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Amplitude attenuation and phase distortion of seismic data are byproducts of the Earth’s anelasticity (Q). These effects are exacerbated under regions of anomalously high absorption, such as shallow gas, causing uneven illumination and migration artifacts. We present a case study from the Norwegian North Sea where we utilize single-iteration, least-squares, visco-acoustic, prestack depth migration to produce a stable Q-compensated image. This used high-resolution, p-wave velocity and attenuation models, derived from visco-acoustic FWI. We show this workflow compensates locally for amplitude loss, eliminates the need for a Q-compensation amplitude gain limit, and enhances illumination, event coherency and AVO attributes, while reducing noise

To improve image resolution in the vicinity of the well, 3D VSP data was acquired at the Atlantis field in the Gulf of Mexico to complement the existing towed-streamer and OBN data. Two unique data challenges require special consideration and innovative techniques in order to unlock the full imaging potential at the Atlantis field: (1) illumination issues related to the receivers being placed in a well that goes through a complicated salt finger; (2) receiver reorientation issues related to the survey’s two-phase acquisition due to receivers being pulled out and placed back into well. We demonstrate how we mitigate the impact of these challenges through improved XYZ vector fidelity reorientation and least-squares RTM.

We investigate the benefits of considering the effects of the Hessian matrix in the reflection FWI (RFWI) reflectivity, i.e., using least-squares RTM (LSRTM) to estimate the short-wavelength component of the model. In addition, a more efficient approach using single-iteration LSRTM, more specifically, using curvelet-domain Hessian filters is proposed. Using synthetic and field data sets, we show how this approach can improve the reflectivity model and, therefore, the synthetic reflection data, which ultimately benefits RFWI. Finally, we discuss some of the limitations of this approach and some of the challenges that are still not addressed by it.

A new broadband Wide-Azimuth Towed-Streamer (WATS) survey was acquired in a shallow water region of offshore China to better resolve reservoir compartments. Two side boats were added as additional source boats to form the WATS acquisition geometry to resolve the shortcomings of narrow-azimuth acquisition along strike direction. This WATS acquisition is much sparser than common WATS surveys in deep water environments due to only one-side WATS configuration. The combination of sparse acquisition, shallow water and deep targets imposes challenges on how to optimally utilize the side-gun data as the key adding on to improve the final image. The 3D effect and severe aliasing expected in the Crossline direction pose tremendous difficulties for side gun data processing. A comprehensive flow for resolving these challenges especially in deghosting, demultiple and regularization for sparse and shallow wide-azimuth data is presented in the paper. A tilted orthorhombic (TORT) velocity model is also built with better constraints from the wide azimuth information for better fault positioning and imaging. Side gun data clearly enhances the final target reservoir imaging and better ties with the well due to better illuminations. A new channel is discovered based on the interpretation from the inverted Vp/Vs ratio, which clearly explains the previous misleading prediction that an exceptional well was drilled to a thinner and shallower channel not connected to the main reservoir.