Slug handling with a virtual harp based on nonlinear predictive control for a gravity separator

Abstract

This paper presents a nonlinear model predictive control approach for a three-phase gravity separator model. The aim of the controller is to dampen slug-induced, oscillatory disturbances in the inflow to the gravity separator. This means that, despite the disturbance, the levels of water and oil as well as the pressure should be held at constant operational setpoints. Additionally, a second objective is to dampen the outflows of water, oil and gas and hence keep too large oscillations in flows from downstream equipment. Several constraints are added such as the height of the weir, maximal and minimal allowable levels and pressures as well as constraints on the outflows.