Influencing Factors And Mechanism Discussed On The Viscosity Of Polymer Solution Preprated By Oilfield Produced Water

Polymer flooding has become the main technical means of precipitation oil, since used by Shengli petroliferous province in 1992. Polymer flooding is constrained to play a good use because of polymer viscosity affected by many factors and low viscosity retention rate. In a pilot polymer/foam folld project in Chengdong of Sinopec Shengli, found that polymer solution viscosity is too low in the field injection process. Normally, polymer solution viscosity(1800mg/L, 70℃) diluted field sewage is above 20mPa?s, but actually 1~5mPa?s. This result can not meet the prescription system and seriously impact on test results.In this paper, through the entire analysis of sewage, understand of the main components of oil sewage. Through the experimental the major components of oil sewage are investigated to ascertain the origins of polymer viscosity losses and polymer viscosity changes law. By infrared and electron microscopy analysis, the mechanism of polymer loss caused by different substances preliminarily discussed. Raise some method of maintaining the viscosity. This is great significance in ensuring that polymer/foam pilot testing successfully implementand flooding technology is promted.The full analysis of oil sewage of United Station of Cheng Do in He Kou finds that oil sewage contains many ions(Salinity 5.99×103mg/L). Experiments find that the effects of metal ions are greater than of inorganic anions in polymer viscosity and high state of metal cation is greater than low state(Fe3+, Al3+>Ca2+, Mg2+>Na+, K+). The effects of viscosity of polymer by is very large. A small amount of Fe2+, S2- make the viscosity drop to the following 10mPa?s. By infrared, NMR and electron microscopic analysis of the polymer solution preparated by sewage containing Fe2+, S2- showed that it has a C=C double bond peak around wave number 3100 and has a C=C H at chemical shift 6.000. So the polymer solution produces new materials with a double bond. Mechanism of lower viscosity thinks that it happens radical chain reaction, so that long chain polymer breaks into small molecules. So it can be produced by inhibiting the free radicals to maintain the viscosity of the polymer. Adding an appropriate amount of reagent hydrogen peroxide or oxygen exposure of sewage effluent can oxidate reducing substances and inhibiting the free radicals produced. Field experiments find that the two ways have a good results in maintaining the viscosity.