Reduced Asphaltene Deposition with Power Ultrasonics

Asphaltene precipitation initiates numerous problems in oil production through reducing the permeability, changing the reservoir rock wetability, well bore blockage as well as creating a significant pressure drop around the production well. Ultrasonic asphaltene deagglomeration and dispersion prevents and remediates the formation of asphaltene flocs and their deposition.

The Problem: Asphaltenes in Crude Oil

Asphaltene is a solid present in crude oil that is considered as troublesome since it causes severe problems during production and transportation of crude from the drilling well. Asphaltenes are a very complex class of molecules and occur in different molecular structures – a factor which contributes to the problem as different forms of asphaltene cause problems with different degrees of severity. Asphaltene’s many different structures also makes it hard to generalize it into a specific family. Therefore, asphaltene is generally classified as a solubility class, since it is characterized as being insoluble in n-alkanes.
Typical problems caused by asphaltenes in crude oil are e.g., dense flocculations and deposits in the reservoir, boreholes, and transportation pipelines, which subsequently leads to operational and production complications and increased processing costs.

Asphaltene aggregation and flocculation depicted in the Yen model.
Courtesy of O. Mullins, Schlumberger.

The Solution: Ultrasonic Reduction of Asphaltene Precipitates

Precipitated and flocculated asphaltene particles can be remediated reliably by power ultrasonication. High-perfromance ultrasonication breaks asphaltene preciptates and flocculates down to a small particle size. Thereby, the asphaltene is dissociated back into very small particles, which do not clog or interfere with crude processing. Ultrasonic dispersers homogenize the particles in the crude oil. Often a chemical stabilizer is added to obtain long-term stability. This means, ultrasonication can reduce macro-structured asphaltene flocculation, which prevents asphaltene deposition on surfaces, pore plugging in the reservoir, wellbore plugging and build-ups in pipelines.

End of brine flooding under ultrasonic waves in different spots of micro-model.
Study and copyright: Deshibi et al.2018 (CC BY-NC-ND 4,0)

Research Proves Effectiveness of Ultrasonic Asphaltene Reduction

Dehshibi et al. (2018) studied the effects of low-frequency, high-power ultrasonication (30kHz) on asphaltene precipitation / flocculation and deposition under temperature control. Ultrasonication reduced asphaltene deposition. Ultrasonic waves and the generated acoustic cavitation caused increasing oil production by oil layering mechanism. Via sonication treatment it was not only possible to break up asphaltene agglomerates, but even to reverse the asphaltene deposition.
Moreover, the application of ultrasonication could prevent the blockage of throats and pores with large agglomerated asphaltene. Thereby, a pressure drop due to asphaltene deposition was avoided and the fluid flow in the pores and throats was improved. Using image analysis it was found that as a result of applying power ultrasound about 80% of precipitated asphaltene did not deposit. “In other words, 80% of asphaltene deposition reduced and consequently probability of blockage of micro channels reduces due to using ultrasonic.” (Dehshibi et al., 2018)
The findings of the study of Deshibi’s research group demonstrated that ultrasonic vibration and cavitation vibration can remove larger asphaltene aggregates from surfaces and move them into the bulk of flow. Furthermore, the ultrasonic processing reduced the amount of aggregated asphaltene (see figure below). Based on the image analysis, about 70% of asphaltene precipitated will not be deposited due to the subjection of the system to sonication.

End of brine (magnesium chloride solution) flooding under ultrasound waves irradiation: (a) the reversibility of the asphaltene deposition (b) asphaltene removal.
Study and copyright: Deshibi et al. 2018 (CC BY-NC-ND 4,0)

Nagy teljesítményű Ultrasonicators

Hielscher Ultrasonics is specialized in the development, prototyping, manufacturing and distribution of high-performance ultrasonic processors for heavy duty applications. Due to exceptional performance, endurance, robustness, and reliability, Hielscher ultrasonic systems are installed for petro-chemical applications worldwide. Typical applications include ultrasonically-assisted oxidative desulphurization, crude oil emulsification, asphaltene deagglomeration, scavenger dispersion, and viscosity reduction of heavy oils. Hielscher Ultrasonics’ industrial ultrasonic processors can deliver very high amplitudes, which are required for heavy duty applications. Amplitudes of up to 200µm can be easily continuously run in 24/7 operation. For even higher amplitudes, customized ultrasonic sonotrodes are available. Hielscher’s industrial systems easily handle very high viscosities and require low maintenance only.
Contact us now to get more information about ultrasonic asphaltene reduction, installation options and prices! Our well-trained, long-experienced will be glad to discuss your process requirements with you!
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