Method for computing finite-frequency seismic migration traveltimes from monochromatic wavefields
AssigneeWesternGeco L.L.C.
InventorJames Wendell Wiggins
Life of this patent
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Abstract
A method for determination of seismic wave travel times from a surface location to at least one subsurface computation point (CP) within a plurality of subsurface location points. A velocity model of a region is defined. A complex monochromatic wavefield is computed, using the velocity model, for the at least one CP. An unwrapped phase of the seismic wave is determined at a neighboring computation point (NCP) proximate to at least one subsurface CP. The travel time of the seismic wave to the at least one CP is determined using the unwrapped NCP phase and the computed monochromatic wavefield for the at least one CP. Travel time maps and table may be created from the determined travel time values.
Claims41
A method for determination of a travel time of a seismic wave from a surface location to at least one computation point (CP) within a plurality of subsurface location points comprising:
- (a) defining a velocity model of a region including said plurality of subsurface location points;
- (b) computing a monochromatic wavefield, using the velocity model, for the at least one CP;
- (c) determining an unwrapped phase of the seismic wave at at least one neighboring computation point (NCP) proximate to the at least one CP in said plurality of location points;
- and
- (d) determining the travel time of the seismic wave to the at least one CP from said determined unwrapped phase and said computed monochromatic wavefield for the at least one CP.
A method for determination of a travel time map for a seismic wave from a surface location to at least one computation point (CP) within a plurality of subsurface location points comprising:
- (a) defining a velocity model of a region including said plurality of subsurface location points;
- (b) computing a monochromatic wavefield, using the velocity model, for the at least one CP;
- (c) determining an unwrapped phase of the seismic wave at at least one neighboring computation point (NCP) proximate to the at least one CP in said plurality of location points;
- (d) determining the travel time of the seismic wave to the at least one CP from said determined unwrapped phase and said computed monochromatic wavefield for the at least one CP;
- and
- (e) storing the travel time values in the form of a map.
A method for determination of a travel time of a seismic wave from a surface location to at least one computation point (CP) within a plurality of subsurface location points comprising:
- (a) defining a velocity model of a region including said plurality of subsurface location points;
- (b) computing a wavefield for at least one selected frequency, using the velocity model, for the at least one CP;
- (c) determining an unwrapped phase of the seismic wave at at least one neighboring computation point (NCP) proximate to the at least one CP in said plurality of location points;
- and
- (d) determining the travel time of the seismic wave to the at least one CP from said determined unwrapped phase and said computed wavefield for the at least one CP.
Dependencies are inferred from the claim text.