Geochemical evidences of natural gas migration and releasing in the Ordos Basin, China

Natural gas, in its migration from source rocks to release zones may travel a long distance and change the geochemical characteristics of the rocks which it flowed through. In order to study the geochemical evidence of the natural gas migration, 24 samples were taken from different natural gas migration zones in the Ordos Basin, China. Five samples of them are from natural gas release zones (dark sandstone samples), 17 samples are from bleaching zones (bleaching sandstone samples), and two samples are from non-release zones (background samples). These samples were analyzed by organic and inorganic geochemical methods. The results of GC traces and ICP-MASS indicate that three zones show different organic and inorganic geochemical characteristics. Natural gas migration and releasing may be recognized by the geochemical evidences.