Depth Imaging Services

Interpretive Velocity Modelling

Geologically-constrained velocity model construction for complex thrust-belt environments.

Depth Migration in Structurally Complex Settings

Depth migration in thrust-belt environments requires an interpretive approach to building a depth-migration velocity model. With low fold in the near surface, low signal-to-noise ratios on the image gathers, and complex horizon geometries, automated velocity-model-building tools often fail to produce an optimal velocity model for TTI anisotropic depth migration. In a setting with such under-constrained velocities, we must use as many geologic constraints as possible in the interpretation of our velocity model. This forms the basis of our Geologically-Constrained Model Building Solution.

Geologically-Constrained Model Building Workflow

Building these velocity models involves close collaboration with the interpretation team. We have software to efficiently build the models and migration algorithms that produce sharp images, but it is the local domain-knowledge that allows us to converge to a geologically accurate velocity model. We further evaluate the accuracy of the model using well calibration and seismic diagnostics such as image gather flatness, reflection continuity and fault sharpness.

3b_stk2-psdm-with-final-vel-model-with-well — o A depth migrated stack and the corresponding velocity model, with the well sonic velocity overlaid to help verify the geologic accuracy of the model

5a_stk-psdm-well-calib — o A final PSDM stack, comparing seismic reflector depths to well top data to ensure proper depth of reflectors and to help confirm the depth model accuracy

A preliminary PSDM stack with velocity model overlay
A final PSDM stack with velocity model, showing improved reflector sharpness and coherency