Hammerstein-Wiener Model Identification of De-oiling Hydrocyclone Separation Efficiency

As the hydrocarbon discharge regulation is becoming more stringent, and emerging sensing and digitization technologies are applied in offshore oil and gas (OG) production, it is beneficial to upgrade the existing control systems by integrating these new measurements/information into the control loops. To achieve this goal, some proper control-oriented models need to be developed. Hydrocyclone-based de-oiling systems are commonly used in the produced water treatment after the three-phase separators in offshore OG production. Control-oriented modeling of these systems has proven a challenging task. In this paper, a system identification approach is taken and polynomial-type Hammerstein-Wiener (HW) models of the separation efficiency are identified for a de-oiling hydrocyclone system using the newly installed online oil-in-water (OiW) measurement. An exhaustive search is used to determine the order of the polynomials and transfer functions. The best model found was a Hammerstein model. The model obtained provides the opportunity to extend the existing de-oiling control framework to include the OiW measurement into feedback loops.