(Seminars for Spring, 2009)
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Date |
Speaker |
Subject |
Notes |
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1/20 |
Praj |
2D Shear Wave VSP Imaging in the Presence of Azimuthal Anisotropy in Rulison Field, Colorado |
The reservoir zone in Rulison Field comprises of thin sands whose lateral extent, geometry and hence connectivity is not well understood. The acoustic impedance (Vp*density) contrast between the sandstone and the encasing shale and the sub-resolution thickness of sandstone does not allow them be detected by the P-wave sources. However, the shear impedance contrast (Vs* density) between the sand-shale interfaces is more thus giving a better chance for their detection using a shear wave VSP survey. In the presentation I would discuss how to image the subsurface using shear waves recorded by multilevel 3C geophones in a walkaway VSP survey shot with collocated orthogonal horizontal vibrators. The current work describes a 2D imaging exercise that can, eventually, be extended to a 3D workflow. |
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1/27 |
Hossein |
Effect of anisotropy on long offset time-lapse seismic |
How the maximum amplitude offset shifts as a result of reservoir changes? How the critical angle changes in a compacting reservoir? I will talk about my work on these problems. |
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2/03 |
Bharath |
Estimation of Shear-wave interval anisotropic attenuation coefficients from mode converted data |
The idea is to use the spectral ratio method together with the PP+PS=SS to derive the attenuation coefficients in a target layer. A layer cake model (orthorhombic symmetry with one of the symmetry planes being the horizontal plane) will be considered. |
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2/17 |
Mamoru |
Influence of lateral heterogeneity on P-wave velocity analysis for transversely isotropic media |
Nonhyperbolic seismic moveout velocity provides distributions of NMO velocity and anisotropic parameter eta, which are useful for reducing depth uncertainty. However, these parameters affected by the existence of lateral heterogeneity may mislead the depth interpretation. I will show the effects of lateral heterogeneity in a simple case and will discuss my research plan. |
2/24 |
Yongxia |
Gaussian beam modeling with First-order ray tracing method in VTI media |
The Gaussian beam modeling is based on the ray tracing method. We will talk about the first-order ray tracing for VTI medium and some tests for the accuracy for travel time and geometrical spreading in the wavefront orthonormal coordinates. Then we will talk about several questions in Gaussian beam method including the beam width, the weighting factor and so on. |
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3/03 |
Xiaoxiang |
Stacking-velocity tomography with borehole data for TTI media |
Inversion for TTI parameters usually needs the combination of P- and S-wave data. If only pure PP reflections and a vertical well are available, combining the information from surface P-wave data with the measurements from the vertical well may helps to estimate some of TTI parameters. I will present my 2D study on this topic. |
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3/17 |
Paritosh |
Shear wave anisotropy study using warping inversion method in Rulison Filed, Colorado |
The objective of the present study is to find the fractured zones and help in proper well planning. Shear wave anisotropy responds to the presence of fractures in the subsurface. In this study a new approach to warping has been proposed for shear wave anisotropy study which aims to determine the velocity changes between fast and slow shear datasets, accounting simultaneous for the observed time shifts and amplitude changes. |
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3/24 |
Alexandre |
PS-wave traveltime and amplitude analysis, Rulison Field, Colorado |
I will be covering the following topics: (1) Traveltime analysis for PS-wave and conversion-point determination. (2) Inversion for the Thomsen parameters delta, sigma, and epsilon from post-stack data and NMO velocity data assuming a VTI media. (3) Amplitude analysis for converted waves and the pseudo-impedance concept. (4) Determination of Gamma(S) splitting from amplitude inversion of PS data. |