摘要
根据近年天然气水合物地质、地球化学和地球物理调查资料,结合2013年钻孔成果,分析南海东北部陆坡海底甲烷渗漏特征及其对水合物成藏的影响,探讨了水合物成因模式。研究表明,南海东北部陆坡海底存在高通量甲烷渗漏体系,甲烷渗漏引起的地质、地球化学指标异常非常明显。大量块状、脉状、结核状渗漏型水合物也被发现,其成因应与高通量甲烷渗漏有关。其典型成因模式是高通量甲烷以游离态渗漏方式沿断层或裂缝体系向浅部地层运移,以气烟囱形式在稳定带的不同部位形成渗漏区,甲烷在气烟囱顶端或侧翼聚集而形成水合物矿藏。影响水合物成藏的断层主要为长期活动的继承性正断层、层间断层以及与海底滑塌密切相关的活动断层,气烟囱对渗漏型水合物成藏有明显的控制作用。
In this paper, the characteristics of methane seepage and its impact on methane hydrate accumulation in addition to the formation model of methane hydrate in the northeastern slope of South China Sea are analyzed by using geological,geophysical and geochemical data during recent investigation as well as drilling results of GMGS2 in 2013.A seepage system with high methane flux in our study area is inferred from evidences of seeps-related geological features, geochemical anomalies. In addition, abundant massive, vein, and nodular gas hydratewere found and its formation is probably associated with high methane flux seep age.Free methane migrates along faults or factures upward to shallower strata,resulting in gas seepage occurring in variable depths within gas hydrate stability zone,which presented as gas chimneys.Methane hydrate reservoirs are inferred to form on the top or flanks of gas chimneys.The faults associated with methane hydrate accumulation consist of active regional normal faults, localized faults, and shallow active faults related toseafloor instability.The accumulation of localized visible methane hydrate is mainly controlled by the gas chimneys.
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2017年第5期761-770,共10页
Natural Gas Geoscience
基金
国家天然气水合物专项(编号:GZH201100301
GZH201100305
GZH200200203)联合资助
关键词
天然气水合物
南海东北部陆坡
甲烷渗漏
渗漏型水合物
成藏模式
Methane hydrate
Northeastern slope of South China Sea
Methane seepages Seepage methane hydrate
Accumulation model
