东海西湖凹陷平湖油气田花港组高分辨率层序地层特征

通过岩心观察、测井与录井资料,对平湖油气田花港组河流相地层进行了高分辨层序地层分析,识别出2个中期旋回(MSC1与MSC2)与20个短期旋回,建立了研究区的层序地层格架。短期旋回分4种类型并以非对称旋回为主。两个中期旋回为非对称旋回,但MSC2对称性更大,反映了可容纳空间的持续增加。在基准面旋回的控制下,沉积相呈现有规律的辫状河曲流河辫状河曲流河交替演化,在每个中期旋回均以辫状河开端,以曲河流结束,由于中期旋回在长期旋回中的位置不同,曲流河的特征也有所不同。位于中期旋回上升半旋回中部的曲流河及底部的辫状河是研究区的有利砂体,尤其是前者最为有利。

High Resolution Sequence Stratigraphic Characters in Huagang Formation of Pinghu Oil and Gas Field in Xihu Depression

High resolution sequence stratigraphic analysis is performed on fluvial facies formation of Huagang Formation in Pinghu Oilfield by core observation and logging and log data analysis. Two mid-term cycles(MSC1 and MSC2) and 20 short-term cycles are identified. A framework of sequence stratigraphy is established in studied area. Four types of short-term cycles are divided and unsymmetrical cycle is dominated. Two of the mid-term cycles are unsymmetrical, but MSC2 is highly symmetrical, which indicates that acceptable space increase is reflected. Under the control of base-level cycle, the sedimentary facies is evolved to the order of braid river-meandering river-braid river-meandering river alternatively. Each mid-term cycle is started from braid river and ended at meandering river. Because of mid-term cycle is on the different locations in the long-term cycles, thus the characteristics of meandering river are different. The meandering river on the middle and braid river on the bottom of the upper MSC cycle is the beneficial sandbodiy in the studied area, especially the former one.