CFD simulations of a bubble column containing enhanced oil recovery chemicals

Chemical enhanced oil recovery (EOR) methods return produced water containing polymers and surfactants which poses a water treatment challenge at offshore facilities. The present work shows that numerical simulations of gas-water systems containing these chemicals remain challenging. Computational fluid dynamics (CFD) was used to predict gas holdup in a laboratory bubble column containing brine and EOR chemicals. The synthetic produced water was treated as non-Newtonian in the simulations to match the experimentally-determined physical properties. Two- and three-dimensional numerical simulations were performed, and the latter were shown to be more appropriate through statistical analysis. Three classical drag models were assessed, and the results indicated that none of them could account for the high liquid viscosities and low surface tensions encountered in the system. A modification to the drag model of Tomiyama et al. (1988) was proposed to account for drag increases at low bubble Reynolds numbers when liquid apparent viscosity is high and surface tension is low. The importance of considering the interaction between apparent viscosity and surface tension was also shown through statistical analysis. CFD predictions of gas holdup showed that the proposed drag modification reduced errors from approximately 30% to less than 10% when compared to the experimental data. Radial profiles of the axial liquid velocity were also assessed and are apparently related to gas holdup prediction.