摘要
Based on gas molecular and stable carbon isotope analyses of 110 gas samples collected from the Upper Paleozoic in the eastern Ordos Basin,it has been concluded that the lower gas-bearing assemblages such as the Benxi,Taiyuan and Shanxi formations mainly contain dry gas characterized by high methane content,low C2+ alkanes content,high dryness and relatively high non-hydrocarbon content.Carbon isotopes of kerogen,desorption hydrocarbons of source rocks and cap rocks indicate that the source rocks have the characteristics of typical coal source rocks. Natural gas of different gas-bearing assemblages generates from underlying humic sources.