Research on the removal of near-well blockage caused by asphaltene deposition using sonochemical method

Near-well blockage caused by asphaltene deposition often occurs during the process of crude oil exploitation. It can reduce the porosity and permeability of reservoirs and seriously affects the migration and exploitation of oil and gas. In this paper, removing near-well blockage caused by asphaltene deposition using sonochemical method is investigated. Six PTZ transducers with different parameters are used to study the deplugging effect. Results show that the optimal ultrasonic frequency and power for plugging removal are 20 kHz and 1000 W respectively. it is found that lower ultrasonic frequency is good for asphaltene deposition plug removal when ultrasonic power is constant; as the power of the sensor increases, the effect of removing the asphaltene deposition plug gets better, ultrasonic power can well make up for the attenuation of ultrasonic energy caused as frequency increases; the effects of removing asphaltene deposition plug for the three cores with different initial gas logging permeability all get worse no matter what type of transducer is used; the effect of asphaltene deposition plug removal for the three cores samples all become better and then tend to be stable as ultrasonic treatment time increases further; considering of reducing construction cost and oil reservoir protection, ultrasonic processing has a lot of unexampled advantages compared with chemical injection, such as good adaptability, low cost, simple operation, non-pollution and benefit for the sustainable development of oil field; affected by the synergistic effect of ultrasonic and chemical agents, the combined treatment effect of ultrasound and chemical agents is significantly better than using ultrasound or chemical agents alone.     

Study on removing calcium carbonate plug from near wellbore by high-power ultrasonic treatment

In this paper, the effects of ultrasonic wave on the removal of inorganic scaling and plugging in cores and the influence of the key wave field parameters, process parameters and core physical parameters on the plugging removal efficiency are systematically studied. The main dynamic mechanism of ultrasonic plugging removal is also systematically analyzed. Results show that the transducer frequency, transducer power, ultrasonic treatment time and initial permeability of core have great influence on the effect of ultrasonic scale removal. When the cumulative treatment time of ultrasonic wave exceeds 60 min, the recovery rate of core permeability tends to be stable. Best effect can be achieved when processing for 80–120 min cumulatively; the plugging removal effect is improved with the increase of ultrasonic transducer power and ultrasonic frequency, but the effect of plugging removal is not obvious with the further increasing of them. In addition, it is proved that the effect of removing calcium carbonate plug from near wellbore by hydrochloric acid solution is slightly better than that by ultrasonic treatment alone. Finally, the micro dynamic mechanism of removing inorganic scale plug by high-power ultrasonic treatment is discussed in view of ultrasonic inorganic scale body crushing, ultrasonic cavitation, ultrasonic friction, ultrasonic peristaltic transport operation and ultrasonic fracture-making and permeability-increasing effect.     

Ultrasonic technology for enhanced oil recovery from failing oil wells and the equipment for its implemention

A new method for the ultrasonic enhancement of oil recovery from failing wells is described. The technology involves lowering a source of power ultrasound to the bottom of the well either for a short treatment before removal or as a permanent placement for intermittent use. In wells where the permeability is above 20 mD and the porosity is greater than 15% ultrasonic treatment can increase oil production by up to 50% and in some cases even more. For wells of lower permeability and porosity ultrasonic treatment alone is less successful but high production rates can be achieved when ultrasound is applied in conjunction with chemicals. An average productivity increase of nearly 3 fold can be achieved for this type of production well using the combined ultrasound with chemical treatment technology.     

Effects of reservoir rock pore geometries and ultrasonic parameters on the removal of asphaltene deposition under ultrasonic waves

Asphaltene deposition around the wellbore is a major cause of formation damage, especially in heavy oil reservoirs Ultrasonic stimulation, rather than chemical injection, is thought to be a more cost-effective and environmentally friendly means of removing asphaltene deposition. However, it seems to be unclear how crucial features like reservoir pore geometries and ultrasonic parameters affect this ultrasound treatment.In this work, five two-dimensional glass micromodels with different pore geometries were designed to assess the impact of pore geometries on the ultrasonic removal of asphaltene deposition. Experiments were undertaken in an ultrasound bath at a set frequency (20 kHz) and adjustable powers (100–1000 W). Direct image analysis before, during and after sonication was used to assess the impact of pore geometry and a change in ultrasonic parameter on the removal of asphaltene deposition. The effectiveness of ultrasound treatment at various sonication periods were found to be reliant on the pore geometries of the individual micromodels. For micromodels with throat sizes 300 µm and pore shapes as circle, square and triangle, an increase in ultrasonic power from 400 to 1000 W resulted in an increase in the percentage of removed asphaltene deposition after 2 h from 12.6 to 14.7, 11.5 to 14.63, and 5.8 to 7.1 percent, respectively.     

Power ultrasound and its applications: A state-of-the-art review

Ultrasonic processing has attracted increasing attention by people because ultrasonic technology may represent a flexible ‘green’ alternative for energy efficient processes. The major challenges for the power ultrasound application in real situations are the design and development of specific power ultrasonic systems for large-scale operations. Thus, new families of power ultrasonic transducers have been developed in recent years to meet actual needs, and this contributes to the implementation of power ultrasound of application in many fields such as chemical industry, food industry and manufacturing. This paper presents the current state of ultrasonic transducers of magnetostrictiv type and piezoelectric type as well as applications of power ultrasound in various industrial fields including chemical reactions, drying/dehydration, welding, extraction, heat transfer enhancement, de-ice, enhanced oil recovery, droplet atomization, cleaning and fine particle removal. The review paper helps to understand the current development of power ultrasonic technology and its applications in various situations, and induce extended applications of power ultrasound to more and more fields.     

Study on ultrasound-assisted precipitation for preparing Ni/Al2O3 catalyst

With the rapid development of oil hydrogenation industry, the development of oil hydrogenation catalyst has also become a research hotspot. In this paper, ultrasound-assisted precipitation technique is used to prepare Ni/Al₂O₃ catalyst. The effect of ultrasonic output power on catalyst performance is investigated. The prepared catalyst is applied to the hydrogenation reaction of castor oil. It is found that the prepared catalyst shows the best hydrogenation performance when ultrasonic output power, frequency and ultrasonic treatment time are 80 W, 40 kHz and 600 min respectively. It also indicates that ultrasound-assisted precipitation technique can reduce the particle size and increase the specific surface area of Ni/Al₂O₃ catalyst so that its activity is improved. In addition, six important elements that should be considered in the development of industrial oil refining catalysts are discussed, and the effects of these factors on the catalyst performance are discussed. Finally, new way for improving catalyst performance is given, and the application of some new materials and methods in oil refining is introduced.     

Ultrasound-assisted desalination of crude oil: The influence of mixing extent,crude oil species,chemical demulsifier and operation variables

Coalescence of water droplets in crude oil has been effectively promoted by chemical demulsifiers integrated with ultrasound. Temporary images of water droplets in W/O emulsions were directly monitored using a metallurgical microscope. Water droplets achieved expansion of 118% at 40 min ultrasonic irradiation time under well mixing conditions. However, water droplets in heavy crude oil undergo less aggregation than those in light crude oil, due to resistance of mobility in highly viscous fluid. In the absence of chemical demulsifiers, water droplets enveloped by native surfactants appeared to aggregate arduously because of occurrence of interfacial tension gradients. Influential significance analyses have been executed by a factorial design method on operation variables, including acoustic power intensity, operation temperature, ultrasonic irradiation time and chemical demulsifier dosages. In this work, the outcomes indicate that the optimal operating conditions for desalination of crude oil assisted by ultrasound were as follows: acoustic power intensity = 300 W, operation temperature = 90℃, ultrasonic irradiation time = 75 min and chemical demulsifier dosages = 54 mg/L. Besides, it was found that the most influential importance of operation parameter was temperature, followed with acoustic power intensity, ultrasonic irradiation time and chemical demulsifier dosages.     

Ultrasound assisted intensified recovery of lactose from whey based on antisolvent crystallization

The current work deals with understanding the fundamental aspects of intensified recovery of lactose from paneer (cottage cheese) whey using the anti-solvent induced sonocrystallization. Ultrasonic horn (22 kHz) with varying power levels over the range of 40–120 W has been used for initial experiments at 100% duty cycle and two different levels of ultrasonic exposure time as 10 min and 20 min. Similar experiments were also performed using ultrasonic bath for the same time of exposure but with at two ultrasonic frequencies (22 kHz and 33 kHz). It was observed that the lactose recovery as well as purity increased with an increase in ultrasonic power at 100% duty cycle for the case of treatment time as 10 min whereas the lactose recovery and purity increased only till an optimum power for the 20 min treatment. In the case of ultrasonic bath, lactose purity increased with an increase in the ultrasonic frequency from 22 kHz to 33 kHz though the lactose recovery marginally decreased. Overall, it was observed that the maximum lactose recovery was ∼98% obtained using ultrasonic horn while the maximum lactose purity was ∼97%. It was also observed that maximum lactose recovery was ∼94% for the case of ultrasonic bath while the maximum lactose purity was ∼92%. The work has enabled to understand the optimized application of ultrasound so as to maximize both the lactose yield and purity during the recovery from whey.     

Ultrasound induced cleaning of polymeric nanofiltration membranes

Cleaning of the flat sheet nanofiltration membranes, using backflushing, chemical cleaning, and ultrasonication operated individually as well as in combination with chemicals, has been studied in the present work. Identical hydrophilic polyamide membranes were fouled individually using an aqueous solution containing a single dye, an aqueous solution containing a mixture of dyes, and a synthetically prepared petroleum refinery effluent. Effect of different parameters such as the concentration of cleaning solution, contact time, frequency, and power of ultrasound on the efficacy of membrane cleaning has been studied. Optimal cleaning was achieved under sonication conditions of frequency of 24 kHz and power dissipation of 135 W. It was demonstrated that application of sonication under optimum conditions without chemical agents, gave about 85% water flux recovery. In the case of combined chemical and ultrasonic treatment, it was clearly observed that the use of chemical agent increased the efficacy of ultrasonic cleaning. The hybrid method recovered the initial water flux to almost 90% based on the use of 1.0 M aqueous NaOH and 4 min of sonication. Overall, the use of aqueous NaOH in combination with sonication showed a better efficiency for cleaning than the individual processes thus demonstrating a new avenue for membrane cleaning.     

Theoretical and experimental investigation of desalting and dehydration of crude oil by assistance of ultrasonic irradiation

In this paper desalting/dehydration process of crude oil by ultrasonic irradiation in a novel batch standing-wave resonator reactor is studied both theoretically and experimentally. The effect of main parameters including ultrasonic irradiation parameters, namely irradiation input power and irradiation time, and also operating parameters, such as temperature and injected water, on the removal efficiencies of salt and water is examined. The obtained results demonstrate that finding the optimum values of the above mentioned parameters is important to prevent a significant decrease in the removal efficiencies of water and especially salt. Thus, crude oil was subjected to optimal ultrasonic irradiation with an input power of 57.7 W, and irradiation time of 6.2 min at temperature of 100 °C. The injected water to dissolve the salt of crude oil was 7 vol.%. Also, the applied settling time and dosage of chemical demulsifier were 60 min and 2 ppm, respectively. Under these optimum conditions the removal efficiencies of the desalting/dehydration process were 84% and 99.8%, respectively, which are suitable for refineries.Also, based on the optimal experimental data, two inferential estimators are developed to obtain the relationships between the salt and water removal efficiencies, and input energy density. These empirical relationships can offer a proper estimation for the salt and water removal efficiencies with irradiation input energy.     

Ultrasound-assisted desolventizing of fragrant oil from red pepper seed by subcritical propane extraction

In the present study, ultrasound was used to remove the residual solvent from the fragrant oil of red pepper seed obtained by subcritical propane extraction. The physical and chemical characteristics, particularly the volatile flavor compounds present of the oil before and after ultrasound-assisted desolventizing were comprehensively analyzed to determine the effect of the desolventizing process on product quality. The results showed that the maximum loss of residual solvent was achieved at a temperature of 90 °C maintained for 70 min with ultrasound applied during the entire process. After this treatment only a small amount of solvent (2.3% based on the total residual solvent originally present) remained in the oil. Although it was hypothesized that ultrasound treatment could result in the loss of volatile components, the analytical results showed no obvious reduction in the components associated with the typical aroma of the oil. After ultrasonic treatment, the oil also had good oxidation stability and quality. Additionally, after ultrasonic desolventizing, the oil samples were more suitable for cooking because they could more effectively minimize oxidation. Thus, these results demonstrate that this new ultrasonic technique is an effective and efficient method for removing the solvent remaining in fragrant oil after subcritical propane extraction.     

Effect of ultrasound on the structural characteristics and oxidative stability of walnut oil oleogel coated with soy protein isolate-phosphatidylserine

In this study, the three-dimensional network system formed by rice bran wax (RBW) was used as the internal structure, and the external structure formed by soybean protein isolate (SPI) and phosphatidylserine (PS) was added on the basis of the internal structure to prepare walnut oil oleogel (SPI-PS-WOG). Ultrasonic treatment was applied to the mixed solution to make SPI-PS-WOG, on the basis, the effects of ultrasonic treatment on SPI-PS-WOG were investigated. The results showed that both β and β’ crystalline forms were present in all SPI-PS-WOG samples. When the ultrasonic power was 450 W, the first weight loss peak in the thermogravimetric (TGA) curve appeared at 326 °C, which was shifted to the right compared to the peak that occurred when the ultrasonic power was 0 W, indicating that the thermal stability of the SPI-PS-WOG was improved by the ultrasonic treatment. Moreover, when the ultrasonic power was 450 W, the oil holding capacity (OHC) reached 95.3 %, which was the best compared with other groups. Both confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) showed that the ultrasonic treatment of appropriate power succeeded in making the SPI-PS-WOG samples more evenly dispersed in the internal structure and denser in the external structure. In terms of oxidative stability, it was found that the peroxide value of SPI-PS-WOG remained at 9.8 mmol/kg oil for 50 days under 450 W ultrasonic power treatment, which was significantly improved compared with liquid walnut oil (WO). These results provide a new idea for the preparation of oleogels, and also lay a theoretical foundation for the application of ultrasonic treatment in oleogels.     

Experimental studies on the effect of ultrasonic treatment and hydrogen donors on residual oil characteristics

Residual oil, the residue after the distillation of crude oil, imposes deleterious effects on refinery due to its high viscosity and asphaltene content. In this context, ultrasonic technology has been widely applied in refining processes given its high efficiency and minimal environmental impacts. To guide the selection of operation parameters, in this work, we probed the effect of treatment duration, power, and hydrogen donor on the characteristics of residual oil under ultrasonic treatments. Underlying mechanisms of ultrasonic treatments, in the absence and presence of hydrogen donors, were verified through systematically analyzing viscosity, component conversion, molecular weight, hydrogen distribution, and functional groups of residual oil. While viscosity reductions under low-power density treatment are caused by colloidal system disaggregation, high-power density treatment can bring in both chemical bond cleavage and colloidal system disaggregation. In addition, adding hydrogen donor can effectively prevent radical recombination, and thus increases the yield of saturate. These results provide fundamental understandings on the effects of ultrasonic treatments.     

Application and mechanism of ultrasonic static mixer in heavy oil viscosity reduction

In the present study, heavy oil viscosity reduction in Daqing oil field was investigated by using an ultrasonic static mixer. The influence of the ultrasonic power on the viscosity reduction rate was investigated and the optimal technological conditions were determined for the ultrasonic treatment. The mechanism for ultrasonic viscosity reduction was analyzed. The flow characteristics of heavy oil in the mixer under the effect of cavitation were investigated using numerical modeling, and energy consumptions were calculated during the ultrasonic treatment and vis-breaking processes. The experimental results indicated that the ultrasonic power made the largest impact on the viscosity reduction rate, followed by the reaction time and temperature. The highest viscosity reduction rate was 57.34%. Vacuole was migrated from the axis to the wall along the fluid, accelerating the two-phase transmission and enhancing the radial flow of the fluid, which significantly improved the ultrasonic viscosity reduction. Compared to the vis-breaking process, the energy consumption of ultrasonic treatment process was 43.03% lower when dealing with the same quality heavy oil. The optimal process conditions were found to be as follows: ultrasonic power of 1.8 kW, reaction time of 45 min and reaction temperature of 360 °C. The dissociation of the molecules of heavy oil after ultrasonication has been checked. After being kept at room temperature 12 days, some light components were produced by the cavitation cracking, so the viscosity of the residual oil could not return to that of the original residual oil, which meant that the “cage effect” was not reformed.     

Effects of low-frequency ultrasonic pre-treatment in water/oil medium simulated system on the improved processing efficiency and quality of microwave-assisted vacuum fried potato chips

The effects of low-frequency ultrasonic pre-treatment in water/oil medium simulated system on the improved processing efficiency and quality of microwave-assisted vacuum fried potato chips were investigated. The water medium system (distilled water and 5% NaCl osmotic solution) and oil medium system (90 °C) were designed with different power levels of ultrasound to simulate the ultrasonic conditions. Results showed that the changes of moisture content, water loss, solid gain and dielectric properties of potato slices were facilitated by the ultrasonic treatment. LF-NMR analysis showed the binding force between the moisture and structure in the material was significantly (p < 0.05) weakened. The changes become greater with the increase of ultrasonic power levels. Microscopic channels and disruptions were induced on the microstructure by the ultrasonic treatment. The effective moisture diffusivity of vacuum fried (VF) potato chips was increased by about 56.2%-67.0% and 53.9% with the combination of microwave energy and the ultrasonic pre-treatment in water and oil medium simulated system, respectively. The oil uptake, hardness, shrinkage, total color change and water activity of vacuum fried samples were significantly (p < 0.05) decreased by the assist of microwave energy combined ultrasonic pre-treatment.     

Impact of ultrasonic treatment process on pour point of vegetable oils based liquid insulation

This study presents an application of ultrasonic technology in the high voltage liquid insulation domain towards the reduction of pour point of vegetable oil samples for the utilization of vegetable oils as liquid insulation in cold climate areas on power transformers. Pour point reduction has been achieved by processing the vegetable oil samples by using ultrasonic treatment process with 100 W and 30 kHz ultrasonic waves for various exposure times of 15, 30, 45 and 60 min. Edible vegetable oils such as sunflower oil, palm oil, sesame oil and non edible vegetable oils such as honge oil, neem oil and punna oil are considered as two categories of vegetable oils for this experimental investigation. Ultrasonic treatment process results in the reduction of pour point of vegetable oils to meet out the standard value of pour point for liquid insulation as per IEEE Standard C57.147, 2018. A significant reduction in pour point temperature of vegetable oil samples have been obtained with an increased exposure time. The obtained variations in pour point after exposure with ultrasonic waves may be due to the possible changes in crystallization kinetics of fatty acids components of vegetable oil samples due to energy input of ultrasonic waves. The experimental results have given a way towards the positive encouragement and development with ultrasonic treatment for achieving low pour point vegetable oils as liquid insulation in power transformers for applications on cold climatic areas.     

超声促进胶体聚沉作用的研究

本文研究了超声促进胶体聚沉作用，选用了具有代表性的原糖溶液和老抽酱油为研究对象，研究结果表明，适宜的超声参数能十分显著加速胶体的聚沉，为物理场手段降去胶体提供一个新的途径。     

Ultrasound-assisted alkali removal of proteins from wastewater generated during oil bodies extraction

In this study, an ultrasonic-assisted alkaline method was used to remove proteins from wastewater generated during oil-body extraction, and the effects of different ultrasonic power settings (0, 150, 300, and 450 W) on protein recovery were investigated. The recoveries of the ultrasonically treated samples were higher than those of the samples without ultrasonic treatment, and the protein recoveries increased with increasing power, with a protein recovery of 50.10 % ± 0.19 % when the ultrasonic power was 450 W. Amino acid analysis showed that the amino acids comprising the recovered samples were consistent, regardless of the ultrasonic power used, but significant differences in the contents of amino acids were observed. No significant changes were observed in the protein electrophoretic profile using dodecyl polyacrylamide gel, indicating that sonication did not change the primary structures of the recovered samples. Fourier transform infrared and fluorescence spectroscopy revealed that the molecular structures of the samples changed after sonication, and the fluorescence intensity increased gradually with increasing sonication power. The contents of α-helices and random coils obtained at an ultrasonic power of 450 W decreased to 13.44 % and 14.31 %, respectively, whereas the β-sheet content generally increased. The denaturation temperatures of the proteins were determined using differential scanning calorimetry, and ultrasound treatment reduced the denaturation temperatures of the samples, which was associated with the structural and conformational changes caused by their chemical bonding. The solubility of the recovered protein increased with increasing ultrasound power, and a high solubility was essential in good emulsification. The emulsification of the samples was improved well. In conclusion, ultrasound treatment changed the structure and thus improved the functional properties of the protein.     

Effects of homogeneous and ultrasonic treatment on casein/phosphatidylcholine complex-emulsions: Stability and bioactivity insights

Casein (CAS), a typical protein emulsifier, has functional properties limited by its chemical structure in practical production applications. This study aimed to combine phosphatidylcholine (PC) and casein to form a stable complex (CAS/PC) and improve its functional properties through physical modification (homogeneous and ultrasonic treatment). To date, few studies have explored the effects of physical modification on the stability and biological activity of CAS/PC. Interface behavior analysis showed that compared to homogeneous treatment, PC addition and ultrasonic treatment could decrease the mean particle size (130.20 ± 3.96 nm) and increase the zeta potential (−40.13 ± 1.12 mV), indicating the emulsion is more stable. The chemical structural analysis of CAS showed that PC addition and ultrasonic treatment promoted changes in its sulfhydryl content and surface hydrophobicity, exposing more free sulfhydryl groups and hydrophobic binding sites, thereby enhancing its solubility and improving the stability of the emulsion. Additionally, storage stability analysis revealed that the incorporation of PC with ultrasonic treatment could improve the root mean square deviation value and radius of gyration value of CAS. These modifications resulted in an increase the binding free energy between CAS and PC (−238.786 kJ/mol) at 50 °C, leading to an improvement in the thermal stability of the system. Furthermore, digestive behavior analysis indicated that PC addition and ultrasonic treatment could increase the total FFA release from 667.44 ± 22.33 μmol to 1250.33 ± 21.56 μmol. In conclusion, the study underscores the effectiveness of PC addition and ultrasonic treatment in enhancing the stability and bioactivity of CAS, offering novel ideas for designing stable and healthy emulsifiers.     

Degradation of 4-chloro 2-aminophenol using combined strategies based on ultrasound,photolysis and ozone

The present work investigates the degradation of 4-chloro 2-aminophenol (4C2AP), a highly toxic organic compound, using ultrasonic reactors and combination of ultrasound with photolysis and ozonation for the first time. Two types of ultrasonic reactors viz. ultrasonic horn and ultrasonic bath operating at frequency of 20 kHz and 36 kHz respectively have been used in the work. The effect of initial pH, temperature and power dissipation of the ultrasonic horn on the degradation rate has been investigated. The established optimum parameters of initial pH as 6 (natural pH of the aqueous solution) and temperature as 30 ± 2 °C were then used in the degradation studies using the combined approaches. Kinetic study revealed that degradation of 4C2AP followed first order kinetics for all the treatment approaches investigated in the present work. It has been established that US + UV + O₃ combined process was the most promising method giving maximum degradation of 4C2AP in both ultrasonic horn (complete removal) and bath (89.9%) with synergistic index as 1.98 and 1.29 respectively. The cavitational yield of ultrasonic bath was found to be eighteen times higher as compared to ultrasonic horn implying that configurations with higher overall areas of transducers would be better selection for large scale treatment. Overall, the work has clearly demonstrated that combined approaches could synergistically remove the toxic pollutant (4C2AP).