The radiative properties in the near-infrared band of crude oil emulsion dispersed in the seawater

Abstract

The complex refractive index and radiative properties of crude oils are essential parameters for remote sensing, which is paramount for accurately and quantitatively detecting marine oil spills. In this study, the complex refractive index in the near-infrared band of crude oil from Daqing Oilfield is measured by the combined transmission - KK transformation method, and the absorption spectral features are analyzed. A modified-Mie method is employed to calculate the radiative properties of crude oil droplets immersed in an absorbing medium, and the impact of medium absorption is examined. Furthermore, the spectral absorption/scattering coefficient and scattering phase function of the oil-in-water (OW) emulsion dispersed in seawater are calculated, and the corresponding correlations between the radiative properties and chemical compositions of the crude oil are analyzed. The research reveals that the differences in the components of crude oil and seawater result in variations in the absorption peaks/troughs in their absorption spectra curve, which subsequently cause a gradual increase/decrease in absorption and scattering coefficients as the volume fraction of emulsion increases. The quantitative correlations of the absorption/scattering coefficient with the volume fraction of OW emulsion are presented, which are significant for improving the quantification monitoring of emulsified oil spills and identifying different types of pollutants.