Rapid determination of coalbed methane exploration target region utilizing hyperspectral remote sensing

This study reveals the common surface mineral characteristics over coalbed methane (CBM) enrichment regions from spaceborne Hyperion images and the possibility of hyperspectral remote sensing for prospecting coalbed methane exploration target region with an inexpensive, large-scale, rapid and convenient way. For this study, a typical scheme including bands removal, atmospheric correction, SNR estimation, Minimum Noise Fraction (MNF), Pixel Purity Index (PPI) and n-dimensional visualization, was applied on Hyperion image in Qinshui Basin, China, to accurately extract mineral endmembers. The endmember spectra of carbonate and clay mineral were identified based on the diagnostic absorption feature, while no endmember of ferrous iron mineral was found. The absorption feature parameters of carbonate (absorption position and especially asymmetric factor) and clay mineral (absorption position, left and right shoulder positions) were quantitatively estimated, which showed the endmember spectra of carbonate and clay mineral from hyperspectral images in this paper were correct. In addition, this study proposed an interesting research direction: measuring the asymmetric absorption factor to facilitate the identification of carbonates. Furthermore, Spectral Angle Mapper (SAM) and Spectral Feature Fitting (SFF) were used to map carbonates and clay minerals. Two assessment methods, visual interpretation based on field spectra and X-ray diffraction (XRD) analysis, were utilized to evaluate the mapping accuracy, which showed total agreements of 84.03% and 72.58%, respectively. The results in this paper suggested that both carbonates and clay minerals were rich while there was hardly any ferrous iron mineral, on the surface of CBM enrichment regions. In addition, another similar experiment was carried out in Ordos Basin and also showed similar surface mineral characteristics on CBM enrichment region.