oa Analyzing and Quantifying Uncertainty in Time-Depth Conversion

Static geological models are made of horizons and faults which define their geometry. Both faults and horizons (in depth) are uncertain objects, which result from a time-to-depth conversion procedure involving variables such as time maps, velocity maps, markers at wells that in turn might all be affected by a given level of uncertainty. Even faults location may be uncertain and impact Gross Rock Volumes (GRV) calculated in the geological model. This paper details methods which allow simultaneous calculation of depth maps and the associated uncertainty. Focus is put on how to quantify the impact on the global uncertainty on GRV of each Time-Depth conversion input parameter uncertainty. The relative impact of each individual source of uncertainty is calculated on a real case study and the quantitative effect of combining the different sources is estimated and analyzed.