"During sharply declining oil price environments (1998, 2001, 2009, and 2016) operators are forced to shift to optimization of existing assets at minimal costs. For mature (water) floods, one low-cost optimization strategy is adjusting well rate targets in a systematic manner.  While it is easy to identify high water cut/water rate producers, it is difficult to identify which injector(s) are responsible for the inefficient offset oil production and associated fluid cycling, making the setting of injection targets difficult without a calibrated reservoir (simulation) model.  However, detailed calibrated reservoir models require simulation expertise, are time consuming to build, and can even be considered over-kill for managing monthly rate targets.  Reservoir surveillance techniques sidestep this problem by using measured well data combined with simpler models to create a feedback loop that is informative and valuable for reservoir management."