 |
Pre stack time migration
Arcis has the ability to run pre stack Kirchhoff time
migration on 2D and 3D data with output either to gathers or stack. The migration can be done to the original input grid or any user specified output grid.
Hardware /turnaround considerations
Arcis' PSTM algorithm is set up to run on several compute nodes at a time. Arcis has
a 32 node AMD Opteron cluster and a 128 node Sun Opteron cluster.
These are primarily dedicated to pre stack migrations in addition to the normal processing hardware so fast turnaround can be provided.
Alias filtering
The program provides full anti-aliasing filtering and options to lessen the filtering at user request.
Output grid
The data can be migrated to the natural cdp grid of the input data or to finer or coarser grids as requested by the client.
Migration to gathers
The option used for migration to gathers requires defining bins by ranges of offsets. All traces with offsets in the range for a given bin are migrated to produce one output trace at each cdp for that bin. The user controls the number of bins and the offset range of each. Offset ranges can vary from bin to bin.
AVO friendliness
The data can be normalized to lessen the acquisition footprint due to irregular sampling in offset space. This normalization is essentially the method outlined by Caning and Gardner in Geophysics Volume 63, no. 4, pp 1177-1183, 1998.
QC measures
Several QC measures are routinely employed in the migration process. Impulse response analysis is routinely done to assist in selecting appropriate aperture controls.
Arcis can provide migrated output gathers from constant amplitude synthetic data with the same geometry as the actual data. These gathers provide an excellent way to QC the effectiveness of the AVO weighting discussed above and to identify potential problems areas due to the limits imposed by the acquisition.
Velocity analysis
Arcis has an interactive program for analyzing and picking migration velocities on panels of data that have been migrated with different velocity functions using the same migration program. Normally an initial velocity model and percentages of that model are used as input to the interactive velocity analysis program. Interpreters are welcome to use this program to pick their own velocities and can actually see the effects of velocities on their data.
This program can display migrated gathers as well as stacks.
|
|
