After reaching a plateau, the production of oil reservoirs starts to decline, which substantially determines their life expectancy. Declining production data from three 58- to 71-yr-old oil pools in Alberta, Canada, have been documented and analyzed to show and predict their life span. Two declining phases of oil production can be distinguished: a short 4–11-yr substantially declining phase and a long 23–35-yr gradually declining phase. Well-fitted power regressions of the two declining phases of the pools have been observed with high correlation coefficients of 0.95–0.99 and used to forecast future annual oil production for the next 30 yr, yielding projected life spans of at least 88 to 101 yr. These pools have been producing oil at high water cuts of greater than 0.9 for 30–38 yr, currently more than 0.980 and 0.996, but still have potential to continue to deliver for at least another 30 yr. Production data from two pools indicate that 11% of original oil in place and 16%–26% of cumulative oil output were produced at a high water cut of greater than 0.9. These observation results can be used to judge other similar reef oil pools’ future production potential. This study provides a physical example to test the Hubbert curve and implies that the Hubbert curve should provide only the minimum future ultimate recoveries and the shortest future production times.