Marine gas hydrates, fluid flow, and structure at convergent margins

海洋天然气水合物、流体流动和收敛边缘的结构

• 批准号: 156159-2006
• 负责人: Spence, George
• 金额: $ 2.54万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=391865
• 关键词: Marine; gas; hydrates; fluid; flow

Methane hydrate is "flammable ice" found on continental slopes where water depths are greater than about 600 m. The amount of methane contained in the hydrate reservoir is enormous. Hydrates thus represent a massive potential energy resource, as well as possibly playing a major role in controlling global climate and seafloor slumping. A major focus of my research is to determine the distribution and concentration of methane hydrate off Vancouver Island, and subsequently to understand how they are formed. Much of my work will be linked to results from the Integrated Ocean Drilling Program (IODP), currently drilling (Oct 2005) off Vancouver Island. My research activities will include analysis of marine seismic data collected on ocean bottom seismometers (OBSs) in Aug 2005. I will examine seismic traveltimes and amplitudes to determine the seismic velocity structure at two of the major sites of the IODP program; the IODP results will calibrate the seismic models, which then provide estimates of hydrate distribution out to distances of 1-2 km away form the drillholes. A larger-scale OBS seismic survey is planned for 2007, over an area 5 km by 2 km that includes several fluid vent features where massive hydrate has been recovered just below the seafloor. A unique feature of this cruise, which is in collaboration with the U of Southampton and the U of Toronto, is that measurements of seafloor resistivity will be collected over the same volume using controlled-source EM equipment. With both resistivity and seismic velocity, the estimates of hydrate concentration may be much improved. A third field survey, planned tentatively for 2008, is an OBS program focusing on fluid vent structures in the Nootka fault region off Vancouver Island, just seaward of the continental slope. Information on these structures may provide support for future IODP drilling here. Since many earthquakes occur on the Nootka fault, continuous monitoring of a drillhole (perhaps as a node of the NEPTUNE fibre-optic network) may demonstrate that vent activity may be directly linked to earthquakes.

甲烷水合物是在水深超过600米的大陆斜坡上发现的“可燃冰”。水合物储层中所含的甲烷量是巨大的。因此，水合物是一种巨大的潜在能源，并可能在控制全球气候和海底塌陷方面发挥重要作用。我的研究的一个主要重点是确定温哥华岛附近甲烷水合物的分布和浓度，并随后了解它们是如何形成的。我的大部分工作将与综合大洋钻探计划（IODP）的结果有关，该计划目前正在温哥华岛附近钻探（2005年10月）。我的研究活动将包括分析2005年8月海底地震仪（OBSs）收集的海洋地震数据。我将检查地震走时和振幅，以确定IODP计划的两个主要地点的地震速度结构; IODP结果将校准地震模型，然后提供距离钻孔1-2 km的水合物分布估计。计划在2007年进行一次更大规模的OBS地震勘探，范围为5公里乘2公里，包括几个流体喷口特征，在这些特征中，就在海底以下发现了大量水合物。这次巡航的一个独特之处是，将使用可控源EM设备在同一体积内收集海底电阻率测量值。这次巡航是与南安普顿大学和多伦多大学合作进行的。利用电阻率和地震速度，可以大大提高水合物浓度的估计。第三次实地调查暂定于2008年进行，这是一个大洋断裂系统方案，重点是温哥华岛外、大陆坡向海方向的努特卡断层区的流体喷口结构。关于这些构造的信息可以为未来的IODP钻探提供支持。由于许多地震发生在努特卡断层上，对钻孔（也许是海王星光纤网络的一个节点）的连续监测可能表明，喷口活动可能与地震直接相关。