石油羧酸盐及其复配体系中混合胶束对界面活性的影响

Effects of Mixed Micelles from Petroleum Carboxylate and Its Combined System on Interfacial Activities

为揭示石油羧酸盐界面活性的结构成因,深入研究石油羧酸盐和磺酸盐的复配规律,选取了平均碳数分别为23.16、26.01、28.70的大庆原油馏分作原料制备石油羧酸盐,优选了一种平均碳数和油酸钠碳数相近的石油羧酸盐并将其界面活性与油酸钠进行了比较研究。此外,针对矿化度较高(矿化度11948.4 mg/L)、石油羧酸盐可以在低碱甚至无碱条件下单独达到超低界面张力的红岗油田,考察了石油羧酸盐和石油磺酸盐形成的混合胶束对复配体系界面活性的影响。研究结果表明,平均碳数和油酸钠碳数相近的石油羧酸盐的界面活性远优于油酸钠,其原因是石油羧酸盐由不同碳链长度的分子组成,由于亲水亲油性(HLB值)的差别,长链分子和短链分子在油水界面上插入深度不同,混合胶束的极性基团之间的斥力较单一分子组成的油酸钠极性基团间斥力小,分子间排列较紧密,界面吸附量较大。石油羧酸盐和磺酸盐的复配体系在矿化度较高的红岗油田具有很好的复配效果,石油羧酸盐和磺酸盐复配体系的界面活性比单剂好,达到初始界面张力的时间明显比单剂的短。石油羧酸盐单剂体系及复配体系中的混合胶束均使界面活性显著提高。

In order to reveal the structural cause of the interracial activity of petroleum carboxylate and further research the combination law of petroleum carboxylate with sulfonate, three fractions of Daqing crude oil with average carbon number of 23.16, 26.01, 28.70, respectively, were selected as the raw materials to prepare a kind of petroleum carboxylate whose average carbon number is close to the carbon number of sodium oleate. The interracial activities of sodium oleate and the petroleum carboxylate were detected and compared. Meanwhile, aiming at the Honggang oilfield with higher salinity of 11948.4 mg/L, where petroleum carboxylate could reach ultralow oil-water interracial tension with and without weak alkaline Na2CO3, the effects of mixed micelles formed from petroleum carboxylate and petroleum sulfonate on interfacial activites of the combined system were investigated. The research results showed the interfacial activities of petroleum carboxylate whose average carbon number is close to the carbon number of sodium oleate, were much better than that of sodium oleate, because petroleum carboxylate was composed of molecules with different length of carbon chain and having different hydrophilic lipophilic balance （HLB） values, respectively, and having different insertion depth of molecules at oil-water interface subsequently, the distance of polar groups became far and polar group＇ s repulsion reduced. As a result, their mixed micelles arranged more closely, the interfacial adsorption increased and the interfacial activity was better than that of sodium oleate which composed of identical molecules. The combination effect of petroleum carboxylate and alkyl benzene solfonate in Honggang oilfield with the higher salinity was good also. the difference of HLB value between carboxylate and sulfonate made the mixed micelles from petroleum carboxylat/petroleum sulfonate combined system arrange more closely, so that the interracial activity of the system was better, and the time to reach the initial ultralow interracial tension （IFT） was shorter than that of a single surfactant.