Optimization of the demulsification of water-in-heavy crude oil emulsions using response surface methodology

The current work investigates the effect of oil to kerosene ratio, space velocity, temperature, demulsifier dosage, and wash water ratio on the performance of demulsification of water-in-heavy crude oil emulsions. For this purpose, an electrostatic desalting pilot plant has been utilized to carry out the experiments. Performance has been evaluated by determining the water removal efficiency (WRE) and the salt removal efficiency (SRE) based on operating parameters. Besides, the central composite design based on the response surface methodology was applied to design the experiments, model and optimize the water and salt removal processes. Moreover, the analysis of variance has been used to evaluate the significance of developed models, as well as operating parameters. It was observed that the proposed models for the WRE and SRE were found to be highly significant and presented the p-values < 0.0001. In addition, R2 and adjusted-R2 values were 94.78 and 92.01% for the WRE model, and 97.90 and 95.80% for the SRE model, which also emphasizes the high accuracy of both models. The obtained results demonstrated that the oil to kerosene ratio had the greatest impact on WRE as well as SRE compared to other studied parameters. The results show that the addition of the optimum value of 25 vol% kerosene to the emulsion could increase the maximum WRE and SRE by about 17.4, and 8.1%, respectively. At the same time, adding this volume of kerosene to the oil, in addition to such an increase in WRE and SRE, simultaneously reduced the optimum required demulsifier dosage and wash water ratio from 48 to 27 ppm and 8.5 to 5.5 vol%, respectively. Furthermore, the added kerosene also could increase oil space velocity from 0.5 to 0.7 1/h. The results of numerical optimization indicate that the optimal conditions to maximize the water and salt removal efficiencies were as follows: 75:25 (v/v), 0.7 1/h, 125 degrees C, 27 ppm, and 5.5 vol%, for oil to kerosene ratio, space velocity, temperature, demulsifier dosage, and wash water ratio, respectively. The maximum efficiency of water and salt removal from heavy crude oil under optimal values were achieved 92.89 and 98.73%.

Automated summary

This study investigates the effect of oil to kerosene ratio, space velocity, temperature, demulsifier dosage, and wash water ratio on the performance of demulsification of water-in-heavy crude oil emulsions. The results show that the oil to kerosene ratio has the greatest impact on water removal efficiency (WRE) and salt removal efficiency (SRE).