Similarity-weighted Super-virtual Interferometry to Enhance First Breaks

LÜ Xuemei1, AN Shengpei1, HU Tianyue1,†, CUI Yongfu2

1. School of Earth and Space Sciences, Peking University, Beijing 100871; 2. Tarim Oilfield Company, Petrochina, Korla 841000; † Corresponding author, E-mail: tianyue@pku.edu.cn

Abstract When strong noise exists on local seismic traces with low signal-to-noise ratio (SNR), super-virtual interferometry (SVI) method can be used to increase the SNR of first breaks on far-offset traces, but may decrease the SNR of first breaks around the noisy traces. To solve this problem, the similarity-weighted super-virtual interferometry is developed. Correlation and convolution are applied to stack the first arrivals on neighboring traces in common phase, and consequently increase the SNR of first arrivals. The introduction of similarityweighted function improves the ability to suppress strong local abnormal noise. Both the synthetic and field data examples demonstrate the effectiveness of the proposed method to enhance seismic first breaks. At last, a discussion about the applicabilities and the anti-noise abilities of the proposed method is included. Key words first breaks; low signal-to-noise ratio; interferometry

复杂近地表条件下的油气勘探已成为地震勘探技术发展的前沿, 如中国西部的山前带、沙漠和戈壁地区, 这类工区的静校正问题突出, 直接影响地震勘探效果。目前能够有效地解决复杂地表静校正问题的方法是基于层析成像建模的静校正方法, 即利用初至旅行时, 通过层析成像建立近地表模型,由此计算炮检点的静校正量[1]。然而, 层析建模的精度依赖初至到时的准确性, 如果到时不准, 会极大地影响静校正的效果。复杂近地表地区的地震数

据信噪比往往很低, 局部道集可能存在工业电及外源噪声等强干扰, 常规初至拾取方法难以准确拾取初至, 需要在初至拾取前, 通过预处理方法加强初至波信噪比。

超虚干涉法(super-virtual interferometry, SVI)最早用于加强远偏移距折射波初至[2], 是完全数据驱动的方法, 不依赖地震数据的频率或视速度信息。SVI 通过互相关和叠加提取检波点间的折射波响应,再通过褶积和叠加重建炮检点间的折射波信号。在