A Decade of Time-to-depth Conversion in Field S

A qualitative and quantitative comparison of Field S’ 3D seismic-related velocity models was conducted, involving five (5) different sets of 3D seismic velocity:

1. The trend of the seismic velocity at well location
2. The conformance of velocity, TWT and depth structural maps to one another
3. The structural consistency of the depth maps with respect to geology
4. The residual depth errors at well location
5. Blind well test

We then highlight the impact of the different velocity models on gross bulk volume (GBV) calculation, where the different velocity model will give a range of uncertainty for GBV and depth maps. This will later be input into static and dynamic model and later influence the field’s hydrocarbon resource assessment.

The latest 3D seismic-related velocity model coming from the 2013 PP APSDM migration velocity (in average velocity function) is observed to be the most superior velocity model out of the five (5) models as it follows the well velocity trends closely, has high level of conformance between velocity and TWT and depth maps, is structurally consistent with respect to geology, contains the least depth error at well location, and is able to best estimate the well tops in the blind well test.