Common Reflection Surface (CRS) Processing in Complex Geology -- An
Alternative to Prestack Depth Migration
?
By
Henning Trappe1, Guido Gierse1, Juergen Pruessmann1
(1) TEEC, Isernhagen, Germany
Imaging in complex geology environments faces numerous problems like rapid
lateral changes, discontinuous reflectors, a high noise level, and multiple
contamination. Reliable velocity
models often cannot be defined, neither in time
nor in depth, since primary reflections are hardly visible in the prestack data,
or cannot be discriminated from multiples.
Macro-model independent imaging could represent an approach to reduce these difficulties. The Common Reflection Surface (CRS) stacking technique offers several advantages with respect to the conventional NMO/DMO processing:
-
No velocity
model is required. However, available
velocity
information
may be used as a constraint.
-
The CRS stacking parameters are automatically determined from the seismic
data for each point of the stack. This local adaptation optimizes the image of
strong structure and velocity
changes.
- The hyperbolic stacking surfaces extend across several CMP locations. The resulting high fold leads to a strongly increased signal-to-noise ratio.
- The CRS method assumes subsurface reflectors that are characterized by local dip and curvature. This leads to an enhanced imaging of curved and dipping structures.
Application examples show an improved image of complex geology by the CRS
method in comparison to conventional imaging. Poststack depth migration
of the
CRS stack produces a high-resolution depth section, that can be superior to
prestack depth
migration
results in data environments that do not allow a
reliable
velocity
model building.