鄂尔多斯盆地三叠系延长组超低渗透储层致密史与油藏成藏史

The relationship between compacting history and hydrocarbon accumulating history of the super-low permeability reservoirs in the Triassic Yanchang Formation in the Ordos Basin

邓秀芹 刘新社 李士祥

Deng Xiuqin Liu Xinshe Li Shixiang

针对鄂尔多斯盆地湖盆中部三叠系延长组超低渗透岩性油藏形成机理,在包裹体宿主矿物成岩序列和均一温度分析基础上,明确了钠长石中的烃类包裹体形成于晚侏罗世早期的早期充注过程中,石英加大边中包裹体形成于早白垩世生排烃高峰期,含铁碳酸盐中的烃类包裹体形成于早白垩世末抬升降温过程中的早期阶段,为晚期充注的产物。同时结合现今储层孔隙发育特征,探讨生排烃高峰期储层古孔隙度和古渗透率,提出生排烃高峰期延长组超低渗透储层尚未形成,含铁碳酸盐胶结是造成储层致密的决定性因素。

According to the genesis of the super-low permeability reservoirs in the Late Triassic Yanchang Formation in the central Ordos lacustrine basin,diagenetic sequences and homogenization temperature of host minerals of inclusions were analyzed.Hydrocarbon inclusions in albite were formed during the early charging in the early of the Late Jurassic;hydrocarbon inclusions in quartz overgrowth developed during the peak hydrocarbon generation and expulsion in the Early Cretaceous;while those in ferruginous carbonates were generated during the early phase of the uplifting and cooling process at the end of the Early Cretaceous and were the products of late charging.Taking account of current development characteristics of pores in the reservoirs,palaeo-porosity and palaeo-permeability of reservoirs during the peak hydrocarbon generation and expulsion were discussed.It is proposed that the super-low permeability reservoirs had not been developed during the peak hydrocarbon generation and expulsion,and that cementing of ferruginous carbonates is the crucial factor for the compacting of reservoirs.

10.11743/ogg20090205