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.
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.
- Particle size reduction of asphaltene
- Breaking down of asphaltene agglomerates
- Flocculation inhibition
- Viscosity reduction of the crude
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.
High Performance 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!
The table below gives you an indication of the approximate processing capacity of our ultrasonicators:
|Batch Volume||Flow Rate||Recommended Devices|
|1 to 500mL||10 to 200mL/min||UP100H|
|10 to 2000mL||20 to 400mL/min||UP200Ht, UP400St|
|0.1 to 20L||0.2 to 4L/min||UIP2000hdT|
|10 to 100L||2 to 10L/min||UIP4000hdT|
|n.a.||10 to 100L/min||UIP16000|
|n.a.||larger||cluster of UIP16000|
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Literature / References
- Reza Rezaei Dehshibi, Ali Mohebbi, Masoud Riazi, Mehrdad Niakousari (2018): Experimental investigation on the effect of ultrasonic waves on reducing asphaltene deposition and improving oil recovery under temperature control. Ultrasonics Sonochemistry Vol. 45, 2018. 204-212.
- Amani, Mahmood, Retnanto, Albertus, AlJuhani, Salem, Al-Jubouri, Mohammed, Shehada, Salem, Rommel Yrac (2015): Investigating the Role of Ultrasonic Wave Technology as an Asphaltene Flocculation Inhibitor, an Experimental Study. International Petroleum Technology Conference, Doha, Qatar, December 2015.
- Khosrow Naderi, Tayfun Babadagli (2010): Influence of intensity and frequency of ultrasonic waves on capillary interaction and oil recovery from different rock types. Ultrasonics Sonochemistry, Volume 17, Issue 3, 2010. 500-508.
- Goual Lamia (2012): Petroleum asphaltenes. In: Crude Oil Emulsions – Composition Stability and Characterization. InTechOpen 2012.
- Salehzadeh, M., Akherati, A., Ameli, F. and Dabir, B. (2016): Experimental study of ultrasonic radiation on growth kinetic of asphaltene aggregation and deposition. Canadian Journal of Chemical Engineering 94(11). 2202-2209.
Facts Worth Knowing
Asphaltenes consist primarily of carbon, hydrogen, nitrogen, oxygen, and sulfur, as well as trace amounts of vanadium and nickel. The C:H ratio is approximately 1:1.2, but varies depending on the asphaltene source. Asphaltene is defined as “the heaviest component of petroleum fluids that is insoluble in light n-alkanes such as n-pentane or n-heptane, but soluble in aromatics such as toluene” (Goual 2012)
Asphaltene can be identified and classified by the following characteristics:
- Solid: Asphaltene is a solid phase that is homogenized in the crude oil at reservoir conditions.
- n-Alkane insoluble: Asphaltene is classified as a solubility class since it has several structures, and thus, it is extremely difficult to provide a generalized structure for it. It is therefore defined as the highest molecular weight component in the crude oil that is insoluble in light n-alkanes such as n-pentane or n-heptane and soluble in aromatics such as toluene or xylene.
- Highly polar: Asphaltene is one of very few components of crude oil that is highly polar, in contrast to crude oil as a whole, which is considered nonpolar.
- Heteroatoms: Asphaltene is associated with hetero-atoms, mainly manifested in nitrogen, oxygen, and sulfur.