Seismic Noise Removal Whilst Preserving the Amplitude Response
Tony Rebec and Dimitri Bevc
3DGeo Inc, 17171 Park Row # 390, Houston, TX 99084
Noise in the seismic record is mostly highly undesirable and can take on many different forms. This noise is either random or coherent in nature and it is the later which has typically caused the headaches for both the processor and the interpreter alike. Physical noise generation caused by the acquisition effort itself is a key offender coupled with topography and near surface conditions. Environmental noise typically emanating from surface facilities or transportation is difficult to control but needs addressing. In addition energy bouncing around in the subsurface in the form of familiar coherent multiples needs to be dealt with. On the other hand geologic noise generated in the subsurface can be extremely useful in diagnosing changing subsurface conditions and may be useful in defining the reservoir. During the seismic processing workflow misplaced signal can also show up as noise. The attenuation of these forms of noise has been a continuing battle from day one, both in the field and in the processing facility. Noise caused by the acquisition effort and environmental noise are typically addressed in the shot domain whereas subsurface multiple energy is addressed in the cdp domain. Here we describe a proprietary approach for both domains which subtracts out the noise without distorting the signal. The tools used are not new in the seismic processing world and thus the methodology can be addressed by using commercially available software packages. This noise attenuation approach is heavily related to the type of noise present and preserves the signal amplitudes at all offsets. Initially the noise is separated out from the signal followed by a noise component analysis looking for residual signal which is then added back to the originally separated signal component. This approach avoids the possibility to create artifacts in any domain (FK, Tau, Radon etc.) and at the same time preserves the signal amplitudes rendering it AVO friendly and suitably conditioned for further time or depth imaging.
AAPG Search and Discovery Article #90076©2008 AAPG Pacific Section, Bakersfield, California