Figure 1. Demonstration of the simultaneous-source geometry. (a) Two-source shooting for denser coverage. (b) Two-source shooting for wider coverage. Red points denote shot positions for source 1. Green points denote shot positions for source 2. Blue points denote receiver positions. Red and green strings denote the shooting rays. Arrows denote the shooting directions. Borrowed from Chen et al. (2014b).
Because of many reported success of deblending, more and more focus is now moved towards the direct imaging of blended data. However, one of the most important components in the direct imaging of simultaneous-source data is the macro subsurface velocity model of the targeted area. In this paper, we focus on the velocity analysis of the simultaneous-source data. We demonstrate that it is possible to directly apply the common velocity scanning procedures to the blended data in the common-midpoint (CMP) domain. We also propose to use the newly developed similarity-weighted semblance (Gan et al., 2015a; Chen et al., 2015b) to perform the velocity analysis. Both synthetic and field data examples show that the similarity-weighted semblance can help obtain higher-resolution and more reliable velocity spectrum than the conventional semblance, especially in the case of simultaneous-source data. The direct imaging of simultaneous-source data based on the directly picked velocity is also carried out via the prestack kirchhoff time migration (PSKTM) approach. The performance shows that the migrated image from blended data based on the picked velocity from similarity-weighted semblance is very close to the migrated image from unblended data.