Wave-equation time migration |

**Sergey Fomel and Harpreet Kaur**

Bureau of Economic Geology,

John A. and Katherine G. Jackson School of Geosciences

The University of Texas at Austin

University Station, Box X

Austin, TX 78713-8924

sergey.fomel@beg.utexas.edu

Time migration, as opposed to depth migration,
suffers from two well-known shortcomings: (1) approximate equations
are used for computing Green's functions inside the imaging
operator; (2) in case of lateral velocity variations, the transformation between the image ray coordinates and the Cartesian coordinates is undefined in places where the image rays cross. We show that the first
limitation can be removed entirely by formulating time migration
through wave propagation in image-ray coordinates. The proposed approach constructs a time-migrated image without relying on any kind of traveltime approximation by formulating an appropriate geometrically accurate acoustic wave equation in the time-migration domain. The advantage of
this approach is that the propagation velocity in image-ray
coordinates does not require expensive model building and can be
approximated by quantities that are estimated in conventional
time-domain processing. Synthetic and field data examples demonstrate the effectiveness of the proposed approach and show that the proposed imaging workflow leads to a significant uplift in terms of image quality and
can bridge the gap between time and depth migrations. The image obtained by the proposed algorithm is
correctly focused and mapped to depth coordinates it is comparable to the image obtained by depth migration.

- Introduction
- Wave-equation and image rays
- Workflow: Wave-equation time migration
- Step 1. Time migration velocity analysis
- Step 2. Dix conversion
- Step 3. Wave-equation time migration
- Step 4. Conversion from time to depth
- Step 5. Velocity model building

- Examples

- Conclusions
- Bibliography
- About this document ...

Wave-equation time migration |

2022-05-23