Patent ID: 7508736

Claim:
A method of evaluating an earth formation, the method comprising: activating a seismic source at at least one source position and generating seismic waves into the earth formation; receiving at least two components of seismic data at at least one receiver position, a portion of the received seismic data resulting from (I) a reflection of seismic waves at a free surface, and (II) an interaction of seismic waves with a portion of the earth formation; processing the at least two components of seismic data including said portion resulting from said reflection and producing a migrated image of the earth formation; and conducting further operations based at least in part on the produced image; wherein processing the received at least two components of seismic data further comprises: building a mirror velocity model symmetric to the free surface using a subsurface velocity model, and projecting the at least one receiver position to a virtual position on the mirror velocity model.