Eliminating upper harmonic noise in vibroseis data via numerical simulation

Abstract

SUMMARY In conventional vibroseis signal processing, algorithms including cross‐correlation and deconvolution are applied to convert the raw trace data into a seismic section. However, their performance deteriorates when the trace data are corrupted by the harmonic noise. An important issue of vibroseis data enhancement is the treatment or suppression upper harmonics. In this contribution, I present algorithm to eliminate the harmonic distortion, all at once, in both down‐ and up‐sweep conventional vibroseis data using a simulation process for harmonic distortion in the correlated data. This technique consists of four steps: (1) cross‐correlating the raw data with fundamental sweep then dividing the trace to several windows and detecting the windows contain fundamental energy for each response reflector; (2) calculating the harmonic amplitude ratio when applying the Fourier transform on the upper harmonic components and the fundamental, and dividing the upper harmonic components by the fundamental to remove the unknown convolutional effects; (3) using the harmonic amplitude ratio to simulate the upper harmonics associated with the fundamental energy in down‐ and up‐sweep data. When the harmonic amplitude ratio is convolved with a portion of data containing the fundamental energy in the correlated data in time domain, I can get simulation for the upper harmonics existed in the original data and (4) subtracting the simulated harmonics from correlated traces using direct optimization procedure. Accordingly, I developed a procedure for attenuating upper harmonics in the positive and negative times of the correlated traces depending on accurate simulation for the correlated harmonics. The procedure was tested on both synthetic and field data sets. The correlated trace thus obtained will be freed substantially of correlation noise; that is the correlation‐ghost sweeps (produced by severe harmonic distortion at positive and negative correlation times) are eliminated without degrading the seismic information content of the trace.

Separation of blended data by iterative estimation and subtraction of blending interference noise

“…Note that in practice the use of downsweeps is often avoided because of the presence of harmonics (Abd El-Aal, 2010). Alternatives are the use of upsweeps with different lengths or, in the case of the same sweep length for all sources, application of the method in one of the other domains discussed earlier.…”

Ambient noise for determination of site dynamic properties at Hurghada and Safaga cities, Red Sea, Egypt

“…Application of the passive seismic techniques is used frequently in Egypt to obtain fundamental site frequency and amplification factors for seismic hazard assessment at several areas (Abd el-aal, 2008(Abd el-aal, , 2010a(Abd el-aal, , 2010b(Abd el-aal, , 2010c(Abd el-aal, , 2013Abdel-Rahman et al, 2012;El-Hady et al, 2012;Toni, 2007Toni, , 2012Abd el-aal and Soliman, 2013;El-Eraki et al, 2013;Abd el-aal et al, 2015). The rapid increasing in urbanization, tourist beach resorts and land use planning in the Red Sea coastal areas are the motivation of the current study.…”