摘要
近年来海底峡谷和海域天然气水合物的调查和研究表明,二者在空间分布上具有一定的相似性,同时海底峡谷强烈的侵蚀作用和良好的内部建造,与海域天然气水合物的聚集、分布和成藏具有直接或间接的关联。通过对目前海底峡谷和海域天然气水合物的资料调研和系统分析,指出海底峡谷和海域天然气水合物的相关性主要表现在3个方面:侵蚀-沉积作用与有利沉积体的分布、侵蚀-沉积作用与含烃流体渗漏的相互作用、侵蚀-沉积作用与海域天然气水合物的动态成藏。将海底峡谷和水合物的关联性应用到珠江口盆地海底峡谷群,初步分析了二者的关联。研究认为该区域的海底峡谷将会对有利沉积体进行破坏和改造,使其表现为"斑状/补丁状"的平面分布特征,影响了水合物的分布和实际产出;此外,峡谷侵蚀-沉积作用导致了先前形成的水合物的分解,一部分的甲烷等气体将会进入到海水之中,而受有利沉积体上部细粒均质层的遮挡,大部分的含气流体将被"继续"限制在有利沉积体之中而形成新的水合物,这可能是该区域内细粒沉积物中水合物饱和度较高的原因。
Recent researches on the submarine canyon and the marine gas hydrate indicated that they had the similar spatial distribution.Moreover,because of the erosion and internal architecture,submarine canyons showed the good relationship with the accumulation and distribution of marine gas hydrates.Based on the inte-grated analysis of studies in the past decade,the correlations between canyons and hydrates could be summa-rized as three points,i. e.erosion and sedimentation of canyons controlling the distribution of deposits favorable for hydrate,potential leak mechanism between submarine canyons and hydrocarbon-bearing fluid release,and the dynamic accumulation of gas hydrates influenced by submarine canyons.The correlations were used in the submarine canyons in the Pearl River Mouth Basin.On the one hand,these canyons could erode the favorable deposits and further influence the distribution of gas hydrates,and on the other hand,due to the erosion and sedimentation of canyons,the pre-existing hydrates might be dissociated.Impeded by the fine-grained homoge-neous layer,most of the dissociated gases would be restricted in the favorable deposits and form the new hy-drates,which could be used to help understanding the relatively high saturation of gas hydrate in the fine-grained sediments in the Shenhu Area,northern South China Sea.
出处
《现代地质》
CAS
CSCD
北大核心
2015年第1期155-162,共8页
Geoscience
基金
国家自然科学基金项目(41202080)
中国石油科技创新基金研究项目(2013D-5006-0105)
油气藏地质及开发工程国家重点实验室(成都理工大学)开放基金项目(PLC201407)
广东省自然科学基金博士启动项目(S2012040006333)
中国科学院重点部署项目(KGZD-EW-301)
关键词
海底峡谷
侵蚀-沉积作用
天然气水合物
成藏机制
submarine canyon
erosion and sedimentation
gas hydrate
accumulation mechanism
