# Impact of Adverse Mobility Ratio on Oil Mobilization by Polymer Flooding

## TL;DR

This study shows that low polymer concentrations can effectively mobilize oil in high viscosity conditions, reducing environmental and economic costs.

## Contribution

The study reveals that low polymer concentrations can achieve high oil recovery at adverse mobility ratios by utilizing water channels.

## Key findings

- Low polymer concentrations (40 ppm) achieved high recovery rates at adverse mobility ratios.
- Increasing polymer concentration beyond a threshold did not significantly improve oil recovery.
- Polymer rheology enhances oil mobilization through pre-established water channels.

## Abstract

Polymer flooding is a widely used enhanced oil recovery (EOR) method for improving energy efficiency and reducing the carbon footprint of oil production. Optimizing polymer concentration is critical for maximizing recovery while minimizing economic and environmental costs. Here, we present a systematic experimental study which shows that even very low concentrations of polymers yield relatively high recovery rates at adverse mobility ratios (230 cP oil). A series of core flood experiments were conducted on Bentheimer sandstone rock, with polymer concentrations ranging from 40 ppm (1.35 cP) to 600 ppm (10.0 cP). Beyond a mobility ratio threshold, increasing polymer concentration did not significantly enhance recovery. This plateau in performance was attributed to the persistence of viscous fingering and oil crossflow into pre-established water channels. The study suggests that low concentrations of polymer may mobilize oil at high mobility ratios by making use of the pre-established water channels as transport paths for the oil and that the rheology of the polymer enhances this effect. These findings enable reductions in the polymer concentration in fields with adverse mobility ratios, leading to substantial reductions in chemical usage, energy consumption, and environmental impact of the extraction process.