A stabilizing NMPC strategy with zone control for Electrical Submersible Pumps-lifted oil wells

Abstract

This work presents the first application of a stabilizing nonlinear model predictive control (NMPC) strategy for optimal operation and control of an Electric Submersible Pump (ESP)-lifted oil well system. The proposed stabilizing control law uses slacked terminal equality constraints to limit the control cost and a zone control scheme to deal with the up- and downthrust operational envelope-type ESP time-varying constraints, resulting in a nonlinear program more computationally tractable. The control scheme is also flexible to incorporate optimizing targets in its formulation aiming at economic performance improvements. The effectiveness of the proposal is carried out in a typical real well scenario for the nominal case. Analysis of optimizing target on the choke valve opening also demonstrates the economic gains in terms of ESP power savings. In addition, the computational effort evaluation corroborates with the feasibility of the controller for real-time implementation purposes.