Control strategy and algorithms to be utilized in a programmable logic control for automating injection rates of demulsifier and wash-water in a Gas-Oil-Separation Plant (GOSP). The logic control system can be programmed on a Distributed Control System (DCS) of the plant. The automating system is developed with the objective of optimizing demulsifier and wash water usage, improving plants water removal efficiency and minimizing process upsets from insufficient injection of demulsifier or wash water.