Correct mixed-modes imaging using multi-parameter CIGs

In this study, we propose a workflow for mixed-modes imaging and velocity analysis using multi-parameter CIG analysis in the migrated domain. When conventional imaging is applied to mixed-modes data, the resulting images can be misleading due to strong cross-talk between different propagation modes that contaminates them with spurious events. This problem persists even when the true P- and S-velocity models are used. However, in the multi-parameter CIGs, events migrated with a wrong velocity or propagation mode will have a distinct behavior that can be used to either filter them or update the velocity model. In addition, mixed-modes have distinct AVA variations that are optimally observed using the multi-parameter CIG analysis. These variations can be used for efficient propagation mode estimation and subsequent separation. Finally, P-waves images and velocity models are relatively easier to obtain. During the migration process, their structural information, such as reflectors' depth and dip, can be automatically recovered through migrated gathers analysis. This information can be in turned used as a filter applied for mixed-modes imaging or as a constraint in their velocity analysis procedures. Through a complex synthetic example, we demonstrate the application of the suggested workflow and its efficiency in building genuine mixed-modes images.