珠江口盆地白云凹陷古近系沉积相类型

Types and Distribution of the Paleogene Sedimentary Facies in Baiyun Depression of Pearl River Mouth Basin

以珠江口盆地白云凹陷的钻井和地震资料为基础,根据测井相、地震相综合分析白云凹陷文昌组与恩平组主要层序的沉积相发育演化特征。通过有限的单井资料在白云凹陷共识别出了三角洲相、扇三角洲相及湖泊相三种沉积相;三角洲沉积相在测井曲线上表现为从下至上由细变粗的反旋回,局部出现次一级的正旋回;扇三角洲沉积相测井曲线整体表现为从下至上由细变粗的反旋回及次一级的反旋回;湖泊沉积相表现为以泥岩沉积为主,局部夹有砂坝或碳酸盐滩坝。研究区发育9种地震相类型,地震相证据充足,为研究沉积相发育规律提供了可靠的依据。研究表明盆地的持续沉降造就了白云凹陷深湖相发育时间长,形成厚层烃源岩;受番禺低隆起影响,白云凹陷北坡缓坡带发育三角洲相,在西南至南部陡坡带发育扇三角洲相,部分三角洲的发育具有继承性。

Based on the drilling and seismic data in Baiyun Depression,development and evolution of sedimentary facies are comprehensively analyzed in the Wenchang and Enping Formation,Baiyun Depression of Pearl River Mouth Basin. Through the limited well data,three sedimentary facies,delta facies,fan-delta facies and lacustrine facies,are identified in Baiyun Depression; Logging curve of delta facies shows an inverse cycle,but subset normal cycle in some parts; Logging curve( gamma-ray) of fan-delta curve shows an inverse cycle and subset normal cycle overall; Lacustrine facies mainly are mudstone deposition,partly mingled with sand bar or carbonate beach bar. Nine types of seismic facies are identified in Baiyun Dpression. The research shows that the continuinous subsidence of the basin causes the long time of the deep lacustrine facies development and the formation of the thick-layer resource rock. Influenced by lower Panyu Uplift,a delta facies developed in the northern gentle slope in Baiyun Depression,fan-delta facies developed from southwestern to southern abrupt slope. And the development of partial delta facies has a succession.