【作者】 孙启良；

【导师】 吴时国；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 海洋地质， 2011， 博士

【摘要】 南海北部深水区蕴藏着丰富的油气及天然气水合物资源。但是,由于我国对深水区油气及天然气水合物资源研究起步较晚,许多重要的科学和生产问题都尚未解决。本文根据高精度的三维(3D)和二维(2D)地震资料、多波束资料和钻井资料,对南海北部深水区(包括琼东南盆地南部、中建南盆地北部、珠江口盆地深水区等)的聚集流体逸散系统的特征、类型和影响因素及它们活动所造成的结果(沉积物变形和海底麻坑)进行了研究。通过研究,得到以下认识:(1)对南海北部聚集流体逸散类型进行了识别、划分和总结。南海北部的聚集流体逸散系统主要包括构造断层流体逸散系统、多边形断层流体逸散系统、溶蚀碳酸盐岩流体逸散系统、岩浆侵入流体逸散系统、砂体侵入流体逸散系统和管状流体逸散系统。其中多种流体逸散类型,如多边形断层、溶蚀碳酸盐岩通道和砂岩侵入体等是在南海北部地区首次发现的;(2)首次发现许多巨型麻坑,这些麻坑平均直径超过1.6公里,平均深度约100米。研究区内的巨型麻坑是目前世界发现的最大尺度的麻坑。麻坑作为流体逸散在海底的证据,具有重要的学术价值和实践价值。研究区内的巨型麻坑是流体逸散和底流活动共同作用下形成的;(3)在研究区首次发现一种新型的沉积物变形。这种沉积物变形在平面上表现为大型凹陷,直径达数公里,深度达几十米;三维上表现为圆锥形。通过仔细的分析,这种软沉积物变形是在红河断裂活动所引起的地震和局部隆起的触发下,下部的流体向上运移,使上部沉积物发生塑性变形和差异压实所形成的。根据这些认识,重建了其形成过程。对聚集流体逸散和软沉积变形的研究具有重要的意义。这主要体现在(1)它们能指示油气及天然气水合物的动态成藏;(2)可以造成海底不稳定,引起海洋石油钻探、海底管道和电缆布设的风险。更多还原

【Abstract】 The deep-water area of the Northern South China Sea (NSCS) is rich in hydrocarbon and gas hydrate resources. However, because the study of deep-water hydrocarbon and gas hydrate in NSCS is only carried out in recent several tens years, many important scientific and practical topics should be urgently studied. This thesis try to study the characteristics, classifications, influenced factors and their results (soft sediments deformation and mega-pockmarks) of focused fluid-flow escape systems in NSCS, including southern Qiongdongnan Basin, northern Zhongjiannan Basin and the deep-water area of Pearl River Basin, basing on high-resolution 3D seismic data, 2D seismic data, multibeam data and well data. Through the study, the thesis concludes that: (1) the focused fluid-flow escape systems in NSCS including tectonic faults, polygonal faults, carbonate dissolution, sandstone intrusion, igneous intrusion and pipes, and the escape systems such as, polygonal faults carbonate dissolution and sandstone, are first reported in NSCS; (2) documented the largest pockmarks in the worldwide. Here, these pockmarks are named mega-pockmarks. The average diameter of mega-pockmarks is above 1600 m and the average depth is ca. 100 m. The pockmarks are as the manifestation of fluid-flow escape on the seabed, which are important for the study of hydrocarbon exploration. The genesis of mega-pockmarks in the study area is caused by strong fluid-flow escape and bottom current together; (3) first documented a new type of soft sediment deformation. The soft sediment deformation is showed as depression-ridge structures on the seabed. The depressions are multi-kilometers in diameter and several tens meters in depth. Basing on careful observation and analysis of seismic data and multibeam data, we propose that this soft sediment deformation is attributed to fluid-flow escape and differential compaction, which are triggered by the earthquakes and uplifts related with the activities of Red River Strike-Slip Fault. The study of focused fluid-flow escape systems and soft sediment deformation is very important, because (1) they are usually related with hydrocarbon and gas hydrate accumulation and destroy and (2) they can cause seabed instabilities which should be considered when explorationists and engineers design wells and pipe locations.更多还原