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15. The Frequency Response as a Function of Time for the Seismic Source Used in the Large Offset Wells
Source publication
This work is addressing the need to have accurate predictive models for transport in the vadose zone. Crosswell methods are aimed to provide a detailed understanding of how the physical properties (layering, lithology, etc.) affect the transport of fluids. Understanding of contaminant migration through the vadose zone has not only been hampered by...
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Figure 4.15 and Figure 4.16 are data from the long offset seismic test. These data are quite surprising also in that sesimic data of such high frequency can be propagated so far in this vadose-zone environment. Figure 4.15 shows good energy up to 300 hertz. Figure 4.16 is a composite of the different levels, showing good P-wave and S-wave energy. This is very encouraging for future imaging at the tank ...
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Figure 4.15 and Figure 4.16 are data from the long offset seismic test. These data are quite surprising also in that sesimic data of such high frequency can be propagated so far in this vadose-zone environment. Figure 4.15 shows good energy up to 300 hertz. Figure 4.16 is a composite of the different levels, showing good P-wave and S-wave energy. This is very encouraging for future imaging at the tank ...
Citations
... The 32 wells penetrating to a depth of ~18 m over a 16 m by 16 m grid, with thousands of probe-derived water content measurements, provided an ideal data set for comparison with the radar data. Also available at the site were results from studies employing crosswell radar (Majer et al., 2001) which provided information about the magnitude of, and the controls on, subsurface electromagnetic properties. The first objective of our study was to determine whether the locations and amplitudes of the radar reflections corresponded to changes in water content. ...
... Of specific relevance to our study are the results from the work of Majer et al. (2001) that show six images of EM slowness (1/v) obtained from crosswell radar measurements made between four wells, approximately 4 m apart, at our study site at Hanford. The EM slowness in each pixel was used to determine and a good correlation was found betweenvalues near the wells and w derived from the neutron probe data. ...
... We then used these -values to determine a model of the EM velocity at well D8 (v = c/ ). The velocity values were found to range from 0.11 to 0.16 m/ns, the same range reported by Majer et al. (2001), with an average velocity of 0.14 m/ns. The 1-D (i.e. ...
Surface-based ground-penetrating radar data were collected at the Hanford Site in Washington, U.S.A. to assess the use of radar reflection images as a means of quantifying the spatial variability of subsurface water content. Available at the selected test site were two sets of water content data derived from neutron probe measurements that had been made to a depth of ~18 m in 32 wells. The comparison of probe-derived water content data, synthetic radar data, and the acquired radar data indicated a good correspondence between the changes in probe-derived water content and the location of reflections in the radar data. Geostatistical analysis was conducted on the two sets of probe-derived water content values and the amplitudes of the reflections in the radar reflection image to determine the horizontal correlation length of water content. The experimental semivariograms for the water content data were fit with a single exponential model with a correlation length of 10 m. The semivariogram for the radar data was fit with a nested structure containing a dominant long-range structure with a correlation length of 14 m, and a smaller-scale structure with a correlation length of 0.3 m. Quantifying the scale triplet the spacing, extent, and support for the two forms of measurement provided a framework for comparing and assessing the derived correlation structures.
This is a letter report to Fluor Hanford, Inc. The purpose of this report is to summarize state-of-the-art, minimally intrusive geophysical techniques that can be used to clarify subsurface geology, structure, moisture, and chemical composition. The technology review focused on geophysical characterization techniques that provide two- or three-dimensional information about the spatial distribution of subsurface properties and/or contaminants.
