Focusing of elastic waves for microseismic imaging
Focusing of elastic waves for microseismic imaging
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DOI：
10.1093/gji/ggu398
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发表时间：
2014
影响因子：
2.8
通讯作者：
J. Douma;R. Snieder
中科院分区：
文献类型：
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作者：
J. Douma;R. Snieder
微震事件产生压缩波和剪切波，可以在接收器处记录。我们提出了一个理论，表明弹性P波和S波分别反向传播到原来的源位置。这些重新聚焦的P和S波场没有奇异性。我们还展示了一种技术，提高了使用弹性波的每种波类型的空间焦点图像的能力。改进的空间焦点获得的速度模型中，界面边界是近似的，但其中的平均慢度是正确的。反褶积设计了一个信号，从接收器重新广播，只使用在每个接收器记录的波，使得波场在源位置有一个最佳的时间焦点。我们从理论上和数值上证明，改善弹性波的时间聚焦导致改善空间聚焦的每种波类型。该技术仅涉及对记录数据的简单预处理步骤，因此与微震成像的总成本相比，其成本可以忽略不计。
Microseismic events generate compressive waves and shear waves which can be recorded at receivers. We present a theory that shows how elastic P and S waves separately backpropagate to the original source location. These refocused P and S wavefields are free of singularities. We also demonstrate a technique that enhances the ability to image the spatial focus for each wave type using elastic waves. The improved spatial focus obtained is achieved in a velocity model for which the interface boundaries are approximate but where the mean slowness is correct. Deconvolution designs a signal to be rebroadcasted from the receivers, using only the waves recorded at each receiver, such that the wavefield has an optimal temporal focus at the source location. We demonstrate theoretically and numerically that improved temporal focusing of elastic waves leads to improved spatial focusing for each wave type. This proposed technique only involves a simple preprocessing step to the recorded data and its cost is hence negligible compared to the total cost of microseismic imaging.