Abstract:

Characterized by higher contents of methane, the lower Paleozoic dissolved gases in central gas field in Erdos have a little amount of heavy hydrocarbon and non- hydrocarbon compositions basically indicating a dry gas feature of high-over maturation(C₁/C_1-5>0.95). Differences between "East block & West block" in compositions of the lower Paleozoic dissolved gases(high contents of heavy hydrocarbon C₂⁺,benzene,toluene in compositions of dissolved gas in the east block while in the west block above compositions are either very low or absent) reveal that east and west block dissolved gases come from different sources. Dissolved gases from the east block are combinations of coal-formed gas in the upper Paleozoic and oil-type gas in the lower Paleozoic, whereas dissolved gases from the west block mainly come from oil-type gas in the lower Paleozoic.

Key words: lower Paleozoic, dissolved gas, Coal-formed gas, Oil-type gas, Ordos