Wavefield Tomography Based on Local Image Correlations

Seismic imaging includes the estimation of both the position of the structures that generate the data recorded at the surface and a model that describes the propagation in the subsurface. The waves recorded at the surface are extrapolated in the model by solving a wave equation, and they are crosscorrelated with a synthetic source wavefield simulated in the same model. Reflectors are located where the source and receiver wavefields match in time and space. If the velocity model is inaccurate, the reflectors are positioned at incorrect locations. We propose an objective function in the image space that does not require common-image gathers (CIGs). We consider pairs of images from adjacent experiments and reformulate the semblance principle in the physical space, instead of the extended space at selected CIGs. We use penalized local correlations of two images to estimate shifts in the image space.