Precautions when using polymer mud

High water area

It is very important to keep the orifice cofferdam (also known as slow slurry tank) full of slurry during drilling. If sufficient slurry head pressure cannot be ensured, the consequences will be sand falling off the hole wall, causing excessive sediment, or the hole will collapse in severe cases. If you pour the missing side, you won't even be able to form a hole.

Enter size

It is strictly forbidden to fill the bucket during drilling. The entry size of a single bucket should be controlled at about 90% to 95% of the drilling bucket capacity. It is absolutely not allowed to fill the bucket.

If you fight a lot, there are two disadvantages:

1. It is not easy to tell whether the dirt on the top of the drill bucket was squeezed out from the bucket or fell from the wall.

Second, filling the bucket will cause the muck produced during the drilling process to be squeezed out from the top opening of the drill bucket and mixed in the mud. After the hole is formed, the muck will sink to the bottom of the hole to form sediment.

In actual operation, 0.40m is reserved before drilling. After 20 to 30 minutes of sedimentation, the 0.40m is drilled into the hole in two steps, each time adding 0.20m to remove the sediment in the hole.

Hole cleaning

Notes on hole cleaning:

When cleaning holes, you need to pay attention to the "three slowness" principle - drilling slowly, drilling slowly, and lifting the drill slowly.

The purpose of drilling slowly and drilling slowly is to avoid stirring up the sediment.

Lift the drill slowly to avoid squeezing out the sediment from the gap in the bottom plate of the drill bit.

The process is as follows:

For the first drill, slowly drill down to the bottom of the hole, lightly drill the bottom, close the bucket door and slowly lift it up. Do not control the slurry after lifting the hole opening, and throw it all out. ​

Drill the second drill slowly to the bottom of the hole, lightly tap the bottom, close the bucket door and let it sit for about 3 to 5 minutes to allow the sediment to fall into the bucket. Do not control the slurry after raising the hole, and throw it all out. ​

By analogy, the third drill is the same as the second drill until all the sediment is fished out.

Hydration and grouting after hole formation

In areas where grout seeps out quickly (the grout seepage speed is greater than 1m per hour), various methods should be used to ensure the grout head pressure to avoid sand falling off the hole wall or hole collapse due to loss of pressure.     

1. If there is a fixed power supply, you can use a 220V small pump with a 1-inch pipe to continuously add slurry into the hole.

2. If there is no fixed power supply, a steel mud box can be used to store full slurry, and the siphon method can be used to refill the hole; if there is no mud box, soil can be surrounded at the hole entrance to form a large-capacity slow slurry tank.

Frequently asked questions and solutions when using polymer mud

Why is there always sediment?

Causes of sediment formation and related treatment measures

1. Too little mud material is used, resulting in poor wall protection. After the hole is formed, the hole wall continues to lose sand, forming sediment.

Treatment measures: Increase the amount of material used.

2. The mud pump is placed at the bottom of the mud tank to pump the sediment at the bottom into the hole.

Treatment measures: Lift the pump and leave the bottom of the pool.

3. The drill bucket is worn too much and the gap in the bottom cover is large. During the hole cleaning process, the sediment is squeezed out of the gap and flows back into the hole.

Treatment measures: Leave 0.40m unfinished before forming the hole. After settling for 20 to 30 minutes, divide the 0.40m into two holes, each time drilling 0.20m, to remove the sediment in the hole.

4. If there is too much footage in a single bucket, the slag produced during the drilling process will be squeezed out from the top opening of the drill bucket and mixed in the slurry. After the hole is formed, it will sink to the bottom of the hole to form sediment.

Treatment measures: The footage of a single bucket should be controlled at about 90% to 95% of the drilling bucket capacity, and the bucket must not be filled to the full.

5. The hole was not completely cleaned, and the drill was lifted and lowered too much, which stirred up the sediment and mixed it into the slurry again. It seemed to be clean, but after a period of time, it settled to the bottom of the hole.

Treatment measures: Drill slowly and drill slowly to avoid stirring up the sediment. Lift the drill slowly to avoid squeezing out the sediment from the gap in the bottom plate of the drill bit.

6. The hole cleaning was not complete. When there was 2m of sediment measured, it was actually 3m or more, because the upper 1m was not sedimented and the hanging hammer penetrated.

Treatment measures: Increase the number of times the drill bucket is fished.

7. In the high water level area, the mud leaks after the hole is formed and the mud head pressure is lost, causing sand to fall off the hole wall.

Treatment measures: Continuously add grout through various methods to ensure the pulp head pressure.

8. When lowering the long casing, the slag attached to the inner wall of the casing was not scraped off during drilling. After the hole was formed, it fell to the bottom of the hole to form sediment after being soaked for a long time.

Treatment measures: Use a drill bucket to scrape it off when drilling.

9. When using a drill bucket to retrieve sediment, the drill bucket returns incorrectly and scrapes the hole wall, forming new sediment.

Treatment measures: Return the drill bucket accurately when fishing out slag.

Common hole cleaning methods

1. The drilling bucket fishing method is the most common, simple to operate, and does not require additional hole cleaning equipment. The disadvantage is that it is easy to clean the holes incompletely.

2. The turbid water replacement method is relatively simple to operate. The disadvantage is that it takes a long time to clean the hole.

3. The gas lift reverse circulation hole cleaning method is more common in the south and has high hole cleaning efficiency and thoroughness. This method requires the purchase of a set of equipment such as an air pump and gas tank. The disadvantage is that it is inconvenient to operate in deep holes.

4. Sand suction pump hole cleaning method is more common in the south and has high hole cleaning efficiency and thoroughness. This method requires the purchase of a high-power sand suction pump.