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This paper describes the further development of the virtual flow meter concept based on the author's simulator of an unsteady gas–liquid flow in wells. The results of comparison with commercial simulators based on real well data are given as practical applications. The results of the comparison of the simulators demonstrated high correspondence (<10% error) for a number of target parameters. The description of the architecture and results of testing the algorithm for automatic settings of the model parameters are given. Operating speed was the key criterion in the architecture development. According to the test results, it became possible to achieve the adaptation accuracy of 5% specified. [ABSTRACT FROM AUTHOR]

The paper investigated the problem of selecting/finding the optimal process conditions for gas condensate wells. The well process conditions imply a set of parameters that characterize its operation. The optimization of process conditions provides for the efficient operation of an oil and gas field while meeting the defined boundary and initial conditions, and allows for the process/production goal to be achieved. This paper proposed using the tree-structured Parzen estimator (TPE), which allows for the results from previous iterations to be considered, in order to identify the most promising region of conditions, thereby increasing the optimization efficiency. The movement of multiphase fluid inside the pipeline system (also in the borehole) must be calculated to solve the process optimization problem. The optimization module was integrated into the hydraulic and unsteady state multiphase flow calculations inside the well and the pipeline. The platform created allows for the process conditions at gas condensate fields to be identified via the use of numerical methods. The proposed optimization algorithm was tested in delivering the task of optimizing the process conditions in 13 producing wells in a part of a real gas condensate field in Western Siberia. The engineering problem of optimizing the production of gas and the gas condensate was solved as a consequence of the calculations performed. [ABSTRACT FROM AUTHOR]

A Monte Carlo algorithm based on the use of transfer matrices is developed to describe the stochastic dynamics of the rotational--translational motion of aerosol clusters taking into account fluctuations in the molecular fluxes of the gas medium. In the general case, the cluster is immersed into a rarefied gas medium, the temperatures of its surfaces may differ from the temperature of the surrounding gas, for example, due to absorption of visible and infrared radiation. The motion of the cluster is described based on Langevin motion equations. The algorithm allows one to calculate parameters of the probability distribution of a six-dimensional vector consisting of components of the momentum and angular momentum vectors transmitted to the cluster by molecular flows. The numerical method allows one to apply preliminary analytical averaging modulo velocities of molecules for both the average values of the components of momentum and angular momentum and their correlation characteristics, which significantly reduces the calculation time. [ABSTRACT FROM AUTHOR]

The article focuses on the problem of bribery and corruption in towns in the south of Ukraine between the end of the eighteenth century and the first half of the nineteenth century. The main focus is on the activities of public officials and deputies of municipal self-government. It is noted that the flourishing state of corruption and bribery in the region began to form under the conditions of the new socio-cultural situation that resulted from the fast processes of incorporation, colonization, adaptation, and modernization. The distance from the centre weakened control on the part of the State, and therefore corruption and bribery acquired new forms in the south of Ukraine in comparison with other regions of the Russian Empire. Also regional features of the flourishing state of corruption and bribery have been noted. Conclusions are made that corruption and bribery became usual occurrences of local life against which municipal communities came out, permanently forming an interaction mechanism with civil society. It is also noted that the struggle of local communities with different cases of bribery had practical results: a lot of officials were punished, and eventually sentenced to long terms of imprisonment. [ABSTRACT FROM AUTHOR]

Some applications of thin film transistors (TFTs) need the bottom-gate architecture and unpassivated channel backside. We propose a simple routine to fabricate indium doped ZnO-based TFT with satisfactory characteristics and acceptable stability against a bias stress in ambient room air. To this end, a channel layer of 15 nm in thickness was deposited on cold substrate by DC reactive magnetron co-sputtering of metal Zn-In target. It is demonstrated that the increase of In concentration in ZnO matrix up to 5% leads to negative threshold voltage (VT) shift and an increase of field effect mobility (μ) and a decrease of subthreshold swing (SS). When dopant concentration reaches the upper level of 5% the best TFT parameters are achieved such as VT = 3.6 V, μ = 15.2 cm²/Vs, SS = 0.5 V/dec. The TFTs operate in enhancement mode exhibiting high turn on/turn off current ratio more than 106. It is shown that the oxidative post-fabrication annealing at 250°C in pure oxygen and next ageing in dry air for several hours provide highly stable operational characteristics under negative and positive bias stresses despite open channel backside. A possible cause of this effect is discussed. [ABSTRACT FROM AUTHOR]

This paper describes testing of the INSIM-FT proxy simulation method (interwell-numerical-simulation model improved with front-tracking method) to assess the dependencies between production and injection wells, as well as to assess the forecast of oil/liquid production by wells depending on their operation parameters. The paper proposes the approach of taking into account the influence of various production enhancement operations. The method was tested on a synthetic hydrodynamic model and on a sector of a real field. The results show a good match between historical data and simulation results and indicate significant computational efficiency compared to classical reservoir simulators. [ABSTRACT FROM AUTHOR]

Gas injection has already proven to be an efficient shale oil recovery method successfully tested all around the world. However, gas-enhanced oil recovery methods have never been implemented or tested for the greatest Siberian shale oil formation yet. This article proposes numerical simulation of a hydrocarbon gas injection process into a horizontal well with multiple hydraulic fractures perforating Bazhenov shale oil formation in Western Siberia characterized by ultra-low permeability. A complex field-scale numerical study of gas injection for such a formation has never been performed before and is presented for the first time in our work. The hydrodynamic compositional simulation was performed utilizing a commercial simulator. A sensitivity study for different operating parameters including cycle times, bottom-hole pressures for the production and injection period, and injected gas composition was performed after the model was history matched with the available production data. Some uncertain reservoir properties such as relative permeability curves were also sensitized upon. Two different ways of accounting for multiple hydraulic fractures in the simulation model are presented and the simulation results from both models are compared and discussed. Eventually, huff-n-puff injection of a hydrocarbon gas resulted in a 34–117% increase in oil recovery depending on the fracture model. [ABSTRACT FROM AUTHOR]

There has been a large amount of experience in recent decades in the use of magnetic fields on reservoir fluids. This paper discusses the effect of a magnetic field on wax precipitation. An analytical model is developed to quantify the wax deposition rate on the tubing surface during the magnetic treatment of reservoir oil. It has been established that the passage of the oil flow through a non-uniform magnetic field causes a high-intensity electric field for a sufficiently long period of time, the effect of which decreases the solubility of wax in oil, increases the intensity of wax precipitation in oil, and reduces the wax deposition on the tubing surface. The model accounts for the fact that the wax deposits present on the tubing surface are a highly efficient heat insulator that changes the temperature regime of the flow and the temperature of the tubing wall. This circumstance changes the rate of deposits but does not make these deposits less harmful to wells' operation. A method for calculating the equilibrium wax concentration and changing the solubility of wax in oil under a constant electric field has been developed. We show that the effect of magnetic treatments on wax deposition rises with the increase in the concentration of asphaltenes in the oil and water cut. [ABSTRACT FROM AUTHOR]

• Available experimental techniques are reviewed along with basic physical principles description. • Technical requirements are formulated focusing on methods associated with transient combustion. • No universal method exists to measure transient burn rate with required accuracy and time resolution. • Attention is paid to the development of microwave, X-ray radiography and laser recoil techniques. • The work on developing novel experimental approaches must be continued. Various energetic materials, including solid rocket propellants, have found numerous applications in aerospace technology in the past decades. This growing interest initiated an increasing number of experimental and technological studies, leading to a wide range of published experimental data. Due to the intrinsic challenges of data acquisition and processing, assessing the accuracy of the measurement results is important. In this paper, a review of existing experimental techniques for measuring the regression rate of energetic materials is presented along with a description of the fundamental physical principles used for developing the particular methods. Special attention is paid to recent developments in measurements of highly-dynamic processes. Technical requirements for correct determination of regression rate are analyzed focusing on the methods associated with transient combustion. Emphasis is placed on laboratory-scale methods intended to obtain correct and reliable data on regression rate in well-characterized environments that can be used for comparison with theoretical predictions. The measurement methods are divided into direct and indirect ones. It is shown that direct high-speed photography could not be effectively used for recording regression rate oscillations with frequencies higher than 30–50 Hz. The same limitation applies to classical ultrasound techniques and X-ray radiography. However, radiography techniques based on synchrotron and terahertz radiation are promising. Special attention is paid to development of microwave and laser recoil methods that provide high spatial and temporal resolution capable of correctly determining transient regression rate. [ABSTRACT FROM AUTHOR]

The aim of this work was to improve the solubility of various anti-HIV APIs extruding them with polyvinyl alcohol to allow a reduction in patient drug burden. There are no previously known cases of successful use of this polymer to improve the solubility of APIs using a convenient industrial technology. Anti-HIV API solid dispersion samples were obtained using hot melt extrusion with polyvinyl alcohol, and were studied with solubility testing, as well as various methods of confirming amorphousness (differential scanning calorimetry, X-ray powder diffraction). This study confirmed the presence of amorphousness and a significant increase in the solubility of the API in various dissolution media. According to the obtained data, the best samples were selected and utilized in tablet formulations, which successfully passed in vitro dissolution testing. The results of in vitro dissolution testing showed the improvement of dissolution kinetics for all APIs. These results showed the usefulness of hot melt extrusion with polyvinyl alcohol in a ratio of at least 1-3 or 1-5 for the studied APIs and improved the dissolution kinetics of the proposed tablet formulations compared to the controls. [ABSTRACT FROM AUTHOR]

The aim of this work was to compare mesoporous carriers based on silica and magnesium aluminosilicate in the amorphous solid dispersion production. Darunavir has been selected as an active pharmaceutical ingredient that is classified as a Class 2 BCS substance and exists in two commercially available forms: crystalline ethanolate and amorphous. In the course of the study, the conditions for the preparation of amorphous samples with the selected carriers were evaluated within the framework of the most common methods for obtaining solid dispersions - hot-melt extrusion, solvent wetting, and spray drying. It was determined that the obtained dispersion properties almost completely repeat the properties of the corresponding carriers. The resulting dispersions were examined in a dissolution test and the best ones was used to formulate tablets, which were studied in an in vitro dissolution test with the original Prezista. The proposed tablet formulation showed improved dissolution compared to the original one. It was also found that silica supports have a greater positive contribution to darunavir dissolution - both ethanolate or amorphous forms. Image, graphical abstract [ABSTRACT FROM AUTHOR]