Method for velocity model building and analysis
AssigneeWesternGeco L.L.C.
InventorsColin J. Thomson, Philip Kitchenside
Life of this patent
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Abstract
Method for velocity model building and analysis using wavefield-coordinates reflection operators in wave-equation migration or reverse-time migration.
Claims22
A method for obtaining an image for interpreting subsurface geology in geophysical exploration, comprising:
- constructing, by a system having a processor, a wavefield-coordinates reflection operator with a given velocity model, where the wavefield-coordinates reflection operator is a function of coordinates of a source wavefield and a receiver wavefield without being a function of midpoint-offset coordinates, and the wavefield-coordinates reflection operator relates the source wavefield to the receiver wavefield;
- and
- determining and correcting, by the system, an error in the velocity model using the wavefield-coordinates reflection operator.
The method of 1, wherein constructing the wavefield-coordinates reflection operator comprises:
- propagating the source and receiver wavefields to locations in a subsurface.
The method of 2, wherein propagating the source and receiver wavefields comprises propagating by extrapolation.
The method of 2, wherein propagating the source and receiver wavefields comprises propagating by migration.
The method of 2, further comprising using and interpreting dynamic and kinematic attributes of the wavefield-coordinates reflection operator.
The method of 1, wherein determining the error in the velocity model using the wavefield-coordinates reflection operator comprises determining the error by perturbation analysis.
The method of 1, wherein the determining and correcting of the error in the velocity model comprises:
- fitting the wavefield-coordinates reflection operator on a layer-by-layer basis;
- and
- layer-stripping to correct the error in the velocity model.
The method of 7, wherein layer-stripping to correct the error in the velocity model comprises:
- fitting the reflection operator to obtain an estimate of a dip angle of a reflector and a vertical distance to the reflector.
The method of 1, further comprising displaying the wavefield-coordinates reflection operator for locating a dip.
A system for obtaining an image for interpreting subsurface geology in geophysical exploration comprising:
- at least one processor;
- a non-transitory computer readable medium containing instructions that when executed by the at least one processor cause the at least one processor to:
- construct a wavefield-coordinates reflection operator with a given velocity model, where the wavefield-coordinates reflection operator is a function of coordinates of a source wavefield and a receiver wavefield without being a function of midpoint-offset coordinates, and the wavefield-coordinates reflection operator relates the source wavefield to the receiver wavefield;
- and;
- determine and correct an error in the velocity model using the wavefield-coordinates reflection operator.
The system of 13, wherein constructing of the wavefield-coordinates reflection operator comprises propagating the source and receiver wavefields to locations in a subsurface.
The system of 14, wherein the at least one processor is to further use and interpret dynamic and kinematic attributes of the wavefield-coordinates reflection operator.
The system of 13, wherein determining and correcting the error in the velocity model comprises:
- fitting the wavefield-coordinates reflection operator on a layer-by-layer basis;
- and
- layer-stripping to correct the error in the velocity model.
The system of 16, wherein layer-stripping to correct the error in the velocity model comprise:
- fitting the wavefield-coordinates reflection operator to obtain an estimate of a dip angle of a reflector and a vertical distance to the reflector.
A non-transitory computer readable medium containing instructions that when executed by a computer cause the computer to:
- construct a wavefield-coordinates reflection operator with a given velocity model, where the wavefield-coordinates reflection operator is a function of coordinates of a source wavefield and a receiver wavefield without being a function of midpoint-offset coordinates, and the wavefield-coordinates reflection operator relates the source wavefield to the receiver wavefield;
- and;
- determine and correct an error in the velocity model using the wavefield-coordinates reflection operator.
Dependencies are inferred from the claim text.