Simulation study on synergetic effect of low saline water and polymer flooding

Low saline water and polymer injections are well established as effective enhanced oil recovery (EOR) techniques. However, the synergetic effect of combining the two methods is not fully studied and founded. In this study, three reservoir simulation case studies are carried out to compare the incremental oil recovery during the low flooding of saline water, polymer flooding and combined the low flooding of saline and polymer. The first two case studies employ different well patterns but of the same reservoir model. This was achieved by reconfiguring the placement of injector(s) and producer wells. In the first case, only one injector and one producer wells are located in the two far corners of the model. In the second case, four injectors and one producer wells are arranged in a 5-spot pattern. The numerical simulation results show that low salinity and high polymer concentration flooding has the highest oil recovery. It is also observed that the 5-spot well pattern has higher aerial sweep efficiency, with incremental recovery up to 67.3. The third case study involves a heterogeneous reservoir model which is simulated using stochastically generated permeability. In all the cases, the incremental oil recovery observed during combined low salinity and polymer flooding is significantly higher than the incremental oil recoveries observed when the two are injected independently. The improved oil recovery is attributed to the synergy of the wettability alterations and better sweep efficiency of low salinity water flooding and polymer flooding, respectively. © 2023 The Authors.