Phase Decomposition for Interpretation of Thin Layers–Possibilities and Limitations

摘要

The relatively new method of phase decomposition (Castagna et al. 2016) is complex to understand and use, but has good potential for the analysis of lateral changes in thin layers. To develop a better understanding of this technology, a set of synthetic models of wedges and the subsequent phase gathers for these models was calculated and analyzed. The results obtained from this analysis demonstrate that changes in the phase depend on the layer thickness and the proportion between the reflection coefficient of the top and the bottom of the layer. We can see that the phase split and shifted from the original in tuning zones. For wedges with Reflection Coefficient (RC) in different polarity for top and bottom, phase gathers were more differentiated than for wedges with RC in the same polarity for top and bottom. For analyzing phase difference, we use prestack offset visualization technology (Fink 2010), which helps visualize changes in phase in the tuning zone by horizon. For analyzing lateral changes in the tuning zone, we must select zones with equal thickness of thin layers, because thickness also influences phase changes and will mask lateral property changes. The proposed method of using phase decomposition will help to analyze the property changes of the thin layer below traditional seismic resolution.