A-team Seminar - Fall, 2013

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

(Seminar for Fall, 2012)

Date

Speaker

Subject

Notes

11/21/13

Dr. Paul Fowler

Orthorhombic imaging: using quaternions to represent 3D rotation parameters

Paul will show a few examples of why orthorhombic imaging is becoming important both for unconventional plays and for imaging around salt bodies. One of the practical issues we face in doing orthorhombic imaging is representing and manipulating 3D rotations to keep track of the spatially varying orientations of the symmetry planes. Computer graphics, robotics and aero- and astronautical engineering have all figured out that quaternions provide an efficient method for handling problems of 3D rotations, and He will argue that we should do likewise in geophysics. Time permitting, He will try to make a bit of a case that quaternions are not really so obscure or weird as they might seem when one first encounters them, but actually represent a simple example of an important branch of modern mathematics, namely Lie Groups

11/07/13

Round Table Discussion

10/31/13

Tong Bai and Yogesh Arora

Discussion of the paper in TLE titled "A timely and necessary antidote to indirect methods and so called P-wave FWI" by Arthur B. Weglein.

10/10/13

Dr. Tariq Alkhalifah

Effective velocity models to extrapolate anisotropic wavefields and anisotropic FWI

Isotropic wavefield extrapolation is far more efficient than the anisotropic one, and this is especially true when the anisotropy exhibits tilted (from the vertical) symmetry axis. We use the kinematics of the wavefield, appropriately represented in the high-frequency asymptotic approximation by the eikonal equation, to develop effective isotropic models. These models are used to efficiently extrapolate anisotropic wavefields using the isotropic, relatively cheaper, operators. These effective velocity models are source dependent and tend to embed the anisotropy influence in the inhomogeneity representation.

10/03/13

Round table discussion about the SEG Annual Meeting 2013

The discussion will be mainly about interesting presentations delivered during SEG Annual Meeting 2013

09/12/13

Oscar Jarillo

Source-parameter inversion of microseismic data in VTI media.

During this talk, Oscar will present the results of gradient calculation for source parameters (source coordinates and moment-tensor elements) of a microseismic experiment in an anisotropic VTI medium using the adjoint-state method. He'll also present some issues to consider when solving inverse problems with multiple parameter classes. And finally, Oscar will talk about the behavior and results of source-location inversion using kinematic and waveform methods.

09/05/13

Nishant Kamath

FWI of transmission data for VTI media

Nishant will go over basics of FWI and speak about the expressions for the gradients for (elastic) VTI media. He will show an inversion result for a simple transmission experiment. He will also discuss how the final result relates to gradients and resolution.