3c Seismic And Vsp PDF Download

This study investigates the 3C-3D surface and downhole (VSP) seismic datasets previously collected at the Athabasca Basin McArthur River to Millennium uranium mine sites using a number of unconventional analytical methods. The objective is to understand the potential of the seismic method to delineate subsurface features such as the hydrothermal alteration footprint, the sandstone-basement unconformity and the subvertical thrust fault zone. Methodologies applied include a series of forward and data-driven approaches. First, this study accomplishes the prediction of the compressional and shear wave amplitude and traveltime using angle dependent reflectivity equations and 2D elastic finite-difference waveform models. The numerical predictions are based on the existing and estimated petrophysical data from the local area. Second, this study discovers a number of unique properties of the seismic wave attenuation from surface and downhole seismic datasets. Multiple methods applied to VSP datasets confirm that the attenuation quality factor (Q) in the study area is low and variable. Finally, this study analyzes the traveltime and waveform data collected from the unique 3C-3D-borehole seismic geometry at Millennium to delineate the subsurface geologic structures that are potentially related to the wave attenuation and velocity. A forward 3D visco-elastic waveform model is created to illustrate the observed abnormal amplitude and velocity azimuthal variations with a superimposed effect of intrinsic and scattering. The results from these series of approaches provide updated understandings of the alterations, structural geology, and their relationships with seismic data. These understandings contribute to the suggestions for future seismic imaging work such as converted shear wave processing, downhole seismic acquisition, and alteration footprint tomography.