兴隆台地区沙三段砂体发育模式与岩性油气藏勘探

Sandstone distribution pattern and the exploration of lithologic reservoirs in the Es_3 member of Xinglongtai area,Liaohe Depression

兴隆台地区位于辽河坳陷西部凹陷。沙三段沉积时期,西部凹陷正处于凹陷的强烈断陷期,深水浊流沉积十分发育。当时,处于西部凹陷深陷带的兴隆台地区存在一个水下低凸起,阻止了来自研究区东部的近物源沉积物,浊流携带物被迫倾泄在水下凸起的东坡和深洼中。因此,兴隆台潜山的东斜坡及其向东延伸的深洼区发育上倾尖灭型和透镜状浊流砂体。这些浊流砂体纵向主要分布于层序界面附近的湖侵体系域下部和湖退体系域上部,最大湖泛面附近也有分布。砂体分布与层序界面的这种关系,反映断陷盆地断裂活动是导致湖水升降和发生浊流沉积的主要控制因素。砂体这种分布模式对预测岩性油气藏分布有指导意义。

The Xinglongtai area is located in the Western Sag of Liaohe Depression. In the Early Tertiary, the Western Sag was strongly extended, and turbidity deposit prevailed in the sag. Meanwhile, an underwater highland in the area blocked sand and gravel turbidity current from the eastern sources, and the turbidity was compelled to pour and deposit into the eastern slope of the highland and in the deep sag, forming up dip pinchout and lenticular sandstones. The sandstones occur vertically along sequence interfaces near the bottom of the transgressive system tract and the upper of the regressive system tract, and also along the maximal flooding surface. The distribution pattern of the sandstone （turbidity sandstone） along the sequence interfaces illustrates that faulting is the key-controlling factor on the changes of the water level and turbidity deposit. This distribution pattern of the turbidity sandstones is helpful to predict the distribution of lithologic reservoirs.