南海北部神狐海域天然气水合物的地球物理识别及成因机理探讨

发布时间：2018-03-31 10:21

本文选题：南海神狐海域　切入点：砂岩型天然气水合物　出处：《中国科学院研究生院(海洋研究所)》2015年硕士论文

【摘要】：本文对南海北部神狐海域天然气水合物尤其是富砂储层水合物的地球物理特征及成因机理进行了研究。南海北部神狐海域GMGS-1钻探资料显示,SH4井在深度171-180m存在一个富砂储层,测井结果表明在含水合物沉积层具有高P-波速度、高电阻率、低伽马值、低密度的特征；而含游离气沉积层具有低P-波速度、高电阻率、低伽马值、低密度特征。伽马测井值比已钻获水合物层(SH2,SH3,SH7井)的伽马值明显偏低。利用测井P-速度与伽马测井值的交会分析区别出水合物层与游离气层。通过对三维地震资料解释,发现了SH4井位于峡谷底部一明显NE-SW向冲蚀沟或侵蚀水道内,其下方存在明显的滑塌作用。本文分析了该区砂岩储层水合物的成因机理,认为峡谷底部的浊流向下陆坡流动过程中,在狭窄的水道负地形中发生汇聚作用,速度增加,浊流厚度增加,携带沉积物的能力增强,会沉积较粗粒沉积物。同时,由于峡谷西侧壁沉积速率大,古水道被迅速充填掩埋在现今峡谷脊部之下,粗粒沉积得以保存,而且上部的细粒沉积形成良好的盖层,可以有效阻碍下部天然气的溢出,有利于砂岩型水合物形成。针对神狐海域含水合物层物性参数特征进行了正演模拟及AVO特征分析,研究了水合物储层顶底界面的反射特性；并针对南海北部陆坡神狐海域的测线进行了约束稀疏脉冲反演,结果表明波阻抗反演方法能够作为探测天然气水合物的一种技术手段,并分别基于速度和电阻率估算了水合物饱和度,估算的天然气水合物饱和度高达28%。
[Abstract]:In this paper, the geophysical characteristics and genetic mechanism of natural gas hydrates, especially sand rich reservoirs, in the Shenhu sea area of the northern South China Sea are studied. The GMGS-1 drilling data of Shenhu sea area in the northern South China Sea indicate that there is a sand rich reservoir in the depth of 171-180m. The logging results show that there are high P-wave velocity, high resistivity, low gamma value and low density in hydrate deposits, while those in free gas deposits have low P-wave velocity, high resistivity, low gamma value, low P wave velocity, high resistivity, low gamma value, low P wave velocity, high resistivity, low gamma value, low P wave velocity, high resistivity and low gamma value. The gamma-ray logging value is obviously lower than that of the well SH2H3H3H7, which has been drilled for hydrate formation. The hydrate layer and free gas reservoir are distinguished by the intersection analysis of logging P- velocity and gamma logging value, and the three dimensional seismic data are interpreted. It is found that the SH4 well is located in an obvious NE-SW trench or erosion channel at the bottom of the gorge, and there is obvious collapse under it. The genetic mechanism of hydrate in the sandstone reservoir in this area is analyzed in this paper. It is considered that in the process of the turbidity flow down the slope at the bottom of the canyon, convergence occurs in the negative topography of the narrow watercourse, the velocity increases, the thickness of the turbidity current increases, the ability of carrying sediment increases, and the coarse sediment is deposited. Because of the large deposition rate of the west side of the canyon, the ancient waterway was quickly filled and buried under the current valley ridge, and the coarse grain deposits were preserved, and the upper fine grain deposits formed a good caprock, which could effectively hinder the gas spillage in the lower part. In this paper, the forward modeling and AVO characteristic analysis of the physical parameters of hydrate layer in Shenhu sea area are carried out, and the reflection characteristics of the top and bottom interface of hydrate reservoir are studied. The constrained sparse pulse inversion is carried out in the Shenhu sea area on the northern slope of the South China Sea. The results show that the wave impedance inversion method can be used as a technical means to detect natural gas hydrate. The hydrate saturation is estimated based on velocity and resistivity, and the estimated gas hydrate saturation is as high as 28%.
【学位授予单位】：中国科学院研究生院(海洋研究所)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

【参考文献】