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

Abstract

Emulsions are undesirable in the petroleum industry, as these often lead to numerous problems such as the corrosion of equipment, high-pressure drop in the pipeline, high pumping cost, and poisoning of the catalyst in upstream facilities, thus, add to the overall production cost. These emulsions are mostly encountered during enhanced oil recovery (EOR) because of the chemicals used in the process. Petroleum emulsions are commonly treated using surface-active agents known as demulsifiers. Demulsifiers can disrupt the interface between the water and the oil and separate them into individual phases. This study aims at optimizing some existing parameter conditions to obtain maximum demulsification efficiency of oil-in-water emulsions using two cationic demulsifiers namely, Cetyl-trimethylammonium bromide (CTAB), and Trimethyl-tetradecyl ammonium chloride (TTAC). The bottle test technique was used to investigate the effect of demulsifier concentration, settling time, and oil to water ratio on the demulsification efficiency. Experiments were designed using the Central Composite Design (CCD). The analysis of variance (ANOVA) was used to evaluate the significance of the experimental factors, and the factors were then optimized using response surface methodology (RSM). The results showed that all the factors studied significantly impacted the response (demulsification efficiency) and presented a p-values < 0.0001. The maximum demulsification efficiency of 82.6% and 80% were achieved at the optimum conditions of 850 ppm demulsifiers concentration within 10 h of settling time for both CTAB and TTAC emulsifiers.