At a time when oil resources are becoming scarce and more and more costly to produce, operators are looking for better reservoir production and recovery. Managers must derive E&P strategies that combines profitability and sustainability to make the best of the oil resources available. When looking at it more closely, there are two ways for optimizing reservoir management: improved technology and less uncertainty. The technological side is well documented and discussed in all oil forums as it has been the key factor in the past decades for proving additional reserves. The producing life of entire oil basins, such as the North Sea Basin for example, has been drastically lengthened due to technological improvements; is this not addressing the way oil reserves are defined and computed? More information means less uncertainty, but to what extent is this valid and at what cost? This article explores this uncertainty and shows how properly managing uncertainty can lead to profitability and sustainability