Analyses of oil production data from the Weyburn Midale oil pool reveal that CO₂ injection substantially reduced the decline trend of annual oil outputs in an exponential way with an average decline rate of 2.5%, which is two times lower than that of the worldwide total giant oil fields (5.5% or 6.5%). Based on its production data, it is projected that without CO₂ injection the pool would have ended its life by 2016 with an ultimate cumulative oil output of 448.1 million bbl (71.2 million m³) and a recovery factor of only 24.4%. However, with continuous CO₂ injection, by 2055 when the pool will be celebrating its 100th birthday, it can still produce 4 million bbl (0.6 million m³) of oil annually with a cumulative output of 801.8 million bbl (127.5 million m³) of oil and a recovery factor of 43.7%, whereas an additional 9.2 TCF (259.9 billion m³) of CO₂ will be poured into the pool. By 2100, after 100 yr of CO₂ injection, the pool’s annual oil output could be near 1.5 million bbl (0.2 million m³) and its cumulative oil output would reach 914.0 million bbl (145.3 million m³) representing a recovery factor of 49.8%, whereas 21.3 TCF (604 billion m³) of more CO₂ could be injected into and permanently stored in the pool. The CO₂-enhanced oil recovery could extend the pool’s lifespan to 39 or even 84 more years.