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: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=455451
• 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).

在异质（硬岩）的环境，如加拿大地盾，一些有关的规模和成分的参数需要考虑，使地震研究更成问题。 为了模拟地震波在这些地区的传播，需要了解岩石物理参数（压缩波和剪切波速度和密度）及其在地壳内的分布，这些参数可以直接从钻孔日志（一维）或间接从地质图和岩性分析中得出。我们将从不同的来源收集速度和密度日志，并分析它们的一阶和二阶统计。这些不仅为我们提供了垂直方向上的一维参数，而且通过关联几个钻孔，将提供构建地壳非均匀性三维模型的方法。背景模型中还将增加块状硫化物矿床，已知这些矿床根据其形状、大小和成分分散地震能量。3D弹性/粘弹性正演模拟研究将用于优化3D地面和井中地震数据采集策略。 此外，不均匀性可能导致衰减。 当波在非均匀介质中传播时，由于球面发散和吸收，它们随距离和时间损失能量。人们普遍认为固体地球存在一个平坦的吸收带。一段时间以来，在勘探地震学中，在各种频率（即地面（Hz）、钻孔（KHz）和实验室地震（MHz））下观察到吸收和弥散效应。我们将使用非相关（原始）可控震源数据来测量勘探地震频带中的速度频散和衰减。 正在进行的研究项目将侧重于与陨石撞击有关的独特压力-温度条件（和矿藏）（加纳的博萨姆特维;墨西哥的希克苏鲁布;安大略的萨德伯里;安大略的瓦纳皮泰）;永久冻土和天然气水合物的物理性质（西北地区的马利克）和深层矿物勘探的三维地震研究项目（安大略、魁北克和新玩法）。