Effects Of Suspended Solids In Polymer Flooding Produced Water On Stability Of Emulsion

Polymer flooding technology is a tertiary oil recovery technology wildly used in old oilfield of china such as Daqing and Shengli, which plays a significant role in maintaining oil production in these oilfields.The content of polymer and suspend solids are high in the produced water makes it is difficult to separate the oil from water since the strong interaction between suspend solids, oil and partially hydrolyzed polyacrylamide(HPAM) leading to strong emulsification of produced water. This research starts on the constitutes analysis and separation, analysis of oil fractions enriched by solvent extraction and deposition in the produced water from a polymer flooded reservoir of Gudao, Shengli. The components and their average molecular weight are analysis by IR, molecular weight apparatus. The adsorption amount of various fractions on the surface of inorganic solid such as silica gel is also investigated. The effect of each fraction separated from produced water, HPAM and the interaction between HAPM, silica gel and each fraction on the stability of emulsion are also evaluated by spectrophotometry.The content of HPAM, oil and suspend solids in polymer flooding produced water are 174·5mg.L^-1,3000mg·L^-1 and 311mg·L^-1, and pH is 8.72. Deduced from IR and molecular weight, fraction F1 extracted by petroleum ether is low molecular mass(Mm) and containing more acidic subtances; Fraction F2 extracted by trichloromethane is great in polarity and its molecule weight is high; A1 and A2 are very great in polarity, molecule weight are very high( 2868.2 for A1 and 9317.4 for A2).The adsorptions of different fractions on silica gel are investigated. The results showed that the time of the adsorption equilibrium of fraction F1 having low Mm was 6h and the equilibrium adsorbate uptake was small. The time of the adsorption equilibrium of fraction F2 having high Mm was 5h but the equilibrium adsorbate uptake was high. Because of fractions A1 and A2 with higher Mm can increase absorption amount by coordinate bond and hydrogen bond emerged within the reaction of the heteroatom, condensed rings in A1 and A2 to the surface of silica gel. The time of the adsorption equilibrium of fraction A1 and A2 ware reduced to 2.5h.The effects of modified silica gel of each fractions and HPAM on the emulsion stability ware studied. The results showed that different fractions had different effects on emusion stability. The silica gel modified by high Mm fraction had stronger emulsifying activity than silica gel modified by low Mm fraction. Especially with the presence of HPAM and silica gel modified by high Mm fraction, the emulsion was extremely stable. This is the main reason that the polymer flooding produced water contained high oil content, high levels of suspended,and diffient to treat.