天然气水合物区域矿产资源定量评价模型研究

【作者】 王春娟；

【导师】 杜德文；

【作者基本信息】 国家海洋局第一海洋研究所 ， 海洋地质， 2008， 硕士

【副题名】以墨西哥湾和南海为例

【摘要】 本文总结全球天然气水合物成矿环境条件,分析了主动和被动大陆边缘水合物成矿环境,总结水合物成矿的共有特征;选取典型成矿海区—墨西哥湾,研究其成矿特征,在典型海区内选择天然气水合物赋存区和不存在天然气水合物的统计单元共同组成训练区,建立天然气水合物矿产资源评价的多元线性回归和数量化理论I预测模型以及判别水合物成因类型的费歇尔判别模型;将这些模型尝试应用于未勘探区,估计潜在资源分布和类型,圈定重点靶区,为将来的勘探和调查工作提供参照和依据。根据多元回归和数量化理论I模型预测整个墨西哥湾北部海区天然气水合物的赋存状况,发现墨西哥湾北部海域的天然气水合物基本集中分布在德克萨斯——路易斯安那陆坡至密西西比峡谷一带。向外海以Sigsbee陡坡为界,向内海基本上以陆架与陆坡交界处为界。运用费歇尔判别模型判别水合物中甲烷气属生物成因还是热成因,判别的正确率为82.4%。将多元回归预测模型运用于南海北部陆坡海区,发现南海北部陆坡区水合物主要存在于新生代盆地中,珠江口盆地最有可能存在丰富的水合物,预测概率值70%以上的区域占珠江口盆地的大部分面积。据该模型判断的水合物存在概率较大的海区与前人根据地球物理和地球化学分析的水合物异常区与研究区比较吻合,台西南盆地、东沙海槽和西沙海槽海区存在天然气水合物的可能性较大,资源量极可能达到可开采的程度,推荐珠江口盆地为优先勘探区。将费歇尔判别模型运用于南海北部,发现北部陆坡天然气水合物大部分是热成因气水合物;台西南盆地、琼东南盆地几乎全是热成因水合物;生物成因水合物环珠江口盆地而存在,热成因水合物集中分布在环中。其中神狐海域判断为生物成因水合物,这与该区取得水合物样品的地球化学研究相吻合。同时,将两个判别函数值标于直角坐标系中,发现有些单元的水合物并不能很好的区别属生物成因还是热成因,很可能是微生物和热成因相结合而产生的混和成因水合物。更多还原

【Abstract】 This paper summarizes the global gas hydrate mineralization conditions, analyzes gas hydrate mineralization environment on the active and passive continental margin, summarizes hydrate mineralization common characteristics; it selects the typical sea areas - the Gulf of Mexico, whose statistical units have been selected where some areas have gas hydrate and the others don’t. We select these units as the training area to establish the forecastable model about gas hydrate regional mineral resource estimation by using multiple linear regression and quantitive theoryⅠand Fisher discrimination model used to determining the causes of gas hydrate. These models can be attempted to use in unexplored sea area, in order to estimate latent gas hydrate resources and type, delineate emphases target zone, and provide comparison and base for exploration and research in future.According to the multiple linear regression model we can predict the occurrence of gas hydrate in the entire north slope of Gulf of Mexico and come to the conclusion: the occurrence of gas hydrate in the Gulf of Mexico mostly concentrated in Texas - Louisiana slope to the Mississippi Canyon area. Sigsbee Escarpment out to sea for the boundary, basically inside the sea the junction of shelf and the slope for the other boundary. Fischer discrimination model can be used to determine whether methane in gas hydrate is biological or thermogenic causes, and its correct rate is 82.4%. Multiple regression model will be applied to predict the northern slope of the South China Sea and we find that gas hydrate exists primarily in Cenozoic basin. The Zhujiang Mouth Basin most likely has a wealth of hydrates, and most of the basin area is more than 70% of predicted probability. According to the model , the result that the area where the probability of gas hydrate occurrence is higher is consistent with the conclusion based on previous geophysical and geochemical analysis. Southwest Taiwan basin, the Dongsha Trough and Xisha Trough area mostly have gas hydrate. Its volume of resources can be most likely to be mined, and therefore, Zhujiang Mouth Basin is commend as a priority exploration area.Fischer model can be applied to determine the cause type of gas hydrate in the northern slope of South China Sea and we find that most gas hydrate is thermogenic cause. Gas hydrate in Southeast Hainan basin and Southwest Taiwan basin is almost thermogenic hydrate. Biological gas hydrate exists around Zhujiang Mouth basin, thermogenic gas hydrate concentrated in center, where Shenhu area contained biological hydrate, which is consistent with the judgment using geochemical methods by hydrate samples. At the same time, taking the two discriminant function values to show in the coordinate system, we find it is difficult to determine the cause of hydrate in some units, so it’s probable that such hydrate was formed by mixture causes combining Biological cause with heat and thermogenic cause.更多还原