[Alumnos] SEG Honorary Lecture 2017

[Sociedad Geofísica de la UNLP]

La Sociedad de Alumnos de Geofísica de la FCAG-UNLP (SEG Student Chapter) 
tiene el agrado de invitarlos a participar de la charla titulada 
"Multiparametric traveltimes: Concepts and applications". La misma estará 
a cargo del Prof. Martin Tygel, y se desarrolla en el marco del "Honorary 
Lecture Program" organizado por la SEG.
La charla tendrá lugar el miércoles 30 de agosto a las 14 hs., en el Salón 
Meridiano de la FCAG.

Los esperamos!!

Sociedad Geofísica de la UNLP (SGUNLP)
SEG Student Chapter
FCAGLP

http://fcaglp.fcaglp.unlp.edu.ar/~socgeof/index.html
https://www.facebook.com/sociedad.unlp?fref=ts
https://www.linkedin.com/groups/8288326

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Resumen de la charla:
Traveltime stacking is one of the most fundamental tools in the processing 
of multicoverage seismic data. The most popular stacking traveltime is the 
normal moveout (NMO), upon which the celebrated common-midpoint (CMP) 
method is based. Established in the 1960s, the CMP method remains as an 
obligatory step in any seismic processing sequence. The NMO stacking 
traveltime depends on a single parameter (the NMO velocity) and is 
performed on individual CMP gathers, thus depending on offset only. In 
spite of its well-recognized good properties, such as a valuable 
zero-offset (ZO) stacked section and an NMO-velocity field, NMO stacking 
can be seen to have two main drawbacks: The first one is that it employs 
only a fraction (CMP gathers) of the multicoverage data and, as a 
consequence, takes no advantage of the redundancy contained in the full 
data. The second one is the fact that it delivers a single parameter (NMO 
velocity), not much information extraction from the huge and costly 
seismic data.
In the 1980s, in response to the demands of seismic processing in 
anisotropic media, multiparametric nonhyperbolic moveouts came into play. 
Still dependent on offset only, such moveouts mainly were applied to 
transverse anisotropic media with a vertical axis of symmetry. Moveout 
extensions for more complex anisotropic media are available in recent 
literature, being a topic of active ongoing research.
A vigorous attempt to overcome the limitations of offset dependent 
moveouts came about in the late 1990s by the introduction of 
multiparametric moveouts depending on both midpoint and offset coordinates 
and also fully in 3D. Moreover, the parameters introduced in the new 
traveltimes were seen to be very useful for other imaging purposes, such 
as, e.g., time migration, separation of reflections and diffractions, 
time-to-depth conversion, tomography and, more recently, data 
regularization.
In this lecture, I discuss the multiparametric traveltimes that are the 
most natural extensions of the classical single-parameter NMO and 
time-migration moveouts. More specifically, these are the 3D hyperbolic 
(second-order Taylor polynomial) mainly designed for reflections and 
double-square-root (sum of two hyperbolic moveouts), mainly designed for 
diffractions. Both traveltimes are defined for varying midpoint and 
half-offset coordinates.
Besides a brief discussion of the traveltime expressions and 
interpretation of their parameters, various applications on the 
above-mentioned topics are presented. Finally, perspectives and actual 
challenges of the multiparametric traveltime approach to seismic imaging 
are commented.


Biografía:
Martin Tygel received his BSc in physics (1969) at the State University of 
Rio de Janeiro and MSc in mathematics (1973) at the Catholic University of 
Rio de Janeiro. After being awarded by a fellowship of the Brazilian 
Council of Research and Technological Development (CNPq), he obtained the 
MSc (1976) and PhD (1979) in mathematics at Stanford University. He has 
taught at the Federal University of Rio Grande do Norte (1979–1981) and 
the Federal University of Bahia (1981–1983), being responsible there for 
the mathematical disciplines at the joint graduate program in geophysics 
together with Petrobras. In 1984, he joined the University of Campinas 
(Unicamp), where he is located until today. Prof. Tygel has also been a 
Humboldt scholar (1985–1987) in Hannover (Germany), and also a visiting 
professor at the Universities of Karlsruhe (Germany) (1990) and Trondheim 
(Norway) (2007–2008). In 2002, he received the Conrad Schlumberger Award 
of the European Association of Geophysicists and Engineers.  In 1997, 
Prof. Tygel was one of the founders of the Wave Inversion Technology (WIT) 
Consortium. In 2001, he founded the Computation Geophysics Laboratory at 
the Department of Applied Mathematics at Unicamp, and in 2013, he founded 
the High Performance Geophysics (HPG) Lab at the Center of Petroleum 
Studies also at Unicamp. The latter has a special emphasis in integrating 
geophysics results with high-performance computing (HPC) so as to optimize 
their most direct practical application. Besides his scientific activities 
which include three books and more than 200 publications in international 
journals and proceedings of international congresses, Prof. Tygel has a 
long experience in carrying out projects which involves academia and the 
oil industry. His research interests are in methodologies and algorithms 
of seismic processing, imaging, and inversion that have a sound basis on 
wave propagation and find practical application to exploration and 
monitoring of hydrocarbon reservoirs.