油基钻井液高温乳化剂的制备与性能评价

Preparation and Performance Evaluation of Emulsifier with High Temperature Resistance for Oil-based Drilling Fluid

为了提高油基钻井液用乳化剂的抗温性,以植物油酸、二乙烯三胺、马来酸酐为主要原料,制备了油基钻井液高温主乳化剂(PF-EMUL HT)和辅乳化剂(PF-COAT HT)。利用红外光谱和热重分析表征了2种乳化剂的分子结构及耐温性。通过测定动态界面张力、乳化效率和乳液电稳定性,分析了2种乳化剂的乳化能力及抗温能力,提出了可能的乳化机理。同时,研究了乳化剂加量、油水比、温度和密度对所配制钻井液的影响。结果表明,PF-EMUL HT具有酰胺化基团,PF-COAT HT具有酰胺基、羧基等多官能团结构。2种乳化剂均能有效降低油水界面张力,二者复配制得的乳液经232℃高温老化后的破乳电压大于370 V,乳化效率为96%。配制的油基钻井液在150~232℃、油水比为60∶40~90∶10的条件下老化后均具有良好的稳定性,可满足高温高压井、定向井等的作业需求。

In order to improve the temperature resistance of emulsifier for oil-based drilling fluid,main emulsifier(PF-EMUL HT)and auxiliary emulsifier(PF-COAT HT)were prepared by using vegetable oleic acid,diethylenetriamine and maleic anhydride.The molecular structure and temperature resistance of two emulsifiers were characterized by infrared spectrometry and thermogravimetric analysis.The emulsifying ability and temperature resistance of two emulsifiers were analyzed by measuring the dynamic interfacial tension,emulsification efficiency and electrical stability of the emulsion.The possible emulsification mechanism was also proposed.At the same time,the influences of emulsifier dosage,oil-water ratio,temperature and density on the performance of drilling fluid were studied.The results showed that PF-EMUL HT had amidation group,while PF-COAT HT had multi-functional groups,such as amido group and carboxyl group.These two emulsifiers could effectively reduce the interfacial tension between oil and water.The demulsification voltage of the emulsion prepared by the two emulsifiers was more than 370 V.The emulsification efficiency was 96%after aged at 232℃.The oil-based drilling fluid had favorable stability after aged under the conditions of 150—232℃and 60∶40—90∶10 oil-water ratio,which could satisfy the operation needs of high temperature and high pressure well and directional well.