南海冷泉分布特征及油气地质意义

DISTRIBUTION PATTERN OF COLD SEEPS IN SOUTH CHINA SEA AND ITS GEOLOGICAL SIGNIFICANCE

在系统收集和分析南海海底冷泉资料基础上,应用浅剖和多波束水体影像技术识别海底冷泉,结合地质条件综合研究南海冷泉分布特征,进而分析探讨其油气地质意义。研究结果表明,南海冷泉分布广泛,神狐、东沙西南部、东沙东北部、琼东南、西沙海槽、南沙南部和越南沿岸等海域均发现冷泉,冷泉分布水深为200~3 000m。海底冷泉与深部油气乃至浅层天然气水合物资源有着密切的成因联系。冷泉及其伴生物(冷泉碳酸盐岩)的探测与识别对海洋油气勘探,尤其是天然气水合物勘查的指示作用明显。浅剖和多波束水体影像技术不仅可以探测和识别冷泉,而且两者结合可实现低成本、高效率的海底地质异常体(冷泉碳酸盐岩、泥底辟及气烟囱等)的声学异常探测,极大地提高了海洋油气勘探及天然气水合物勘查的成功率。

In order to study the distribution pattern of cold seeps in the South China Sea,cold seep data is systematically collected and their oil and gas significance discussed.Upon the basis,sub-bottom profiling and multi-beam water column imaging techniques are adopted to identify submarine cold seeps.Studies show that cold seeps are widely distributed in the South China Sea,in the areas of Shenhu,Southwest Dongsha,Northeast Dongsha,Southeast of Hainan island,Xisha Trough,South Nansha,and coastal Vietnam.Cold seeps are mainly found in the areas 200 to 3 000 meters in water depth.Submarine cold seeps are closely linked to deep oil and gas and gas-hydrate resources.Cold seeps and associated rocks or so-colled seep carbonate rocks,are obvious indicators of marine oil and gas,especially gas hydrate.Sub-bottom profile and multi-beam water imaging technology is not only effective to detect and identify cold seeps themselves,but also helpful to detect acoustic submarine geological anomalies,such as cold seep carbonate rock,mud diapirs and gas chimneys,etc.with lowcost and high-efficiency.By using the technique,therefore,the success rate of marine oil and gas and gas hydrate exploration is greatly improved.