Patent ID: 8141646
Filing Date: 2012-03-27
Classification: E21B,F04D

Abstract:
1. A computer-implemented method of detecting an occurrence of gas lock in a multi-stage electrical submersible pump assembly for pumping fluid in a well bore, the well bore extending downward from a surface, the assembly including a multi-stage electrical submersible pump having an inlet and a discharge, a pump motor to drive the pump, and a discharge line for transporting pumped fluid from the pump discharge to the surface, the method comprising: monitoring via a sensor an instantaneous value of a property of a fluid associated with an electrical submersible pump assembly; and comparing the instantaneous value to a threshold value over a predetermined duration by a controller configured to receive data from the sensor and to detect the occurrence of gas lock in the electrical submersible pump assembly, wherein the sensor includes one or more of the following: a differential pressure gauge for measuring a differential pressure of the fluid between the pump inlet and pump discharge, a pressure gage located in a pump stage located toward the inlet to measure a pressure, a fluid temperature sensor located toward the discharge, a free gas detector located in a pump stage near the pump discharge, an electrical resistivity gage located within the pump, a flow meter located within surface production tubing, and a vibration sensor attached to a tubing string to measure an acceleration of the fluid within the tubing string to determine a vibration signature responsive to the measured acceleration of the fluid.