Synthesis Of Petroleum Sulfonate Used For Tertiary Recovery

The petroleum sulfonate (PS) is widely used as a kind of anion surface active agent which is capable of enhancing the oil recovery. It can reduce interfacial tension of oil-water. It is lower in the cost than others and the raw material is easily got. Studying the synthesis of the petroleum sulfonate is significant to enhance the oil recovery.The main content of this paper is about how to reduce the acid-sludge during the production of the Karamay petroleum sulfonate. To solve this problem, firstly, the petroleum sulfonate was synthesized by using the raw material of Xinjiang Karamay vacuum cut 4 fraction oil and SO3 as sulfonation agent; the effects that acetic acid, phosphoric acid, odium sulfate, and sodium p-toluene sulfonic acid decrease the producing of acid-sludge were studied, and the reaction temperature, the amount of additive, and the concentration of NaOH were detected; and the structure and component of acid-sludge was analyzed as the excessive acid-sludge is produced; then the structure of petroleum sulfonate was characterized by mass spectrum (MS), nuclear magnetic resonance (NMR) and infrared spectrum (IR);at last the oil-water interfacial tension of the synthesized PS was studied, especially the interfacial tension of different systems was investigated, such as PS/alkali and PS/alkali/polymer.The analysis results of the acid-sludge show that: the average molecular weight is 376; the degree of branching is 0.06; and there are aromatic hydrocarbon and sulfate group in the sample.Compared with others, acetic acid is the best additive, because it can restrain the formation of acid-sludge. The synthesis conditions are optimized by the single factor with the existence of acetic acid. The optimal reactive condition is: the reaction temperature is 60℃; acetic acid is 2wt% to raw material oil; and the concentration of NaOH is 20%. In this condition the yield of the product is 20.21%, and the content of inorganic salt and acid-sludge is relatively lesser.The structure of petroleum sulfonate was characterized by mass spectrum (MS), nuclear magnetic resonance (NMR) and infrared spectrum (IR).The results show that the average molecular weight of petroleum sulfonate is 442.3; the degree of branching is 0.443; the degree of aromaticity is 0.07; the average number of aromatic hydrocarbon is 1.7~1.9; the average number of saturated hydrocarbon is 22.6~25.5; and the average number of methyl is 6.9~7.8.The results of the oil-water interfacial tension indicated that the oil-water interfacial tension can reach 10-3mN/m level when petroleum sulfonate is dissolved in water. Compared with the other factors, the effect of alkali is remarkable. When the total amount of alkali and PS is 0.8wt%, and the mass ratio is 3 to 2, the ultra low oil-water interfacial tension of 6.1×10-4mN/m can be obtained. So the petroleum sulfonate is suitable to enhance the oil recovery.