Kinematic Time Demigration with an Automatically Generated Velocity Model
M. Gloeckner, B. Schwarz, C. Vanelle and D. Gajewski
Event name: 78th EAGE Conference and Exhibition 2016
Session: NMO and Stacking
Publication date: 31 May 2016
Info: Extended abstract, PDF ( 1.31Mb )
Price: € 20
To obtain an image of the earth's subsurface, time domain methods can be applied as a first step. The implicit common reflection surface (CRS) approach provides a powerful tool for time imaging. We can perform a series of processes, e.g., stacking, time migration and demigration. Demigration describes the process of an inverse migration or a back transformation, respectively. The advantage of this data domain transformations are data enhancement and an intrinsic handling of conflicting dips. Furthermore, the stacking attributes serve as input for a data-driven time migration velocity model building. We suggest a velocity analysis method using the coherence of the migration combined with a threshold, following masking of velocities and subsequent interpolation and smoothing. Diffractions are enhanced in an automated fashion during this procedure. Therefore, no user interaction is required to carry out the migration and the following demigration. Applications to field data show good results for the prestack time migration and a suitably smooth velocity model. The demigration is able to reconstruct major events. The suggested data-driven approach to migration and demigration bears the potential to prestack data enhancement and regularisation without the need for expensive conflicting dip treatment.