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A-Team Seminars - 2015 Fall

All A-Team Seminars take place at 11:00am each Friday in Green Center Room 281, unless otherwise indicated.

 

Date Speaker(s) Title Abstract

10/2

Nabil Masmoudi

Heloise Lynn

Lynn, Inc.

Prestack Azimuthal P-P Reflection Amplitudes – azimuth-blind and azimuth-dependent

In a 3D P-P field dataset recently published at the 2014 SEG Annual Meeting, Lynn showed that the AVOaz anomaly arising at high fracture density locations was accompanied by an azimuthal change in the near-offset amplitudes. The azimuthal variation in the near-offset amplitudes has a higher magnitude (factor of 2) than that predicted by any existing theory. The azimuthal variations in the near-offset amplitudes under consideration fit the cos 2theta azimuthal variation criteria associated with one set of vertical aligned fractures. This type of observation was seen throughout the dataset at various locations, wherein independent calibration data gave indications of the local fracture azimuths. This presentation of several sets of field data wherein the above is observed is offered in the hopes of interesting someone to derive a theory that will match the field data.

9/25

Aimé Fournier

University of Colorado, Boulder

Seismic uncertainty analysis methods, recent results and potential applications

This talk presents a review of seismic uncertainty analysis (SUA) methodology developed at Schlumberger HTC. In principle, SUA enables a complete probability distribution of a spatially dependent tilted transversely isotropic earth model and of its derived quantities; but in practice, there are challenging and significant choices e.g., regarding prior model, and what kind of uncertainty questions/answers are useful to a client. If the client can provide or approve a formulation of the way their project's economic value depends on the earth model and on exploration, development etc. decisions, then formal Decision Analysis (DA) can guide those decisions. Recent reports suggest that potential environmental impacts of fracking raise enough concern to warrant formal Risk Analysis. I hope to stimulate a discussion about the extent to which SUA and DA may support that analysis, and what additional technology remains to be transferred or invented.

9/18

Nabil Masmoudi

Nabil Masmoudi

Multi-stage Orthorhombic model inversion

Orthorhombic anisotropic model inversion is extra challenging because of the multiple parameter nature of the inversion problem. Choosing a suitable set of parameters to describe the model and designing a practical inversion strategy is essential. By analyzing the radiation patterns for the different acoustic orthorhombic parametrizations starting with the often utilized Thomsen-Tsvankin parametrization style, we assess the parameters potential trade-off and resolution in orthorhombic FWI. Then, we introduce a new parametrization that allows us to develop a multi stage model inversion starting with isotropic FWI, followed by VTI, and finally orthorhombic.

 

 

 

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