珠江口盆地深水区白云凹陷气烟囱特征及成藏模式

Characterisitcs and Accumulation Model of Gas Chimneys in Deep Water Area of Baiyun Sag,Pearl River Mouth Basin

以高分辨率三维地震资料为基础,结合地震属性,在珠江口盆地深水区白云凹陷识别出了大量的气烟囱现象。气烟囱可分为根部、过路区和顶部三个组成单元,各个单元具有不同的地震异常特征,主要通过同相轴的侧向变化,振幅、频率、连续性的局部增强和减弱,AVO响应以及它们的组合来识别。气烟囱根部是气体释压的初始部位,是气源供应区;过路区是流体泄压所经过的区带,在整个气烟囱结构的空间中占有主体地位;顶部常形成气藏。对白云凹陷建立了气烟囱顶部聚集和侧翼聚集两种气藏成藏模式,它们均由古近系文昌组—恩平组的河湖相沉积提供烃源。

Based upon high resolvable 3D seismic data as well as seismic attributes,a great many gas chimneys are discovered in deepwater Baiyun Sag,the Pearl River Mouth Basin.A gas chimneys can be divided into three components： the root,the leakage zone and the top of the leakage zone.Every one may be of different seismic reflection anomaly including lateral changes of events,local amplitude,frequency and continuity.The roots of gas chimneys are the initial parts of releasing gas pressure and also the source of supplying gas.The leakage zones are the main parts of whole gas chimneys for fluid to pass through.Gas reservoirs are commonly present at the tops of the leakage zones.Two models related with gas accumulation are built.One is the model of gas accumulation at the flanks and the other is the one at the tops of gas chimneys.The hydrocarbon in those chimneys is all derived from Paleogecene to Neogene lacustrine sediments.