Control of Electrical Submersible Pumps in two-phase liquid-liquid flow

• Grant number: 19/10249-2
• Support type: Scholarships in Brazil - Doctorate
• Effective date (Start): July 01, 2019
• Effective date (End): June 30, 2022
• Field of knowledge: Engineering - Mechanical Engineering - Transport Phenomena
• Cooperation agreement: Equinor (former Statoil)
• Principal researcher: Alberto Luiz Serpa
• Grantee: Mauricio Barrios Castellanos
• Home Institution: Faculdade de Engenharia Mecânica (FEM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 17/15736-3 - Engineering Research Centre in Reservoir and Production Management, AP.PCPE

Abstract

Electrical Submersible Pumps (ESP) are multi-stage centrifugal pumps used in the petroleumindustry as a method of artificial lift. These types of equipment operates submerged in the wellfluid and supply the energy required to transport the fluid to the surface. This fluid can be amixture of oil, gas, water, and sand. The case of water and oil characterizes the two-phaseliquid-liquid flow. ESP subjected to this type of flow are prone to form emulsions andintermittent flow patterns that can cause significant changes in behavior, referred here asoperational damages, such as process instabilities, decrease in flow rate and significantchanges in fluid viscosity, leading in the most critical case to a total shutdown of the system.Therefore, the pump control system should be able to maintain the operating conditionswithin ranges considered appropriates.Conventional control methods are based on a proper system representation. Therepresentations of ESP under liquid-liquid flow present several uncertainties that makenecessary the implementation of more robust control strategies. The presence of operationaldamage requires changes in the operating conditions to ensure the performance of thepumping system. The most widespread control method in this type of problem is based oncontrol of flow, pressure, and rotation, using proportional integral derivative (PID) controllers.Since the model has uncertainties and significant variations due to behavior changes, in manysituations operational conditions changes are required. It is appropriate to use DamageTolerant Active Control (DTAC) strategies, which consist of using signals obtained by themonitoring system, such as vibration, temperature, pressure, and flow, for the identification ofoperational damages, and then lead the system to operate in a suitable operational point.The objective of this research project is to propose and implement strategies of damagetolerant control in ESP systems submitted to liquid-liquid flow. These strategies should be ableto tolerate operational instabilities due to the formation of undesired flow patterns andemulsions, changing the operating point for a proper performance of the pump system. Forthis purpose, it is proposed a validation in experimental bench, based on the monitoring of thecondition of a centrifugal pump subjected to the liquid-liquid flow, in different operatingconditions, considering different flow patterns and emulsion formation, and finally, evaluatingthe performance of the designed controllers.