A-team Seminar - Fall, 2012

Wednesday, 3:00-4:00 PM, Green Center, Room 281.

(Seminar for Fall, 2012)






Round-table discussion

Discussion about research projects for this semester


Nishant Kamath

Derivation of expressions for gradients in FWI for VTI media

Oscar and Nishant are trying to use Full waveform inversion (FWI) using the adjoint state method in order to estimate anisotropy parameters and source location (in the case of microseismic data) for VTI media. Nishant will go over some of the derivations that lead to the expressions for the gradients of the objective function w.r.t model parameters (which is equivalent to a scaled version of the model updates). Hopefully the discussions will clarify some of the questions we ourselves have regarding the maths. The end results (specifically for VTI media) have been verified using expressions found in two different papers, and they match.


Oscar Jarillo

Derivation of the expressions for the gradients of the source parameters in FWI for VTI media

Last week, Nishant derived the expressions for the gradients of the anisotropic velocity parameters in VTI media. In this seminar, Oscar will derive the expressions of the gradients of the source parameters by using a different approach than the one Nishant explained previously. In addition, Oscar will show how to go from the general expressions of the gradients to the expressions for each model parameter individually. Finally he will mention some important points to consider when trying to implement the adjoint-state method for moment-tensor sources in elastic anisotropic media.


Bharath Shekar

Kirchhoff modeling in attenuative anisotropic media

In attenuative media, ray-based modeling methods are efficient and easy to implement. In Kirchhoff modeling we need to compute tables of Green's functions (source-diffractor + diffractor-receiver). This can be done using a host of "two-point" ray tracing methods. Another alternative is to perform a weighted summation of Gaussian beams - this is the approach that he uses. He will show examples where he reconstructs Green's functions in unbounded homogeneous and heterogeneous media and scattered data from layered media.


Dr. Gerardo Ronquillo Jarillo -- guest speaker from Instituto Mexicano del Petroleo

Azimuthal seismic attribute analysis of seismic multicomponent data acquired at Cantarell

We present partial results of the integration of azimuthal seismic attributes with well-log data, seismic modeling and correlation with geological models in carbonate reservoirs (Cantarell). First, it is important to understand the geological outcropping carbonate rocks as analogous to the subsurface rocks in the Cantarell reservoir at different scales (regional and well samples). Second, we process multicomponent seismic data with emphasis in rotation of converted PS modes and asymptotic binning. Third, estimation of seismic attribute analysis of prestack and poststack P and PS-wave data. Fourth, correlation of seismically interpreted data with well-log results. Fifth, viscoelastic seismic modeling and multipoint fracture simulation. This kind of studies allow us to obtain a better understanding of the reservoir.


Dr. Michael Slawinski -- guest speaker from Memorial University

Effective Hookean solids obtained by Monte-Carlo method

He will show how to identify the symmetry class of the stiffness tensor and the orientation of symmetry planes (if there are any) using global optimization. This topic is particularly relevant for VSP inversion that can produce a complete stiffness tensor, whose symmetry typically is unknown.


No seminar.


Dr. James Gaiser -- guest speaker from CGGVeritas

Current PS-wave processing challenges


Spring break


Round-table discussion


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No seminar (Rehearsal).


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