Influence of alkaline/surfactant/polymer interaction on characteristics of interfacial tension in Hejian reservoir

The interfacial tension (IFT) characteristics are caused by the interactions among alkaline, surfactant and polymer were investigated in Hejian reservoir (reservoir temperature is 90℃, the total salinity of produced water is 5 192.2 mg/L, the total salinity of flood water is 5 682.6 mg/L, Hejian crude oil).The results demonst rated that the both dynamic and equilibrium IFTs could be lowered to the ultralow magnitude of 10^-2 mN/m as the active concentration of sulfonate CDS-1 was in the range from 0.01% to 0.3%,Unfortunately, the characteristics were diversi ty if Na₂CO₃ is dissolved in 0.05% CDS-1 solution.The equilibrium IFTs increase or decrease unobviously with the increase of alkalinity and could be lowered to the ultra-low magnitude of 10^-2 mN/m.The dynamic IFTs were in the magnitude of 10^-3 mN/m as alkalinity is 0.5% in the alkali CDS-1 solution.The dynamic and equilibrium IFTs increase or decrease unobviously as well as HPAM M2500 is dissolved in the sulfonate CDS-1 or 0.5% Na₂CO₃/0.05% CDS-1 brine.The results provided the basis of selecting surfactant flooding formula in Hejian reservoir.