EVALUATION OF ALKALI-SURFACTANT-POLYMER FLOODING IN OIL-WET RESERVOIR CONTAINING HIGH PERMEABILITY CHANNEL

Abstract

Alkali-Surfactant-Polymer (ASP) flooding is a technique combining benefits of alkaline, surfactant and polymer substances to decrease interfacial tension (IFT) to an ultra-low IFT condition and to reduce mobility ratio to improve sweep efficiency. Simulation results obtained from STAR® commercial simulator showed that the highest oil recovery is obtained from P+AS+P flooding composes of injecting 0.25PV of pre-flushed polymer followed by 0.10PV of alkali-surfactant slug and chased by 0.55PV of post-flushed polymer at chosen chemical concentrations. Incremental of resistance factor can reduce the amount of polymer required. However, upper limit of resistance factor exists. Impact of high permeability channel to incremental of recovery factor compared to waterflooding and relative recovery difference between P+AS+P and AS+P can be predicted from width/height ratio of high permeability channel. Sensitivity analysis shows that parameters which are closely related to relative permeability curves impact the most to ASP flooding such as Corey’s exponent and wettability. Wetting condition can vary recovery factor from 53.73 to 60.62% in AS+P flooding and 60.19 to 68.74% in P+AS+P flooding. Although incremental of recovery factor from P+AS+P flooding compared to waterflooding is higher than that of AS+P flooding in all cases, high sensitivity to variation of parameters could result in negative image of this technique.