中国西部三大海相克拉通含油气盆地沉积-构造转换与生储岩

Sedimentary-tectonic transition and source and reservoir rocks in three major marine cratonic petroleum-bearing basins in western China

从含油气盆地沉积-构造演化的视角和盆地性质转变的动态观出发,把中国西部的油气盆地划分为4种类型,塔里木、四川和鄂尔多斯3个古生代海相盆地具有相似的地质演化和生储体系。泛大陆解体后,震旦纪—早中奥陶世为被动大陆边缘,中晚奥陶世至志留纪为夭折前陆盆地,代表三大陆块与周边洋盆的盆山转换。构造演化在克拉通上的地质响应表现在3个方面:一是沉积了2套烃源岩,即大陆边缘和“夭折”的前陆盆地阶段的沉积物;二是形成古隆起、古暴露和古岩溶,并在克拉通上有4个盆山转换面;三是晚古生代海侵盆地阶梯式地上超在早古生代海退盆地序列之上,导致下生上储和封隔盖层。

In the context of the sedimentary-tectonic evolution of petroleum-bearing basins and from the dynamic concept of transition of basin nature, petroleum-bearing basins in western China are divided into four types. The Paleozoic Tarim, Sichuan and Ordos marine basin have similar geological evolution and a source-reservoir system. After breakup of the supercontinent, all the three basins became passive continental margins from the Sinian to Early-Mid Ordovician and failed foreland basins from the Mid-Late Ordovician to Silurian, reflecting basin-range transition between the three blocks and ocean basins on their margins. The geological response of the tectonic evolution in the craton basins are manifested in three aspects: the first is deposition of two suites of source rock on continental margins and in failed foreland basins; the second is formation of paleo-uplifts, paleo-exposures and paleo-karst and occurrence of four basin-range transition surfaces on the cratons, and the third is that the Late Paleozoic transgressive sequences overlap on the Early Paleozoic regressive sequences in the step-like form, thus resulting in the formation of source rocks below and reservoir rocks above and cap beds.