Factors influencing viscosity of association polymer solution of reservoirs in Bohai Oilfield

It takes a long time to inject association polymer solution(APS) from injection allocation apparatus into wellhead and finally yield it from oil wells.It requires a lot on the viscosity aging of APS,i.e.,the APS viscosity should be kept within a certain range before it flows from wells to surface.Otherwise its EOR effect will be lowered.So the effect law of APS viscosity is studied.The result shows that it is not other ions or dissolved oxygen but the calcium and magnesium ions in formation water of reservoirs in Bohai SZ36-1 oilfield that mainly influence the aging of APS viscosity.APS is more stable when the calcium and magnesium ions of aqueous solution are lower than 400 mg/L and 250 mg/L respectively.It features in high temperature and viscosity increment in the initial stage of aging(within 40 days).