Quantifying Prospectivity and Reducing Drilling Risk with Seismic Uncertainty Analyses: A Gulf of Mexico Case History

One of the most difficult tasks that an exploration geologist must undertake is to correctly assess the economic viability of a potential prospect and the risks associated with drilling it. This is made especially challenging because of uncertainties associated with any single final image on which prospect mapping occurs. One of the largest sources of this uncertainty is the earth model building process itself, which remains non-unique. The seismic industry has, therefore, turned to seismic uncertainty analysis (SUA) workflows to analyze and quantify this model uncertainty and its impact on the final images and so help prospect decision making. We focus on these workflows using a recent case study from the subsalt Gulf of Mexico. Firstly, we show the advantages of including the SUA at more than one stage within the larger model building workflow, rather than solely at the final model analyses point. Secondly, we will also show how spill-point analyses and their gross rock volume estimates can be invaluable tools to aid in risk analyses and decision making to understand the reliability of initial volumetric estimations. Also, we show how likely they are to change through the model building process.