CGGVeritas has always recognized the importance of true 3D processing, and has long experience of processing multi-azimuth data for both land and marine data, having processed both precessing circle data (coils) and orthogonal marine data as long ago as the mid 1980s.

WAZ IMAGING - TTI ANISOTROPY

Wide-azimuth data acquisition allows more reliable and accurate TTI (Tilted Transverse Isotropy) anisotropic parameters to be derived. Inclusion of these anisotropic effects, especially in the Reverse Time Migration (RTM) algorithm, has greatly improved the imaging and depths of complex structures. TTI RTM reliably produces better sub-salt images from WAZ data than those from either isotropic or VTI RTM.

CGGVeritas is unique in using TTI RTM regularly for production imaging.

Full Azimuth Processing

Our true-3D algorithms have been designed to realise the full potential of wide-azimuth data. 2D algorithms applied to azimuth-sectored data do not give the same improvement as 3D algorithms applied to 3D gathers. Our algorithms utilize all of the additional azimuthal information, providing:

• improved noise and multiple suppression
• azimuth dependent velocities which produce flatter gathers
• multi-dimensional interpolation and regularization
• improved anisotropic parameter derivation for superior imaging, especially pre-salt, using TTI Reverse Time Migration
• improved illumination under complex overburdens
• more reliable characterization of naturally fractured reservoirs.

CIG with increasing azimuth in each offset range, before (left) and after (right) azimuthal residual moveout using true 3D velocity analyses

TRUE-3D PROCESSING

Our true-3D processing techniques include:

• AGORA 3D Adaptive Groundroll Attenuation
  • models and adaptively subtracts groundroll or guided waves in 3D
• 3D SRME
  • convolutional or wave equation modelling respecting true offset and azimuth
• 3D Radon De-multiple
  • modelling and subtraction of multiples using a true-3D high resolution parabolic Radon transform
• Tau-Px-Py
  • deconvolution and noise attenuation using the true offset and azimuth for a 3D transformation to tau-px-py
• Revive5D 5D Fourier Regularization and interpolation
  • using up to 5 interpolation dimensions to infill large gaps, increase fold and regularize offset and azimuth distribution.
• Azimuthal Velocity Analysis
  • efficient method of azimuthal velocity analysis provides flatter gathers in the presence of anisotropy or dip moveout.
• True 3D Imaging in time or depth

Stack-raw

Stack - Interpolated/regularized using REVIVE5D