南海北部深水区油气勘探关键地质问题

Some Key Geological Issues on Oil and Gas Exploration in the Northern Deepwater Area of the South China Sea

南海北部深水区已经获得了重大的天然气发现,正逐渐成为全球深水油气勘探的热点区之一。通过与相邻陆架区以及世界上典型深水盆地的类比发现,南海北部深水区具有独特的石油地质特征。南海北部大陆边缘经历了从燕山期主动陆缘向新生代边缘海被动陆缘的转变,其演化过程和成盆机制复杂;陆坡深水区具"热盆"特征,凹陷发育超压,其生烃机制不明;深水区距离物源区较远,缺乏世界级大河系的注入,具远源沉积特征,未发现盐层及其相关构造,其油气成藏条件具有特殊性。此外,南海北部深水区海底地形崎岖、多火山,还面临着地震采集、处理等地球物理难题。因此,南海北部深水油气勘探需要在借鉴相邻陆架区和世界其他深水区成功经验的基础上,一方面深入研究其独特的油气地质特征,另一方面研发适应于我国深水环境的地球物理勘探新技术,切实推动深水油气勘探的进程。

The discovery of natural gas field in the deep water area of the northern margin of the South China Sea （SCS） made it as one of the hot areas in global oil and gas exploration. Comparative studies of deepwater basins in the world and the SCS adjacent continental shelf areas show that the deepwater area of the northern SCS is featured by unique petroleum geology as follows： tectonic transition from the active margin in Yanshan period to Cenozoic passive margin accounts for the complex evolution and basin formation mechanism. The thermal regime is hotter in the deepwater slope area and overpressure phenomenon is generally found in the depressions there, along with ambiguous hydrocarbon formation process. Due to the long distance from the provenance and lack of the material flux from the big rivers, this area is with distal sedimentation. No salt related tectonics is found in this area. All the phenomena mentioned above suggest its unique hydrocarbon formation. Additionally, the topography in deep water area of the northern SCS is rugged, along with multiple volcanoes, which undoubtedly arises difficulties for geophysical data acquisition and process. In a conclusion, the oil and gas exploration in deep water areas in SCS should apply the successful experiences to any other deep water areas in the world, and enhance the basic research on its structural and petroleum geology; meanwhile, the new geophysical technologies for deep water environment also needs to speed up the progress of oil and gas exploration.