Abstract
The objective of this paper is to assess the application of polymer flooding in Trinidad heavy oil reservoirs. Uncertainty analyses on several synthetic models have been performed to evaluate how variations in reservoir properties affect the oil recovery factor (RF) and Net Present Value (NPV).
Three (3) phases were conducted for the polymer flooding assessment. Phase 1 included a core flooding simulation to assess the oil viscosity sensitivity region and the ranges of polymer concentration for optimization. Phase 2 carried out uncertainty analysis using synthetic models to optimize polymer flooding with respect to NPV. Phase 3 discussed more detail analysis of parameters effects and confirmed the observations in previous cases using analytical approach.
Three types of polymer were used in the models, Flopaam 3130S, 3430S and 3630S. In core flooding simulation, optimal range of polymer concentration was estimated between 500ppm to 5000ppm. On recovery-viscosity plot, a high viscosity oil requires a higher polymer concentration to have higher recovery. Our results showed that this trend was not always true mainly due to the low reservoir fracture pressure, since a higher concentration and/or a higher molecular weight polymer require higher injection pressure. Uncertainty analysis in Phased 2 to 3 indicated that °API /viscosity, depth, permeability and polymer concentration had the highest effect on RF and NPV.
This paper also presents optimal polymer concentration versus oil viscosity for Trinidad oil reservoirs. Moreover, this work determines the reservoirs where the polymer flooding is applicable and recommend proxy models to estimate RF and NPV versus reservoir parameters.
