Abstract:
The production rate, useful life and operating efficiency of electric submergible pumping systems (ESP) is improved by operating the system so that the motor is cooled by two passes of production. The two passes of production fluid are achieved by employing a shroud with the inlet at the opposite end of the production fluid intake or by installing the motor below the perforations that allow production fluids to enter a well. The motor is designed with an internal conduit through which the production fluids are pumped. Production fluids remove waste heat from the motor by passing in fluid contact with the exterior of the motor and again by passing through the internal conduit of the motor. The improved cooling permits the motor to be operated at a lower temperature improving life and efficiency, and/or to be operated at higher power at a similar temperature. Additionally, oversized and excess equipment is not required, further improving performance and economics for the user. In another aspect, the invention is a method of pumping fluids using a motor having vortex generators on its exterior surfaces or on the interior surfaces of a surrounding shroud, and a method for determining optimum well operating conditions.