Depth Imaging

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.

RMO Estimation

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
  • Full TTI Wave Equation Migration (WEM)
  • Full TTI Reverse Time Migration (RTM)