Quantifying Model Based Uncertainty Using Seismic Uncertainty Analysis – Case Study Danish North Sea

This work presents a case study of the application of Seismic Uncertainty Analysis (SUA) in the Danish North Sea where uncertainty in the lateral positioning of faults posed a significant drilling hazard. 500 equivalent models were generated and used to reposition nine key structural objects. Statistical analysis and displays of the repositioned objects were generated to reveal the structural uncertainty and provide quantifiable estimates of the model based uncertainty for use in drilling risk mitigation planning. Structural uncertainty in the pre-stack depth migrated seismic image used for interpretation and well planning is a consequence of the non-uniqueness of the Earth model built by tomography. There are several possible models which will satisfy our data and lead to the same overall gather flatness, but each will result in a different image and different depths of the reflection events. The objective of the Seismic Uncertainty Analysis was to quantify the structural uncertainty of target events in the final seismic image via the derivation of many equivalent TTI Earth models.