A depth range manager provide users with a way to run and retain multiple depth range analyses for a drill string operation, including the operational parameters for each analysis. This allows users easily to view and compare the analyses at the different drilling depth ranges. In some embodiments, instead of drilling depth ranges, users may also run and retain multiple different models and analyses using multiple different drilling times. The operational parameters for the multiple different models and analyses may be defined and stored using a flexible one-to-many database structure that accommodates the different sets of operational parameters as well as any existing single-analysis parameters associated with legacy analyses. A graphical interface allows users easily to define and store the operational parameters in the flexible one-to-many database structure.