鄱阳湖浅水三角洲分支河道分布特征

Distribution characteristics of branch channel of shallow delta in Poyang Lake

为揭示浅水三角洲分支河道砂体储层平面展布规律,优选赣江中支入鄱阳湖形成的现代沉积三角洲为代表,利用高清卫星图像测量,统计了河道的分叉角度、分叉频率及河道的弯曲度,并设计了一系列垂直于物源方向的弧形剖面进行分支河道的宽度变化规律研究。结果表明,浅水三角洲分支河道的枝状分叉角度多在30°左右,且随着三角洲的推进,河道分叉的频率下降;河道宽度整体呈减小趋势,且与河道分叉有密切关系:河道宽度减小速率随河道分叉频率的降低而减小;河道接近分叉口过程中宽度明显增大,平均增幅达108%;分叉后的河道宽度明显小于分叉前的主干河道,平均减幅为49%。

Contemporary delta in Poyang Lake was preferred to quantitatively characterize the sand body distribution rule of branch channel of shallow delta. The branching angle, branching frequency and bending of channel were measured by high-definition satellite pictures. The width variation of the branch channel was studied by intensive sampling on the base of a series of parallel curved profiles vertical to the provenance direction. The result shows that the channel is a dendritic shape with the branching angle being about 30°, and the branching frequency decreases with the advancing of the delta. The channel width has a decreasing tendency with the advancing of the river, and the variation is serious influenced by the branching process. The channel width decreasing rate decreases with the decreasing of the branching frequency; around the branching location, the channel width increases about 108% in average; the branch channel decreases about 49% compared to the width of pre-branching channel.