Laboratory Study on the Potential EOR Use of HPAM/VES Hybrid in High‐Temperature and High‐Salinity Oil Reservoirs

Abstract

Polymer flooding represents one of the most efficient processes to enhance oil recovery, and partially hydrolyzed polyacrylamide (HPAM) is a widely used oil‐displacement agent, but its poor thermal stability, salt tolerance, and mechanical degradation impeded its use in high‐temperature and high‐salinity oil reservoirs. In this work, a novel viscoelastic surfactant, erucyl dimethyl amidobetaine (EDAB), with improved thermal stability and salinity tolerance, was complexed with HPAM to overcome the deficiencies of HPAM. The HPAM/EDAB hybrid samples were studied in comparison with HPAM and EDAB in synthetic brine regarding their rheological behaviors and core flooding experiments under simulated high‐temperature and high‐salinity oil reservoir conditions ( T : 85°C; total dissolved solids: 32,868 mg/L; [Ca 2+ ] + [Mg 2+ ]: 873 mg/L). It was found that the HPAM/EDAB hybrids exhibited much better heat‐ and salinity‐tolerance and long‐term thermal stability than HPAM. Core flooding tests showed that the oil recovery factors of HPAM/EDAB hybrids are between those of HPAM and EDAB. These results are attributed to the synergistic effect between HPAM and EDAB in the hybrid.