松辽盆地三肇凹陷姚家组震积岩岩心识别

Core identification of seismite in Yaojia formation of Sanzhao depression in Songliao Basin

通过岩心观察和描述,结合地质背景研究,在松辽盆地三肇凹陷白垩系姚家组一段识别出震积岩。震积岩主要识别标志有液化砂岩脉、地层破裂构造、震裂缝和微断层、层内褶皱、泄水脉和层理变形、自碎角砾构造及不协调岩块等,并通过对震积标志特征和成因机制的研究,建立了震积岩垂向序列。震积岩的发现对三肇凹陷姚家组油气勘探的意义在于:地震活动可以降低储层孔渗参数、增加油气运移通道;地震引起的断裂可以使三角洲前缘水下分流河道和河口坝砂岩体形成良好的岩性圈闭;地震引起的三角洲前缘滑塌可以使浊积岩发育,为形成岩性油藏创造条件。

Seismite has been identified through core observation and description in conjunction with the study of geological background for the first member of Cretaceous Yaojia formation in Sanzhao depression of Songliao Basin. The identification signs of seismite include liquefacient sandstone dykes,formation breakdown structure,seismic fissure and microfault,intraformational fold,dykes derived from draining and deformed bedding,auto-clastic brecciated structure and discord rock block,etc. A vertical seismite sequence has been defined through the study of the characteristics and genetic mechanism of seismite marks. The discovery of seismite is of great significance to oil and gas exploration in Yaojia formation of Sanzhao depression. Seismic activity can reduce reservoir porosity and permeability and increase the pathways of hydrocarbon migration; the cracks caused by seismic activity can render good lithologic traps in the underwater distributary channels and mouth bar sands of delta front; the slumping of delta front induced by seismic activity may lead to turbidite development,providing conditions for forming lithologic reservoir.