在固井过程中遇到孔洞型或裂缝型漏失地层时,水泥浆会漏失低返,造成环空流速下降,降低顶替效率、影响胶结质量和油气井产能.运用自制设备评价多种防漏水泥浆体系的性能,并分析S90水泥浆体系防漏机制.结果表明:S90纤维水泥浆体系模拟堵塞3 mm孔板和缝板,5 MPa可承压10 min;在S90纤维水泥浆体系中加入特种黏结剂KE50后,模拟堵塞4 mm孔板和缝板,7 MPa可承压10 min;在水泥浆漏失过程中,S90体系中长纤维、短纤维和特种黏结剂形成致密的、牢固的纤维网格,减慢和阻止水泥浆体通过,在裂缝周围形成致密的滤饼后防漏效果显著；净浆、胶乳水泥浆和低密度水泥浆无防漏作用.%The lost circulation of slurry appears frequently when the vuggy formation and crack formation are encountered during cementing. Lost circulation of slurry will decrease the annular velocity, the displacement efficiency, performance of interface bonding and oil well productivity. The performances of several kinds of anti-lost-circulation slurry systems were evaluated by self-made equipment, and the anti-lost-circulation mechanisms of S90 slurry were analyzed. The results show that the S90 fiber slurry system could plug 3 mm hole and crack plate, and it can bear the pressure of 5 Mpa for 10 minutes. The S90 slurry system added special bonding element KE50 could plug 4 mm hole and crack plate, and it can bear the pressure of 7 Mpa for 10 minutes. During the process of lost circulation of slurry, the long fibers, short fibers and cement could form tight and fast fiber net, which can slow and prevent slurry passing. A tight filter cake is formed around fractures, so the anti-lost-circulation effect is good. While the clean slurry, latex slurry and low-density slurry have no anti-lost-circulation effect.
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