一种新型超深水低温早强剂

近年来，中海油在中国南海已经开发了多口超深水井，水深最深超过2000 m，极端的低温环境对水泥石的强度发展提出了严峻的挑战。针对超深水的固井技术难题，开发出了新型超深水低温早强剂ACC与NS，并对其低温下的增强性能展开了研究。结果表明，ACC与NS的最佳加量分别为8%和3%；在3～15℃的低温下，ACC与NS能提高水泥石的24 h和48 h抗压强度；在15℃下，采用水化热分析仪和超声波强度分析仪对水泥浆进行24 h不间断监测，与空白样和原有早强剂相比，ACC和NS能够使水泥水化放热量和水化反应速率明显增加，水泥石强度发展速率得到明显地提升，同时静胶凝强度过渡时间明显缩短。该新型早强剂ACC与NS已经在中国南海WN-XX井进行了现场应用，效果良好。 

A New Low Temperature Early Strength Agent for Ultradeep Water Operation

CNOOC has in recent years drilled several ultra-deep water wells in South Sea of China, the deepest water depth has been more than 2,000 m. Extremely low temperature has imposed serious challenges to the strength of set cement. Two new low temperature early strength agents, ACC and NS, have been developed to deal with well cementing challenges in deep water drilling. Studies on the effects of ACC and NS on the early strength of cement slurry at low temperatures showed that the optimum concentrations of ACC and NS was 8% and 3%, respectively. At low temperatures between 3℃ and 15℃, ACC and NS can improve the 24-hour and 48-hour compressive strengths of set cement. Continual monitoring of cement slurries for 24 hours at 15℃ using hydration heat analyzer and ultrasonic strength analyzer showed that, compared with blank sample cement slurry and original early strength additives, addition of ACC and NS obviously increased the amount of heat of hydration and hydration reaction rate of cement. The rate at which the strength of the set cement was developing was obviously increased, while the transition time of the gel strength of the cement slurry was obviously shortened. ACC and NS have been used satisfactorily on the well WN-XX in China's South Sea.