A new method to select demulsifiers and optimize dosage at wet crude oil separation facilities

The current practice for crude oil demulsifier selection consists of pre-screening of the best performing demulsifiers followed by field trials to determine the optimum demulsifier dosage. The method of choice for demulsifier ranking is the bottle test. As there is no standard bottle test method, there are different methodologies reported in the literature. In this work, a new approach to bottle test and field trial was described which improved significantly the selection and dosage of the demulsifier. The bottle test was optimized by measuring an accurate mass of demulsifier. This method produces repeatable results. This bottle-test methodology was benchmarked against field trial results performed in oil processing plants. The field trials were also improved to avoid the accumulation effect of demulsifier, when optimizing their dosage. The field data for the optimization of demulsifier dosage was analyzed mathematically; and a graphical method to determine the optimum range is described.