长江口外海域浅层气地震反射形态特征及分布

SEISMIC SHAPE FEATURES AND DISTRIBUTION OF SHALLOW GAS IN THE SEA AREA OFF THE YANGTZE RIVER ESTUARY

通过对长江口外海域浅层气地震反射特征的研究,发现该地区浅层气地震反射形态特征丰富,按不同形态特征分类如下:(1)按整体形态特征分为:幕状反射、柱状反射、气烟囱状反射;(2)按顶界面形态特征分为:不规则顶界面、较规则顶界面;(3)按侧面形态特征分为:侧面竖直、侧向突出;(4)按组合形态特征分为:垂向多层强反射、横向间断的浅层气反射、竖向变化的浅层气反射。总结了调查区内浅层气反射形态特征的分布规律,编制了长江口外海域浅层气分布图。讨论了浅层气反射区内部的强反射分布形态与浅层气空间运移路径的对应关系。

There are various kinds of shallow gas seismic reflections in shape in the region off the Yangtze River estuary.They can be classified into following categories：（1）According to general shape：the curtain-like reflection,the column-like reflection and the gas chimney-like reflection;（2）According to the shape of the top interface：shallow gas with irregular top interface and shallow gas with regular top interface;（3）According to the shape features on lateral：upright and protruded shallow gases;（4）According to the combined shape features：shallow gas with multiple-layer strong reflection in vertical direction,with reflection interrupted on lateral and with reflection varying in vertical direction.Based on the above mentioned shallow gas shape features,we mapped and summarized the distribution pattern of shallow gas in the region,and discussed the relationship between the strong reflections and the migration pathway.