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Modeling Waterflood Sweep Improvement at Prudhoe Bay and Determining Key Controls on Incremental Oil Recovery
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, IOR 2017 - 19th European Symposium on Improved Oil Recovery, Apr 2017, Volume 2017, p.1 - 38
Abstract
We present a model of how a Thermally Activated Particle (TAP) system works and model the incremental response of a pattern in Prudhoe Bay, Alaska. The model has also been applied on a range of descriptions to determine the major controls on incremental oil recovery and the best circumstances to apply TAP.
Polymeric “kernel” particles expand as a result of breaking labile cross-links through a hydrolysis reaction under the influence of temperature and time. The expanded particles adsorb and provide Residual Resistance Factor to water. The model builds on conventional reservoir simulation of cold water injection and polymer flooding by including reaction kinetics of the particles and the dependence of reaction rate and other polymer properties on temperature as well as the extent of reaction. To address the uncertainty in the mechanisms, the model considers both mechanical entrapment and physical adsorption, linking the amount and impact of the entrapment to the ratio of the particle size to the estimated pore-throat size.
Previously reported slim tube data and recent coreflood studies on Prudhoe Bay core indicate physical adsorption to be the dominant mechanism. The application of the model to the treated pattern captures the timing and magnitude of the incremental response. The overall size and the resistance of the in-situ block are comparable to that interpreted from the Pressure Fall-Off analysis.
Realistic type pattern models and idealized descriptions have been used to model TAP performance for a range of slug sizes and waterflood maturities. The primary controls on incremental oil recovery are the slug size, pattern maturity, mobility ratio and heterogeneity. Traditional measures of heterogeneity do not correlate well with incremental recovery. Instead, the best correlations appear to be with the ratio of the swept volume, at breakthrough, to the total pore-volume and the slope of cumulative water-oil ratio to the instantaneous water-oil ratio, with larger slopes indicating better candidates.