Imaging of polymer flooding using MRI

Abstract

Magnetic Resonance Imaging (MRI) was used to evaluate the microscopic displacement efficiency of Enhanced Oil Recovery (EOR) processes in unconsolidated porous media. In this work, the centric scan SPRITE imaging technique was used to visualize and quantify the dynamic displacement of waterflooding, polymer flooding and in-situ permeability reduction through a model sand-pack. Alcoflood 935, a party hydrolyzed polyacrylamide, was the polymer used in this study. A weak polyacrylamide gel was applied into a high-permeability glass channel in the sand matrix model as a permeability-reducing agent. MRI measurements were validated macroscopically by mass balance. The effects of sand wettability and polymer concentration on residual oil displacement were investigated. Wettability of the sand affected the distribution of fluid saturations within the sand-pack, polymer flooding characteristics, and residual oil recovery. Trapping and mobilization of non-wetting phase drops through the channel were visualized. The oil recovery profiles obtained from MRI showed an agreement with mass balance measurements. Visualizations from MRI allow better understanding of the dynamic microscopic mechanisms of fluid displacement through unconsolidated porous media. This technique also showed preliminary studies for flooding experiment in consolidated rocks. The experimental results demonstrated the MRI is a powerful tool to investigate the residual oil mobilization and in-situ fluid saturations during flood testing processes.