Wellhead optimization of the demulsification of water-in-oil emulsion using response surface methodology

Abstract

Stable emulsion formation is a common but undesirable phenomenon during enhanced oil recovery processes. Although much research has been conducted to examine the mechanisms of emulsification and demulsification, most of the studies were conducted offline on a laboratory scale and were aimed to optimize the separation-efficiency, which neither represents the actual well situation nor gives a direct measure of the oil recovery rate. Therefore, this study aims to conduct wellhead optimization of the demulsification process, targeting the enhancement in the oil production rate. The effect of the demulsifier dosage and the gas-lift rate on the production rate was investigated online, and the process was optimized using response surface methodology (RSM). The results revealed that both factors and their interaction significantly affected the production rate and presented P-values <0.05. A predictive model was developed for the production rate with R 2 value of 95.46% indicating the high accuracy of the model. The optimum conditions of 250 MSCF/day gas-lift rate and 25 Qt/day demulsifier dosage corresponding to 40 BOPD production rate were achieved. These conditions were verified online, with 0.25% error compared to the predicted value, confirming the excellent accuracy and reliability of the wellhead optimization results.