Hardrock seismic imaging

硬岩地震成像

• 批准号: 249857-2007
• 负责人: Milkereit, Bernd
• 金额: $ 3.18万
• 依托单位: University of Toronto
• 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=394524
• 关键词: Hardrock; seismic; imaging

In heterogeneous (hardrock) environments such as the Canadian Shield, a number of parameters related to scale and composition need to be considered that render seismic studies more problematic. To model the propagation of seismic waves in these areas requires knowledge of petrophysical parameters (compressional and shear wave velocities and densities) and their distribution within the crust, which can be derived directly from borehole logs (in 1-D) or indirectly from geological maps and lithological analysis. We will collect velocity and density logs from various sources and analyze them for their first and second order statistics. These not only give us the 1-D parameters in the vertical dimension but by correlating several boreholes will provide the means of constructing a 3-D model of crustal heterogeneity. Added to the background model will be massive sulfide deposits, which are known to scatter seismic energy according to their shape, size and composition. 3D elastic/visco-elastic forward modeling studies will be used to optimize 3D surface and borehole seismic data acquisition strategies. In addition, heterogeneities may cause attenuation. As waves travel in heterogeneous media, they lose energy with distance and time due to spherical divergence and absorption. It is commonly accepted that a flat absorption band exists for the solid earth. The effects of absorption and dispersion have been observed in exploration seismology at various frequencies (i.e. surface (Hz), borehole (KHz), and laboratory seismics (MHz)) for some time. We will use uncorrelated (raw) Vibroseis data to measure velocity dispersion and attenuation in the exploration seismic frequency band. Ongoing research projects will focus on unique pressure-temperature conditions (and mineral deposits) related to meteorite impacts (Bosumtwi, Ghana; Chicxulub, Mexico; Sudbury, Ontario; Wanapitei, Ontario; the physical properties of permafrost and gas hydrates (Mallik, NWT) and 3D seismic research projects for deep mineral exploration (Ontario, Quebec and New Brunswick).

在诸如加拿大盾牌之类的异质（硬石）环境中，需要认为与尺度和组成相关的许多参数需要使地震研究更加问题。 为了模拟这些区域中地震波的传播，需要了解岩石物理参数（压缩和剪切波速度和密度）及其在地壳中的分布，这可以直接从井眼日志（以1-D）或间接的地质图和地质图和岩性分析得出。我们将从各种来源收集速度和密度日志，并分析其第一阶和二阶统计数据。这些不仅为我们提供了垂直尺寸中的1-D参数，而且通过将几个钻孔相关联，将提供构建地壳异质性3-D模型的方法。添加到背景模型中的将是巨大的硫化物沉积物，已知会根据其形状，大小和成分散射地震​​能量。 3D弹性/Visco弹性远期建模研究将用于优化3D表面和井眼地震数据采集策略。 另外，异质性可能导致衰减。 随着波浪在异质介质中传播时，由于球形差异和吸收，它们会随着距离和时间而失去能量。通常认为，存在于固体地球的平坦吸收带。一段时间以来，在探索地震学（即表面（Hz），钻孔（KHz）和实验室地震学（MHz））中，吸收和分散体的影响已在一段时间内观察到。我们将使用不相关的（原始）颤音数据来测量勘探地震频带中的速度分散和衰减。 正在进行的研究项目将重点关注与陨石影响有关的独特压力温度条件（和矿物质）（Bosumtwi，Ghana；墨西哥，墨西哥木薯；安大略省的萨德伯里；安大略省；安大略省；安大略；不伦瑞克）。