Detecting the sources of methane emission from oil shale mining and processing using airborne hyperspectral data

Abstract

Methane (CH4) is one of important greenhouse gases that affects the global radiative balance after carbon dioxide (CO2). Previous studies have demonstrated the detection of known sources of CH4 emission using the hyperspectral technology based on in situ vertical CH4 profile or ground CH4 emissions data. However, those approaches have not yet to detect the unknown terrestrial sources of CH4 emission at local-scale or regional-scale. In this paper, the Shortwave Airborne Spectrographic Imager (SASI) was employed to detect concentrated sources of CH4 emissions based on the absorption of CH4 in the shortwave infrared (SWIR) region. As a result, a band ratio (namely RCH4, RCH4 = Band91/Band78) determined through wavelet transform singularity detection has proposed for detection of the terrestrial CH4 emissions sources using SASI hyperspectral radiance image data, and elevated CH4 locations in the oil shale retorting plants were identified. Additionally, SASI surface reflectance data and multiple reference spectra in the spectral angle mapper (SAM) were used to classify surface sources of CH4 release. High-resolution Google Earth imagery and thermal imaging camera (FLIR GF320) had also verified that the CH4 releasing sources are mainly the oil shale mining field and the retorting plant. Therefore, the high-resolution imaging hyperspectral spectrometer can provide a powerful tool for detecting terrestrial CH4 release sources at local-scale to reduce the greenhouse gas emissions related to hydrocarbon development.