When cleaning the Drifter Bit and drill pipe, we must first understand the cause of the sediment at the bottom of the hole.

1. Residue between the drift bit bucket teeth and the bottom cover of the drill bucket.
2. The bottom cover is not closed tightly.
3. When drilling into mud and sand and flowing into plastic formations, the drilling slag into the drilling bucket will be seriously lost during lifting, and sometimes even all of it will be lost in the borehole.
4. The soil body cut by the outer edge of the drift bit drill bucket, because the bottom of the hole is a plane that cannot enter the entrance of the barrel, so it remains on the edge of the bottom of the hole.
5. The bucket teeth are loosely arranged, and the loss between the teeth is inevitable.
6. The back-feeding length of the drilling bucket is too large, and the loading is too full, and the slag is extruded from the drainage hole of the top cover.

According to the characteristics of the drift bit construction method, we have developed two methods of clearing holes and achieved good results.

At the same time, we can also control the speed of the sedimentation rate of the slag by changing the difference between the specific gravity of the slag and the mud and increasing or decreasing the viscosity of the mud. For example, we must try to reduce the sedimentation rate of the slag. , We can reduce the specific gravity and viscosity to speed up the settling speed of the drift bit mud.

If the bottom of the hole can't hit the standard, what should we do? For this reason, we must clear the hole, otherwise the pile top settlement is large and the bearing limit value is reduced. The common methods for drift hole cleaning are the settlement method and the replacement method. The so-called settlement method is the final hole After the soil residue settles to the bottom of the hole, the hole is cleaned, and the replacement method is to clean the bottom of the hole immediately after the final hole, that is, before the soil residue has been deposited from the mud, the mud in the hole is freshly prepared with mud A method of replacing outside the hole.

For forward and reverse circulation drilling, it is appropriate to use slurry replacement and clearing, because it can use its own drift drill bit to perform forward and reverse circulation slurry replacement, and the rotary drilling drill pipe does not have the function of conveying circulating fluid. For this method to clear holes, it is also necessary to re-equip the drill pipe and corresponding drift bit equipment, which is obviously not feasible, and the settlement method commonly uses the pipe suction pump method, air lifting method, and submersible mud pump method.

These methods also have some problems in use, mainly the influence range of the slag suction port. When the hole diameter is 1.5 meters, if the position of the slag suction port cannot be moved or the bottom of the hole is not stirred by the tool, the slag drilling away from the radius is more Difficult to remove.