Abstract: In consideration of the impact of oil pollution on marine ecological environment,real time on-line monitoring of oily wastewater discharged from offshore platforms is very necessary. A set of on-line monitoring system for oil in water based on ultraviolet fluorescence method was established in an oilfield in Bohai Sea. Through analysis of on-line monitoring data of offshore platforms in the past year,it is found that the measured oil concentrations at different temperatures decrease with the temperature rise. The flow of production water can cause turbidity in the water quality. Due to the influence of turbidity,there is a significant difference between on-line measurement values and platform laboratory measurement values. Due to oil pollution and biological adhesion,there may be significant data drift during the maintenance cycle. Therefore,it is necessary to compensate and correct the factors that have a significant impact on fluorescence characteristics （temperature,turbidity,etc.） and strengthen light window protection,in order to further improve the adaptability and reliability of the on-line monitoring system for oil in water in offshore platforms.

Key words: offshore oil platform, production water, oil in wate, ultraviolet fluorescence, on-line monitoring