Do your analytic models really yield accurate predictions?

The author documents the analysis of an actual strategic petroleum reserve (SPR) mission and compares the result obtained during the mission with results predicted by availability models. The drawdown (removal of oil) from an oil storage unit at the Sulphur Mines SPR site was started in late 1990 and completed in late 1991. During this period, the facilities were exposed to every climatological extreme occurring on the Louisiana Gulf Coast. A preliminary data analysis revealed that weather caused a higher than expected outage, which was not predicted by the model. Also significant was the down-time resulting from such weather-related shutdowns. The findings of this analysis indicated limitations in the computer model on addressing all events which may result in down-time. However, when actual drawdown factors and down-time events are compared with those included in the computer model, site availability during the decommissioning drawdown was higher than predicted