莺歌海盆地黄流组一段限定-非限定朵体构型及其演化

Confined to unconfined: architecture and evolution of lobes in the member 1 of Huangliu formation, Yinggehai Basin

浅海陆架扇是当前海洋沉积研究的前沿.基于三维地震资料、钻测井资料,利用地震相分析和沉积动力学方法,研究限定朵体、非限定朵体的构型、沉积演化及其动力学机制.研究结果表明:(1)陆架盆地浊流沉积体系发育水道-堤岸复合体、限定朵体和非限定朵体3类沉积单元.(2)浊流沉积体系受陆架盆地地形的影响,早期发育限定朵体,晚期发育水道-堤岸复合体、非限定朵体.(3)浊流在陆架盆地坡脚发生水跃,浊流动力学特征(浊流流速、Fr数)的变化--高速、超临界流在水跃后转换为低速、亚临界流,并伴随着浊流活动的侵蚀和沉积活动,导致了限定朵体向非限定朵体的转化.朵体构型及其演化研究对该地区优质储层预测具有重要指导意义.

Shelf fans are currently of great interest to submarine sedimentologists.In this paper,3 D seismic data,core logging data,seismic facies,and sedimentary dynamic of turbidity currents were used to obtain insight into the architecture and evolution of confined to unconfined lobe and dynamic mechanism,and three conclusions are made:(1)Turbidity flow depositional systems in a shelf basin are composed of three depositional elements which are channel-levee complex,confined lobe and unconfined lobe.(2)The sedimentary systems of turbidity currents were influenced by the topography of the shelf basin.In an early stage,confined lobes were formed in this study area.During the late stages of the flow,they tended to form channel-levee complexes and unconfined lobe.(3)Turbidity current forms hydraulic jump which mark the flow transition from high velocity,supercritical to subcritical flow at the toe of slope.The dynamic of turbidity currents is a key control for the transition from the confined to unconfined lobes.It is important for reservoir prediction to study the architecture and evolution of the lobes.