琼东南盆地深水区松南-宝岛凹陷反转构造带发育特征及油气地质意义

Characteristics of inversion structure belts and their hydrocarbon geological significance in the Songnan-Baodao Sag in deep water area of the Qiongdongnan Basin

利用新三维地震资料对松南-宝岛凹陷反转构造带发育特征、形成期次进行研究,并从构造背景及力学机制两个方面探讨反转构造的成因机制。研究结果表明,松南-宝岛凹陷反转构造带主要发育一系列"上凸下凹"的大型褶皱背斜,伴生NWW向弱走滑断裂构造和NNW向张剪构造。反转构造及其伴生构造符合NEE右旋剪切应力场特征,形成时间与东沙运动一致,表明该反转构造带可能受晚中新世南海东北部东沙运动产生的右旋走滑应力场作用控制。反转构造有利于研究区圈闭的重建和改造,对琼东南盆地东部新区油气运移和重新优选分配的认识,具有重要的油气地质意义。

Three dimensional seismic data were used to describe the inversion structures and their formation stage in the Songnan-Baodao Sag.Combined with tectonic settings and geodynamics of the South China Sea,the mechanism of reverse structures was discussed.The results show that the inversion structure belts of Songnan-Baodao mainly formed by a series of large fold anticline.The anticline is characterized by a raised top and a concave bottom.A series of the weak strike-slip faults which are NWW trending and the tensional shear of NNW trending structures were detected along the inversion structures belt.The inversion structures and their associated structures conform to the characteristic of NEE right shear stress field.The inversion time is consistent with the Dongsha movement.That indicates the inversion structures can be controlled by the right-lateral sliding stress field generated by the Dongsha movement in the northeast South China Sea during the Late Miocene.The inversion structures are beneficial to the reconstruction and modification of traps in the study area.In addition,it has important geological significance to understand hydrocarbon migration and redistribution in the eastern new area of Qiongdongnan Basin.