Imaging seismic data in complex structures by introducing the partial diffraction surface stack method

Abstract

The common reflection surface (CRS) stack method is known as a generalized stacking velocity analysis tool and was originally introduced as a data-driven method to simulate zero-offset sections. However, this method has some difficulties in imaging complex structures and low-quality data. The problem of conflicting dips is one of the drawbacks of the CRS method addressed in many studies. The common diffraction surface (CDS) method was explicitly introduced to overcome this problem. In one study, the problem was resolved by combination of the CDS method and the common offset CRS method. The method was called the common offset CDS method showed successful application on improving image quality in semi-complex media. In this study, we combined the partial CRS with the CDS to derive the partial CDS for more efficient resolve of the conflicting dips problem. In the partial CDS, thresholds in the angle spectrum were removed for full contribution of all possible dips to have volume of operators for a sample point. The aperture definition in the partial CDS is the same as in the partial CRS, where an offset and time variant aperture is used. The new method was applied on a simple synthetic data set with much diffraction points imbedded in the model. Then it was applied to a semicomplex data set to enhance the body of mud volcanoes and faults. For better comparison, it was applied to two more real data sets from a complex overthrust zone to improve the seismic quality and remove the geological ambiguities in the interpretation. In the synthetic data example, more conflicting dips were resolved than in the other methods. In all real data examples, the enhanced partial CDS data were depth-migrated to compare them with the pre-stack depth migration of partial CRS gathers. More details of the geological structures can be observed in the new results.