Abstract
This paper presents results of a comprehensive study to improve our understanding of High Mobility Ratio Water Flood (HMRWF) and to improve its performance prediction. Published data on heavy oil water injection field projects are limited. Several successful HMRWF projects have been reported, and they show significant oil recovery at high water cut. However, the range of reported recovery is large – waterflood recoveries of ~ 1-2% to 20% OOIP have been reported for similar reservoirs. Higher viscosities result in lower recovery
Mechanistic study using fine-scale simulations show that viscosity (or mobility) ratio primarily controls oil recovery response, and that the recovery is lower at higher viscosity ratios. Further, viscous fingers dominate high viscosity ratio floods, and mobile water can significantly reduce recovery. Field-scale simulation results indicate that heterogeneity plays a more important role for a HMRWF (than conventional waterfloods). The amount of primary production prior to the start of the waterflood has a larger effect on incremental oil recovery for high mobility ratio floods. Further, highly-correlated, thin, thief zones reduce recovery of HMRWF more severely, and rock wettability (relative permeabilties) strongly influences oil recovery. These results indicate that accurate viscosity and relative permeability measurements are essential for a reliable performance prediction.
