A submersible pump, called as sub pump or electric submersible pump (ESP) is a device which has a motor close-coupled to the pump body. The whole assembly is submerged in the fluid, water to be pumped. Submersible pumps push the water, fluid to the surface as opposed to jet pumps working.
Submersible pumps including pump-end and motor assembled used installation are a multistage centrifugal pumps operating in a vertical direction. Produced water, liquids, after being subjected to great centrifugal forces caused by the high rotational speed of the impeller (about 3,000 rpm), lose their kinetic energy in the diffuser where a conversion of kinetic to pressure energy takes place. This is the main operational mechanism of radial and mixed flow pumps.
Nowadays, submersible pumps are found in many applications, a borehole and most typically used for residential, commercial, municipal and industrial water extraction (abstraction), water wells and in oil wells.