| Autor: |
R. James Brown, Zandong Sun, Peter M. Manning |
| Rok vydání: |
1993 |
| Předmět: |
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| Zdroj: |
SEG Technical Program Expanded Abstracts 1993. |
| DOI: |
10.1190/1.1822460 |
| Popis: |
A four-source multioffset three-component (3-C) VSP experiment was carried out in a 3-D prospect area. The data were processed with a view to studying coal anisotropy and comparing the resolution of multioffset-VSP and 3-D surface data. Converted-wave processing is carried out in order to enhance any anisotropic effects due to coal fracturing. Imaging ambiguities on conventional seismic data caused by coal measures are also discussed for the case of a reef lying underneath coal. Shear-wave birefringence or splitting occurs only in anisotropic solids and is diagnostic of anisotropy. This can he related to rock properties (such as aligned fractures or cracks. thin layering, aligned grains. etc.) and to the symmetry properties of these fabric elements. Significant energy has shown up on the minimized (trensverse) component for both the A and B sources after data rotation. This is not believed to he due to rotation error because there is a significant difference (about IO ms on the first trace) between the arrival times of the A single three-component geophone was moved up converted-wave coal reflection on the two rotated horizontal from 1460 m to 700 m at 10-m intervals. At each location. components. This does not happen for sources C and D. This four different sweeps were applied simultaneously. The arrival-time difference between radial and transverse survey geometry is shown in Figure 1. components on the CCP maps is about 6 ms for both sources A and B. The birefringence analysis method presented here is embodied in an algorithm developed hy Harrison (1992). |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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