Effective Viscosity in Porous Media and Applicable Limitations for Polymer Flooding of an Associative Polymer

Yefei Wang,Wuhua Chen,Yan Yang,Shixun Bai,Peng Zhang

doi:10.2516/ogst/2013149

Abstract

Hydrophobically associating polyacrylamide (HAPAM) is considered to be a promising candidate for polymer flooding because of its excellent apparent viscosifying capability. Compared with partially hydrolyzed polyacrylamide (HPAM), the resistance factor and residual resistance factor caused by HAPAM tend to be higher. However, the effective viscosity of HAPAM is lower than that of conventional polymer at a concentration of 2 000 mg/L. The dynamic retention capacity of HAPAM is about 2.3 times that of HPAM. The oil displacement efficiency of HAPAM is lower than that of conventional polymer at a concentration of 2 000 mg/L in the homogeneous sandpack model. The oil displacement efficiency of HAPAM is higher than that of HPAM only in the heterogeneous model (permeability ratio 2.8). Neither high nor low permeability ratios are good for the oil displacement efficiency of HAPAM.

Highlights

Regarding the use of partially hydrolyzed polyacrylamide (HPAM) for high-temperature and high-salinity reservoirs, there are many unfavorable factors [1] such as thermal oxidation degradation, salt sensitivity and mechanical degradation.To overcome these weaknesses of HPAM, hydrophobically associating polyacrylamide (HAPAM) has been paid more and more attention [2]
To maintain the effectiveness and persistence of fluid displacement, the residual resistance factor should be reduced in order to increase the effective viscosity in porous media, because the retention should be kept low in order to ensure an in-depth propagation of the viscous polymer slug
The results show that the application of HAPAM in polymer flooding has some limitations

Summary

INTRODUCTION

Regarding the use of partially hydrolyzed polyacrylamide (HPAM) for high-temperature and high-salinity reservoirs, there are many unfavorable factors [1] such as thermal oxidation degradation, salt sensitivity and mechanical degradation. Zhang et al [13] and Ye et al [14] reported that HAPAM can generally form aggregates with super-molecular and network structures even in porous media Based on these results, HAPAM can establish a higher resistance factor and residual resistance factor in porous media. To maintain the effectiveness and persistence of fluid displacement, the residual resistance factor should be reduced in order to increase the effective viscosity in porous media, because the retention should be kept low in order to ensure an in-depth propagation of the viscous polymer slug. The results show that the application of HAPAM in polymer flooding has some limitations

Materials

Experimental Procedures

RESULTS AND DISCUSSION

Dynamic Retention Capacity

Ability to Enhance Oil Recovery

Microstructures in Porous Media

CONCLUSIONS