Genetic model of the hydrate system in the fine grain sediments in the northern continental slope of South China Sea
Genetic model of the hydrate system in the fine grain sediments in the northern continental slope of South China Sea
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DOI：
10.3969/j.issn.0001-5733.2009.07.019
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发表时间：
2009-07
期刊：
影响因子：
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通讯作者：
Wu Shiguo;Dong Dongdong;Yang Sheng-xiong;Zhang Guang‐xue;Wang Zhi-jun;Li Qing-ping;Liang Jinqiang;Gong Yue-hua;Sun Yun-bao
中科院分区：
文献类型：
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作者：
Wu Shiguo;Dong Dongdong;Yang Sheng-xiong;Zhang Guang‐xue;Wang Zhi-jun;Li Qing-ping;Liang Jinqiang;Gong Yue-hua;Sun Yun-bao
在南海北部海域，通过钻探首次获得了天然气水合物样品。为深入认识这一独特堆积体系的形成机制，本文以钻井区高精度二维和三维多道地震资料为基础，通过精细的地球物理解释和地质分析，探讨了控制该体系形成的因素。控制细粒沉积物中天然气水合物系统成藏的关键因素有三个：（1）大量含流体甲烷气参与了天然气水合物的形成;南海北部海域活跃的流体流动使热液和/或生物气向浅层运移，并在天然气水合物稳定带（GHSZ）形成水合物。流体流动包括泥底辟和气烟囱构造。它们通常具有正地形起伏、声波浑浊和下推以及地震剖面上的低反射强度的特征。天然气烟囱可到达GHSZ，有利于BSR的开发。这说明活跃的流体流动与天然气水合物的形成和聚集有着密切的关系。(2)断裂的幕式过程在天然气水合物的生成过程中起着重要作用。它可能为热成因或生物成因天然气向上运移进入天然气水合物稳定带（GHSZ）提供通道。增加了水合物晶体生长的孔隙空间。(3)海底滑坡诱发了该区异常超压活动和断裂发育。在此基础上，提出了钻井海区高浓度天然气水合物的形成模式。
Gas hydrate samples were obtained firstly in China by drilling on the northern margin of South China Sea (SCS). To understand the formation mechanism of this unique accumulation system, this paper discusses the factors controlling the formation of the system by accurate geophysical interpretation and geological analysis, based on the high precision 2-D and 3-D multichannel seismic data in the drilling area. There are three key factors controlling the accumulation of the gas hydrate system in fine grain sediment: (1) large volume of fluid bearing methane gas Joins the formation of gas hydrate. Active fluid flow in the northern South China Sea makes both thermal gas and/or biogenic gas migrate into shallow strata and form hydrate in the gas hydrate stability zone (GHSZ). The fluid flow includes mud diapir and gas chimney structure. They are commonly characterized by positive topographic relief, acoustic turbidity and push-down, and low reflection intensity on seismic profiles. The gas chimneys can reach to GHSZ, which favors the development of BSRs. It means that the active fluid flow has a close relationship with the formation and accumulation of gas hydrate. (2) The episodic process of fracture plays an important role in the generation of gas hydrate. It may provide the passage along which thermogenic or biogenic gas migrated into gas hydrate stability zone (GHSZ) upward. And it increases the pore space for the growth of hydrate crystal. (3) Submarine landslide induced the anomalous overpressure activity and development of fracture in the GHSZ. The formation model of high concentration gas hydrate in the drilling sea area was proposed on the basis of above analysis.