南海北部超深水区兴宁凹陷古近纪沉积充填特征

探讨南海北部兴宁凹陷古近纪沉积充填特征,为超深水油气勘探提供基础地质依据。结合邻区研究成果,通过系统的地震层序地层学和地震相等综合分析,表明兴宁凹陷古近系文昌组、恩平组和珠海组之间均为不整合接触;古近系共识别出12个Ⅲ级层序。文昌组、恩平组为陆相湖盆沉积,具有缓坡带三角洲发育、缓坡浅水区滨浅湖发育、陡坡带扇三角洲发育及凹陷中心部位半深湖-深湖发育的特点;珠海组则为浅海三角洲沉积。总体的海侵沉积过程形成了恩平组湖相泥岩烃源岩与文昌组和珠海组砂岩储层的时空组合,指示研究区具有一定的油气勘探潜力。

Characteristics of deposition filling of Paleogene in the modern ultra deep water area of Xingning sag in the north area of South China Sea

The sedimentary and filling characteristics of Paleogene in the Xingning depression are studied in order to provide geological basis for the hydrocarbon exploration in the modern ultra deepwater area.On the basis of systematic analysis of seismic sequence stratigraphy and seismic facies,combined with the previous research results in adjacent area,it is showed that unconformity contact occurs among the Paleogene Wenchang Formation,Enping Formation and Zhuhai Formation in the Xingning depression and a total of 12 Ⅲ-sequences are recognized in the Paleogene.Terrestrial lacustrine deposition occurs in the Wenchang and Enping Formation,with delta deposition on gentle slope zone,shore to shallow lake on gentle slope shallow water zone,fan delta on steep slope zone and semideep-deep lake on depression center.Shallow delta deposition occurs in Zhuhai Formation.The overall process of transgressive sedimentary forms the space-time combination of the lacustrine mudstone source rocks in Enping Formation and sandstone reservoir in Wenchang Formation and Zhuhai Formation,a favorable oil and gas exploration potential in the study area.