This research focuses on the development of a quasi-isothermal pressure regulator based on the principle of flow mixing after energy separation. Currently, no established methods exist for designing pressure reduction devices that utilize energy separation effects, and this study aims to fill this gap. The paper presents experimental results on the performance of a pressure reduction device operating based on the Hartmann–Sprenger effect. This study investigated the hypothesis that by selecting the size of resonators, relative distances, and their mutual location, it would be possible to realize pressure regulation, simultaneously providing both the maintenance of a significant effect and the full provision of the functions of pressure regulators operating in non-stationary conditions. The experiments involved three resonators (45.5 mm, 70.5 mm, and 97.5 mm) in regurgitant mode. The findings revealed that the smallest resonator demonstrated the highest rate of temperature increase, with an average value of 2.36 K/s. The medium resonator exhibited the highest reliability under non-stationary conditions, while the largest resonator provided the highest temperature, with a maximum excess of 102 K over the temperature in front of the nozzle. The primary goal of this study was to develop technology suitable for installation at a pressure reduction station, considering mass and dimensional constraints.

The present paper provides a brief overview of the existing methods for energy separation and an analysis of the possibility of the practical application of the Hartmann–Sprenger effect to provide quasi-isothermal pressure reduction of natural gas at the facilities within a gas transmission system. The recommendations of external authors are analyzed. A variant of a quasi-isothermal pressure regulator is proposed, which assumes the mixing of flows after energy separation. Using a numerical simulation of gas dynamics, it is demonstrated that the position of the resonators can be determined on the basis of calculations of the structure of the underexpanded jet without taking into account the resonator and, accordingly, without the need for time-consuming calculations of the dynamics of the processes. Based on the results of simulating the gas dynamics of two nozzle–resonator pairs installed in a single flow housing, it is shown that, in order to optimize the regulator length, the width of the passage between the two nearest resonators should be greater than or equal to the sum of diameters of the critical sections of the nozzles. Numerical vibroacoustic analysis demonstrated that the most dangerous part of the resonator is the frequency of its natural oscillations.

Effective fluid-loss control in oil wells is a critical concern for the oil industry, particularly given the substantial reserves situated in carbonate reservoirs globally. The prevalence of such reservoirs is expected to rise with the slow depletion of hydrocarbons, intensifying the need to address challenges related to deteriorating reservoir properties post well-killing operations. This deterioration results in significant annual losses in hydrocarbon production at major oil enterprises, impacting key performance indicators. To tackle this issue, this study focuses on enhancing well-killing technology efficiency in carbonate reservoirs with abnormally low formation pressures. To address this issue, the authors propose the development of new blocking compositions that prevent the fluid loss of treatment fluids by the productive reservoir. The research tasks include a comprehensive analysis of global experience in well-killing technology; the development of blocking compositions; an investigation of their physico-chemical, rheological, and filtration properties; and an evaluation of their effectiveness in complicated conditions. The technology’s application in the oil and gas condensate fields of the Volga-Ural province showcases its practical implementation. This study provides valuable insights and solutions for improved fluid-loss control in carbonate reservoirs, ultimately enhancing well performance and hydrocarbon recovery.

The results of studying the problem of active sediment formation when mixing residual fuels, caused by manifestation of incompatibility, are presented. A laboratory method has been developed for determining the compatibility and stability of fuels allowing identification of a quantitative characteristic of sediment formation activity. Laboratory studies were performed, and incompatible fuel components were identified. Tests were made to determine the quality indicators of samples and group individual composition of fuels. Results on the content of total and inorganic carbon in the obtained sediments were determined using Shimadzu TOC-V SSM 5000A. Chemical composition was determined and calculated on LECO CHN-628 analyser. Group composition of hydrocarbon fuels contained in the sediment was studied by gas chromato-mass spectrometry on GCMS-QP2010 Ultra Shimadzu. To obtain additional information on the structural group composition of fuel sediment, IR spectrometry was performed on IR-Fourier spectrometer IRAffinity-1. X-ray diffraction analysis of sediment samples was made using X-ray diffractometer XRD-7000 Shimadzu; interplanar distances d(002) and d(100) as well as L-c and L-a crystallite sizes served as the evaluation criteria. Microstructural analysis of total sediment was performed by scanning electron microscopy. The results of the research confirmed that the content of normal alkanes in the fuel mixture mainly affects sediment formation. Recommendations were drawn on preserving the quality of fuels and reducing sediment formation during storage and transportation.

Storage tanks for petroleum products must comply with the requirements of technical, technological and environmental safety. The corrosion rate increases with prolonged storage of petroleum products in tanks. To prevent the destruction processes for reliable operation of tanks caused by metal corrosion some solutions are needed. Active formation of general sludge occurs in the storage of fuel oil, which contains corrosion-active substances, because of the incompatibility of fuels. The paper assesses the effect of total oil sludge in tanks on the corrosion process and on the reliability of tanks. Studies of the formation of a common sediment caused by incompatibility when mixing petroleum products are conducted. The paper proposes a solution which allows to reduce the formation of total oil sludge and to ensure reliable operation of reservoirs.

Natural gas pressure-reduction stations dissipate a significant portion of the gas pressure energy during conventional throttling. The recovery of this energy at small-capacity stations remains challenging due to low gas flow rates and variable operating conditions. This study investigates the application of a volumetric expander–generator regulator based on a vane-type positive-displacement expander as a combined pressure control and energy recovery device for small natural gas pressure-reduction stations. A mathematical model of gas-dynamic processes in the expander–generator regulator was developed and verified using experimental data obtained from a laboratory-scale compressed-air test facility. Experimental investigations were carried out within four pressure-drop ranges of 25–65, 45–105, 75–175, and 125–285 kPa under both rotor-speed stabilization and outlet-pressure stabilization modes. Based on the experimental results, second-order regression models were developed to describe the dependence of rotor speed on operating pressures and were subsequently used to estimate annual energy recovery. The results indicate that outlet-pressure stabilization provides higher energy recovery than rotor-speed stabilization across the investigated operating ranges. Depending on operating conditions, the estimated annual recovered energy ranged from 83 to 2265 kWh, which is sufficient to cover the auxiliary power demand of cabinet-type pressure-reduction stations and cathodic protection systems. The experimental validation presented in this study was performed using compressed air as the working medium. Therefore, the obtained quantitative results should be regarded as a laboratory-scale assessment of the feasibility of the proposed approach rather than a direct validation of a natural-gas expander–generator system. The results suggest the potential applicability of volumetric expander–generator regulators for energy recovery at small-scale gas pressure-reduction stations operating under variable flow conditions.