Performance Properties and Displacement Efficiency of High Concentration Solution of Superhigh Molar Mass HPAM Polymer

The viscosity(at 7.31 s-1),the shearing resistance,and the oil displacement efficiency of high concentrated(2.0 and 2.5 g/L) fresh water solution of HPAM polymer of ultrahigh molar mass(UHMM) η=2.59×107 are studied comparatively at 45℃.The solution viscosity vz concentration curve is demonstated for this UHMM polymer.The viscosity retention of UHMM polymer solution having been aged in 60 days is increased from 87.8% to 90.6% and to 92.9% when polymer solution concentration increases from 1.0 g/L to 1.8 g/L and to 2.5 g/L,respectively.As compared with a high molar mass(HMM) polymer of η=1.94×107,the percentage reduction in solution viscosity after shearing,the viscosity retention,and the 1st normal stress difference,expressing solution elasticity,for the UHMM polymer are larger with polymer concentration having a similar effect.In laboratory flooding experiments on 5 heterogeneous(coefficient of permeability variation 0.72) and 5 homogeneous artificial cores of Kg≈1.0 μm2,solutions of moderate molar mass(MMM) polymer with η=1.3×107 and of normal concentration 1.0 g/L,of HMM polymer with η=1.60×107—1.90×107 and of UHMM polymer with η=2.59×107 of high concentration 2.0 and 2.5 g/L are injected and the enhancement in oil recovery by polymer flood in amount of 2020(mg/L)·PV after water flood is arranged in order: UHMM polymer in high concentrated solutionHMM polymer in high concentrated solutionMMM polymer in normal concentration polymer.