冀中坳陷饶阳凹陷古近系层序地层学及演化模式

Sequence stratigraphy and evolution models of the Paleogene in Raoyang Sag,Jizhong Depression

根据陆相地层层序在地震剖面和电测曲线上的识别标志、岩石类型组合特点以及古生物等方面的特征,将饶阳凹陷古近系划分出3个二级层序、10个三级层序。其中层序Ⅰ、Ⅱ为裂谷初始期湖泊层序,层序Ⅲ、Ⅳ、Ⅴ、Ⅵ、Ⅶ为裂谷强活动期湖泊层序,层序Ⅷ、Ⅸ、Ⅹ为河流层序。其中裂谷期湖泊层序可以划分为3个体系域,即低位体系域、湖侵体系域和高位体系域,而河流层序可划分为基准面上升体系域和基准面下降体系域。针对研究区目的层段层序发育的特点,在层序地层单元划分和对比的基础上,结合构造发育史和地层厚度的变化所反映的古地形,建立了该区层序地层学演化模式,并初步分析了不同层序演化模式与油气的关系,预测了不同层序的地层油藏。

Based on the identification features of continental stratigraphic sequences on seismic profiles and wire-line logs, the characteristics of lithologic combination and palaeontology, the Paleogene in the Raoyang Sag is divided into three second-order sequences and ten third-order sequences.Third-order sequences Ⅰ and Ⅱ are lacustrine sequences developed in the initial rifting phase of basin formation, while sequencesⅢ , Ⅳ, Ⅴ , Ⅵ and Ⅶ are lacustrine sequences developed in the strong rifting phase, and sequences Ⅷ, Ⅸ and Ⅹ are fluvial sequences. Lacustrine sequences can be divided into three system tracts： low stand, transgressive and high stand system tracts. Fluvial sequences can be divided into base level rising and base level falling system tracts. Based on the identification and correlation of sequence stratigraphic units, sequence stratigraphic models of the target strata in the study area are established according to the characteristics of the stratigraphic sequences, the tectonic evolution history and palaeotopography reflected by the variation of strata thickness.A preliminary analysis is made on the relationship between sequence stratigraphic models and oil-gas exploration potentials, and the stratigraphic oil pools in each sequences are predicted.