Publisher : Korean Society of Earth and Exploration Geophysicists
DOI : 10.7582/GGE.2012.15.1.039
Title & Authors
Detection of the gas-saturated zone by spectral decomposition using Wigner-Ville distribution for a thin layer reservoir Shin, Sung-Il; Byun, Joong-Moo;
Recently, stratigraphic reservoirs are getting more attention than structural reservoirs which have mostly developed. However, recognizing stratigraphic thin gas reservoirs in a stacked section is usually difficult because of tuning effects. Moreover, if the reflections from the brine-saturated region of a thin layer have the same polarity with those from the gas-saturated region, we could not easily identify the gas reservoir with conventional data processing technique. In this study, we introduced a way to delineate the gas-saturated region in a thin layer reservoir using a spectral decomposition method. First of all, amplitude spectrum with the variation of the frequency and the incident angle was investigated for the medium which represents property of Class 3, Class 1 or Class 4 AVO response. The results show that the maximum difference in the amplitude spectra between brine and gas-saturated thin layers occurs around the peak frequency independent of the incident angle and the type of AVO responses. In addition, the amplitude spectra of the gas-saturated zone are greater than those of brine-saturated one in Class 3 and Class 4 at the peak frequency while those of phenomenon occur oppositely in Class 1. Based on the results, we applied spectral decomposition method to the stacked section in order to distinguish the gas-saturated zone from the brine-saturated zone in a thin layer reservoir. To verify our new method, we constructed a thin-layer velocity model which contains both gas and brine-saturated zones which have the same reflection polarities. As a result, in the spectral decomposed sections near the peak frequency obtained by Wigner-Ville Distribution (WVD), we could identify the difference between reflections from gas- and brinesaturated region in the thin layer reservoir, which was hardly distinguishable in the stacked section.
Liu, Y., and Marfurt, K. J., 2006, Thin bed thickness prediction using peak instantaneous frequency, 76th Ann International Meeting, Soc. Expl. Geophys., Expanded Abstract, 968-972.
Liu, Y., and Schmitt, D. R., 2003, Amplitude and AVO responses of a single thin bed, Geophysics, 68, 1161-1168.
Li, Y., and Zheng, X., 2008, Spectral decomposition using Wigner-Ville distribution with applications to carbonate reservoir characterization, The Leading Edge, 28, 1050-1057.
Marfurt, K. J., and Kirlin, R. L., 2001, Narrow-band spectral analysis and thin-bed tuning, Geophysics, 66, 1274-1283.
Partyka, G. A., Gridley, J. A., and Lopez, J. A., 1999, Interpretational aspects of spectral decomposition in reservoir characterization, The Leading Edge, 18, 353-360.
Ralston, M., Rauch-Davies, M., Kuang, L., Xia, H., and Yang, D., 2007, General Method to Reduce Cross-Term Interference in the Wigner-Ville Decomposition, 77th Ann International Meeting, Soc. Expl. Geophys., Expanded Abstract, 870-874.
Ren, H., Goloshubin, G., and Hilterman, F., 2007, Spectral cross plot, 77th Ann International Meeting, Soc. Expl. Geophys., Expanded Abstract, 199-203.
Wu, X., and Liu, T., 2009, Spectral decomposition of seismic data with reassigned smoothed pseudo Wigner-Ville distribution, Journal of Applied Geophysics, 68, 386-393.