Troubleshooting Common Problems During Drilling

Troubleshooting Common Problems During Drilling

During drilling operations, encountering difficulties such as slow penetration rates or downhole anomalies is common. Understanding the basic causes and solutions will help owners and field personnel communicate effectively with contractors, make informed decisions, and ensure the smooth progress of the project.

I. Drilling Difficulties (Slow or No Penetration)

Problem: The drill bit rotates but penetrates very little, and the equipment is under heavy load.

Main Causes and Solutions:

Drill bit wear or mismatch: The most common reason. Ordinary drill bits wear down quickly in hard rock or gravel layers.

Solution: Immediately pull the drill string to inspect the drill bit and replace it with a more durable alloy drill bit or roller cone bit.

Encountering hard rock formations: The formation itself has extremely high hardness.

Solution: Evaluate the necessity and cost of continuing drilling. Discuss with the contractor whether to replace with a more powerful drill bit or use impact drilling, or consider completing the well at the current depth (if sufficient water flow has been achieved).

Poor mud (circulation fluid) performance: In soft formations, overly viscous mud can cause "mudding up" of the drill bit.

Solution: Adjust the mud composition, reduce viscosity, and improve circulation to remove cuttings.

II. Loss of Circulation Fluid in the Well (No or Little Return Flow)

Problem: A large amount of water or mud pumped into the well is lost, with very little return flow.

Main Causes and Solutions:

Drilling through fractured or porous formations: Circulation fluid leaks into the formation.

Solution: Introduce sealing materials into the well (such as clay balls, sawdust, or specialized sealing agents) to increase mud viscosity and seal the fractures.

Severe leakage that cannot be sealed:

Solution: It may be necessary to install casing (well pipe) to isolate the leaking layer, and then continue drilling with a smaller diameter drill bit.

III. Drill String Sticking (Drill String Cannot Be Lifted or Rotated)

Problem: The drill string is stuck in the well, which is a relatively dangerous situation.

Main Causes and Solutions:

Wellbore collapse or narrowing: In loose formations, the wellbore becomes unstable and traps the drill string.

Solution:  Strictly prohibit forceful lifting or twisting. Attempts should be made to start the pump to establish circulation, inject high-viscosity drilling fluid to stabilize the wellbore, and gently move the drill string with the equipment.

Drill cuttings deposition: Due to prolonged pump downtime, drill cuttings settle and bury the drill string.

Approach: Attempt to restore circulation and flush out the sediment.

Core principle: With the goal of "unsticking" the drill string, prioritize gentle methods such as circulation and movement to avoid exacerbating the problem. Complex stuck pipe situations require professional tools.

IV. Turbid (sandy) water or low water yield

Problem phenomenon: Water remains turbid after well completion, or the water yield does not meet standards.

Main causes and solutions:

Filter pipe (screen pipe) or filter layer failure: Unqualified filter material, uneven filling, or excessively large pores in the filter pipe.

Approach: The primary and most economical measure is to perform a powerful and thorough secondary well cleaning. If ineffective, professional investigation of the well structure may be required.

Incomplete well cleaning: This is the most common reason for turbid water in new wells.

Approach: Insist that the contractor clean the well until the water is clear and free of sand, using this as a core acceptance criterion.

Did not drill to the main aquifer: Incorrect depth or location.

Approach: Verify the geological records and assess whether further drilling is needed.

Summary: Prevention is key, scientific response is crucial.

Most problems are related to geological interpretation, operating procedures, and maintenance. The core response logic is:

Frequent observation: Pay attention to return materials and equipment parameters.

Early diagnosis: Quickly identify possible causes based on the phenomena.

Gentle first: Prioritize gentle methods such as circulation and parameter adjustment.

Professional later: For complex problems, seek professional technology and tools in a timely manner.

As the owner, your main role is that of an "informed supervisor." By understanding these approaches, you can more professionally discuss the problems, solutions, and cost implications with the contractor, thus making informed decisions and jointly promoting the successful completion of the project.