Absolute Imaging has extensive expertise to provide 2D and 3D Depth Imaging in onshore and offshore environments. Depth expertise includes ray and wave equation-based migrators, isotropic and anisotropic analysis, and model building for accurate simulation of wave propagation in complex subsurface areas. Model refinement includes methods of travel time error estimation, constrained velocity inversion, and grid and/or horizon-based tomography. Well information can also be used in the initial model creation or for model-updating workflows. A variety of analysis tools provide for model validation and seismic/ray/model overlay visualization. Depth Imaging helps reduce drilling risk in subsurface geological structures like thrust faults, fault shadows, reefs, subsalt, sub-basalt, salt flanks, gas plumes, and those with subtle lateral velocity variations.
Initial Model Building
The initial velocity model is constructed using available velocity information from the time processing (PSTM velocity), well measurements, interpretation, near surface modeling, and geostatistics.
At Absolute Imaging a variety of RMO estimation methods are available. Depending
upon the data complexity and S/N ratio, the following strategies can be implemented to improve the quality of the residual move-out values:
High Resolution Automatic residual move-out using FastVel
Layer or Horizon based automatic RMO using Velocity Navigator
Layer or Horizon based manual RMO picking using Velocity Navigator
Velocity Refinement using High Resolution Tomography
Based on the geological complexity and goals of the project, the following strategies can be used in order to update Vp, Vs, Epsilon, Delta, Dip, and Azimuth (TTI). Methodologies can be combined together in order to achieve the highest quality & faster convergence.
1. 3D Grid Based Tomography
Updates velocity volumes (Vpz, Vsz), as well as Epsilon and Delta, simultaneously on a regular grid
2. 3D Layer Based Tomography
Geologically constrained solutions
Updates velocity volumes (Vpz, Vsz), as well as Epsilon and Delta, simultaneously along the depth model horizons
3. 3D Well Tie Tomography
Well or horizon mis-tie maps are used as constraints to update velocity volumes (Vpz, Vsz) as well as Epsilon and Delta
Preserves gather flatness
Pre-stack Depth Migration (PSDM)
A key component of successful Depth Imaging is the selection of appropriate migrators. Absolute Imaging has a variety of migration algorithms appropriate for differing geological settings:
Full TTI Kirchhoff Migration
Full TTI Common Reflection Angle Migration (CRAM) – Advanced Beam Migration