# US 8,542,554 B2 · Method for velocity model building and analysis > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,554 B2 - Document ID: US8542554B2 - Status: Granted - Kind: B2 - Application number: 12/709,868 - Filed: 2010-02-22 - Published: 2011-05-12 - Granted: 2013-09-24 - Earliest claimed: 2009-11-10 - Assignees: WesternGeco L.L.C. - Applicants: Colin J. Thomson; Philip Kitchenside - Inventors: Colin J. Thomson; Philip Kitchenside - Web page: https://patentgrep.com/patent/US8542554B2 ## CPC - G01V 1/303: {for determining velocity profiles or travel times} - G01V 2210/6222: Velocity; travel time - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) ## Abstract Method for velocity model building and analysis using wavefield-coordinates reflection operators in wave-equation migration or reverse-time migration. ## Claims ### Claim 1 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. ### Claim 2 The method of 1, wherein constructing the wavefield-coordinates reflection operator comprises: propagating the source and receiver wavefields to locations in a subsurface. ### Claim 3 The method of 2, wherein propagating the source and receiver wavefields comprises propagating by extrapolation. ### Claim 4 The method of 2, wherein propagating the source and receiver wavefields comprises propagating by migration. ### Claim 5 The method of 2, further comprising using and interpreting dynamic and kinematic attributes of the wavefield-coordinates reflection operator. ### Claim 6 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. ### Claim 7 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. ### Claim 8 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. ### Claim 9 The method of 1, further comprising displaying the wavefield-coordinates reflection operator for locating a dip. ### Claim 10 (depends on 1) The method of claim 1, further comprising combining the source wavefield and receiver wavefield to obtain the image of a subsurface. ### Claim 11 (depends on 1) The method of claim 1, wherein the wavefield-coordinates reflection operator represents a reflection response of a subsurface for locations in the subsurface below a given depth. ### Claim 12 (depends on 1) The method of claim 1, further comprising: refining the velocity model based on the error; and re-iterating the constructing, determining, and correcting tasks for the refined velocity model. ### Claim 13 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. ### Claim 14 The system of 13, wherein constructing of the wavefield-coordinates reflection operator comprises propagating the source and receiver wavefields to locations in a subsurface. ### Claim 15 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. ### Claim 16 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. ### Claim 17 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. ### Claim 18 (depends on 13) The system of claim 13, wherein the at least one processor is to further combine the source wavefield and receiver wavefield to obtain the image of a subsurface. ### Claim 19 (depends on 13) The system of claim 13, wherein the at least one processor is to further: refine the velocity model based on the error; and re-iterate the constructing, determining, and correcting tasks for the refined velocity model. ### Claim 20 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. ### Claim 21 (depends on 20) The non-transitory computer readable medium of claim 20, wherein the instructions when executed cause the computer to further combine the source wavefield and receiver wavefield to obtain an image of a subsurface. ### Claim 22 (depends on 20) The non-transitory computer readable medium of claim 20, wherein the instructions when executed cause the computer to further: refine the velocity model based on the error; and re-iterate the constructing, determining, and correcting tasks for the refined velocity model.