Cause analysis and countermeasures for common problems in drilling operations

Cause analysis and countermeasures for common problems in drilling operations

During the drilling process, problems such as difficulty in drilling, abnormalities in the well, or substandard water quantity and quality are often encountered. Understanding its common causes and mastering basic response ideas will help communicate effectively with the construction party and ensure the smooth progress of the project.

1. Difficulty in drilling (slow or no penetration)

Cause analysis:

Drill bit wear: The drill bit has been dulled due to long-term use, and the cutting efficiency is low.

When encountering hard strata: such as hard rock layers and thick pebble layers, ordinary drill bits cannot effectively break them.

Improper mud performance: In soft formations, the mud is too thick or has a high solids content, resulting in "mushy drill", which wraps the drill bit and affects cutting.

Insufficient drilling pressure or rotational speed: The equipment parameters are improperly set and the required energy for breaking the formation is not reached.

Response suggestions:

Check the drill immediately and replace it with a new or more suitable drill bit (such as alloy drill bit or roller cone drill bit).

Adjust the mud properties according to the formation, such as diluting the mud appropriately and strengthening sand removal.

Within the capabilities of the equipment, increase the drilling pressure or adjust the rotational speed reasonably, but avoid reckless actions that may cause the drill pipe to break.

2. Loss of circulating fluid in the well (either in or out)

Cause analysis:

Drilling encounters fissures, caves or high-permeability sand layers: a large amount of circulating fluid is lost into the formation.

The density or viscosity of the mud is too low to form an effective "mud skin" barrier on the well wall.

Response suggestions:

Immediately put plugging materials into the hole, such as sawdust, clay balls, special plugging agent, etc.

Increase mud viscosity and density to seal cracks.

If the leakage is severe and cannot be plugged, consider running technical casing to isolate the formation.

3. The drill is stuck (the drill tool cannot be lifted or rotated)

Cause analysis:

Well wall collapse: In loose formations, the mud protective wall fails and debris falls and locks the drilling tool.

Drill cuttings deposition: Due to pump shutdown or poor circulation, a large amount of drill cuttings settles around the drilling tool.

Formation shrinkage: Certain clay layers swell when exposed to water, squeezing the drill tool.

Response suggestions:

First principle: Do not lift or twist forcibly to avoid "getting stuck and getting stuck".

Try to maintain circulation, adjust mud properties, and cooperate with light lifting and slow rotation of moving drilling tools.

If the drill collapses and gets stuck, try injecting high-viscosity thick mud to stabilize the well wall before moving again.

Complex stuck drills require professional tools (such as jars) or process processing.

4. Well deviation (the borehole is not straight)

Cause analysis:

The hole is not opened correctly or the drill is not leveled.

When drilling into an inclined hard rock layer, the drill bit slides along the layer.

Improper drilling parameters, such as excessive drilling pressure and excessive rotational speed.

Response suggestions:

Strictly calibrate the level of the drilling rig before starting drilling, and use "light pressure lifting" to ensure verticality in the initial stage.

After the well deviation is discovered, reduce the drilling pressure and rotational speed, and use a centralizer or a more stable drill tool assembly to correct the deviation.

Severe well deviations may require backfilling part of the well section before re-drilling.

5. The water output is small or the water is muddy

Cause analysis:

The main aquifer was not drilled: the depth was insufficient or the formation was misjudged.

The location of the water filter pipe (flower pipe) is not aligned with the aquifer.

Defects in the well-forming process: the filter material (gravel) is not filled up to standard or the well is not cleaned thoroughly, resulting in blockage of the waterway.

Response suggestions:

Check stratigraphic records to confirm whether the aquifer has been drilled through. If it is not reached, further deepening should be considered.

Check the structure of the well. If the position of the water filter pipe deviates greatly, it may need to be pulled out and lowered again.

Carry out powerful and thorough secondary well cleaning, which is the most common and effective method to solve the problem of turbid water and small water volume. If it still doesn't work, you need to professionally check whether there is an internal blockage or pipe problem.

Summary: Focus on prevention and respond prudently

Most problems stem from poor judgment of the formation, improper operation, or poor mud maintenance. The key is to diligently observe the return material (cuttings), monitor equipment parameters (such as pump pressure, torque) in real time, and make timely adjustments according to formation changes. When encountering problems, give priority to using gentle circulation, activities and other measures to resolve them, and avoid blindly acting recklessly. For complex problems, seeking the support of experienced technical personnel in a timely manner is the most economical way to avoid the expansion of accidents and ensure the quality of completed wells.