The present review paper discusses the different aspects related to the chemical transformation of oil components through ultrasound assistance. Ultrasound intensifies heat and mass transfer processes in oil production and treatment, which is used to separate water–oil emulsions, optimize pumping, clean the bottomhole zone, and more. The main reason for the positive effect of ultrasound is the cavitation phenomenon, which forms vapor–gas bubbles that cause changes in the structure and properties of dispersed phases, intensifying processes such as dissolution, extraction, and emulsification. The inhomogeneities in the medium being processed also reduce resistance to bubble formation and increase the intensity of technological processes. It is believed that ultrasonic treatment of heavy oil influences the colloid structure of oil. Such effects were observed in several studies. Despite the widespread use of ultrasound in oil processing, the chemical transformation of hydrocarbons during ultrasonic treatment remains an understudied area, particularly for heavy oil. Furthermore, the transformation mechanism of high-molecular-weight fragments of oil under ultrasonic energy is still poorly understood. Heavy oil can benefit greatly from ultrasonic treatment, both after production for pipeline transportation or plant processing and in the reservoir. This is due to the improved mobility of oil in rock and the chemical transformation of high-molecular components, such as resins, asphaltenes, and paraffins. These transformations contribute to the overall improvement of heavy oil processing, making it a crucial area for further research and development. In this review paper, we will explore the latest innovations in oil processing, specifically focusing on the chemical transformation of oil components through ultrasound assistance. This will include a comprehensive analysis of the underlying mechanisms of ultrasonic treatment and their impact on the chemical composition of oil. The review will also include a discussion of the current state of the art and future directions for research in this field, highlighting the potential for further advancements in the use of ultrasound in oil processing.

Ultrasound technologies are well-known for their ability to intensify the heat and mass transfer processes. Hence, ultrasonic treatment processes are widely applied for the separation of oil–water emulsions, optimization of oil pumping processes, cleaning the bottomhole zone, etc. However, the main phenomenon under the positive influence of ultrasonic waves on such processes is the cavitation bubbles implosion on the water–oil boundary. It is well-known that ultrasound energy contributes to the reversible viscosity reduction in heavy oil systems. However, it is possible to exhibit chemical destruction of the weakest carbon–heteroatom bonds in the structure of the asphaltenes. This study investigates the influences of controllable ultrasound waves with frequency ranges of 20–60 kHz under the exposure time of 60 s on the rheology of a heavy crude oil sample produced from the Ashalcha reservoir (Tatarstan Republic, Russia). The specific feature of this study is the application of multi-frequency ultrasonic exposure with a wide spectrum of side harmonics with the frequency up to 400 kHz. The results of the Saturates, Aromatics, Resins and Asphaltenes (SARA) analysis method support the chemical consequences of ultrasonication of crude oil. The content of resins under the irradiation of ultrasound waves altered from 32.5 wt.% to 29.4 wt.%, while the number of aromatics hydrocarbons raised from 24.3 wt.% to 34.1 wt.%. The Gas Chromatography—Mass Spectroscopy (GC-MS) analytical analysis method was applied to qualitatively compare the composition of saturated and aromatics fractions between the initial and upgraded heavy crude oil in order to show the chemical destruction of asphaltene bonds after the ultrasonic treatment. It was demonstrated that ultrasound waves allowed chemical conversion of asphaltene fragments that led to irreversible viscosity reduction. The viscosity of the heavy oil sample under the favorable ultrasonic irradiation conditions reduced from 661.2 mPa·s to 178.8 mPa·s. This advantage can be used to develop enhanced oil recovery methods and partial upgrading processes in downstream conditions.

The application of ultrasonic waves in the processing of hydrocarbons is a new promising technology that has developed rapidly in recent years. However, the acoustic-induced cavitation erosion phenomenon is poorly studied. In this paper, a comparison study of cavitation erosion was carried out in water and oils with different viscosities produced from Ashal’cha and North Komsomol using an ultrasonic reactor operating at an industrial frequency of 20 kHz. The acoustic spectra obtained from hydrophones during the ultrasonic treatment of fluids can be characterized by using subharmonics of the main frequency and a continuous white noise level. Moreover, the cavitation erosion of aluminum foil under various ultrasound irradiation times and power levels was thoroughly investigated. It has been found that the process of ultrasonic cavitation has a less erosive impact on metal foil in oil due to its high viscosity. In addition, the formation of microflows in the oil phase, which also intensify the erosion process, is hindered. Cavitation erosion in the Ashal’cha oil sample exhibited a higher intensity compared to that in the North Komsomol oil sample. It was found that upon increasing ultrasound intensity in the case of the viscous (Ashal’cha) oil sample, cavitation stability was disrupted. In turn, this led to a reduction in the collapse energy of the cavitation bubbles. The results we obtained enable the assessment of cavitation erosion in crude oil and could be used to improve methodologies for monitoring and optimizing cavitation processes in crude oil.

Separation of water-in-oil emulsion is a significant part of the cost of oil production due to the use of expensive demulsifiers and additional heating of the emulsion by burning associated petroleum gas. The article discusses an acoustic method that enables the increasing of the rate of separation of the emulsion. In field conditions, tests were carried out in which the efficiency of separation in the acoustic field was determined depending on the temperature of the product, the concentration of the demulsifier, and the frequency and time of exposure to the emitter. The results obtained allow us to talk about a significant reduction in the consumption of demulsifiers, a decrease in the influence of temperature on the phase separation process and an increase in the efficiency of oil treatment at existing facilities.

The article presents the results of a study of the use of ultrasonic technologies to increase the strength of cement mortar in the production of building and concrete structures, as well as to improve the rheological parameters of grouting mortar during the construction (drilling) of wells. During the experiment, the concrete mortar was treated for 3 minutes with an ultrasonic multi-frequency acoustic field (frequency 20.0-40.0 kHz, signal power-200-400 W/dm 3) in devices of various geometric shape. Ordinary Portland Cement (OPC) of class G-100 was used in the composition of the solution without plasticizer additives in order to exclude their influence. The ratio of water and cement in the solution was 0.44, the density-1.90 g/cm 3. Typical elements of flow channels were used as volumes where ultrasonic exposure is carried out. The hydrodynamic regime of the processes in the water-cement suspension was modeled at the beginning of the experiments by slow mixing with a paddle agitator (200 Rev./min), and on closing stage, in order to prevent the effect of hydrodynamic cavitation failure, at a speed of 1000 Rev./min. The maximum compression and bending stresses are measured after the mixture solidified in a steam bath (T =60°C, 24 h.) on a hydraulic stand. Conducted experiments have confirmed that ultrasonic exposure using resonant accumulators and flow hoses: has a positive effect on the hydration reaction and the structure of cement stone in the concrete sealing phase; accelerates the intensity of compressive strength. (from 24.3 MPa to 41.5 MPa); uniformity of structure; reduces the influence of temperature on strength gain (reduces energy consumption); increases the reliability of building structures, and in the case of well construction-provides a strong adhesion of the production column with rock. In general, the results of the study allowed: to formulate a technology for the production of heavy-duty concrete mixtures; to develop a set of equipment for the preparation of concrete (grouting mortar) with specified characteristics at production objects. Keywords: ultrasonic multi-frequency acoustic field, high-strength concrete mix, water separation of mortar, cement stone (paste), compressive and bending strength of concrete mix

The purpose of this research is to study the possibilities of modeling oil-water emulsion in the laboratory. The study of the ratio of components and conditions of dispersion (formation) of oil-water emulsions on their stability at different settling temperatures using a laboratory model can optimize the separation of oil-water emulsions in field conditions. The possibility of modeling commercial oil and water emulsions in laboratory conditions is investigated, the average diameters of water globules in simulated oil and water emulsions at different times of their formation are determined, and the obtained average globule diameters are compared with the average diameter of globules in a stable commercial oil-water emulsion.