Polymer Flooding for Enhanced Oil Recovery Evaluated with Magnetic Resonance Imaging and Relaxation Time Measurements

Improved performance of polymer flooding for enhanced oil recovery requires knowledge of petrophysical properties of the rock and fluid systems. To better understand the effects of different rocks and fluids on the behavior of polymer flooding, magnetic resonance imaging (MRI) and magnetic resonance (MR) T2 lifetime measurements, were employed to monitor oil displacement by water flooding and polymer flooding in a series of rock and fluid systems. In situ oil saturation profiles were determined from the MRI measurements. Water wet and oil wet core plugs saturated with crude oil and mineral oil showed different oil saturation profile changes and T2 relaxation time variation during core flooding. The T2 Log Mean Ratio (TLMR) is proposed to normalize T2 trends from different rock/fluid samples. The mechanisms of improved mobility ratio and polymer stripping were examined based on in situ oil saturation profile change and relaxation time change during oil displacement.