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HDD Machine common cases and solutions 10

The following aspects need to be paid attention to in mud design:

1 Try to use a high molecular polymer slurry system in the sand layer. The performance of the system is stable during use. Increasing the viscosity of the slurry through polymer polymerization can greatly enhance the cementing effect of the slurry on the sand particles, and it can quickly be around the hole wall The formation of a mud cake ring with small thickness and good toughness quickly establishes a positive pressure difference between the inside and outside of the hole, forming a good support for the hole wall! In addition, the polymer slurry is not easily diluted by the intrusion of groundwater, which better maintains engineering safety ;

2 Try to use high viscosity “high yield value mud!”

Because the sand particles are coarse and have a large specific gravity, the suspension performance of the mud itself must be sufficient to be discharged out of the hole; in addition, because the sand layer is rich in groundwater, the drill cuttings also contain a large amount of water, which will affect the mud Cause a great dilution effect! Therefore, when designing the mud, the water content of the sand layer should be ascertained in detail, combined with the designed reaming diameter, “reaming gradation,” mud displacement,” reaming speed and other parameters, to estimate the unit time in advance The water entering the mud accounts for the proportion of the amount of mud pumped in this period. During the ground test, it should be ensured that the designed mud still has sufficient suspension performance after being mixed with this proportion of clean water, that is, the water should be fully considered when designing the mud index. Dilution

3 Reasonably control the mud displacement, which not only guarantees timely removal of drill cuttings, but also avoids excessive scouring of the hole wall; in addition, lubricants can be added during the dragging process, which will help reduce the dragging

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