Method, media, and signals for processing seismic data to obtain a velocity field

An apparatus for producing an initial velocity field estimate for a control plane from seismic data associated with said control plane and comprising time-amplitude representations associated with source-receiver locations spaced apart by an offset distance and having a midpoint therebetween, the seismic data being arranged into common midpoint (CMP) gathers associated with respective CMP locations and the control plane having an edge intersecting a plurality of the OMP locations, the apparatus comprising:

• a) means for producing a starting velocity field estimate from an initial range of velocity values and an initial range of time values;
• b) means for producing a migrated starting velocity field from said starting velocity field estimate and said seismic data;
• c) means for producing pre-stack imaged gathers by performing a 2-dimensional pre-stack imaging process on said seismic data;
• d) means for producing normal moveout gathers in response to said migrated starting velocity field, including performing a normal moveout operation on said pre-stack imaged gathers;
• e) means for adjusting said migrated starting velocity field in response to said normal moveout gathers and said migrated starting velocity field to produce a plurality of time-velocity values for each of the CMP locations, said plurality of said time-velocity values acting as said initial velocity field.

An apparatus for producing an initial velocity field estimate for a control plane from seismic data associated with said control plane and comprising time-amplitude representations associated with source-receiver locations spaced apart by an offset distance and having a midpoint therebetween, the seismic data being arranged into common midpoint (CMP) gathers associated with respective CMP locations and the control plane having an edge intersecting a plurality of the CMP locations, the apparatus comprising:

• a) a component configured to produce a starting velocity field estimate from an initial range of velocity values and an initial range of time values;
• b) a component configured to produce a migrated starting velocity field from said starting velocity field estimate and said seismic data;
• c) a component configured to produce pre-stack imaged gathers by performing a 2-dimensional pre-stack imaging process on said seismic data;
• d) a component configured to produce normal moveout gathers in response to said migrated starting velocity field, including performing a normal moveout operation on said pre-stack imaged gathers;
• e) a component configured to adjust said migrated starting velocity field in response to said normal moveout gathers and said migrated starting velocity field to produce a plurality of time-velocity values for each of the CMP locations, said plurality of said time-velocity values acting as said initial velocity field.