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运用含油气砂岩自生伊利石K-Ar定年方法,探讨分析了鄂尔多斯盆地东北部上古生界二叠系油气成藏的期次和时间。结果表明,二叠系不同含油气层段均不同程度地经历了与烃源岩两次主生烃作用相应的(175～155 Ma和145～115 Ma)原生油气成藏事件,峰值年龄主要集中在中侏罗世晚期的165 Ma和早白垩世早期的130 Ma。其中,下二叠统油气成藏期以较宽的时域分布(178～110 Ma),中、上二叠统则相对较晚地分布在(160～108 Ma),且上二叠统的起止时限主要集中在(160～125 Ma);二叠系样品年龄的空间分布总体呈现其油气成藏过程具有自南(178～122 Ma)向北(131～108 Ma)年龄逐渐减小的渐次运聚成藏特点。因此,包括上二叠统在内的二叠系不同层段均不同程度地经历了早-中侏罗世和早白垩世的两期原生油气成藏作用,上二叠统气藏现今显示的次生成藏特点很可能是在原生油气成藏基础上后期叠加改造或次生成藏的结果。
Using the self-generated illite K-Ar dating method of oil and gas sandstone, the period and time of Permian hydrocarbon accumulation in the Upper Paleozoic in the northeastern Ordos Basin were discussed. The results show that all the different oil-bearing intervals in the Permian experienced varying degrees of primary hydrocarbon accumulation (175-155 Ma and 145-115 Ma) corresponding to the two main hydrocarbon generation processes of the source rock, with the peak age mainly concentrated 165 Ma in the middle Middle Jurassic and 130 Ma in the early Early Cretaceous. Among them, the Lower Permian oil and gas accumulation period is relatively wide in the time domain (178-110 Ma), and the Middle and Upper Permian are relatively late in the distribution (160-108 Ma), and the Upper Permian The period of onset and end of the study mainly lies in the range of (160-125 Ma). The age distribution of the Permian samples shows a gradual decrease in oil-gas accumulation process from south (178-112 Ma) to north (131-108 Ma) Yun gather accumulation characteristics. Therefore, the different Permian stages, including the Upper Permian, experienced two stages of the early-Middle Jurassic and Early Cretaceous hydrocarbon accumulation. To some extent, the Upper Permian gas reservoirs now show The characteristics of secondary reservoir formation are likely to be the result of superimposed reformation or secondary reservoir formation on the basis of primary hydrocarbon accumulation.