珠江口盆地白云深水扇特征及油气成藏主控因素

揭示中国南海北部珠江口盆地白云深水扇的时空展布和油气成藏规律.无论在理论上、还是在向深海进军的油气勘探实践上都具有十分重要的意义.以层序地层学理论为指导的地震剖面精细解释,在白云凹陷北部陆坡区发现了大量深水扇沉积体,它由众多的盆底扇、斜坡扇、低位楔和下切水道构成.盆底扇和斜坡扇多期叠加,平面上成朵叶状,并与下切水道相连.研究表明,白云深水扇成藏的主控因素包括:(1)白云凹陷具有适合油气生成的活跃烃源岩;(2)拥有包括断层、不整合面、连续分布的砂体以及流体底辟带在内的发达的输导网络;(3)低水位期发育的深水扇体与其上覆的高水位期泥岩共同形成了有利的储盖组合;(4)超压的累积和释放对深部烃源岩的排烃起到了重要作用.因此,白云深水扇具有良好的成藏条件,是珠江口盆地深水勘探的有利目标.

Characteristics of the Baiyun Deep-Water Fan and Main Accumulation Controlling Factors in Pearl River Mouth Basin, South China Sea

It's very significant to discover the law of distribution of the time and space and oil-gas reservoir formation of Baiyun deep water fans in Pearl River Mouth basin, South China Sea. Based on the detailed seismologic interpretation guided by sequence stratigraphy theory, a lot of deep water sedimentary bodies, which composed of basin floor fans, slope fans, lowstand wedge and downcut channels, have been found in northern continental slope of Baiyun sag. The basin floor fans and the slope fans developing during several periods overlapped each other in vertical, distributed lobately horizontally, and connected with downcut channels. The research shows that the main accumulation controlling factors of the Baiyun deep-water fan include: (1) there are active source rocks with great petroleum generation potentiality in the Baiyun sag; (2) there developed conducting frameworks, which include faults, continue distribution sandstones, unconformable surface and diapiric zone; (3) the deep-water fans developed during low water periods and the mudstone layers over them developed during high water periods, which are both good factors for petroleum store and cover; (4) the accumulation and leakage of overpressure are important for the hydrocarbon expelling from source rocks. So the Baiyun deep-water fan has good accumulation conditions and it can be a favorable object for deep water exploration in the Pearl River Mouth basin.