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测试并分析了柴北缘各油气田的14个天然气样品的氦、氩稀有气体同位素比值,并进行了气源对比。研究发现,柴北缘天然气40Ar/36Ar值分布在951～1712,平均1098,多数样品40Ar/36Ar较通常认为源于侏罗系的天然气40Ar/36Ar明显偏高,研究认为本区不存在幔源高40Ar/36Ar流体的介入,储层年代效应也不可能造成天然气40Ar/36Ar明显偏高,因此柴北缘天然气40Ar/36Ar明显偏高,主要是由于源岩年代积累效应引起的。据估算,气源岩年龄分布范围为164.7～460.8Ma,平均为345.1Ma,可能多数来源于石炭系。这一认识得到了柴北缘广泛分布有石炭系源岩和已发现源于石炭系原油的支持。柴北缘石炭系天然气的发现预示了柴北缘石炭系是一个新的油气勘探层系,从而拓展了柴北缘天然气勘探领域。
The ratios of rare gas isotopes of helium and argon in 14 natural gas samples of each oil and gas field in the northern margin of Qaidam Basin were tested and analyzed. The results show that 40Ar / 36Ar values of natural gas in the northern Qaidam distribute in 951 ~ 1712 with an average of 1098. Most of the samples 40Ar / 36Ar are generally considered to be significantly higher in the 40Ar / 36Ar natural gas from the Jurassic. It is believed that there is no mantle-source high Therefore, the 40Ar / 36Ar natural gas in the north margin of the Qaidam Basin is obviously higher, mainly due to the accumulation effect of source rocks. However, the 40Ar / 36Ar fluids are not interbedded with the 40Ar / 36Ar fluids. It is estimated that the gas source rock age distribution range from 164.7 to 460.8Ma, with an average of 345.1Ma, probably from the Carboniferous. This understanding has been widely distributed in the northern margin of the Qaidam Basin with Carboniferous source rocks and has been found to be supported by the Carboniferous crude oil. The discovery of Carboniferous natural gas in the northern margin of the Qaidam indicates that the Carboniferous in the northern margin of the Qaidam basin is a new oil and gas exploration system and thus expands the field of natural gas exploration in the northern Qaidam.