Nonlinear Model-Based Control of Unstable Wells

Abstract

This paper illustrates the potential of nonlinear model-based control applied for stabilization of unstable flow in oil wells. A simple empirical model is developed that describes the qualitative behavior of the downhole pressure during severe riser slugging. A nonlinear controller is designed by an integrator backstepping approach, and stabilization for open-loop unstable pressure setpoints is demonstrated. The proposed backstepping controller is shown in simulations to perform better than PI and PD controllers for low pressure setpoints, and is in addition easier to tune. Operation at a low pressure setpoint is desirable since it corresponds to a high production flow rate. The simulation results are presented to illustrate the effectiveness of proposed control scheme.

Model-based control of slugging: advances and challenges

“…In this section, we briefly describe four lumped parameters models: the Jansen model for gas-lifted wells, the Storkaas and Jahanshahi models for risers with low-points, and the Di Meglio model, for vertically inclined wells. This list is not exhaustive and other efforts include the models proposed in Kaasa et al [2007], Da Silva and Nydal [2010]. An extensive comparison of the capabilities of these different models is presented in Jahanshahi and Skogestad [2011].…”

Nonlinear model-based control of two-phase flow in risers by feedback linearization

“…A back-stepping design has been used by Kaasa et al (2007) and Kaasa et al (2008) for nonlinear control of slug flow in risers. Di Meglio et al (2010a) proposed a partially linearizing feedback controller that uses the mass of liquid in the riser for state feedback.…”

Mitigação de golfadas em sistemas offshore utilizando modelo dinâmico simplificado.

“…Já o termo ( ) representa a transferência de massa causada pela massa que flui de uma seção para a outra. SKOGESTAD, 2003), "Modelo de Eikrem 1 ", "Modelo de Kaasa" (KAASA et al, 2007),…”