Key factors of viscosity reduction of polymer brine produced fluid in oilfield

The residual HPAM manifested itself in the viscosity of polymer flooding produced liquid in the tertiary phase, the initial viscosity of polymer solution directly affects the impact of oil-bearing wastewater treatment. In this paper, viscosity reduction rate of polymer solution was measured by Ubbelohde viscometer. From the experimental study on related factors such as pH, content of anions and cations in the water quality, viscosity average molecular weight, and shear rate, the result of experiment suggested that viscosity of FP3640C polymer solution would be apparently reduced among pH 2~4, viscosity reduction rate of solution would be lower while pH>7; Mg²⁺,Ca²⁺ in JZ9-3 formation brine causes apparently reduction of viscosity; Na⁺, K⁺ could cause apparently reduction of viscosity while the concentration varied in the range from 2 500 to 4 000 mg/L; with the extension of the operation time under the temperature of 60℃ , viscosity of polymer solution would be reduced till the 30th days; viscosity of solution reduced with increasing shear rate, viscosity would be slowed down to a stable level while rotation speed reached 8 000 r/min.