As crude oil is always produced with water in the oilfield industry, very tight water-in-crude oil emulsions can form due to turbulence phenomena in the choke valve at the wellhead or in production pipelines. In order to better understand the main physicochemical and hydrodynamic parameters that govern the formation of concentrated emulsions through the choke-valve, we have developed a specific experimental liquid-liquid loop in the laboratory. The experimental set-up comprises (1) a flow entry section that allows the production of narrow size droplets distribution, (2) a vertical pipe containing a circular restriction, and (3) a zone of separation of water and oil (continuous gravity box settler). Droplets size upstream and downstream the restriction are measured by image analysis delivered by a high speed video camera. Pressure drop is measured across the orifice by a differential pressure sensor. The objective of the present study is to predict the evolution of the size distribution of the liquid/liquid dispersion downstream the restriction as a function of hydrodynamic parameters and physico-chemical properties of the system. First results show that the experimental set-up design provides an easy observation of droplets break-up through the restriction. They confirm the main tendencies proposed by global models in the case of dilute dispersions. In addition, experiments based on the observation of single drop break-up allowed to identify different break-up mechanisms and to derive relevant statistical quantities.

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