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Date submitted2024-03-20
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Date accepted2024-11-07
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Date published2025-04-25
Analysis of the stress state of rocks transformation near a horizontal well during acid treatment based on numerical simulation
The article presents an overview of the assessment and modelling of the stress state of rocks in the near-wellbore zone of horizontal wells during acid stimulation of the formation for improving the efficiency of oil and gas field development. A numerical finite element model of near-wellbore zone of the reservoir drilled by a horizontal section was compiled using one of oil fields in the Perm Territory as an example. The distribution of physical and mechanical properties of the terrigenous reservoir near the well was determined considering transformation under the action of mud acid for different time periods of its injection. Multivariate numerical simulation was performed and the distribution of horizontal and vertical stresses in near-wellbore zone was determined with regard for different values of pressure drawdown and changes in stress-strain properties depending on the area of mud acid infiltration. It was found that a change in elastic modulus and Poisson's ratio under the influence of acid led to a decrease in stresses in near-wellbore zone. Analysis of the stress distribution field based on the Coulomb – Mohr criterion showed that the minimum safety factor of rock even after the effect of mud acid was 1.5; thus, under the considered conditions of horizontal well modelling, the reservoir rock remained stable, and no zones of rock destruction appeared.
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Date submitted2024-03-29
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Date accepted2024-06-03
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Date published2024-07-04
Potential use of water treatment sludge for the reclamation of small-capacity sludge collectors
- Authors:
- Olga M. Guman
- Irina A. Antonova
In small settlements, collectors for the sludge produced during water treatment processes are small-sized and located in the vicinity of drinking water storage reservoirs or in coastal areas. Sludge removal is not economical. Besides, the relief depressions formed after sludge disposal are required to be reclaimed. In ore mining regions, where the main settlements of the Urals are located, sludge produced in water treatment has high contents of heavy metals typical of ore mining provinces. Consequently, places of sludge accumulation are potential sources of water pollution. The article discusses the possibility to mix sludge with slaked lime and local overburden with the help of special equipment. So far water treatment sludge in the region has been used to reclaim the surface of solid waste landfills by creating anaerobic conditions for waste decomposition. When placed inside the embankment dams as an independent object, sludge needs to be improved for the increase of its bearing capacity and the ability to bind heavy metals. The article aims at the substantiation of the composition and properties of the reclamation material made of the water treatment sludge mixed with local overburden and slaked lime (technosoil). For this reason the paper describes the composition of the sludge in a sludge collector, the composition and properties of the overburden rocks as a component of the mixtures with water treatment sludge, the composition and properties of the mixtures of water treatment sludge with overburden rocks and Ca(OH)2 as a component dewatering sludge and neutralizing toxicants. Furthermore, the research work provides the technology created for the optimal processing of the water treatment sludge in the process of the reclamation of a sludge collector. The research results and the experience obtained in reclamation of disturbed lands in the region have confirmed the possible use of technosoil for the reclamation of small-capacity sludge collectors. The analysis of the chemical composition and physical and mechanical properties of the mixtures under study has shown that the most economical and environmentally sound reclamation material is a mixture of water treatment sludge, loose overburden dump soils and Ca(OH)2 in a ratio of 60 : 30 : 10 %.
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Date submitted2024-03-07
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Date accepted2024-06-14
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Date published2024-07-04
Anomaly detection in wastewater treatment process for cyber resilience risks evaluation
Timely detection and prevention of violations in the technological process of wastewater treatment caused by threats of different nature is a highly relevant research problem. Modern systems are equipped with a large number of technological sensors. Data from these sensors can be used to detect anomalies in the technological process. Their timely detection, prediction and processing ensures the continuity and fault tolerance of the technological process. The aim of the research is to improve the accuracy of detection of such anomalies. We propose a methodology for the identification and subsequent assessment of cyber resilience risks of the wastewater treatment process, which includes the distinctive procedure of training dataset generation and the anomaly detection based on deep learning methods. The availability of training datasets is a necessary condition for the efficient application of the proposed technology. A distinctive feature of the anomaly detection approach is a new method of processing input sensor data, which allows the use of computationally efficient analytical models with high accuracy of anomaly detection, and outperforms the efficiency of previously published methods.
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Date submitted2023-07-25
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Date accepted2024-05-02
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Date published2024-08-26
Finite element analysis of slope failure in Ouenza open-pit iron mine, NE Algeria: causes and lessons for stability control
Slope failures in mining engineering pose significant risks to slope stability control, necessitating a thorough investigation into their root causes. This paper focuses on a back analysis of a slope failure in the Zerga section of the Ouenza – Algeria open-pit iron mine. The primary objectives are to identify the causes of slope failure, propose preventive measures, and suggest techniques to enhance stability, thereby providing crucial insights for monitoring slope stability during mining operations. The study commenced with a reconstruction of the slopes in the affected zones, followed by a numerical analysis utilizing the Shear strength reduction method within the Finite element method (SSR-FE). This approach enables the examination of slope stability under both static and dynamic loads. The dynamic load assessment incorporated an evaluation of the vibrations induced by the blasting process during excavation, introducing seismic loading into the finite element analysis. The findings reveal that the primary triggering factor for the landslide was the vibration generated by the blasting process. Furthermore, the slope stability was found to be critically compromised under static loads, highlighting a failure to adhere to exploitation operation norms. The challenging geology, particularly the presence of marl layers where maximum shear strain occurs, contributed to the formation of the landslide surface. The study not only identifies the causes of slope failure but also provides valuable lessons for effective slope stability management in mining operations.
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Date submitted2021-02-09
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Date accepted2023-09-20
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Date published2024-02-29
Analysis of experience in the use of preformed particle polymer gels in the development of high-water-cut production facilities in low-temperature oil reservoirs
- Authors:
- Sergei V. Galkin
- Yuliya A. Rozhkova
Foreign practice of oil production in high-water-cut conditions suggests using the technology of injection of preformed particle gel (PPG) suspension into injection wells. After swelling, the polymer particles become elastic and are able to penetrate through highly permeable watered intervals into the remote reservoir zone, forming a polymer “plug”. Thus far, the domestic experience of application of this technology boiled down to testing foreign compounds. We have looked into the possibilities of PPG technology application in geological and technological conditions of high-water-cut fields of Perm Krai. The paper proposes PPG reagents effective in low-temperature reservoirs (20-35 °С) and at relatively high salinity of formation water (more than 200 g/l). The world experience of PPG technology application was analyzed to identify the principal scheme of reagent injection, to establish variants of sequence of injection of PPG particles of different sizes, as well as the possibility of regulating the morphological characteristics of polymer gel particles during synthesis depending on the porosity and permeability of the reservoir. A prerequisite for the technology is the ability to remove PPG particles after treatment from the bottom-hole zone of the formation; for this purpose, tests were carried out on a breaker compound based on sodium persulfate with synergizing additives. PPG technology is effective in reservoirs with high permeability heterogeneity. Two types of high-water-cut production facilities potentially promising for PPG realization have been identified for oil fields of Perm Krai. The first type includes carbonate Tournaisian-Famennian reservoirs with pronounced macrofracturing, in which the PPGs are used for colmatation of flushed large fractures. The second type is terrigenous Visean deposits with increased oil viscosity from 5 to 100 mPa∙s and high permeability of reservoirs (> 0.5 μm2). For both types of reservoirs, areas have been selected that are promising for the implementation of PPG technology.
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Date submitted2023-04-11
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Date accepted2023-09-20
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Date published2023-10-27
Current state of above-ground and underground structures of the Alexander Column: an integral basis for its stability
- Authors:
- Regina E. Dashko
- Angelina G. Karpenko
The Alexander Column as a compositional center of the architectural ensemble of Palace Square in Saint Petersburg, Russia, has always been a matter of concern for both the public and specialists due to progressive deterioration of its granite shaft caused by crack formation. The article examines previous studies related to the inspection and restoration of the column's shaft and other parts above ground level, as well as reasons for crack initiation and propagation in the column. An analysis was performed on the anomalies in the Fennoscandian Shield and the structural-tectonic conditions at the Montferrand quarry site, revealing the presence of faults and circular features within the studied area. The research considers N.Hast's measurements of excess tectonic stresses in anomaly zones (southeastern Finland), which acted horizontally and resulted in the development of tensile cracks within the granite massif and later in the column’s shaft after its installation. The most dangerous type of deformation for the Alexander Column is its tilt in the northeast direction, recorded in 1937 and 2000. The article analyzes the construction features of the column's foundations and additional underground elements, as well as soil and groundwater characteristics based on archival data. The contamination history of the underground space is taken into account, and an analogy-based method is used to assess the engineering-geological and hydrogeological conditions of the underground load-bearing structures within the placement zone of the Alexander Column and the New Hermitage buildings. The results of visual observations on the nature of deterioration and deformation of the pavement around the monument, as well as its pedestal, indicating the development of uneven settlement of the foundation, are presented. The article concludes with general recommendations for organizing and implementing comprehensive monitoring to forecast the deformation dynamics of the Alexander Column.
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Date submitted2022-08-10
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Date accepted2023-02-28
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Date published2024-02-29
Selection of the required number of circulating subs in a special assembly and investigation of their performance during drilling of radial branching channels by sectional positive displacement motors
The task of sludge removal to the surface during construction of directional and horizontal wells and strongly curved radial channels is relevant. For stable operation of technical system “Perfobore”, it is proposed to use a circulating sub that ensures efficient cleaning of channel wellbore from the drilled rock. Two schemes of technical system “Perfobore” are considered, consisting of two seven-meter coiled tubing, a positive displacement motor, a bit and one circulating sub in the first scheme and two subs in the second scheme. For each of the schemes CFD modeling was implemented to determine values of pressure and speed. It was found out that the use of two circulating subs in the assembly is more efficient. In order to confirm the numerical experiment, bench tests were carried out. It was determined that the designed circulating sub can eject up to 25 % of pumped drilling fluid. The bench tests of full-size technical system “Perfobore” for drilling 14-meter channels with two circulating subs showed that the axial load on positive displacement motor produced by hydraulic loader was 3000 N and pressure drop depending on flow rate was 1.5-2.0 MPa. This allows the motor to operate at maximum power.
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Date submitted2022-09-15
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Date accepted2022-11-17
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Date published2022-12-29
Comprehensive assessment of hydraulic fracturing technology efficiency for well construction during hydrocarbon production
The oil and gas industry has been an integral and fundamental sector of the Russian economy for the past few years. The main problems of this industry have traditionally been the deteriorating structure of oil reserves; depreciation of main assets; slowdown and decline in oil production. Recently these have been complicated by a number of new negative trends related to underinvestment, limited financial resources, deteriorating access to new equipment and technologies. The task of the research is to make a comprehensive assessment of hydraulic fracturing technology during well construction and to increase the recovery and intensification of hydrocarbons production. In this research, modeling techniques were used to assess the productivity of each fracture. Geophysical methods (seismic survey) were used to determine the geomechanical properties of the formation. Comprehensive assessment of hydraulic fracturing technology during well construction was carried out, which allowed to increase vertical permeability and unite disparate parts of the reservoir in practice, and to determine the development efficiency of the hydrocarbon field.
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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 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 submitted2021-12-19
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Date accepted2022-05-13
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Date published2022-07-13
Development of a pump-ejector system for SWAG injection into reservoir using associated petroleum gas from the annulus space of production wells
Implementation of SWAG technology by means of water-gas mixtures is a promising method of enhanced oil recovery. The use of associated petroleum gas as a gas component in the water-gas mixture allows to significantly reduce the amount of irrationally consumed gas and carbon footprint. Relevant task is to choose a simple, reliable and convenient equipment that can operate under rapidly changing operating conditions. Such equipment are pump-ejector systems. In order to create water-gas mixture it is proposed to use associated gas from the annulus space. This solution will reduce the pressure in the annulus space of the production well, prevent supply disruption and failure of well equipment. The paper presents a principal technological scheme of the pump-ejector system, taking into account the withdrawal of gas from the annulus space of several production wells. The layout of the proposed system enables more efficient implementation of the proposed technology, which expands the area of its application. Experimental investigations of pressure and energy characteristics of the ejector have been carried out. Analysis of the obtained data showed that it was possible to increase the value of maximum efficiency. The possibility of adapting the system in a wide range of changes in operating parameters has been established. Recommendations on selection of a booster pump depending on the values of working pressure and gas content are given.
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Date submitted2021-07-05
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Date accepted2022-01-24
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Date published2022-04-29
Ensuring the excavation workings stability when developing excavation sites of flat-lying coal seams by three workings
- Authors:
- Oleg I. Kazanin
- Andrei A. Ilinets
On the basis of analysis of mining plans and field studies at mines of JSC SUEK-Kuzbass, it is shown that in conditions of increasing the size of excavation columns during the development of flat-lying coal seams the stress-strain state of the rock mass along the workings length changes significantly. The necessity of predicting the stress-strain state at the design stage of the workings timbering standards, as well as subsequent monitoring of the workings roof state and its changes in the mining operations using video endoscopes, is noted. The results of numerical studies of the stress-strain state of the rock mass during the development of excavation sites by three workings for various combinations of width of the pillars between the workings for mining-geological and mining-technical conditions of the “Taldinskaya-Zapadnaya-2” mine are provided. The stresses in the vicinity of the three workings are compared with the values obtained during the development of the excavation sites by double drift. A set of recommendations on the choice of the location of the workings, the width of pillars, timbering standards that ensure the stable condition of the workings throughout the entire service life at the minimal losses of coal in the pillars is presented.
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Date submitted2021-03-11
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Date accepted2021-04-12
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Date published2022-04-29
Operation mode selection algorithm development of a wind-diesel power plant supply complex
- Authors:
- Yaroslav E. Shklyarskiy
- Daria E. Batueva
The power supply system is affected by external disturbances, so it should be stable and operate normally in compliance with power quality standards. The power supply system goes into abnormal modes operation when, after a short-term failure or disturbance, it does not restore normal mode. The electrical complex, which includes a wind power plant, as well as a battery and a diesel generator connected in parallel, is able to provide reliable power supply to consumers which meets the power quality indicators. The article develops an algorithm that is implemented by an automatic control system to select the operating mode depending on climatic factors (wind) and the forecast of energy consumption for the day ahead. Forecast data is selected based on the choice of the methods, which will have the smallest forecast error. It is concluded that if the energy consumption forecast data is added to the automatic control system, then it will be possible to increase the efficiency of the power supply complex. In the developed algorithm the verification of normal and abnormal modes of operation is considered based on the stability theory. The criteria for assessing the normal mode of operation are identified, as well as the indicators of the object’s load schedules for assessing the load of power supply sources and the quality standards for power supply to consumers for ranking the load by priority under critical operating conditions and restoring normal operation are considered.
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Date submitted2021-01-19
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Date accepted2021-07-27
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Date published2021-10-21
Geological and structural characteristics of deep-level rock mass of the Udachnaya pipe deposit
- Authors:
- Evgenii V. Serebryakov
- Andrei S. Gladkov
For hard rock massifs, structural disturbance is a key indicator of mining structure stability. The presence of intersecting structural elements in the massif reduces rock strength and leads to formation of potential collapse structures. In addition to that, disjunctive deformations that penetrate rock strata serve as channels for fluid migration and connect aquifers into a single system. It was established that the largest of them –faults of east-northeastern, northeastern and northwestern directions – form the kimberlite-bearing junction of the Udachnaya pipe. These faults represent zones of increased fracturing, brecciation and tectonic foliation, distinguished from adjacent areas by increased destruction of the rock mass. Specifics of tectonic fracture distribution within structural and lithological domains are determined by the presence of multidirectional prevailing systems of tectonic fracturing, as well as by differences in their quantitative characteristics. With some exceptions, the main systems form a diagonal network of fractures (northeastern – northwestern orientation), which is typical for larger structural forms – faults. Despite the differences in dip orientation of the systems, most of them correspond to identified directions, which is typical for both kimberlites and sedimentary strata. Overall disturbance of the massif, expressed in terms of elementary block volume, reaches its peak in the western ore body. For such type of deposits, friction properties of fracture structures have average values. Consideration of geological and structural data in the design and development of new levels of the deposit will allow to maintain the necessary balance between efficiency and safety of performed operations.
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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 submitted2019-05-14
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Date accepted2019-07-05
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Date published2020-04-24
Development of spacer fluids and cement slurries compositions for lining of wells at high temperatures
Article is devoted to creation of new compositions of process solutions for lining of directional wells at high temperatures. Developed compositions provide high durability characteristics of cement stone. It is shown that with an increase in packing density of cementing slurry components durability characteristics increase and porosity and permeability of cement stone decrease, whereas an increase in temperature and pressure leads to a significant increase in compressive and bending durability, which is associated with presence of quartz in them. It has been established that introduction of special structure-forming additives to the composition of developed cementing solutions allows formation of sedimentation-resistant cement systems that can provide an increase in durability characteristics of cement stone and, in general, quality lining of directional wells. Study of rheological properties of developed cementing compositions showed that the systems have high yield strength at increased temperatures and pressures. Developed compositions of water-based spacer fluids increase the cleansing degree for both casing and rocks surfaces from mud and clay cake residues, which improves the cementing quality of oil and gas wells. Mechanism for increasing the washing ability of spacer fluids and durability characteristics of cement stone, depending on composition and properties of their constituent components, is disclosed.
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Date submitted2020-01-09
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Date accepted2020-01-17
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Date published2020-02-25
Methodology for Calculating the Stability of the Polymer Operating String in Permafrost
- Authors:
- V. A. Stetukha
- I. I. Zheleznyak
The goal of this paper is to develop a methodology for calculating the stability of an annular cross-section string casing made of polymer material used for the development of mineral deposits by underground leaching in permafrost formations. The aim was to determine the geometric parameters of the casing and to ensure its operational reliability. The relevance of the research is associated with the peculiarities of external influences on the string, for example, a geotechnological well operating in permafrost formation under conditions of additional exposure to ice pressure during freezing of water in the borehole annulus. This effect is usually accompanied by deformation of the casing due to ice pressure, which can lead to string collapse, abnormal operation and the risk of contamination of the geological environment. The proposed calculation method for a polymer casing is based on simulation of objects using the finite element method. We used the spatial finite elements to model the interaction of key elements of the geotechnological natural-technogenic complex: a polymer casing, ice in the annulus space and homogeneous or heterogeneous rock masses adjacent to the well. The results of the study are presented in the form of tables and patterns of displacements, which reflect stresses and strains in the elements of the calculation scheme. The analysis of the obtained results confirms the possibility of using polymer casings of different technological purposes in various conditions of permafrost formation, including extreme ones. The results of the redistribution of pressure created by ice during the freezing of water in the borehole annulus to the rock mass and the string are evaluated. Interdependent deformations of the rock mass and operating string during freezing of water in the borehole annulus are determined. The necessity of considering the properties of the rock mass in determining the pressure on the string is established. The conditions for the collapse of the string with a different combination of its parameters are revealed.
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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 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 submitted2019-01-11
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Date accepted2019-03-17
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Date published2019-06-25
Improving methods of frozen wall state prediction for mine shafts under construction using distributed temperature measurements in test wells
- Authors:
- L. Yu. Levin
- M. A. Semin
- O. S. Parshakov
Development of mineral deposits under complex geological and hydrogeological conditions is often associated with the need to utilize specific approaches to mine shaft construction. The most reliable and universally applicable method of shaft sinking is artificial rock freezing – creation of a frozen wall around the designed mine shaft. Protected by this artificial construction, further mining operations take place. Notably, mining operations are permitted only after a closed-loop frozen section of specified thickness is formed. Beside that, on-line monitoring over the state of frozen rock mass must be organized. The practice of mine construction under complex hydrogeological conditions by means of artificial freezing demonstrates that modern technologies of point-by-point and distributed temperature measurements in test wells do not detect actual frozen wall parameters. Neither do current theoretical models and calculation methods of rock mass thermal behavior under artificial freezing provide an adequate forecast of frozen wall characteristics, if the input data has poor accuracy. The study proposes a monitoring system, which combines test measurements and theoretical calculations of frozen wall parameters. This approach allows to compare experimentally obtained and theoretically calculated rock mass temperatures in test wells and to assess the difference. Basing on this temperature difference, parameters of the mathematical model get adjusted by stating an inverse Stefan problem, its regularization and subsequent numerical solution.
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Date submitted2019-01-01
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Date accepted2019-03-03
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Date published2019-06-25
Strategic approach to assessing economic sustainability objects of mineral resources sector of Russia
The article gives a new definition of economic systems (ES) stability with its distinct strategic content. The main approaches to assessment of sustainability, based on the use of strategic cards, including Balanced Scorecard (BSC), are considered. Synchronous management of effectiveness, risks and chances of the ES exhausts the agenda of managing economic sustainability of ES when it operates in the face of a wide range of challenges. BSC in mineral resources sector (MRS) can be built during the aggregation of BSC by industry and individual enterprises. The use of 4 ´ 6 matrix formalism is proposed as the main tool for modeling economic sustainability of the ES.
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Date submitted2018-11-09
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Date accepted2019-01-22
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Date published2019-04-23
Determining the stability of the borehole walls at drilling intervals of loosely coupled rocks considering zenith angle
- Authors:
- P. A. Blinov
During development of drilling projects, a whole array of data is needed considering the properties of rocks and the conditions of their bedding. Accounting for geomechanical processes occurring in the near-wellbore zone allows avoiding many complications associated with the violation of the wellbore walls stability at all stages of its construction and operation. Technological and technical factors such as vibration and rotation of the drilling string, formation of launders during the descent and ascent of the assembly, pressure pulsation during the start and stop of pumps, hydrostatic and hydrodynamic pressure of the drilling fluid, its composition and properties, have a great influence on the stress-strain state of the medium opened by the well. The washing fluid circulating in the well should provide backpressure to the reservoir, not interact with the rocks chemically, colmatage channels in porous and fractured rocks, preventing penetration of the mud into the medium, by creating an impermeable barrier at drilling clay seams that are prone to swelling, cracking, etc. The article discusses the method for determining the stability of the directed well walls, taking into account the penetration of drilling mud into the pores and fractures of rocks. The technique will allow adjusting the zenith angle of the well during the workout of an unstable interval at the design stage, or selecting a drilling fluid composition to ensure fail-safe drilling.
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Date submitted2018-11-18
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Date accepted2019-01-17
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Date published2019-04-23
Calculation of elastoviscoplastic displacement of well walls in transversal and isotropic rocks
- Authors:
- A. G. Gubaidullin
- A. I. Moguchev
The relevance of the work is justified by the need to improve the technical and economic indicators of well construction based on forecasting and preventing drilling tools sticking due to the narrowing of an open well bore in the intervals of transversely isotropic rocks. A mathematical model of elastic-viscous-plastic displacement of the walls of inclined and horizontal wells has been developed during the narrowing of the open borehole due to rock creep in the intervals of transversely isotropic rocks. In the program developed based on this mathematical model, the calculation of the elastic-viscous-plastic displacement of the walls of an obliquely directed and horizontal well in the reservoir of argillite from the Western Siberia deposit was carried out. As a result of the calculation, it was established that after opening the rock with bits, the cross-section of the open borehole due to the rock creep eventually takes the form of an ellipse, the small axis of which is in the plane of the upper wall of the well and decreases with time.
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Date submitted2018-01-15
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Date accepted2018-03-24
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Date published2018-06-22
Designing of well trajectory for efficient drilling by rotary controlled systems
- Authors:
- M. V. Dvoinikov
The main directions of increasing the efficiency of drilling wells by improving methods for designing profiles of directional and horizontal wells are identified. The feasibility and necessity of using at drilling with rotary controlled systems the trajectories of directed wells' profiles with continuous curving, that do not contain conjugated sections, on the basis of plane transcendental curves are theoretically substantiated and experimentally confirmed. An algorithm and software are developed that allow optimal selection of a profile or a trajectory section, taking into account minimization of twisting, bending, compressive and tensile stresses that ensure the efficiency of technical and technological parameters of well drilling.