运用流体包裹体研究鄂尔多斯盆地上古生界天然气成藏

Study of gas charging in the Upper Paleozoic of Ordos Basin using fluid inclusion

鄂尔多斯上古生界砂岩储层流体包裹体均一温度具有明显的单峰分布特征，对应的均一温度分别为70～110℃、110～140℃、140-200℃，各温度段均与油气充注有关。在70～140℃温度段，有机质成熟并进入生油高峰期，水一岩作用活跃，机械压实、硅质胶结作用明显，形成大量流体包裹体，上古生界致密储层基本形成。在140-200℃温度段，有机质进入高成熟一过成熟阶段，水一岩作用不明显，仅形成少量的石英、方解石、白云石胶结物及极少量流体包裹体，包裹体中烃类成熟度和烃类组分与气田相似，是天然气的大量成藏期。因此，鄂尔多斯盆地上古生界致密储层形成时间要早于气藏形成时间。

The homogenization temperature of the fluid inclusion in the Upper Paleozoic sandstone reservoir of Ordos Basin was characterized by the clear single peak distribution corresponding to the homogenization temperature range of 70- 110℃, 110- 140℃ and 140-200℃, which were relative to oil-gas charging. In the range of 70-140℃, the organic matters matured and got the oil-generation peak. The interaction of water and rock flourished, and the mechanical compaction and siliceous cementing were evident. Great deals of fluid inclusions were formed, and the tight reservoir of the Upper Paleozoic was generated. In the range of 140-200℃ ,the organic matters entered into the high-post mature stage. The interaction of water and rock was not evident. A few quartz, calcareous, dolomite cement and fluid inclusion were formed. The composition and maturity of hydrocarbon in inclusion were similar as those in gas reservoir. There existed the main moment of gas charging in this stage. So, the formation time of tight reservoir in the Upper Paleozoic of Ordos Basin is earlier than that of gas charging.