辽河西部凹陷南段沙河街组三段震积岩特征及石油地质意义

Characteristics and petroleum geologic significance of seismites in the Member 3 of Shahejie Formation in south section of western sag,Liaohe depression

以区域构造背景为基础,通过对28口井近1000 m岩心的详细观察,在辽河西部凹陷南段古近系沙河街组三段中识别出典型的震积岩。其代表性沉积构造有:微断层和地裂缝、液化砂(砾)岩脉、震动液化卷曲变形、环状层理、负载构造、震积角砾岩和震浊积岩等,其中液化砂岩脉和震积角砾岩是主要类型;震积岩垂向序列划分为阶梯状断层段、液化砂岩脉层段、液化卷曲变形层段、震裂岩和自碎角砾岩层段、震塌岩和内碎屑副角砾岩层段、震浊积岩层段6个部分。震积岩研究有助于恢复古构造演化史和寻找岩性油气藏及构造-岩性油气藏;微断层、地裂缝和液化砂岩脉有利于改善储层条件,地震流体可促进烃源岩演化和成岩作用,同时震积角砾岩本身也是良好的储层。

Based on the analysis of regional tectonic setting,this study identifies typical seismites of the Palaeogene Member 3 of Shahejie Formation in the south section of western sag,Liaohe depression through detailed observation of cores approximately at a depth of from 28 drillholes.In the study area,representative sedimentary structures include micro-faults,ground fissure,liquefied sandstone （conglomerate） dykes,liquefied crinkled deformation caused by vibration,annular bedding,load structure,seismo breccias,and seismo turbidites.Of these,liquefied sandstone dykes and seismo-breccias are the major types.The vertical sequence of seismites is classified into six intervals,i.e.,step fault interval,liquefied sandstone dyke interval,liquefied crinkled deformation interval,interval of shattered rock and autoclastic breccia,interval of seismic-induced collapsed rock and intraclastic parabreccia,and seismo turbidite interval.Research of seismites helps the reconstruction of paleostructural evolution and the discovery of lithologic and structure lithologic hydrocarbon reservoirs.The presence of micro faults,ground fissure,and liquefied sandstone dykes is conducive to the improvement of reservoir conditions.Seismic fluid facilitates the diagenesis and evolution of hydrocarbon source rocks,while shattered breccia itself provides a good reservoir rock for hydrocarbon accumulation.