Volodymyr Biletskyi

This study investigates the post-hydraulic fracturing evolution of the fracture-pore space in a heterogeneous layered reservoir under the influence of the Rehbinder effect. Engineering models of dual porosity, fractal geometry of fracture networks, physicochemical mechanics of the Rehbinder effect, and empirical data on the influence of surface active substances (SASs) on permeability after hydraulic fracturing (HF) have so far developed separately. Therefore, there was a lack of a single model that would connect the geometry of the branched fracture network with the porosity and permeability of the reservoir. In this work, those four directions have been synthesized into one model: the initiation of the primary crack at grain contacts is described by the Griffiths-Irwin criterion, and a secondary fractal ("herringbone") branching model for granular and thin-layered rocks has been built. Through the adsorption opening of the pore space, this geometry is related to the kinetics of subcritical crack growth and surfactant adsorption and, therefore, to the effective porosity φ(t) and anisotropic permeability k∥(t) / k⊥(t). The model was tested on a three-component material “sand-siltstone-shell rock”: by a laboratory triaxial experiment and a stochastic (Monte Carlo, 300 realizations) digital experiment of the same composition with neural network smoothing. As a result, it was found that with increasing surfactant concentration, the critical crack initiation pressure decreases, and the maximum opening and front movement speed increase, reaching saturation when the surfactant concentration approaches 0.30%. At the same time, the permeability increases by 112–224% in 48 h, while the porosity changes by only 0.04–0.20 percentage points. The effective volume function Veff(t) and the criterion for reasonable duration of the technological pause have been proposed – the moment of saturation Veff(t) when its increment dVeff/dt falls below the predefined technological threshold. This makes it possible to reasonably determine the moment of completion of post-hydraulic fracturing space evolution and the start of production without additional costs

Методика. Експериментальний технологічний ланцюжок напівпромислової установки “Механобрчормета” включав бункер вихідної руди, пластинчастий живильник, похилий стрічковий конвеєр, проміжний бункер, стрічковий живильник, завантажувальну течку та власне відцентрову дробарку ЦД-50.Дробленню піддавали криворізькі залізисті кварцити вихідної крупності 100–0 мм з вмістом класу крупності +100 мм 21,1 %. Швидкість обертання розгінного ротора складала проєктну величину n = 200–1200 хв¯¹ (відповідно швидкість вильоту частинок з ротора – від 23,0 до 180 м/с).Результати. Встановлено залежність технологічних показників дроблення й енергетичних параметрів роботи відцентрової дробарки ЦД-50 на залізистих кварцитах Криворізького залізорудного басейну у напівпромислових (полігонних) умовах від частоти обертання розгінного ротора.Наукова новизна. Отримано залежності ступеня дроблення, середньозваженої крупності продуктів дроблення, масової частки у дробленому продукті класів крупності –10,0; –5,0; –1,0 мм, а також споживаної дробаркою потужності на холостому ходу при швидкості вильоту дробленого зерна 180 м/с і при максимальній продуктивності дробарки від частоти обертання розгінного ротора.Практична значущість. Встановлено, що зі збільшенням частоти обертання розгінного ротора зростає вихід класів –5,0; –10 мм, ступінь дроблення матеріалу та зменшується середньозважена крупність дробленого продукту. Середньозважена крупність при цьому скорочується від 13,0 до 2,3 мм, а ступінь дроблення зростає від 4 до 24,0; причому простежується тенденція до зниження кратності дроблення при підвищенні продуктивності. Як випливає з аналізу результатів випробувань, максимальний приріст класу –5,0 мм сягнув 85,6 %, класу –10,0 мм становив 85,8 % при максимальній частоті обертання ротора 1200 хв¯¹ та продуктивності 30,0 т/год.Також встановлено, що споживана приводом потужність зі збільшенням частоти обертання ротора зростає від 26 до 185 кВт при навантаженні 30 т/год, а на холостому ходу – від 10,0 до 40,0 кВт. Питома витрата електроенергії без урахування ступеня дроблення змінюється від 0,8 до 6,0 кВт∙год/т вихідного живлення.Одержані дані практично уможливлюють вибір раціонального швидкісного режиму роботи відцентрово-ударної дробарки для одержання запланованих технологічних показників дроблення залізистих кварцитів Криворізького залізорудного басейну та надають можливість співвідношення їх з енергетичними параметрами роботи дробарки.

Purpose. Development of highly effective dewatering methods along with preservation of technological properties of hydro-transported coal is one of the key tasks for improving modern pipeline hydrotransportation systems. Accordingly, the purpose of this study is to develop the models of “pressure loss in the pipeline – hydrotransport velocity” i = f (V) for the “water-coal-fuel oil” mixtures of different compositions, which reflect regularities of the combined process of “hydro-transport – oil agglomeration of coal”. Methods. Physical modelling of the combined process of “hydrotransport – oil agglomeration of coal” was conducted under the test-field conditions involving specialized hydrotransport installations, i.e. a coal oil granulation stand and a hydraulic study stand. Relying on the experimental data, the trend curves were constructed, for each of which corresponding polynomial functions were determined. Findings. In terms of test field, experimental dependencies of head losses in the pipeline i = f (V) for the water-coal-oil agglomeration slurry were obtained based on the processing of the resulting family of statistical models for a hydrotransportation process of the indicated slurry. Originality. For the first time, polynomial regularities have been obtained that demonstrate the dependence of head losses in the pipeline i = f (V) on the composition and structure of solid and liquid phases of the water-coal-oil-agglomeration slurry. Practical implications. The research results can be used while developing the combined technology “hydrotransport – oil agglomeration of coal” and for designing corresponding industrial or main coal pipelines.

In the article, the authors raise the topical issue of historical falsifications, considering them as an element of information warfare. Applying the historiographical method and interpreting the facts of the creation of historical misinformation as manipulation of public consciousness, they present a specific case of historical research on the discovery of the Donetsk coal basin. Therefore, a review of the scientific and encyclopedic literature of Russia, the USSR and Ukraine devoted to the coverage of this issue was made; archival historical documents that show the real picture of the discovery of coal in Donbas have been put into scientific circulation; the manipulative discourse of influence on the mass consciousness is tracked in order to create a mythological narrative about the “Russianness” of Donbass. It has been proven that the falsifications of Russia and the USSR regarding the history of the first discovery of coal in the Donbass have been going on for almost the entire period of the industrial development of the region and to this day, it is an example of an information war against Ukraine. The archival historical documents released by the authors unequivocally indicate that the official discoverers of coal deposits in Donbas were other historical figures than those described in Russian and Soviet scientific and encyclopedic literature, and they are of Ukrainian origin. The methods of spreading the mythological narrative and their actualization during the Russian-Ukrainian war are defined, which are typical for the manipulation of mass consciousness.

Purpose. Determining the rational operating parameters for granite crushing under impact in the field of centrifugal forces to obtain cubiform crushed stone. In order to achieve the purpose set, the task is to determine the operating parameters for obtaining the main grain-size classes: -50.0 + 20.0; -40.0 + 20.0; -20.0 + 10.0; -10.0 + 5.0 and 5.0 mm. Methods. The crushing process of granite crushed stone is studied in the conditions of the Kolomoievskyi Granite Quarry, Dnipropetrovsk region. Granite crushed stone with an initial grain-size of 100.0-0.0 mm and strength grade of M1400 is subjected to crushing. The accelerating rotor rotation frequency is the design value n = 200-1200 min-1. Fine crushing of granite is performed in a centrifugal-impact crusher by a free impact in the field of centrifugal forces. Findings. The optimal speed modes of centrifugal crusher operation, which provide the production of high-quality crushed stone with a maximum content of 90-95% cubiform fractions, have been substantiated. Originality. The yield dependences have been obtained of the grain-size classes: -50.0 + 20.0; -40.0 + 20.0; -20.0 + 10.0; -10.0 + 5.0 and 5.0 mm depending on the speed mode of the centrifugal crusher operation. Practical implications. The operating parameters for obtaining the main grain-size classes of cubiform crushed stone from granite have been determined: -50.0 + 20.0; -40.0 + 20.0; -20.0 + 10.0; -10.0 + 5.0 and 5.0 mm. In particular, it has been determined that for the production of cubiform crushed stone with -50.0 + 20.0 mm grain-size, the rotor rotation reasonable speed is 400-500 min-1 (the speed of material departure from the accelerating rotor is 45-50 m/sec); for cubiform crushed stone of -40.0 + 20.0 mm grain-size, the speed mode is 200 min-1 (25 m/sec); for cubiform crushed stone of -20.0 + 10.0 mm grain-size – 600-650 min-1 (70-80 m/sec), respectively. The maximum content of cubiform fractions in the -20.0 + 10.0 mm grain-size class is 95%, which is achieved at a rotor speed of 650-700 min-1 (departure speed is 75-80 m/sec). The maximum content of cubiform fractions in the -10.0 mm grain-size class is 94-95%, which is achieved at the accelerating rotor speed within 700-800 min-1 (departure speed is 70-80 m/sec). The obtained data make it possible to practically choose a rational speed mode of the centri-fugal-impact crusher operation to obtain the maximum yield of cubiform crushed stone.

У цій праці автори мають на меті одержати статистичну математичну модель цементно-зольного тампонажного каменю з функцією відгуку – міцність каменю. Зокрема, сформульовано задачу щодо встановлення впливу на міцність тампонажного каменю домішки у вигляді кислої золи-виносу теплових електростанцій (пуцоланова домішка). Методи дослідження. Для одержання статистичної моделі використано ротатабельний центральнокомпозиційний план експерименту. Результати оброблено із застосуванням методу комп’ютерного математичного моделювання за допомогою системи STATGRAPHICS Plus for Windows. Наукова новизна. З’ясовано, що гіперповерхня G (X₁, X₂) має точку екстремуму. Це дає змогу оптимізувати за факторами X₁, X₂ склад тампонажної суміші.Практична значущість. Отримані результати дають можливість прогнозувати міцнісні характеристики каменю на основі цементно-зольного складу.Результати. Одержано статистичну математичну модель цементно-зольного каменю на основі цементу загальнобудівельного призначення марки ПЦІ-500-Н. За отриманими Парето-графіком, гіперповерхнями й контурними кривими визначено характер і ступінь впливу кожного з членів полінома на цільову функцію – міцність цементного каменю G (X₁, X₂, X₃). Найбільшу статистичну значущість мають фактори моделі Х₁, Х₃, фактор Х₂ є статистично найменш значущим. Результати моделювання підтверджують, що водосумішеве співвідношення не має значного впливу на міцність тампонажного каменю в заданому діапазоні рецептур. Максимальна міцність тампонажного каменю G = 13,582 МПа має місце в точці оптимуму з координатами: Х₁ = 0,689; Х₂ = −0,295; Х₃ = 1,105.

Formulation of the problem. Solving the problems of urban transport communications, in particular the constantly growing intensity of automobile traffic in megalopolises, is one of the main directions of minimizing the environmental and man-made risks of the urban environment. Global concepts of greening large cities pay considerable attention to the possibilities of underground space to take on the functions of the most dangerous and risky surface objects and communications, since the impact of any underground object on the environment is much lower (than similar on the surface) and can be better controlled. At the same time, planning for the development of underground transport infrastructure should be based on a systematic methodology and tools for analyzing complex systems. Purpose. It consists in the use of system tools (BOCR method - criteria of benefits, opportunities, costs and risks) for planning underground transport infrastructure of large cities to ensure minimization of environmental and man-made risks of urban space and prioritization for the construction of road tunnels (for example, the General Plan of the Kiev city). Methodology. A methodology and decision support toolkit for calculating the priorities of alternatives based on hierarchical and network criteria models are proposed. The modified BOCR method developed by the authors (N. Pankratova, N.I. Nedashkovskaya) was applied to assess decision alternatives taking into account benefits, costs, opportunities and risks. Results. System models of two road tunnels, according to the General plan of the Kiev city until 2025 were developed. Assessment of the models using the BOCR method (criteria for benefits, opportunities, costs and risks) was performed. The priorities of alternatives for tunnels' routes aggregated over a network of parameters and a reasonably expedient sequence of their construction were calculated according to the criteria for reducing the environmental and man-made risks of the urbanized space. Scientific novelty. For the first time, the target function of the system model for the development of underground infrastructure in large cities is to minimize the environmental and man-made risks of urban space. The capabilities of the modified BOCR method have been expanded and two alternative tunnel track models have been successfully tested. Practical significance. The research methods and results provide investors, city state administrations and public organizations with an effective toolkit for assessing the priority of the construction of underground urban facilities to regulate urban development in order to improve environmental standards and the safety of life in megacities.

A new competitive class of plugging compositions (weighted non-shrink plugging materials) has been created using as components a fly ash from thermal power station, a weighting additive and a superplasticizer. X-ray phase analysis identified the composition of new materials formed in the hydration process of the developed plugging compositions. The kinetic curves of the plugging material expansion in a wide temperature range have been obtained. Rational temperature regimes of plugging materials hardening according to the criteria of strength and gas permeability of cement stone have been determined.

The article is devoted to an actual issue: the development of internal downhole heat exchangers technology to combat hydration in injection wells. Purpose: development of conceptual solutions for the use of geothermal coolant in the internal well heat exchanger of the injection well. A scheme of an internal downhole heat exchanger with a geothermal heat carrier has been developed, and includes a supply line of a geothermal carrier through the heat exchange surface of the injection well into the productive reservoir of the oil field. The scheme provides targeted utilization of thermobaric energy of a geothermal source to combat hydration in the injection well. A mathematical apparatus for describing the process of heat utilization and heat exchange in injection well is proposed. It is established that the capacity of one geothermal well discovered at the oil depths in the Dnipro-Donetsk basin is sufficient to eliminate hydration in 1-3 injection wells, and determines the feasibility of their joint work.