Sedimentary Evolution of Gravity Flow Disposition of Yinggehai Formation in Qiongdongnan Basin
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摘要: 琼东南盆地是我国重要的油气富集区和水合物前景区,研究其深水沉积体系的展布和演化过程对于油气和水合物勘探具有重要意义。利用高精度三维地震资料,对琼东南甘泉凸起西部陆坡沉积体系进行研究。通过地震相识别的方法,分析了该地区浊积水道和滑塌体两种不同成因沉积体的沉积特征:浊积水道受底流作用影响,和陆坡走向平行,发育有不对称的天然堤;通过地震剖面的精细解释,在水道上部和下部发育两套滑塌体:下部滑塌体为正常滑塌体,由多期的滑塌过程组成,滑塌体叠置现象明显;上部为水道注入型滑塌体,由于外部流体的注入,使水体的密度和黏度下降,故滑塌范围较广,成层性明显。通过均方根属性切片与沉积模式重建的方法,将其沉积过程分成三期:即滑塌、侵蚀和再滑塌并受底流改造三个阶段。Abstract: Qiongdonan Basin is one of China's important hydrocarbon and hydrate-bearing basin. The study of its sedimentary characteristic and deep water deposition system evolution plays a significance role to the future exploration. Based on the high precision 3D seismic data, we analysis the depositional system of the western of Ganquan Uplift in the deep area of Qiongdongnan Basin. Through the method of seismic attribute extraction and recognition, we distinguish the sedimentary characteristics of two different sedimentary bodies, including turbiditic channel and slump. The channel, influenced by the bottom flow, is parallel with the continental slope of South China Sea and combining with the asymmetric levee. Through seismic section interpretation, we can also distinguish the two sets of slide disposition. The bottom slide is a kind of normal disposition with several variable period. The top slide disposition, due to the injection of bottom flow, has a lower density and viscosity. Because of the decrease of the density and viscosity of water, these kinds of slide have wide influence range and significantly layered property. With the help of RMS-attribute slice and sedimentary reconstruction of Yinggehai Formation, we divide the evolution into three stages: the stage of sliding, the stage of erosion by bottom flow channel, and the stage of re-sliding.
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Key words:
- slump /
- turbidite channel /
- sedimentary characteristics /
- sedimentary evolution /
- Qiongdongnan Basin
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