To estimate it, often logarithmic spectral ratios of the non-stationary seismic signal between two depth levels are linearly inverted. We conclude that the results of previous studies are due to the combination of the residual influence of overburden after processing and imaging, and the weak anisotropy responses from the reservoir.Īccurate estimation of seismic quality factor (Q) is important in seismic data processing to correct for the velocity dispersion effects and to compensate for absorption losses through inverse Q filtering. We suggest that the C-wave data could be useful to constrain fracture interpretation in the Barrett model. The converted wave ( C-wave) has a stronger VVAZ response compared to the P-wave. Anisotropic geometrical-spreading correction improves the amplitude-versus-azimuth (AVAZ) inversion results when reflectivity modeling models orthorhombic overburden. The reservoir thickness (125m or 65ms TWT) or NMO velocity anisotropy (6-7%) needs to be at least doubled to obtain a stable VVAZ inversion. This shows that the P-wave VVAZ responses generated by the reservoir itself are weak, which leads to an unstable VVAZ inversion to estimate the interval NMO velocity anisotropy.
We then expose the reservoir anisotropic response by using an isotropic overburden in the reflectivity modeling. The true anisotropic response is obscured in the Barrett data (generated by finite element modeling) due to the mild lateral velocity variations and orthorhombic anisotropy in the overburden. Anisotropic prestack reflectivity modeling exposes the true orthorhombic response of the 1D medium in the form of Common Offset and Common Azimuth (COCA) gathers. 1D model properties (orthorhombic for both overburden and reservoir) are first extracted from the actual Barrett model properties at two locations. Therefore, we perform a feasibility study to understand the influence of the overburden and reservoir properties, and the processing and inversion steps, which together determine the success of the fracture interpretation from seismic data.
However, these analyses provide fracture property estimation that is inconsistent with the actual model properties. Several P-wave azimuthal anisotropy studies have been conducted for the SEAM II Barrett model data.
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