LIU M H, LI Y H, YANG M, et al. Influence and compensation of turbidity, temperature and pH on the fluorescence characteristics of offshore oil-in-water[J]. Journal of Henan Polytechnic University(Natural Science), doi: 10.16186/j.cnki.1673-9787.2024030074.

Received：2024-06-01

Revised：2024-07-25

Online：2024-09-13

Influence and compensation of turbidity, temperature and pH on the fluorescence characteristics of offshore oil-in-water(Online)

LIU Minghui¹, LI Yahui², YANG Min³, WANG Xinle¹, LIN Chen¹, WANG Hanyu³,FENG Yongkang¹,PAN Zihe⁴

(1.CNOOC EnerTech Safety and Environmental Protection Branch R&D Institute, Tianjin 300457;2. Laoshan Laboratory, Qingdao 266200;3.North China Sea Marine Technical Center, Ministry of Natural Resource,Qingdao 266033;4.Institute of Resources and Environmental Engineering,Taiyuan 030031)

Abstract: Objectives In order to solve the problems encountered during the process of measuring oil content  in produced water of offshore oil platforms by using UV fluorescence, such as large temperature changes, mixing of a small amount of suspended sediment, and pH changes caused by the addition of pharmaceuticals.Methods The research target of this study is the oil in water samples using Bohai Sea crude oil as the solute. Fluorescence spectrophotometer and in-house developed near-ultraviolet oil-in-water sensor were applied, based on the fluorescence spectral characteristics of the samples, the fluorescence peaks of the sample solution and its nearby spectral line data were analyzed and investigated to analyze the effects of temperature, turbidity and pH changes on the fluorescence spectra of the oil-in-water, and to compensate for the interferences caused by the changes of the different parameters and to correct for the interferences.Results The results show that the changes of temperature, turbidity and pH of the produced water of the offshore oil platform can affect the fluorescence intensity value, but the position of the fluorescence peak has not shifted significantly. After the analysis of the data collection, the fluorescence intensity is negatively correlated with the temperature, with a fitting coefficient of 0.9835; with the turbidity it is negatively correlated with a fitting coefficient of 0.9804; with the pH it is positively correlated with a fitting coefficient of 0.9752; by constructing the temperature, turbidity and pH compensation model, the relative error between the compensated fluorescence intensity value and the benchmark true value is calculated. By constructing the compensation models for temperature, turbidity and pH, and calculating the relative errors between the compensated fluorescence intensity values and the reference values, the overall relative error of the temperature compensated model is less than 5 % based on the fluorescence value at 25 °C, and less than 2 % up to 35 °C; the overall relative error of the turbidity compensation model is less than 2 % based on the 0 turbidity fluorescence value, and the overall relative error of the pH compensation model is less than 3% based on the actual empirical value of pH=6.7 for the platform water samples.Conclusions The compensation model can correct the influence of environmental changes on the detection of oil concentration in water by UV fluorescence method, and effectively improve the detection accuracy of UV fluorescence method.

Key words：oil-in-water; UV fluorescence; environmental factor; impact analysis; compensation

CLC: X853