Forecasting Fractures in Coal Seams by Using Azimuthal Anisotropy from P-Wave Seismic Data
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- 作者：Shou-hua DONG ; Jian-hua YUE ; Fen-xuan ZHANG
- 关键词：coal fracture ; azimuth anisotropic analysis ; P-wave
CLC number ; P 631.4 - 刊名：Journal of China University of Mining and Technology
- 出版年：2007
- 出版时间：March 2007
- 年：2007
- 卷：17
- 期：1
- 页码：11-14
- 全文大小：157 K
文摘
If the thickness of coal seams and the lithology of both roofs and floors of coal seams have not changed at all or only a little, then it is thought that the elastic anisotropy of coal seams depends mainly on fractures and obeys the horizontally symmetric model of an azimuth anisotropy. For a fixed offset, the amplitude A of the reflection P-wave and the cosine of 2 φ has an approximately linear relation, (φ is the source-detector azimuth with respect to the fracture strike. Based on this relationship, many things can be done, such as the extraction of macro bins, the correction of re-sidual normal moveout, the formation of azimuth gather, the transformation and normalization of azimuth gathers and the extraction of reflection wave amplitudes of coal seams. The least squares method was used to inverse theoretically the direction and density of fractures of coal seams. The result is in good agreement with the regional geological struc-ture, indicating that the azimuth anisotropic analysis of the P-wave is feasible in evaluating the density and direction of fractures in coal seams.