青海大场矿区永冻层低温钻井液试验研究

Experimental Study of Cryogenic Drilling Fluid Suitable for the Permafrost of Dachang Mining Area in Qinghai

针对大场矿区永冻层钻进过程中出现的冻钻、塌孔和钻井液絮凝等特点,结合矿场钻探地质资料,在粗分散抑制性抗低温钻井液体系基础上,利用正交实验法优选出了适宜大场矿区永冻层钻进的配方。配方:1 000mL水+2%Na2CO3(钠基膨润土的2%)+4%钠基膨润土+10%NaCl+2%KCl+5%乙二醇+0.15%Na-CMC(高黏)+0.3%LV-PAC(低黏)。实验表明该配方在-10℃条件下仍能保持良好的性能,未出现冻结、絮凝等现象;同时,运用DPS软件分析了该钻井液的流体类型,结果表明该钻井液为幂律流体,在低温下该钻井液的非牛顿性增强,流动性能较好。

According to the problem occurred in the drilling on permafrost of Dachang mining area, such as freezing drill, collapse and drilling fluid flocculation, and basing on the system of coarse dispersion sup pressing anti-cryogenic fluids, this paper applies orthogonal test method to explore the best formulation which is suitable for the permafrost drilling in Dachang mining area. The experimental results show that the optimized formulation is ： water ： 1 000 ml-- Naz CO3 ： 2 %（2 % of sodium bentonite） ＋ sodium bentonite ： 4 % ＋ NaCl ; 10%＋ KCl; 2 % ＋ glycol ： 5 % ＋ Na-CMC （ high viscosity） ： 0. 15 % ＋ LV-PAC （ low viscosity） ： 0.3 %. With this formulation, the drilling is in good performance even at the temperature of --10℃ with- out freezing or floculation. Meanwhile, this paper analyzes the type of the drilling fluid by using DPS soft- ware. The results indicate that the drilling fluid is power-law fluid. The non-Newtonianism of the drilling fluid even enhanced at low temperature and in good flowing property.