Experimental study and modeling of asphaltene deposition on metal surfaces via electrodeposition process: The role of ultrasonic radiation, asphaltene concentration and structure

Abstract

Asphaltene deposition in the wellbore is considered as a major operational challenge while producing some crude oils. It has been claimed that, external fields, such as electric field and ultrasonic radiation, could help tackling this issue. Although the effect of electric field on the aggregation size and the aggregation rate of asphaltene particles has been investigated before, its correlation with asphaltene deposition in the presence and absence of ultrasonic radiation is not known. In this study, the asphaltene deposition on metal surfaces was first mimicked using an electrodeposition process, and then the effect of ultrasonic radiation on electrodeposition of asphaltene were measured and analysed. Our observations showed that the electric filed itself does not unstable the dissolved asphaltene, and the asphaltene deposition on electrodes, under the effect of DC electric filed, first requires the formation of asphaltene aggregates. The maximum deposition was generated at 2 kV/cm, the exposure time of 300 s to the electric field, and the weight ratio of toluene to heptane 4.2%. It was also found that the structure and composition of asphaltenes, especially their polarity and aromaticity, affect asphaltenes deposition. Among different adsorption kinetic models, the nth-order kinetics model was selected to estimate the amount of deposited asphaltene. Finally, simultaneous ultrasound radiation during the process of electrodeposition, reduced the deposition rate on the metal blades from an average of 65 wt % of the total asphaltene content to 10 wt%. The findings of this study highlight the role of composition and structural properties of asphaltene on its surface deposition in the wellbore. More importantly, simultaneous radiation of ultrasonic waves during electrodeposition process confirms the effectiveness of ultrasonic radiation, as a quite new asphatene remediation technique.