南海北部陆架盆地非构造油气藏

南海北部陆架盆地内具有形成非构造油气藏的有利条件。在历史时期内水平面的频繁变化,使得岩性带在纵横向上都发生交织变化而产生岩性油气藏,尤其是在盆地低水位期形成的盆底扇、斜坡扇等低位扇;历史时期构造活动频繁,形成多个构造面和构造不整合,与之相适应的产生了多种不整合油气藏等。勘探实践与研究成果表明,海域盆地内的非构造油气藏前景区主要有:(1)深水区的盆底扇发育区,如琼东南盆地中央坳陷、珠江口盆地白云凹陷;(2)大型古三角洲的前缘区,如莺歌海盆地临高构造带和珠江口盆地惠州凹陷;(3)斜坡区及隆起区的不整合尖灭带或剥蚀带,如莺歌海盆地莺东斜坡带、琼东南盆地崖城13-1构造带;(4)莺歌海盆地底辟周缘构造背景上的陆架、陆坡、盆底砂岩体等。

Non-structural reservoirs in northern shelf basins of South China Sea

The northern shelf basins of South China Sea have the favorable conditions for the formation of non-structural reservoirs. In the geological history, frequent sea level fluctuations resulted in both vertical and lateral lithologic variations, leading to the formation of lithologic reservoirs, especially the low-level fans deposited on both the basin floor and slope during the lowstand. Frequent tectonic movements in the geological history resulted in many structural planes and structural unconformities, and so various types of unconformity reservoirs had correspondingly been formed. Exploration practices and research achievements show that the potential areas for non-structural reservoirs in offshore basins are as follows: (1) deep water areas where submarine fans are well developed, such as the central depression in Qiongdongnan basin, and Baiyun sag in Zhujiangkou basin; (2)frontal areas of large paleodeltas, such as Yingdong slope zone in Yinggehai basin and Yacheng 13-1 structural zone in Qiongdongnan basin; (3)sandbodies developed on the shelf, slope and basin floor around the diapiric structures in Yinggehai basin.