低油水比乳状液稳定性影响因素分析

Analysis of Factors Affecting Stability of Low Oil-water Ratio Emulsion

为获得低油水比下性能稳定的油基钻井液,油包水乳状液的稳定性是关键。通过电稳定性测试法、静态稳定性测试法、微观形态测试法分析了乳化剂加量、有机土加量和温度对油水比为60∶40的油包水乳状液稳定性的影响。研究结果表明:4%乳化剂加量下乳液滴细小且分散均匀,破乳电压最高,乳状液稳定性最佳。环境温度100℃和120℃下,乳状液液滴大小变化不大,破乳电压接近,稳定性差别不大,继续提高温度至150℃,乳状液液滴显著增大,破乳电压陡降,稳定性明显变差。有机土加量为2%时,显微镜放大400倍下乳状液液滴肉眼不可见,破乳电压超过400 V,且静置25 h后析油率仅0.1%,稳定性显著提高。通过关键处理剂材料作用机理分析并优选合适处理剂加量,是保证低油水比乳状液稳定的一大关键,对现场油基钻井液性能维护有实际指导意义。图15表2参15。

In order to obtain oil-based drilling fluids with stable performance at low oil to water ratios,the stability of water-in-oil emulsions is critical.The effects of emulsifier addition,organic soil addition and temperature on the stability of water-in-oil emulsion with oil-water ratio of 60/40 were analyzed by electrical stability test,static stability test and micro-morphometry.The results showed that when the addition of the emulsifier was 4%,the emulsion droplets were fine and dispersed evenly,the demulsification voltage was the highest and the emulsion stability was the best.At the temperature of 100℃and 120℃,the emulsion droplet size changed little,and the demulsification voltage was close,indicating that there was little difference on stability.However,when the temperature increased up to 150℃,the emulsion droplets augmented significantly,the demulsification voltage droped sharply,stability significantly deteriorated.When adding 2%organic soil,the emulsion droplets under 400 times objective lens were invisible to the naked eye,the demulsification voltage exceeded 400 V,and the oil separation rate was only 0.1%after standing for 25 hours,as a result,the stability was remarkably improved.Analyzing the mechanism of key materials and optimizing the amount of appropriate treatment agent were important to ensuring the stability of emulsions with low oil-to-water ratio,which had practical guiding significance for on-site oil-based drilling fluid performance maintenance.