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: Application of the continuous wavelet transform on seismic data for mapping of channel deposits and gas detection at the CO2SINK site, Ketzin, Germany. -Geophysical Prospecting, 57, 1, 111-123 DOI: 10.1111/j.1365-2478.00723.x. AbstractConventional seismic data are band limited and, therefore, provide limited geological information.Every method that can push the limits is desirable for seismic data analysis. Recently, time-frequency decomposition methods are being used to quickly extract geological information from seismic data and, especially, for revealing frequency dependent amplitude anomalies. Higher frequency resolution at lower frequencies and higher temporal resolution at higher frequencies are the objectives for different time-frequency decomposition methods. Continuous Wavelet Transform techniques, which are the same as narrow-band spectral analysis methods, provide frequency spectra with high temporal resolution without the windowing process associated with other techniques. Therefore, this technique can be used for analyzing geological information associated with low and high frequencies that normally cannot be observed in conventional seismic data. In particular, the Continuous Wavelet Transform is being used to detect thin sand bodies and also as a direct hydrocarbon indicator. This paper presents an application of the Continuous Wavelet Transform method for mapping of potential channel deposits, as well as remnant natural gas detection by mapping low frequency anomalies associated with the gas. The study was carried out at the experimental CO 2 storage site at Ketzin, Germany (CO 2 SINK). Given that reservoir heterogeneity and faulting will have significant impact on the movement and storage of the injected CO 2 our results are encouraging for monitoring the migration of CO 2 at the site. Our study confirms the efficiency of the Continuous Wavelet Transform decomposition method for detection of frequency dependent anomalies which may be due to gas migration during and after the injection phase and in this way it can be used for real-time monitoring of the injected CO 2 from both surface and borehole seismics. : Application of the continuous wavelet transform on seismic data formapping of channel deposits and gas detection at the CO2SINK site,

Restricted resolution imposes limits on the detection of subsurface geologic features using surface seismic data. Despite great improvements in acquisition and processing techniques in recent years, seismic data still suffer from limited resolution. Detailed subsurface information on the geologic conditions at depth cannot always be attained from conventional surface seismic data. For the area of this study, the carbon dioxide ͑CO 2 ͒ storage site at Ketzin, Germany, high seismic resolution is required for mapping the internal structure of the main target reservoir. Processing of the 3D surface seismic data using conventional methods did not provide optimum resolution. The spectral blueing technique attempts to enhance the surface seismic data resolution. Well-log data generally show a blue spectrum with higheramplitudes at the higher frequencies than the commonly assumed white reflection series. By designing and applying one or several operators to poststack data, it has been possible to better match the reflectivity series and improve resolution. Applying the blueing operator to prestack data was investigated to possibly improve seismic resolution, produce more consistent results, and cause fewer ringing artifacts than when applied to poststack data. Prestack blueing, poststack blueing, and no blueing of the Ketzin 3D seismic data were compared with zero-offset vertical seismic profile ͑VSP͒ and synthetic seismograms. The comparison shows that prestack spectral blueing can indeed enhance seismic resolution with fewer artifacts associated with it than the poststack technique. The prestack and poststack spectral blueing approaches improve the well to seismic tie.