Coupling True-amplitude Common-shot Reverse Time Migration to Velocity Analysis
Y. Li and H. Chauris
Event name: 79th EAGE Conference and Exhibition 2017
Session: Velocity Model Estimation - Theory I
Publication date: 12 June 2017
Info: Extended abstract, PDF ( 698.02Kb )
Price: € 20
Migration Velocity Analysis is a technique to determine the background velocity model representing the macro structure of the subsurface. It is supposed to be a powerful tomographic imaging tool but in practice, only limited number of applications on real data have been reported. Recent studies proposed to replace migration, adjoint of Born modeling, by the asymptotic inverse in the context of extended subsurface offset domain. Following the same strategy, we develop a wave-equation based Inversion Velocity Analysis approach in the original surface-oriented shot domain. We derive the gradient of the modified Differential Semblance Optimization objective function. We discuss the advantages and limitations through applications on 2D synthetic data sets, first on a single reflector embedded in a homogeneous model and then on the Marmousi model. The main advantage of inversion over classical migration velocity analysis is an automatic compensation for geometrical spreading and illumination, leading to more stable velocity gradient, especially after Gaussian smoothing over a wavelength distance.