Common Reflection Azimuth Migration
AssigneeExxonMobil Upstream Research Company
InventorGraham A. Winbow
Life of this patent
Estimating the term…
Abstract
Method for migration of seismic data into datasets having common azimuth angle at the reflection point. A velocity model is selected that prescribes subsurface P and/or S wave velocities including any required anisotropy parameters. (41) For shot locations on a surface grid, rays are traced on to a 3D grid of points in a target region of the subsurface. (42) At least the travel times of the rays and their dip angles at each subsurface point are stored in computer memory as they are computed. (43) Using the stored ray maps, the seismic data are migrated into seismic image volumes, each volume being characterized by at least an azimuthal angle bin, the azimuthal angles being computed from said ray dip angle information. (44)
Claims21
A method for migrating 3D seismic data to create depth images of reflector surfaces in a subsurface region where azimuth information at each image point is desired for petroleum exploration or production, said method comprising performing steps (a)-(c) one data trace at a time:
- (a) for each combination of the trace's corresponding seismic source and receiver locations and an image point, using a ray-based imaging method to determine direction angles at the image point of a first seismic ray connecting the source to the image point and of a second seismic ray connecting the receiver location to the image point;
- (b) geometrically determining mathematical relationships from which azimuthal angle at the image point of a plane defined by each first and second seismic ray pair can be solved knowing the ray direction angles;
- and
- (c) migrating the seismic data trace into data volumes labeled by a common azimuthal angle of the rays at each image point.
Dependencies are inferred from the claim text.