Study on Polymer Flooding Effect Evaluation and Parameter Optimization of High Viscosity Ordinary Heavy Oil Reservoir

Abstract

AbstractDue to the long-term water injection in heavy oil reservoirs, the injected water penetrates along the high permeability zone, resulting in low sweep efficiency. Polymer flooding can enlarge the sweep area and improve the oil displacement efficiency, but the development effect varies greatly under different reservoir parameters and injection parameters. Firstly, the dynamic characteristics of polymer flooding in the middle and high water-cut stage of high viscosity ordinary heavy oil reservoirs are analyzed. Secondly, the combination of reservoir parameters and injection parameters is optimized by using orthogonal analysis method, which takes the incremental recovery factor, the incremental oil per ton of polymer, or the comprehensive index as the evaluation index. The results show that the typical characteristics of polymer flooding stage are “three rises and three drops”, and the typical characteristics of subsequent water flooding stage are “three drops and three rises”. Taking the incremental oil per ton of polymer as the evaluation index, when the reservoir thickness is 24 m, the vertical permeability variation coefficient is 0.58, the permeability is 1000 mD, the reservoir rhythm is positive rhythm, the injection-production ratio is 0.9, and the polymer solution concentration is 1500 mg/L, the water cut is 80%, the injection rate is 0.1 PV/a, and the dosage of polymer system is 100 mg/L\(\cdot\)PV, the polymer flooding effect is better. This paper proposed the optimal parameter combination of polymer flooding, which can effectively improve the development effect and provide guidance for field production.KeywordsHigh-viscosity heavy oilPolymer floodingResponding characteristicsReservoir parametersInjection parameters