible to make a conclusion about the possibility of industrial extraction of mine methane using vertical surface wells for its subsequent utilization in power plants, which does not imply the usage of hydraulic fracturing technology.
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Date submitted2019-07-23
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Date accepted2019-09-19
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Date published2019-12-24
Estimation of abrasiveness impact on the parameters of rock-cutting equipment
Development of equipment, which provides access to underground mineral deposits and their extraction, requires the use of all the accumulated experience and advanced scientific research in the area of mechanical rock cutting. The most important issues of using mechanical rock cutting tools are their wearability and consumption, which have an impact on technical and economic indicators of project efficiency. The paper describes Russian and foreign practices of estimating tool wear resistance, expressions to determine critical cutting speed, methods to evaluate tool consumption. It is demonstrated that wearability of mechanical tools and associated effects are to a large extent defined by rock abrasiveness. It is highlighted that in Russia the index is calculated using Baron-Kuznetsov method, which is briefly described in the paper. In many countries with a highly-developed mining industry, rock abrasiveness is estimated with a Cerchar Abrasiveness Index (CAI), recommended by the International Society for Rock Mechanics. Its description is also presented in the paper.
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Date submitted2019-05-26
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Date accepted2019-07-23
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Date published2019-10-23
Ensuring Stability of Undermining Inclined Drainage Holes During Intensive Development of Multiple Gas-Bearing Coal Layers
At high rates of production face advance, requirements towards reliable operation of undermining drainage holes get raised. The issue of maintaining high intensity of gaseous seams development under naturally increasing gas content, mining depth and capacity of production equipment poses a problem. The greatest threat comes from the loss of hole stability in the bearing pressure affected zone (in front of the face) and in the intensive shift area of overhanging rock corbels (behind the face). Intensification of air leaks due to deformation of borehole channel leads to impoverishment of removed methane-air mixture and an increasing risk to disturb safe aerogas regime in the mining area. The paper describes a mechanism of how coal-face operations affect the state of underground holes and formation of overhanging rock corbels. A typification of basic kinds of borehole deformations is presented. Authors point out critical disadvantages of the most widely-used technological schemes of gaseous seams development under high load on the production face, which hinder normal operation of a gas drainage system. As a result of research, a dependency of shot hole number, as well as the distance between shot hole axes and the borehole, on the stress state of the borehole outline has been defined more precisely. Basing on that, a formula to calculate drilling parameters of the discharge hole system has been suggested. Implementation of these measures will allow to increase the efficiency of underground gas drainage and to maintain growing intensity of gaseous coal seam development.
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Date submitted2018-11-03
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Date accepted2019-01-21
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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.
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Date submitted2018-07-15
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Date accepted2018-09-07
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Date published2018-12-21
Justification of rational methods for provision of air to faces of operating coal mines of Vietnam during deepening of mines
- Authors:
- S. G. Gendler
- Tkhe Kha Nguen
Based on the analysis of the mining and geological conditions for developing coal deposits in Vietnam, the existing mining safety regulations, the application of methods for calculating the air supply of working and development faces using the methane factor and modern methods of mathematical modeling of the ventilation of mines threr was developed the procedure for analyzing the efficiency of air distribution management considering the proposed indicator - energy efficiency coefficient for ventilation systems, determined by the efficiency of air use and energy consumption. Relations have been obtained that determine the relationship between the aerodynamic resistance of negative regulators, the number of simultaneously developed working and development faces, the performance of main ventilation fans and the consumed electric power.