چكيده به لاتين
Produced oil from oil wells due to having large amounts of gas and brine and other impurities, should be processed at surface facilities (degassing, dehydration and desalting) before sending to refineries and export terminals. After degassing, desalting (separation of emulsion from the crude oil) is the first step of crude oil processing. Desalting is important for industrial and commercial reasons as well as for environmental protection. Traditionally, in order to decrease the salt content of the crude oil, different methods such as utilizing heat, adding chemicals (demulsifiers) and electrical energy are used in petroleum industry. However, during the years of oil production, the salt content of oil increases as the oil column shrinks and water level expands. These result in decreasing the quality of the produced oil.
Since there are limitations in utilizing the traditional methods of oil desalting, the use of novel technologies for desalting the crude oil seems to be essential. In this work, by conducting a series of experiments, using ultrasonic waves as a novel method for desalting the crude oil and reduction demulsifiers consumtion is presented. According to the results of the experiments, suggestions have been made to apply the desalination process using the ultrasonic waves. Compared to the traditional methods of desalting, this new method is simple and less expensive (due to lower consumption of demulsifiers), and has better results in reduction of the salt content from the crude oil. The results showed that with utilizing the ultrasonic waves, salt content of crude oil of unit Ahwaz 1 with 40 ppm demulsifier decreased from 471 mg/l to 76.18 mg/l, and salt content decreased from 9.19 wt% to 1.1 wt%, with a desalting rate of 83.38% and a dewatering rate of 88.03%. Also, salt content of crude oil unit Ahwaz 4 with 30 ppm demulsifier decreased from 353 mg/l to 49.2 mg/l, and the water content decreased from 11.36 wt% to 2 wt%, with a desalting rate of 86.06% and a dewatering rate of 82.4%. These results obtained at the highest temperature of 80 °C and frequency of 10 kHz, in which the consumption of demulsifiers was decreased by half. In other words, the ultrasonic method would reduce the consumption of demulsifiers while increasing the process efficiency. The research findings also showed that the combination of ultrasound and demulsifier could be the most efficient way of desalting. Using ultrasound waves without any demulsifiers depicted a small effect on desalting process.
Keywords: Crude oil, Ultrasound, demulsifier, Water emulsion in oil, Desalination
