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Results
Case History: The Evolution of Full-Waveform Inversion – Southern Trend Trinidad
LaDart, Susan (BP) | Behura, Jyoti (BP) | Mika, Jim (BP) | Albertin, Uwe (BP)
Summary The Southern Trend area of Trinidad is characterized by gas chimneys and shallow gas distortions that are difficult to image due to the poor data quality from conventionally acquired data. The goal of seismic tomography is to estimate a velocity model, so that migration produces an optimum image. In this case the post- migration reflection tomography does a good job updating the velocities outboard of the gas prone areas, but not in areas where significant gas is present. In order to improve imaging in these areas, full-waveform inversion was applied to improve the velocity model, with the primary goal of improving the migrated image. Both isotropic and anisotropic inversions, including updating of anisotropic parameters were run, and the results will be shown in this paper.
SUMMARY Using only surface reflection data and first-arrival information, we generate up- and down-going wavefields at every image point using the algorithm of Rose (2002b,a) and Wapenaar et al. (2011, 2012a). An imaging condition is applied to these up- and down-going wavefields directly to generate the image. Since the above algorithm is based on exact inverse scattering theory, the reconstructed wavefields are accurate and contain all multiply scattered energy in addition to the primary event. As corroborated by our synthetic examples, imaging of these multiply scattered energy helps illuminate the subsurface better than reverse-time migration. We also demonstrate that it is possible to perform illumination compensation using our imaging algorithm that results in improved imaging at large depths.
SUMMARY Existing methods of internal multiple prediction are either computationally expensive or not automated. Here, based on stationary phase arguments, we introduce a method for predicting internal multiples that is not only fully automated but also computationally inexpensive. The procedure is completely data driven and requires no velocity information or reflector identification. An additional advantage of the proposed method is that it can also be used to predict source- and receiver-ghosts. The method, however, is limited to gently-dipping reflectors. Through synthetic examples and field data, we demonstrate the effectiveness of our methodology.
- North America > United States (0.31)
- Europe > United Kingdom > North Sea (0.16)
- Europe > Norway > North Sea (0.16)
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.47)
Integrated Migration and Internal Multiple Elimination
Wapenaar, Kees (Delft University of Technology) | Thorbecke, Jan (Delft University of Technology) | van der Neut, Joost (Delft University of Technology) | Slob, Evert (Delft University of Technology) | Broggini, Filippo (Colorado School of Mines) | Behura, Jyoti (Colorado School of Mines) | Snieder, Roel (Colorado School of Mines)
SUMMARY Standard seismic migration, applied to data with internal multiple, leads 10 images with ghosts. The reason is that one-way wave field extrapolation operators give erroneous downgoing and upgoing fields in the subsurface, which in the correlation process lead to ghosts. By using "data-driven wave field reconstruction" it 'possible to obtain the correct downgoing and upgoing wave fields in the subsurface. Using these in the correlation process leads to ghost-free images.
Noise Suppression in Surface Microseismic Data by τ - p Transform
Forghani-Arani, Farnoush (Colorado School of Mines) | Batzle, Mike (Colorado School of Mines) | Behura, Jyoti (Colorado School of Mines) | Willis, Mark (Halliburton) | Haines, Seth (U.S. Geological Survey) | Davidson, Michael (ConocoPhillips)
SUMMARY Surface passive seismic methods are receiving increased attention for monitoring changes in reservoirs during the production of unconventional oil and gas. However, in passive seismic data the strong cultural and ambient noise (mainly surface-waves) decreases the effectiveness of these techniques. Hence, suppression of surface-waves is a critical step in surface microseismic monitoring. We apply a noise suppression technique, based on the t - p transform, to a surface passive seismic dataset recorded over a Barnett Shale reservoir undergoing a hydraulic fracturing process. This technique not only improves the signal-to-noise ratios of added synthetic microseismic events, but it also preserves the event waveforms.