Seismic imaging with and without velocity

A new type of seismic imaging, based on Feynman path integrals for waveform modeling, is capable of producing accurate subsurface images without precise knowledge of a reference velocity model. Instead of the usual optimization of the semblance objective function, a weighted summation over all representative curves avoids the need of velocity analysis, with its common difficulties of subjective and time consuming manual picking. The path integral imaging can be applied to stacking to zerooffset, timeand depth migration. In all these cases, a properly defined weighting function plays a vital role, to emphasize contributions from traveltime curves close to the optimal one and suppress contributions from unrealistic curves. The path integral method is an authentic modelindependent technique, in the sense that there is strictly no parameter optimization or estimation involved. Synthetic and real data examples shows that it has the potential of becoming a fully automatic imaging technique.