鄂尔多斯中部气田下古生界天然气的气源研究

鄂尔多斯中部气田下古生界天然气藏的气源是目前尚未解决的重要问题。利用天然气组分的碳、氢同位素、氩同位素、轻烃组成和生物标志物组成等多指标的综合对比 ,系统地研究了中部气田下古生界天然气的气源 ,明确了油型气和煤成气的主要分布区块 ,并估算了各区块气源的混合比。研究认为 ,鄂尔多斯中部气田下古生界天然气既有石炭系—二叠系来源为主的煤成气 ,又有下古生界自身来源为主的油型气。中部气田东部区块的天然气主要为煤成气 (石炭系—二叠系来源约占 70 % ) ,中部气田北部、西部及南部区块的天然气主要为油型气 (下古生界自身来源约占 6 0 %～ 70 % )。

THE SOURCES OF LOWER PALEOZOIC NATURAL GASES IN CENTRAL GAS FIELD IN ERDOS

The sources of the Lower Paleozoic natural gases in central gas field in Erdos are an important problem that has not been resolved by now. In this paper, the sources of the Lower Paleozoic gas reservoirs in central gas field in Erdos are systemically studied, by using the comprehensive source correlation of several indicators including carbon and hydrogen stable isotopes, argon stable isotope, light hydrocarbon and biomarker compositions. The main distribution areas of coal formed gas and oil type gas have been pointed out. The mixing ratios of gas sources from different areas in central gas field in Erdos are preliminary calculated. In central gas field in Erdos, there are both coal formed gas and oil type gas ,and the former comes from the Permo Carboniferous coal measures and the latter originates from the Lower Paleozoic marine carbonate. The coal formed gas is mainly located in the eastern part of central gas field (about 70% gas source from the Permo Carboniferous source rocks) while oil type gas exist in the northern, western and southern parts of in central gas field in Erdos ( about 60-70 percent gas source from the Lower Paleozoic carbonates).