基于河水位变化的层序地层模式——以济阳坳陷孤东油田为例

THE SEQUENCE STRATIGRAPHIC MODEL BASED ON THE VARIANCE OF RIVER LEVEL—TAKE THE GUDONG OILFIELD IN THE JIYANG DEPRESSION AS AN EXAMPLE

对渤海湾盆地济阳坳陷沾化凹陷上第三系馆陶组上段的沉积地层开展了高分辨率层序地层学研究,建立了层序地层格架模型和油藏精细地质模型,为提高油气采收率奠定了基础。与已有的国内外层序地层划分方法不同,文中依据沉积构造、岩性及颜色、粘土矿物类型和地球化学元素含量及其在垂向上的变化等特征所反映出的河水位的变化情况,划分出河流洪泛期、丰水期和枯水期;识别出洪泛期、丰水期和枯水期3种体系域类型,分别发育漫积、侧积和慢积3种准层序组沉积类型。由此建立了洪泛期体系域、丰水期体系域辫状河、丰水期体系域曲流河和枯水期体系域4种河流相沉积模式。

Taking the upper member of Guantao Formation of the Neogene in the Zhanhua Sag of the Jiyang Depression, the Bohaiwan Basin as an example, a study of the high-resolution sequence stratigraphy has been carried out. Based on the study, the paper presents a new principle and method for identifying sequence. Using the data from the sedimentary structure character, lithology ,color of rocks, the changing of clay types and geochemistry elements enrichment which reflect the change of river level, mark off the flooding system tract, high water level system tract and low water level system tract. The corresponding deposition processes of parasequence sets are flooding deposition, lateral accretion and slow deposition. Based on three system tracts, the facies model of four river types are established.