沾化凹陷桩西地区沙三段-沙一段沉积相及其演化

Sedimentary Facies and Its Evolution of the 3rd-1st Members of Shahejie Formation in Zhuangxi Area,Zhanhua Sag

沾化凹陷桩西地区沙三段-沙一段沉积时期构造复杂,沉积类型多样。在研究区17口取心井岩心观察和描述的基础上,结合地震、测井、录井等资料,对桩西地区沙三段-沙一段的扇三角洲、浊积岩和滩坝等沉积体特征及演化进行了系统分析。在沉积相研究的基础上,根据单因素分析多因素综合作图法,选取砂砾岩厚度、砂砾岩百分含量、碳酸盐岩厚度及生物灰岩百分含量分布等单因素,对桩西地区沙河街组不同层段的沉积相平面展布特征进行了深入研究,并探讨了其演化规律。结果表明:桩西地区沙三段沉积时期在靠近长堤断层的湖盆边缘沉积扇三角洲砂体,在湖盆中心同生断层下降盘沉积浊积岩砂体;沙二段沉积时期在靠近长堤断层的湖盆边缘沉积扇三角洲砂体,在桩西潜山周缘和研究区西北边缘处沉积互层的砂质滩坝和生物滩;沙一段沉积时期主要在靠近湖盆边缘沉积生物滩和湖相碳酸盐岩,在湖盆中心部位沉积泥岩和油泥岩。

Complex geological structures and various sedimentary facies are typical characteristics of the3rd-1st members of Shahejie Formation in Zhuangxi Area,Zhanhua Sag.Based on observations and descriptions of cores from 17 wells in combination with seismic data and logging data,this paper systematically studies the sedimentary characteristics of fan deltas and turbidite fans and bar in these members of Shahejie Formation in the region.This study mapped and analysed the sedimentary facies distribution of different stratigraphic section in the Zhuangxi area based on the research of sedimentary facies and the single factor analysis with multifactor comprehensive mapping method.The single factors include sandstone thickness,sandstone strata thickness ratio,carbonate thickness and biological limestone percentage.The results show that fan deltas dominate the edge of the lake basin,close to Changdi fault of the 3rd member of Shahejie Formation.Turbidite fan dominates the declining of growth fault in the lake-basin center.While fan deltas exist in the edge of lake basin,next to Changdi fault in the 2nd member of Shahejie Formation.Sandy beach and life-form shoal are developed in the far northwest corner and around the Zhuangxi Buried Hill.Life-form shoal and lacustrine carbonate depositions are the main sedimentary facies in the 1st member of Shahejie Formation,while mudstone and oil shale deposit is found in the lake basin center.