Bottomhole Area Research Articles

Применение новых технологий кислотной обработки пластов для восстановления продуктивности пласта

Oil recovery, measured by the oil recovery factor (ORF), is a key indicator of the efficiency of oil production. In Russia, the ORF decreased to 0.3 while in the United States this indicator increased to 0.4. About 90% of Russian oil is produced by large holdings, the structure of reserves is shifting towards hard-to-recover, which requires the use of new methods to increase oil recovery. Primary and secondary production allows only 20-50% of oil to be extracted, what makes the use of tertiary methods necessary. The development of horizontal wells with multistage hydraulic fracturing contributes to the development of new field sites, but requires careful preparation of wells to minimize risks and cost increases. Cleaning the bottomhole area using acidic formulations is often the only cost-effective way to restore the productivity of a horizontal well. The improved method of acid composition reduction using a guar gel with delayed “crosslinking”, which ensures uniform treatment of all productive zones of the formation is considered in article. The technology allows for continuous multi-stage acid treatment, temporarily blocking highly permeable areas and increasing the coverage of acidic effects on poorly drained areas. The calculation of the diverter volume considers the average efficiency of the liquid after mini-fracturing, adjusting the volume depending on the efficiency of the liquid at each port.

The bottomhole stress field analysis and the rate of penetration enhancement mechanism of a new type of central-grooved single-cone/multi-blade hybrid bit for deep well drilling

In this work, a high efficiency rock-breaking idea of forming an isolated rock column in the center of the deep bottomhole, that is, a convex-stepped bottomhole and a new type of central-grooved single-cone/multi-blade hybrid bit (CSMHB) are proposed due to the problems of poor drillability of rock, low efficiency of rock breaking at the center of bit and low rate of penetration (ROP) in the deep hard formation drilling. Based on the poroelasticity theory, a numerical simulation model of the stress field of convex-stepped bottomhole is established, and the dynamic changes of the stress field of convex-stepped bottomhole with time are analyzed. Meanwhile the rock strength failure of the convex-stepped bottomhole under the stress field is analyzed based on the three-dimensional Coulomb criterion, which preliminarily reveals the ROP enhancement mechanism of the CSMHB. The research shows that after the convex-stepped bottomhole is opened, the convex area of the bottomhole is subjected to tensile stress in the circumferential, radial and axial directions. In the bottomhole area broke by PDC cutting structure, the part near the central rock column is also subjected to tensile stress in the circumferential, radial and axial directions, while the other area is subjected to compressive stress. The action range of tensile stress and the damage range of the central rock column at the bottomhole expand with the increase of the indent length and diameter of the single-cone bit respectively. The average effective stress and damage function at the center of bottomhole decrease with the increase of the indent length and diameter of the single-cone bit respectively.

Soil stress state at the roadhead

Choosing the optimum tool shape for soil cutting is an urgent task for shaftsinking and tunnelling as well as in soil treatment for agriculture. The roadhead shape at the available load determines the stress-strain state of soil and development depth in the bottomhole area. By changing the roadhead contour, the penetration efficiency can be increased, while the feed force and tool wear can be reduced.Purpose: The aim of the work is to create the roadhead calculation algorithm and determine the stress-strain state of soil near it with a minimum number of boundary conditions, no discretization of the entire region into elements and approximation between nodes.Design/methodology: Test tasks for the proposed methodology for the roadhead and the bottom-hole area. The numerical model of the boundary conditions is based on the integral formulation of the Kelvin elasticity theory problem and uses the potential method as fictitious loads and discontinuous displacements, that makes it possible to minimize the problem with regard to symmetry, obtain a more compact system of equations and give accurate solutions at any domain point.Research findings: The assessment of the stress state of the roadhead of various shape and the bottom-hole zone of soil; loss of soil strength calculated according to the Mohr–Coulomb theory.Originality/value: The proposed method for solving the boundary value problem is recommended as an express method for estimating the roadhead stress state of an arbitrary shape in infinite regions with regard to the symmetry and implementation in Excel.

Теоретические аспекты принципов расчета струйных насосных станций и пути их совершенствования

The article presents analysis of the jet pump designs and methods of their improving, as well as technical approaches to their calculation, which is associated with a reasonable choice of an efficient variant, depending on the required accuracy of engineering calculations with optimal hardware support of pumping stations for solving specific oil and gas transportation tasks. According to the analysis results it has been inferred that one of the reasons for delay in application of jet pumping stations for lifting the fluid from the borehole space is the shortage of reliable surface-type pumping power stations, in particular, for driving the jet unit, as well as a compact set of equipment for purification and preliminary preparation of working fluid in the Russian Federation. For this reason, such units are mainly used for influencing the bottom-hole area, where the long-term permanent operation of jet pumping stations is not important, the mobile field pumping stations being possible as power plants.

Investigation of the influences of asphaltene deposition on oilfield development using reservoir simulation

This paper investigates the deposition of asphaltenes in the porous medium of the studied field in Russia and predicts production profiles based on uncertainty evaluation. This problem can be solved by dynamic modeling, during which production profiles are estimated in two scenarios: with and without the activation of the asphaltene option. Calculations are carried out for two development scenarios: field operation under natural depletion and water injection into the aquifer as a reservoir pressure maintenance system. A full-scale compositional reservoir simulation model of the Russian oilfield was created. Within a dynamic simulation, the asphaltene option was activated and the asphaltene behavior in oil and porous medium was tuned according to our own special laboratory experiments. The model was also matched to production historical data, and a pattern model was prepared using the full-scale simulation model. Technological and the asphaltene option parameters were used in sensitivity and an uncertainty evaluation. Furthermore, probable production profiles within a forecast period were estimated. The sensitivity analysis of the pattern model to input parameters of the asphaltene option allowed determining the following heavy-hitters on the objective function: the molar weight of dissolved asphaltenes as a function of pressure, the asphaltene dissociation rate, the asphaltene adsorption coefficient and the critical velocity of oil movement in the reservoir. Under the natural depletion scenario, our simulations show a significant decrease in reservoir pressure and the formation of drawdown cones leading to asphaltene deposition in the bottom-hole area of production wells, decreasing their productivity. Water injection generally allows us to significantly reduce the volume of asphaltene phase transitions and has a positive effect on cumulative oil production. Injecting water into aquifer can keep the formation pressure long above the pressure for asphaltene precipitation, preventing the asphaltene deposition resulted from interaction of oil and water, so this way has higher oil production.

Gas Condensate Wells: Challenges of Sampling, Testing and Production Optimization

The main problem of fluid sampling during well testing of reservoirs with near-critical fluids (gas condensate and volatile oil) is due to the fact that even a small pressure drawdown usually leads to the formation of a two-phase mixture in the bottom hole area, and it is almost impossible to take representative samples with downhole samplers or a formation tester. Sampling via test-separator and the current non-separation methods are also imperfect. An alternative method—MIKS (Multiphase IsoKinetic Sampling)—of gas condensate well testing was proposed, which is based on emulsifying a multiphase flow to particles of about 1–10 μm. Thereby MIKS would eliminate the problem of particle slippage in a homogeneous flow and enables high-quality sampling directly from the flowmeter line. The initial formation fluid is characterized by the maximum value of the condensate-gas ratio (CGR). Therefore, first, the well effluent would be adjusted to the mode with the maximum CGR using a choke manifold and a multiphase flow meter. Then the flow mixture is transferred to a by-pass line with an emulsifier to achieve an isokinetic flow. Thereafter, pressure samples can be taken into pressurized sampling bottles, in which thermodynamic conditions are preset according to the flow line. The efficiency of sampling and recombining procedures allows for conducting a study of reservoir samples in the field laboratory directly on the rig and obtaining a complete PVT report even before the completion of drilling and abandonment of the well. An additional economic effect is achieved by reducing the costs of transporting and samples storage. Well test equipment setup becomes much more compact and less weight; the costs of drilling time are reduced, which is viably important for well testing on the Arctic conditions. Another major problem in the development of gas condensate reservoirs is avoiding the condensate banking around producing wells. Optimization of condensate production can be achieved by maintaining the well operation mode at maximum CGR level by means of multiphase flowmeters. The formed condensate bank can be destroyed by a combination of methods—hydraulic fracturing, followed by cycling process—purging the formation with dried gas and/or injection of methanol into the formation. Methanol can be obtained from synthesis gas as a by-product in the utilization of associated gas also at the field. The specified set of measures will allow to revive the GC wells that are losing productivity, as well as to extend the period of high productivity of new wells.

Acid treatment of carbonate reservoir with a new dual action microemulsion: Selection of optimal application conditions

Complex emulsifying systems based on acid have been widely used in petroleum production. The advantage of these agents is that the rock dissolution rate is slow and the corrosion activity is reduced. This allows acid to penetrate deeper into the reservoir to increase the drainage area of the well while reducing the destructive impact on the surface of downhole equipment. This work is a continuation of the study of a unique acid emulsion for stimulation of carbonate reservoirs, which is already common in the fields in Russia. The new emulsion has a dual action, capable of forming wormholes in the bottomhole area and dissolving paraffin. The application of a single composition significantly reduces the cost of oil production. The main advantage of the technology is that it does not require workover crew when performing the treatment. The accumulated production experience in the implementation of acid treatments without the workover crew can evaluate whether this technology can be further popularized, showing a very broad prospect. We substantiated the selection criteria of candidate wells for stimulation of reservoir by double-action emulsion. The groups of effective and ineffective operations were determined by linear discriminant analysis. We can identify the factors that determine the final effectiveness of the measure through the analysis of field data. In order to ensure that the predicted value is highly consistent with the actual value, We developed a statistical model to estimate the potential increase in oil flow rate after acidizing. The model was piloted on two wells, which can better justify the design of measures and increase their final efficiency by 17–23%. The results confirm that acidizing technology of carbonate reservoir without workover crew is an excellent alternative to standard acidizing, characterized by reduced operating well time and improved profitability.

Assessment of stress–strain behavior of shaft lining in bottomhole area during sinking by real-time monitoring and computer modeling data

With an increase in the depth of shafting and subsequent risk growth, it becomes necessary to make a maximum accurate estimate of the actual stress–strain behavior of the shaft lining. Real-time monitoring and numerical simulation of the bottomhole zone of a shaft in the process of sinking is proposed as an effective approach to the solution of this problem. The results of an experimental check in three sites of shafts in similar engineering–geological conditions are presented. The real-time monitoring provided control of tensile forces in rock bolts before installation of the main support. Rock bolts 1.8 m long were used with full- and partiallength grouting in the hole. In each test area, 18 strain gauged rock bolts were installed with tensometric sensors glued along the rock bolts. As a result of the research, an array of data on 486 values of tensile forces is obtained. The graphs of the force variation along the rock bolts are plotted at different sizes of its grouting in the borehole. In all experimental sites, the minimum tensional forces in the rock bolts were observed when the bolts were fully grouted in the borehole. When the bolts were partially grouted, the forces were 1.4–1.7 times greater. At the second stage of the research, the 3D finite element models were built for the bottomhole area of vertical shafts in three experimental areas. The calculation took into account the deformation nonlinearity by using stepwise iterative procedures. The comparison of the experimental and numerical simulation results shows the similar qualitative distribution of forces along the rock bolts. According to the quantitative analysis, the maximum deviation of the force values never exceeds 19%. The higher calculated values can be explained by the fact that numerical modeling neglects structural yielding of the rock bolts. The obtained comparative data confirm the correctness of the numerical models. Based on that, the numerical models were then used to find the maximal stresses in the shaft lining, and the structure strength was estimated. As the main method for increasing the bearing capacity of the lining, it is recommended to use concrete of higher strength at depths greater than 700 m.

Применение компьютерного моделирования при выборе параметров работы пылеотсоса, встраиваемого в проходческие комбайны

An increase in the rate of mine workings excavation leads to the ingress of large amount of dust into the mine atmosphere. Ensuring the aerological safety of coal mines drifting faces according to the dust factor is an urgent task. To reduce the level of dustiness of a dead mine roadheading during its sinking, the scrubbers built into the roadheader are used. In this case, the joint operation of the ventilation system and the dust extraction system is not considered. This leads to the risk of occurrence of the stagnation zones or air recirculation near the bottom-hole area. At the intensive ventilation with a high air flow, the dust is removed, and the dust extraction system becomes useless. As the analysis showed, currently there are no methods that allow to take into account these two processes simultaneously. The idea of using computer modeling in the Ansys software package is proposed. To correctly solve the problems of optimizing the scrubber operation, a method is given for determining the grid parameters, as well as for setting the initial and boundary conditions. All the data obtained were verified at the coal mines of Russia. To achieve maximum efficiency, it is proposed to use the dust and aerodynamic criteria of the scrubber operation, which will allow to increase the mining operations safety. The dust criterion characterizes the efficiency of the dust extraction systems. The aerodynamic criterion allows to determine the joint operation mode in which there will be no recirculation and not ventilated zones. To take into account the large number of factors that affect the ventilation of a dead mine working and the operation of the dust extraction system, an artificial intelligence was added to computer modeling in system design. It is implemented in the ANSYS DesignXplorer module. In a given range of changing factors during the operation of artificial intelligence, by performing multiple calculations, such a combination of operating parameters of the two systems is obtained, at which the efficiency is maximum.

Technology for prediction of salt deposition in oil production

The formation of inorganic salts in the bottom-hole area leads to a deterioration of the reservoir filtration properties and a decrease in the productivity of oil wells. The conducted research shows that the decrease in rock permeability due to salt deposition during flooding mainly depends on the number of filtered pore volumes of the injected solution, the rate of injection, temperature, differences in pressure, initial permeability of the rock and the concentration of the solution. The development of an empirical formula for predicting salt deposits in the bottom-hole area and describing the dependence of rock permeability on these factors involves the use of reliable experimental and field data. The authors propose a method for determining the probability of precipitation of some inorganic salts in the well.

Intensification of the process of decomposition of oil-water emulsions stabilized with hydrochloric acid

The major goal of oil and gas companies working in the oilfields on the late stages of development is to maintain a high level of hydrocarbon production. Analysis of well intervention techniques (WITs) in the oilfields of the Samara Region shows that most often the bottomhole area is treated with reagents containing hydrochloric acid, which significantly effects the efficiency of well fluid preparation processes. The paper summarizes the results of studies of the impact of hydrochloric acid on the rheological and near-surface properties of water-in-oil emulsions (WOEs). It is shown that the presence of acid and/or products of its reaction with the oil increases the stability of the water-in-oil emulsion. To enhance the process of decomposition of the water-in-oil emulsion stabilized with hydrochloric acid, a reagent was developed based on the non-ionic surfactants, alkaline agent and solvent, providing a significant reduction of the viscosity of water-in-oil emulsions and improving the efficiency of their decomposition.

ОЦІНКА СТАНУ ПРИВИБІЙНОЇ ЗОНИ ПЛАСТА СВЕРДЛОВИН БОГОРОДЧАНСЬКОГО ПІДЗЕМНОГО СХОВИЩА ГАЗУ ЗА ДАНИМИ ГАЗОДИНАМІЧНИХ ДОСЛІДЖЕНЬ НА УСТАЛЕНИХ РЕЖИМАХ ФІЛЬТРАЦІЇ

A method for estimating the condition of the bottomhole zone of a gas well formation based on the results of interpretation of gas-dynamic well tests on the steady-state filtration conditions (on the example of horizon IV of the Bohorodchany UGS) is proposed. When planning activities to intensify hydrocarbon production, it is important to know the current and maximum capabilities of the formation at the point of its opening by the well. The indicators that characterize the relationship between current and potential opportunities include: skin effect, performance ratio, well perfection rate and the like. The values of these parameters are determined by the results of processing the pressure recovery curvesFor UGS wells, gas-dynamic studies on unsteady filtration regime with registration of bottomhole pressure change over time are not performed, so there are difficulties in determining the estimated parameters of the bottomhole zone and the effectiveness of geological and technical measures for each well.A method for determining the maximum productivity of gas wells on the example of horizon IV of the Bohorodchany UGS using the coefficient C, taking into account the productivity in the Rawlins equation, is proposed.According to the results of the comparative analysis of productivity coefficients with the specific volume of the formation, it is established that there is a fairly good correlation between these parameters. This confirmed the assumption that the productivity factor reflects the filtration characteristics of the formation.The condition of the bottomhole formation zone is estimated by the coefficient of productivity ratios (current to maximum). The decrease in the current productivity ratio below the maximum is due to a decrease in the permeability of the formation in the bottomhole area in the absence of a blockage at the bottom or a column of liquid.The results of this work allow us to identify facilities where it is advisable to apply methods of intensification of hydrocarbon production and evaluate the effectiveness of work without stopping wells to register the bottomhole pressure recovery curve. Key words: well, gas-dynamic well test, productivity ratio

Simulation study on cutting transport in a horizontal well with hydraulic pulsed jet technology

The hydraulic pulse jet is a high-efficiency drilling technology to improve the efficiency of bottom-hole cuttings removal by enhancing the down-hole flow of cuttings. In this paper, an Eulerian-Eulerian two-fluid model on the basis of the kinetic theory of granular flow is applied to simulate the flow behavior of cuttings and drilling fluid in a horizontal well with hydraulic pulsed jet technology. The influences of pulse jet velocity, amplitude, and frequency on hydrodynamic characteristics are analyzed. Increasing the pulse jet velocity can generate higher pressure and crossflow velocity in the bottom-hole area, quickly carry the cuttings out of the bottom-hole area, and form the cuttings bed near the outlet. The improvement of the amplitude of the pulsed jet can form a remarkable and deep jet penetration in the bottom-hole area, which has a positive effect on the cuttings migration at the bottom-hole area and destruction of the cuttings bed in the annulus. For a given average jet velocity in this paper, the optimal value of amplitude is a half of the average jet velocity. The pulse jet frequency has little effect on cuttings migration in the bottom-hole area, while a higher pulse jet frequency can effectively reduce the height of the cuttings bed in the annulus.

Electro Steam Thermal Complex Powered by Wind-Driven Generator for the Treatment of the Oil Formation’s Bottomhole Area

In this article authors propose application of the wind-driven power units as power source of bottomhole electric steam generator for the thermal high-viscosity oil reservoir stimulation. The structure of the electro steam thermal complex is proposed. An analysis of the wind energy potential in the areas where the largest high-viscosity oil deposits in Russia are located is carried out. As part of the complex under consideration, the type of the dependence of the bottomhole electric steam generator’s power on the formation depth has been established. The calculation of the required installed capacity of wind power plants for placement as part of the electro steam thermal complex at the largest high-viscosity oil deposits in Russia has been performed.

ДО ПИТАННЯ ПРОГНОЗУ ВИКИДОНЕБЕЗПЕЧНОСТІ ВУГІЛЬНИХ ПЛАСТІВ ЛЬВІВСЬКО-ВОЛИНСЬКОГО БАСЕЙНУ

Sudden coal and gas outbursts in coal mines are one of the most harmful and at the same time, dangerous gas-dynamic phenomena faced when coal producting. The sudden coal and gas outbursts is the evanescent destruction of the bottom-hole area in the coal bed, which develops from the bottom into the depth of a massif, and the crushed coal with gas is thrown to a long distance from the bottom into the mine, destroying everything in its way, creating the conditions for explosion and fire breaking-out. Sudden outbursts lead to significant material losses for the recovery from an accident and in some cases injuries and human losses. The problem of reliable prediction, prevention, and control of sudden coal and gas outbursts at coal mines remains extremely urgent, due to the constant increase in the depth of mining operations. The analysis of the experience of predicting and preventing the outburst hazard in coal beds of Donets and Lviv-Volyn coal basins is analyzed. At Donbas mines since 1906, there have been more than 7.5 thousand sudden outbursts. Although mining had now reached considerable depths (from 300 to 600 m), the emergence of coal and gas outbursts have not been recorded. The purpose of the research is to determine the depth of the possible emergence of sudden coal and gas outbursts in the LVB, with regard to the peculiarities of the geological structure of the coal-bearing strata in the Lviv-Volyn coal basin. The comparative possible depth estimation in the manifestation of the outburst hazard of the coal beds in the LVB is given. It is calculated according to the normative technique and performed according to the formulas obtained by the statistical analysis for the actual position of the minimum depth of coal and gas outbursts at the Donbas mines. The absence of sudden coal and gas outbursts at LVB mines on the coal beds, which are hazardous according to the prediction data, is performed according to the methods regulated by the normative documents and compiled by the experience of studying the outbursts in Donbas, is explained by the differences in the geological structure of the LVB, the main of which is the presence of thick mass of covering deposits and a significantly greater depth of the methane gas zone. The application of the empirical formulas prediction, which includes the methane gas zone depth index, allows us to account for these differences and it is much more reliable to determine the possible depths of sudden outbursts for LVB, which, all other things being equal, should be greater than in the Donbas. In particular, according to the performed calculations, the outburst hazard situation at the “Stepova” mine is predicted at depths of more than 700 m. As prediction indices for the calculations, values of methane gas zone depths of 450 m were adopted, and the minimum value of volatile-matter yield was 33.3%. This approach can be proposed for predicting the coal and gas outbursts hazard in other Lviv-Volyn basin mines. To determine the predicted depth of the possible emergence of sudden coal and gas outbursts, it is advisable to take into account the depth of the methane gas zone in the prediction calculations.

Study of water-oil mixture separation in bottomhole area via drift flow model

The existing methods to study the movement and pattern of flow in wells with electric submersible pump (ESP) within the ‘bottomhole-pump-wellhead’ system are rather experimental and empirical. Hence, the lack of universal techniques considering all possible operating modes of wells does not allow using the existing techniques to elaborate the measures improving the efficiency of well operation with ESP. Besides, these techniques cannot always be applied to define the optimum operating modes and to determine the need for various well intervention jobs as they are not quite perfect. The improvement of profitability of well operation is intimately connected with deliberate change of flow properties and structure considering various physical properties of fluids and ESP-based operating modes with further formation of fine emulsions. In this regard, the modern petroleum industry is facing an urgent task to study the processes in a bottomhole and a wellbore zones using a generalized mathematical model with further analysis of various perturbing actions on emulsion stability, assessment of its decrease and separation of the water phase within subsurface equipment.

TECHNICS AND STAGES OF WORK ORGANIZATION IN THE TRENCHLESS LAYING OF PIPELINES USING MICROTUNNELLING TECHNOLOGIES

The authors describe technics and stages of work organization in the construction of pipeline crossings through natural and artificial obstacles and construction of underground engineering communications of urban purpose using microtunnelling technologies. The essence of this technology is the penetration in the soil carried out by a tunnelling machine (microscope), the translational motion of which is provided by a powerful jack station, installed in the pit at a depth that corresponds to the depth of laying of the pipeline. The depth of laying of the pipeline should be in stable soils not less than two diameters, and in unstable soils – not less than three diameters from the surface of the earth to the upper creature pipeline. With the help of hydraulic jacks, the microchip is driven into the ground by a length corresponding to the length of the pipe sections used, after which the next pipe is installed on the jack station and the process is repeated. The types of microtunnel tunnelling complexes depending on the system of soil removal and bottomhole load are presented. The technological process of preparation and regeneration of the bentonite solution injected over the shell of the tunnelling machine and the forcing pipe sections to ensure the stability of the bottomhole and reduce the frictional forces between the pipeline and the soil and supplied into the bottomhole area for transportation of the developed soil from the bottomhole is considered. The technique of calculating the required punching force of pipe sections on a rectilinear section to be created by a jack station is proposed. The schemes of arrangement and principles of operation of the three modules (electronic laser system ELS, electronic laser system with hydrostatic water levelling ELS-HWL and gyro navigation system with a pointer to the north GNS-P) of the developed by Herrenknecht AG company for standardization of precise navigation in microtunnelling regardless of the length of the tunnel, its diameter and direction universal navigation system UNS are considered. The main advantages of microtunnelling are precisely in the direction of the plan and the profile (deviation from the design axis within 10-30 mm), fast (average rolling speed is 10-15 m / day) and with the minimum amount of subsidence of the daily surface (does not exceed 10 mm) construction of pipelines in combination with the possibility of laying both a rectilinear and complex curvilinear trajectory, at large depths (up to 100 m) and at considerable distances (up to 1000 m), in the whole range of engineering-technological and hydrogeological conditions.

The Analysis of the Stress-Strain State of the System “Equipment Complex - Support - Rock Mass” in the Bottomhole Area of the Shaft

The development of new deposits enterprises requires the construction of deep and super deep vertical shafts. The duration of their construction reaches 8 - 10 years with multi-billion capital investments. To reduce the payback period of these costs, it is necessary to develop and implement effective solutions to increase the speed of sinking operations through the wide introduction of brand-new mechanized equipment complexes. In response to the sinking in the bottomhole area of the shaft a complex, the following geotechnological system is being formed: "tunneling system - support - rock mass", the regularities of which require further study. For these purposes, an analytical method for calculating the shaft support can be used in the context of consideration of a planar contact problem at various phases of the system operation. The mutual coordination of individual phases in accordance with the classical concepts of the underground structures mechanics is possible with the help of a correction factor to the magnitude of horizontal stresses in the rock mass. In this paper we developed the algorithm which determines this coefficient, taking into account the influence of the main technological factors: the jack system pressure of the complex and the speed of sinking.

Analytical analysis of the stress-strain state of the system “mechanized equipment complex - support – rock mass” in the bottomhole area of the shaft

The development of new deposits requires the construction of deep and super deep vertical shafts. The duration of their construction reaches 8 - 10 years with multi-billion capital investments. To reduce the payback period of these costs, it is necessary to develop and implement effective solutions to increase the speed of sinking operations through the wide introduction of brand-new mechanized equipment complexes. In response to the sinking in the bottomhole area of the shaft, the following geotechnical system is being formed: “tunnelling system - support - rock mass”, the regularities of which require further study. For these purposes, an analytical method for calculating the shaft support can be used in the context of consideration of a planar contact problem at various phases of the system operation. The mutual coordination of individual phases in accordance with the classical concepts of the underground structures mechanics is possible using a correction factor to the magnitude of horizontal stresses in the rock mass. In this paper, we developed the algorithm which determines this coefficient, taking into account the influence of the main technological factors: the pressure of the jack system of the complex and the speed of sinking.

Assessment of Deformations of Earth‘s Surface at Mine Construction on Sub-Soils

The paper provides technical and technological solutions aimed at construction and support erection for up to 50 m deep underground facilities of a relatively moderate extend up to 100 m in unstable mantle rocks, which are carried out by small splitting according to the combined pattern without any specific methods. Thus, reduction of cost and construction period is achievable, which is of a significant importance for resource saving.The authors describe results of studies focused on development of methods to provide support of underground facilities with mass concrete under conditions of semi-stable rocks and application of the combined pattern. Reduction of the splitting value to 0.3 m results in decrease of plastic deformation area by 1.7 times and maximum displacements of adjacent strata contour with 10–15 kPa adhesion factor by 1.5 times.When an optimum volume of modifying agents are added to the composition, concrete strength is improved by 1.7 times after 12 hour curing and by a factor of 7 after 24 hour curing in comparison with that without any additives. The finite element theory was applied at simulating the stress-strain behavior of the non-supported bottom-hole area of rock solid mass and hardening concrete of the monolithic lining erected after wall advance. In such a manner, distribution of maximum strains in the support has been revealed with due regard to concrete hardening.The authors provide a regression model for calculation of an optimal value for splitting and selection of structure and support parameters. Areas of maximum displacements in the solid mass and their influence on the Earth surface deformation have been determined.