Characterization and Dynamic Adjustment of the Flow Field during the Late Stage of Waterflooding in Strongly Heterogeneous Reservoirs

Abstract

The flow field is the fluid dynamic flow path in strongly heterogeneous reservoirs, and its evolution significantly affects the distribution of remaining oil, showing a disordered and highly dispersed mode caused by long-time water injection. By combining traditional flow-field evaluation with flow diagnostics, this paper proposes a methodology to quantitatively characterize and adjust the flow field in real time during the late stage of waterflooding in strongly heterogeneous reservoirs. In the study, the fluid velocity, abundance of predominant remaining oil, and Lorenz coefficient are preferred as the characteristic parameters to evaluate the effect of reservoir and flow heterogeneity on the flow field. Taking the minimization of the Lorentz coefficient as the objective function, the optimal injection and production parameters are obtained by dynamic adjusting the flow field. The results show that as water injection continues, the shape and variation of the flow field are jointly influenced by the reservoir rhythm, vertical permeability contrast, and lateral permeability distribution. The larger the permeability contrast, the greater the influence of the lateral permeability distribution. When the permeability contrast is large, the Lorenz coefficient strongly depends on the lateral permeability distribution. Finally, this method is applied to an actual heterogeneous reservoir, and a better effect of oil increase and water reduction is achieved.