## Annual Report, 2006

## Presentations at Review Meeting, 26 January 2007:
- William W. Symes: Overview
- William W. Symes: Reverse time migration: checkpointing and scaling
- Jianliang Qian: Eulerian methods for traveltime tomography
- William W. Symes: Kirchhoff-based differential semblance using eikonal solvers
- Kirk D. Blazek: The viscoelastic inverse problem
- Tetyana W. Vdovina: Upscaling for acoustinc and elastic wave equations
- Kirk D. Blazek: Theoretical foundation for viscoelasticity
- Jianliang Qian: Eulerian construction of Gaussian Beams
- William W. Symes: Progress and prospects for wave equation velocity analysis

## Expanded Abstracts from SEG 2006:
**DSR Migration Velocity Analysis by Differential Semblance Optimization**, Alexandre Khoury, William Symes (Rice University), Paul Williamson, Peng Shen (Total E & P USA Inc.) (pdf)
**Summary:** The relative efficiency of Common Azimuth wave
equation depth migration based on the double square root equation
makes it an attractive engine for use in automated velocity updating
schemes. One such automated velocity analysis procedure is
Differential Semblance Optimization, which constructs velocity updates
to reduce, and eventually minmize, a quantitative measure of image
gather misfocussing. We review the construction of a differential
semblance velocity analysis tool based on common azimuth migration,
and present some 2D examples. These examples illustrate some of the
promise, and some of the potential pitfalls, of this approach to
velocity analysis.

**Practice and Pitfalls in NMO-based Differential Semblance Velocity Analysis**, Richard W. Verm (Geophysical Development Corp.) and William W. Symes (Rice University) (pdf)
**Summary:** Differential semblance provides an automated
alternative to commonly used velocity analysis methods. For data
exhibiting low structural relief, an implementation based on
hyperbolic moveout is fast enough for 3D velocity estimation on a
workstation. Application of this technique to a time processed land 3D
dataset from the onshore Gulf of Mexico demonstrates this
capability. Compoared to more conventional methods of velocity
analysis, it produced reliable results in very short order.

**DSR Migration Velocity Analysis by Differential Semblance Optimization**, Alexandre Khoury, William Symes (Rice University), Paul Williamson, Peng Shen (Total E & P USA Inc.) (pdf)
**Summary:** The relative efficiency of Common Azimuth wave
equation depth migration based on the double square root equation
makes it an attractive engine for use in automated velocity updating
schemes. One such automated velocity analysis procedure is
Differential Semblance Optimization, which constructs velocity updates
to reduce, and eventually minmize, a quantitative measure of image
gather misfocussing. We review the construction of a differential
semblance velocity analysis tool based on common azimuth migration,
and present some 2D examples. These examples illustrate some of the
promise, and some of the potential pitfalls, of this approach to
velocity analysis.

**Practice and Pitfalls in NMO-based Differential Semblance Velocity Analysis**, Richard W. Verm (Geophysical Development Corp.) and William W. Symes (Rice University) (pdf)
**Summary:** Differential semblance provides an automated
alternative to commonly used velocity analysis methods. For data
exhibiting low structural relief, an implementation based on
hyperbolic moveout is fast enough for 3D velocity estimation on a
workstation. Application of this technique to a time processed land 3D
dataset from the onshore Gulf of Mexico demonstrates this
capability. Compoared to more conventional methods of velocity
analysis, it produced reliable results in very short order.

## Papers, Theses, and Reports:

- William W. Symes:
**Reverse-time migration with optimal checkpointing**, Geophysics. vol. 72, pp. SM213-222, 2007. - Jintan Li and William W. Symes:
**Interval velocity estimation via NMO-based differential semblance**, Geophysics, vol. 72, pp. U75-88. 2007. - William W. Symes:
**Approximate linearized inversion by optimal scaling of prestack depth migration**, Geophysics, vol. 73, pp. R23-35, 2008.