A comparative study on natural gas hydrate accumulation models at active and passive continental margins

Natural Gas Industry B

Wanjun Lyu¹  Jie Chen²  Qingtao Bu²  Qing Li³  Jianming Gong³  Nengyou Wu⁴  Gaowei Hu⁴  Jianye Sun⁴  Jiasheng Wang⁴ 

[1] Corresponding author. Key Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, China Geological Survey, Qingdao, Shandong 266071, China.;Laboratory for Marine Mineral Resources, Pilot National Laboratory for Marine Science and Technology - Qingdao, Qingdao, Shandong 266071, China;College of Marine Science and Technology, China University of Geosciences - Wuhan, Wuhan, Hubei 430074, China;Key Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology, China Geological Survey, Qingdao, Shandong 266071, China;

关键词: Active continental margin;    Passive continental margin;    Natural gas hydrate;    Accumulation model;    Cascadia margin;    Nankai trough;   

DOI  :  

来源: DOAJ

【 摘 要 】

The comparative study on natural gas hydrate accumulation models between active and passive continental margins as well as their controlling factors is of great significance to the guidance of natural gas hydrate exploration. Based on the data and research results of international typical active continental margin hydrate accumulation areas such as the Cascadia margin of the Northeast Pacific, the Nankai trough, etc. and passive continental margin areas like the Blake Ridge, the models of the gas hydrate accumulation system are summarized and numerically simulated, and a preliminary comparison of active and passive continental margin reservoir accumulation models was also carried out. The following results were obtained. (1) The active continental margin provides a driving force and channel for vertical gas migration, which induces deep free gas and in-situ biogas to migrate along the fault. The migration channels are mainly faults, fractures and slumps produced by subduction–accretion. (2) Coarse-grained turbidity sediments such as silt and sandy silt have good porosity and permeability. Moreover, the sediment thickness on the accretionary wedge is large, which provides a good storage space for hydrate accumulation. (3) Numerical simulations of the Blake Ridge, and Niger Delta hydrate accumulation show that the passive continental margin lacks the lateral stress caused by the subduction zone compared with the active continental margin. However, due to the plastic materials in the thick sedimentary layer, high-pressure fluids and volcanic activities outside the continental margin, vertical accretion and tensile stress are generated and the accumulation rate of diffusion-type hydrates mainly depends on the methane supply rate. (4) Organic matter content, gas production rate, geothermal gradient and sedimentation rate at the passive continental margin have different effects on the spatial distribution of hydrate content. Mud volcanoes or diapir structures provide an ideal place for the formation and occurrence of hydrates.

【 授权许可】

Unknown