Innovative Brazil Deepwater BC-10 ESP Operation with Extremely Gassy Well to Mitigate Gas Locking

Abstract The paper reports on the innovative and integrated approach for the Brazil Deepwater BC-10 Electrical Submersible Pump (ESP) operation with extremely high Gas Oil Ratio (GOR> 30K scf/sb) condensate well to safely operate the system and applied surveillance and strategies on fluids with two phases, liquid – gas flow to avoid system instability and gas locking conditions. The Electrical Submersible Pumping (ESP) system applied in Brazil is a multistage centrifugal pump for high rate and high boost applications inside a vessel system (caisson) monitored by Pressure and Temperature sensors installed in each caisson, Venturi flowmeter at the discharge of the pump and motor winding temperature (MWT), ESP vibration and Motor External Pressure for safety operation and to help predict ESP performance. To operate Brazil ESP Caisson systems under extreme gas conditions, an integrated approach was performed to understand system uncertainties since previous attempts cause liquid Level (LL) instabilities with high probability of Gas Locking (GL) conditions causing pump trips due to low flow at the intake decreasing run life and possible pump failures. Considering the design of the system risks of liquid carry over the separated gas riser is also a problem to be managed. Extended study and analysis were performed to predict gas through the pump and detail mitigation plan for table operation of the ESP to increase reliability avoiding trips and gas locking conditions. GL is a condition that may lead to ESP performance problems including ESP failures, in case of prolonged operation. A correlation was used based on pump parameters to calculate in real time pump gas volume faction for safety operation to avoid ESP failures and monitor foam formation in the caisson annular to protect the system from LCO, what can result in integrity issues. Also, a combination of surveillance strategy was applied including VFD setpoints assessment, transient operations and controlling Caisson LL in a manual mode until stability is archived. The main technical contributions of this work are the detailed approach, modeling, and analysis for safety field operation of the Caisson ESP with extremely high GOR to increase pump reliability. This study includes strategies for field operation of the ESP under gassy conditions to mitigate gas locking and excessive trips to the pump.