Hydrocarbon micro-seepage detection by altered minerals mapping from airborne hyper-spectral data in Xifeng Oilfield, China

Abstract

Hydrocarbon micro-seepage can cause oxidation reduction reactions and produce altered minerals in surface sediments and soil. The typical altered minerals mapping by their diagnostic spectral features on hyper-spectral images is an important tool for the petroleum exploration industry. In this study, the airborne hyper-spectral data were used to investigate the altered minerals induced by hydrocarbon micro-seepages by spectral feature fitting (SFF) in the loess coverage area of Xifeng Oilfield. The results reveal that the distribution region of the altered minerals induced by hydrocarbon micro-seepage is larger than the known oilfield exploration area. The potential hydrocarbon micro-seepage region was also revealed by the distribution of altered minerals besides the known hydrocarbon area. A fast index was proposed by the absorption depths of clay and carbonate minerals for assessment of hydrocarbon micro-seepage. And it gave much clearer boundaries for the hydrocarbon micro-seepage in the loess coverage area than those by the altered mineral mapping. In addition, some field samples were analyzed by X-ray diffraction (XRD) and atomic absorption spectrophotometer to validate the results. Within the extents of hydrocarbon micro-seepage, there are lower contents of ferric iron and higher contents of carbonate minerals in these samples. Therefore, it is satisfactory to have the airborne hyper-spectral data to outline the extents of hydrocarbon micro-seepage for further hydrocarbon exploration in the loess coverage area.