松辽北部三肇地区泉四段高分辨率层序学研究

三肇凹陷扶余油层是松辽北部重点的油气勘探领域之一，主要为一套河流-浅水三角洲沉积，由于河道砂体单层厚度薄、侧向变化快，因此急需对该区开展精细的沉积微相研究，以指导后期地层-岩性油气藏勘探。以肇35区块为例，运用高分辨率层序地层学原理，结合岩心、录井、测井资料，识别层序界面特征，建立层序地层格架，并以短期基准面旋回为制图单元，编制高分辨率层序地层格架内的沉积微相展布图，阐明了其演化规律并建立沉积模式。研究表明：泉四段整体为一长期上升半旋回，内部分出7个短期基准面旋回(SSC1-SSC7)，主要发育三角洲平原、前缘2种亚相，进一步分为(水下)分流河道、(水下)决口扇、天然堤等多种微相。7个短期旋回中，SSC1至SSC2基准面缓慢上升，发育上升为主的不完全对称旋回；SSC3至SSC4基准面迅速上升，发育对称旋回和上升为主的不完全对称旋回；SSC5至SSC7基准面上升至最高，发育上升为主的不完全对称旋回。沉积相展布受基准面升降变化控制明显，泉四段自下而上经历了三角洲平原-平原、前缘过渡-三角洲前缘，局部浅湖的演化过程，整体为一次水体由浅变深的湖侵过程。

Study of High Resolution Sequence Stratigraphy of Quan 4th Member,Sanzhao Area in the Northern Songliao Basin

Fuyu oil layer of Sanzhao Depression is one of the important oil-gas exploration areas in the north of Songliao Basin. Fuyu oil layer mainly is a set of river-shallow water delta deposition. Because single layer thickness of channel sand body is thin and its lateral change is quick, the study of sedimentary microfacies is necessary to conduct, which guide the exploration of stratigraphic-lithologic oil and gas reservoirs. Taking Zhao 35 block as an example, applying the high-resolution sequence stratigraphy principle, sequence boundary is identified and sequence stratigraphic is divided. Taking short-term base level cycles as mapping units, sedimentary facies distribution maps within the framework of the sequence stratigraphic are drawn, the vertical evolution laws are analyzed and sedimentary microfacies model is established. The results show that Quan 4^th Member is a long rising half cycle, which can be divided into 7 short-term base-level cycles (SSC1-SSC7). The study area mainly develops delta plain and delta front subfacies, which can be further classified into (underwater)distributary channel, (underwater) crevasse splay, natural levee and so on. SSC1 and SSC2 periods of 7 short-term base-level cycles are unsymmetry cycles dominated by ascending half cycles because of slowly rising base level. SSC3 and SSC4 periods are unsymmetry cycles dominated by ascending half cycles and symmetry cycles because of quickly rising base level. SSC5 to SSC7 periods are unsymmetry cycles dominated by ascending half cycles and base level rises to the highest. Sedimentary facies and its distribution are mainly controlled by the change of base level. The study area experiences the evolution of delta plain subfacies-plain, front subfacies transition-delta front subfacies-local shallow lake facies. In vertical direction, Quan 4th Member exhibits a lake transgression process, whose sedimentary water changed from shallow to deep.