Fishing systems

In the context of groundwater systems, particularly in water well drilling, maintenance, and rehabilitation, fishing systems and equipment refer to the tools and techniques used to recover objects (known as fish) that have been lost, dropped, or stuck inside a borehole or well. These can include broken pipes, tools, pump parts, or debris that obstructs well function.

📌 Why Fishing is Needed

Fishing becomes necessary when:

• Drill rods or casing break and fall into the well.

• Pumps or pump components get detached and fall in.

• Tools used for cleaning or development become stuck.

• Obstructions or debris accumulate, making the well unusable or unsafe.

🛠️ Common Fishing Equipment and Tools

Fishing tools are usually chosen based on:

• The size and type of object being retrieved.

• Whether the object is metallic or non-metallic.

• The depth and diameter of the well.

Here are the main categories:

1. Overshots

• Purpose: To grasp and pull up items from the outside.

• Design: A tapered or bell-shaped tool that slips over the top of the object and grips it.

• Use Case: For retrieving broken-off drill pipes or rods.

2. Spears (or Taps)

• Purpose: To enter the inside of a hollow object and grip it from within.

• Use Case: Useful for retrieving casing or tubing where the internal bore is accessible.

3. Magnets

• Purpose: To retrieve metallic debris, such as broken bits, nails, or shavings.

• Type: Either permanent magnets or electromagnets.

• Use Case: Shallow wells or where magnetic materials are suspected.

4. Bailers and Sand Pumps

• Purpose: To remove non-metallic debris such as sand, silt, or gravel.

• Design: Cylindrical tools with check valves that allow entry but prevent backflow.

5. Jars and Bumper Subs

• Purpose: To apply impact force (upward or downward) to dislodge stuck items.

• Use Case: For freeing items jammed due to swelling, corrosion, or tight fits.

6. Swivel Hooks and Grabs

• Purpose: To hook or latch onto irregularly shaped objects.

• Use Case: Recovering tools, pump parts, or wires.

7. Casing Cutters and Mills

• Purpose: To cut or grind stuck casing or tubing so that it can be removed in sections.

• Use Case: When direct fishing is not possible and removal or bypass is needed.

🔧 Fishing Operations Techniques

• Visual/Camera Inspection: Using borehole cameras to locate and identify the fish before selecting the retrieval tool.

• Tagging: Lowering a tool to feel or detect the fish's top to understand its position and orientation.

• Fishing String Assembly: A combination of tools like jars, safety joints, and the fishing tool attached to the drilling rig.

✅ Best Practices for Fishing in Groundwater Systems

• Maintain detailed logs of all equipment used in the well.

• Use borehole cameras and depth markers for precise location.

• Avoid using excessive force, which may damage the well casing or deepen the problem.

• Always choose the fishing method that ensures the least disruption to the well structure.

🧠 Summary

Fishing systems and equipment are critical for the maintenance and rehabilitation of water wells. These tools help recover lost or stuck equipment, allowing continued access to the groundwater system without having to drill a new well. Success depends on proper diagnosis, tool selection, and operator experience.