Performance Evaluation of a De-oiling Process Controlled by PID, H∞ and MPC

Three different control solutions, named PID, H ∞ and MPC, are proposed and compared for a de-oiling water treatment process used in offshore oil and gas production. All control solutions are designed using the plant-wide control strategy, i.e., the considered process consists of the upstream three-phase separator(s) and the downstream de-oiling hydorcyclone(s), such that their dynamic coupling is systematically coped with. The system performances are evaluated according to the conventional control criteria as well as the emerging online Oil-in-Water (OiW) measurement. The experimental results based on a lab-scaled pilot plant illustrate the huge potential and benefit of advanced control solutions to significantly improve the effluent water quality without sacrificing the system’s throughput, particularly when the process is subject to large disturbances (e.g., slugging inflow).