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在水文地质钻探施工中，如果采用泥浆作冲洗液，而成井时的换浆工作是一个非常重要的环节。尤其利用岩心钻探设备施工第四系大直径井孔，换浆工作显得更为重要。因为岩心钻探的泵量较小，需要增加泥浆浓度方能满足排砂要求，但这对换浆工作带来了许多困难。又因第四系地层具有松散坍塌的特性，较深井孔一般不允许在下管前大量更换泥浆，彻底的换浆工作只能在下管后进行。怎样达到彻底换浆，具
In hydrogeological drilling construction, if mud is used as a flushing fluid, slurry changing work at well completion is a very important link. In particular, the use of core drilling equipment construction Quaternary large diameter borehole, slurry work is even more important. Because of the small pump volume drilled in the core, it is necessary to increase the mud concentration to meet the sand discharge requirements, but this brings many difficulties in the slurry replacement work. Due to the loosely collapsed nature of Quaternary formations, deeper boreholes generally do not allow extensive replacement of mud before the downcomer. Thorough slurry change work can only be performed after the downcomer. How to achieve a complete slurry, with