Slugging attenuation using Nonlinear Model Predictive Control in offshore oil production

The increase in oil production in offshore systems can be achieved by active control, as state in the literature. However, the approach based on linear controllers has performance limitations in real applications, because of valve rate of change, as shown in this paper. As an evolution control approach, we show up the advantages of using a Nonlinear Model Predictive Controller (NMPC) by the Local Linearization on the Trajectory (LLT) algorithm, with the Fast Offshore Well Model (FOWM) as internal model, together with a first idea for tuning the controller parameters. Through a monovariable pressure control strategy, manipulating the production choke, we observed a potential production increase around 9.0% using NMPC. In addition, the multivariable advantage of NMPC strategy is stressed including the gas lift flow as a second manipulated variable. With this structure, it is possible to decrease the production choke variation in 76% and the oil production variability by 80% compared to monovariable structure, with similar production gain.