In modern process automation, the Oil and Gas industry is shifting toward Closed-Loop or Feedback process-control automation to constantly maintain the output at a predetermined set point by means of monitoring and controlling the vital process parameters.

Currently, most produced water treatment systems are acting as a non-feedback process or passive feedback control system (i.e. the outcome of treatment does not dynamically or actively influence the process). The development of an effective and dependable Closed-Loop control system is prevented by the lack of a reliable and accurate monitoring system that continuously measures the concentration of contaminates in the process. However, recent developments in Oil in Water (OIW) analyzers encouraged the authors to conduct a profound study on the development of a Closed-Loop System or Smart Water Discharge™ (SWD).

Goal-oriented Smart Water Discharge (SWD) allows the operator to set parameters for oil concentrations in overboard water at specific values (ppm); the Closed-Loop control system adapts the process conditions and/or employs the excursion tertiary water treatment equipment to maintain the set points.

This paper presents the concepts and algorithms of Smart Water Discharge (SWD), the essential components, the priority of a control system, the control functions, and operator-SWD interactions. Furthermore, the authors illustrate the results of field and lab testing for each component providing valuable information on selection and design of the system (including OIW analyzers, logic controllers and controlling elements).

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