Processing Seismic Data
Publication Date: 2015-Jul-10
The IP.com Prior Art Database
Title: Offset and azimuth resampling of migrated seismic data
The purpose of this process is to better condition migrated seismic data for pre-stack inversion, AVO analysis, or velocity estimation. It utilizes 5D interpolation to produce new seismic traces at optimal offsets and azimuths for pre-stack inversion. It also has the benefit of reducing migration noise and other noise that often contaminate near offset migrated traces.
Seismic data has historically been migrated in the common offset domain, the result of which is a set of seismic traces at each image location that have uniformly incrementing offsets. Recently, orthogonally acquired seismic data is being imaged in the Offset Vector Tile (OVT). This is a more desirable domain for imaging as it preserves azimuthal variability in the post-migration data. It usually also results in less noise in the migrated results. However, the OVT migrated data results in gathers that have very uneven, and duplicated sampling in the offset direction
A common usage of migrated data is to be used as input to pre-stack inversion. Many software packages for pre-stack inversion have been developed and optimized to be run on common offset migrated data. Inputting OVT data can be problematic or not possible in some cases. I propose to use a 5D interpolation on the OVT migrated data in order to produce gathers that are better sampled for input to Inversion. There is flexibility in how this output sampling is defined based on what sort of inversion is to be run, but a couple likely output sampling include:
a) Radial gathers: gathers with fixed offset increments at each of a set of fixed azimuths (e.g. 0-3000m offsets at 100m increments at 0 to 180 degrees at 15degree increments)
b) Offset Gathers: The OVT gathers are input to a 4D interpolation whose output is a set of evenly incrementing offsets. In this case azimuth is dropped from the interpolation. Creating offsets from OVTs would likely occur after residual gather flattening has been run to remove azimuthal variability from the OVT data.
Detailed Description Including Examples and Drawings
Offset-Vector Tile (OVT) migration has become the standards domain for pre-stack migration of orthog...