Oil production is usually associated with the production of water, which may be found as a continuous phase or as a dispersed phase, in emulsions. Emulsions may be found in almost all the production stages: in reservoirs, production wells, production facilities, pipelines, in processing and in storage. The Electric Submersible Pump (ESP) is one of the methods employed in the industry to lift oil from fields located on land as well as at sea. Though this is the most appropriate artificial lift method for oil production when a considerable amount of water is produced, a pump’s efficiency is a greatly reduced when mixtures of water and oil are handled and emulsions begin to form. This paper intends to study the shearing imposed to fluids when flowing through a stage in a Electric Submersible Pump, and its effects in the degree of emulsification of the water and oil mixture. An experimental device was assembled consisting in two disks, one that spins and the other fixed. When flowing through them, a mixture of fluids is subjected to shearing and extensional deformation, and its degree of emulsification, i.e.: the average size and the bubble diameter distribution, may be measured upstream and downstream from the device.