Polymer Flow in Porous Media: Relevance to Enhanced Oil Recovery

Abstract

Polymer flooding is one of the most successful chemical EOR (enhanced oil recovery) methods, and is primarily implemented to accelerate oil production by sweep improvement. However, additional benefits have extended the utility of polymer flooding. During the last decade, it has been evaluated for use in an increasing number of fields, both offshore and onshore. This is a consequence of (1) improved polymer properties, which extend their use to HTHS (high temperature high salinity) conditions and (2) increased understanding of flow mechanisms such as those for heavy oil mobilization. A key requirement for studying polymer performance is the control and prediction of in-situ porous medium rheology. The first part of this paper reviews recent developments in polymer flow in porous medium, with a focus on polymer in-situ rheology and injectivity. The second part of this paper reports polymer flow experiments conducted using the most widely applied polymer for EOR processes, HPAM (partially hydrolyzed polyacrylamide). The experiments addressed highrate, near-wellbore behavior (radial flow), reservoir rate steady-state flow (linear flow) and the differences observed in terms of flow conditions. In addition, the impact of oil on polymer rheology was investigated and compared to single-phase polymer flow in Bentheimer sandstone rock material. Results show that the presence of oil leads to a reduction in apparent viscosity.

Determination of the Effective Viscosity of Non-newtonian Fluids Flowing Through Porous Media

“…Several empirical and semi-empirical models have been proposed to estimate µ eff [17][18][19][20][21][22][23]. Most of these models start from a capillary bundle representation of the different flow paths through a porous medium and estimate an effective shear ratė γ eff by comparing the flow rate of a power-law fluid with that of a Newtonian Poiseuille flow [24] (see also SI). Although analytical solutions can be derived to determineγ eff for powerlaw rheologies, previous studies proposed various empirical correction factors [19,20] to relate Darcy velocity to the effective shear rate.…”

Polymer Injectivity: Investigation of Mechanical Degradation of Enhanced Oil Recovery Polymers Using In-Situ Rheology

“…Also, mechanical degradation was lower for concentrated solutions. Recent review with current knowledge on HPAM polymers flow in porous media concerning theoretical and experimental aspects is given by Skauge et al [46].…”

Qualification of New Methods for Measuring In Situ Rheology of Non-Newtonian Fluids in Porous Media

“…Due to the time-consuming nature of in situ measurements, extensive efforts have been made to relate bulk and in situ rheology. Despite numerous attempts, no universally accepted analytical or numerical model exist [2]. Consequently, polymer in situ rheology is estimated from polymer flow experiments in porous media.…”

“…Generally, these experiments have been performed on linear core plugs [3][4][5][6][7]. However, results from recent years indicate that linear and radial polymer flow are inherently different [2,8]. In addition, it has been observed that presence of residual oil significantly reduces polymer in situ effective viscosity compared to single-phase flow [2].…”

“…However, results from recent years indicate that linear and radial polymer flow are inherently different [2,8]. In addition, it has been observed that presence of residual oil significantly reduces polymer in situ effective viscosity compared to single-phase flow [2]. Based on these results, the radial polymer flow experiment that was history matched in this paper was performed in radial flow geometry in the presence of residual oil since these conditions best mimic the polymer flow out from the injector in oil reservoirs.…”