Reflectance spectroscopy and ASTER imagery applied to unravel mineral assemblage as surface indicators of hydrocarbon micro-seepage in the region of Khuzestan oilfields, Iran

Abstract

The present study makes an attempt to describe spectral characteristics of the surface features in some parts of the Khuzestan region, using reflectance spectroscopy and ASTER data related to the hydrocarbon micro-seepage in Maroun and Mansouri oil fields. The study involves surface sediment sampling with appropriate dispersion of the samples, and laboratory analysis in terms of sediment and mineralogy through spectroscopy analysis and geological map. Soil samples were collected from 45 and 20 locations points for Maroun and Mansouri oilfields, respectively. ASD-Fieldspec3 spectroradiometer and The Spectral Geologist (TSG) software were used to determine the hydrocarbon absorptions and their mineral constituents. Four classes were identified as hydrocarbon absorption ranges, i.e.: 1220–1320 and 1350–1550 nm indicating presence of light hydrocarbons; 1700–1750 and 2290–2360 nm pertaining to heavy hydrocarbons. Results suggest that Maroun oilfield samples have stronger absorptions in heavy hydrocarbons absorption but weaker for the Mansouri oilfield samples. The Mansouri samples have an acceptable absorption in light hydrocarbons absorption (1175 nm). Furthermore, these spectra were used as ground truth for creating mineral zonation maps using Spectral Angle Mapper (SAM) classification applied to ASTER data. The results also suggest that surface indicators of hydrocarbon are associated with alteration minerals such as kaolinite, siderite and goethite for the Maroun oilfield whereas Mansouri oilfield exhibits only kaolinite group of minerals. In addition, a comparison by reflectance between the contaminated and uncontaminated soil samples was also carried out.

Keywords

• ASTER
• Hydrocarbon micro-seepage
• Alteration minerals
• Fieldspec3
• Khuzestan-Iran