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西藏伦坡拉地区海拔4700m，气候恶劣，年平均温度7℃左右。地层主要为大段泥岩，水敏性强，裂缝发育；孔隙压力一般为0．92～0．97g／cm3，多数层段呈负压特性；地温梯度4．0～4．8℃／100m，平均4．26C／100m，属温度异常。钻井时漏失频繁，固井时水泥浆漏失，返深达不到要求，固井合格率56％～76％，优质率38％～47％。针对该地区固井漏失和水泥胶结质量差的突出问题，模拟真实的井底温度和压力，以提高低密度水泥强度为重点，优选出适合低密度水泥浆的外加剂，达到低密度、高早期强度、高流性指数的水泥浆配方。经现场3口井试验，没有发生漏失，其中西伦5井固井质量合格率达98％，优质率达89％。
Tibet Lunpola area 4700m above sea level, poor climate, the annual average temperature of about 7 ℃. The strata mainly consist of large mudstones with strong water sensitivity and fractures. The pore pressure is generally 0.92-0.97 g / cm3, with negative pressure characteristics in most of the intervals. The geothermal gradient is 4.0-4.8 ° C / 100 m, Average 4.26C / 100m, is an abnormal temperature. Loss of drilling fluid frequently, loss of cement slurry cementing, back to reach the required depth, cementing pass rate of 56% to 76%, high-quality rate of 38% to 47%. In view of the outstanding problems of cementing loss and cement cementation quality in this area, the real bottomhole temperature and pressure are simulated to improve the strength of low-density cement, and the suitable additives for low-density cement slurry are optimized to achieve low density and high early age Strength, high flow index of the cement slurry formula. After three on-site tests, no leakage occurred. Among them, the cementing quality of Xilun 5 well reached 98% and the high-quality rate reached 89%.