Chaotic Dynamic Induced by PI Control in Offshore Oil Production Plants

Several dynamic behaviors exhibited in a representative model of a Petrobras offshore oil production plant were studied, considering both open-loop operation and closed-loop operation when using a feedback PI control scheme. The present work evaluated three different SISO control scenarios, taking into account three controlled variables in order to determine the suppression effect of the oscillatory dynamic behavior raised due to the slugging flow phenomenon. It was observed that in the PI anti-slug control scheme, when the pressure at the top of the riser was considered the controlled variable, the dynamics exhibited chaotic oscillations as a function of the PI tuning parameters. The chaotic behavior was characterized, and it was determined the control scenarios and tuning conditions that favor the appearance or impression of complex dynamics behaviors.