1, collapse hole

During the infusion process, if the mud level in the wellbore casing slurry suddenly rises and overflows the casing, and then suddenly drops and bubbles appear, it should be suspected to be a sign of hole collapse, which can be detected by a sounding hammer. If the original sounding hammer was hung on the surface of the concrete without being taken out, it is buried and cannot be lifted, or the sounding hammer fails to reach the original depth when detecting the concrete surface, and there is a lot of difference, it can be confirmed that it is indeed a collapsed hole.

The reason for the collapse of the hole may be water leakage around the bottom of the protective tube, lower water level in the hole or in a tidal river, when the tide is high, the water level difference in the hole decreases, and the original hydrostatic pressure cannot be maintained, and due to the heavy objects stacked around the protective tube or machine vibration And so on can cause collapse hole.

2. The hole body is skewed

When the hole body is deviated or bent, the reason should be analyzed and dealt with. Generally, the drill cone can be hung at the deviated place to sweep the hole repeatedly to make the hole straight; when the deflection is serious, the cohesive soil should be backfilled to the deviated place, and then drilled after the deposit is dense.

3. Reaming and shrinking holes

In case of hole expansion and shrinkage, measures should be taken to prevent hole collapse and prevent the drill cone from swinging too much. Shrinkage is caused by excessive wear of the drill cone, delayed welding repair, or soft soil or clay mudstone that swells in the formation. The former should be welded and repaired in time, and the latter should be protected by mud with a low water loss rate. When shrinkage has occurred, it is advisable to repeatedly sweep the hole up and down with a drill cone to enlarge the hole diameter.

4. Paste drill, buried drill

Paste drills and buried drills often appear in rotary drilling and percussive drilling in positive circulation (including submersible drilling rigs). In case of this, check and calculate the mud consistency, drill slag inlet and outlet, drill pipe inner diameter size, and slag discharge equipment, and control the appropriate footage; if the drilling has been severely stuck, the drilling cone should be stopped and the drill slag should be removed.

5. Sticking

Sticking often occurs in percussion drilling. It is not advisable to lift it forcefully after stuck, but only lightly. When it is not moving, use a small impact drill cone to impact or use punching or suction to loosen the drill slag around the drill cone before lifting it.

6. Falling diamonds

When dropping a drill, it is advisable to quickly use fishing forks, hooks, rope sets and other tools to fish. If the fallen body has been buried by sand, the sand should be removed according to the preceding items, and the fishing tool should contact the fallen body before fishing.