Collaborative Research: 3-D Seismic Imaging of an Active Margin Hydrate System - Oregon Continental Margin

合作研究：活动边缘水合物系统的 3-D 地震成像 - 俄勒冈州大陆边缘

• 批准号: 9907205
• 负责人: Nathan Bangs
• 金额: $ 52.5万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-01-01 至 2003-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9907205&HistoricalAwards=false
• 关键词: Collaborative; Research; Seismic; Imaging; Active

99-06990 Trehu99-07205 BangsRecommended project is for a high-resolution, 3-D marine seismic survey of a 9 x 4 km area on the crest of Hydrate Ridge, on the Cascadia accretionary complex of the offshore Oregon continental margin. The survey will use ocean bottom seismometers (OBS's) to optimize recording of the seismic signals, and will focus on mapping the presence of gas hydrate within the accretionary sediments in this region of high fluid flux. Other goals center on defining the gas hydrate stability conditions; estimation of gas hydrate and free gas volumes, with the free gas trapped beneath bottom simulating reflectors (BSR's) associated with gas hydrate presence; defining pathways of fluid flux and their importance in gas hydrate formation; and slope stability (or instability) related to gas hydrate presence on the Cascadia margin. Specific hypotheses to be tested by the research include: 1) do bright stratigraphic reflections represent developing zones of focused fluid flow; 2) does a double BSR imaged in previous multichannel work within an anticline in the study region represent destabilization of hydrate in response to folding; 3) can tomographic inversion of refracted arrivals image the sub-BSR volume in which free gas is present; and 4) does the presence of hydrate and free gas affect the mechanical properties and thus slope stability and morphology of accretionary complexes. This work will provide the 3-dimensional stratigraphic and structural context for the proposed Ocean Drilling Program drilling (ODP proposal 546-Full) on Hydrate Ridge, which is designed to "ground truth" the factors related to gas hydrate formation and stability.***

99-06990 Trehu99-07205 Bangs推荐的项目是对俄勒冈州近海大陆边缘的卡斯卡迪亚增生杂岩上的水合物脊顶部 9 x 4 公里区域进行高分辨率、3D 海洋地震勘测。 该调查将使用海底地震仪（OBS）来优化地震信号的记录，并将重点绘制该高流体通量区域的增生沉积物中天然气水合物的存在情况。 其他目标集中在确定天然气水合物的稳定性条件；估计天然气水合物和游离气体体积，游离气体被捕获在与天然气水合物存在相关的底部模拟反射器（BSR）下方；定义流体通量的路径及其在天然气水合物形成中的重要性；与卡斯卡迪亚边缘天然气水合物存在相关的斜坡稳定性（或不稳定性）。 研究要测试的具体假设包括：1）明亮的地层反射是否代表集中流体流动的发展区域； 2) 在之前的多通道工作中在研究区域的背斜内成像的双 BSR 是否代表水合物因折叠而不稳定； 3) 折射到达的层析成像反演可以对存在游离气体的子 BSR 体积进行成像； 4) 水合物和游离气体的存在是否会影响力学性能，从而影响边坡稳定性和增生杂岩的形态。 这项工作将为拟议的海洋钻探计划在水合物脊上的钻探（ODP 提案 546-Full）提供 3 维地层和结构背景，该钻探旨在“地面真实”与天然气水合物形成和稳定性相关的因素。** *