Crude oil is usually produced from the ground in a form of an oil-and-water emulsion. Prior to the treatment of crude oil in the refineries, the removal of water is necessary to prevent corrosion in the pipeline and the refinery equipment. Chemical agents and heat are the most common methods used in order to break the emulsion and enhance the separation of oil and water. The selection of the appropriate chemical (also known as demulsifier or emulsion breaker) is performed by an old, but well-accepted method in the oil industry, the "bottle test". Even though it is widely used, this procedure may be very tedious and time consuming. A typical set of bottle tests may include the testing of several hundred samples. This is partially due to the inability to preselect a promising set of demulsifiers, due to the variability of crude emulsions. As a result, the identification of new methods for fast evaluation of demulsifier performance is highly desirable.

During this study, the microfluidic platform was explored in an effort to identify a novel, fast, and accurate technique for the evaluation of crude oil demulsifiers. An X-junction microfluidic channel was used to generate water droplets in dry crude oil in a controlled manner. The addition of demulsifying agents in the oil phase resulted in the generation of droplets of varying size, and droplet coalescence downstream in the device. In an effort to better understand the microfluidic responses, and their relationship to the macroscopic performance of demulsifiers, these results were examined and compared against bottle test data of the crude oil/water emulsion. A strong correlation among the water drop and oil dryness performance (bottle test response) and the droplet coalescence and relative standard deviation of droplet size (microfluidic response) was observed. This study proves that the microfluidic platform has the potential to serve as an alternate and fast method for demulsifier screening.

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