For interest23 Feb 2026 11:39
When parts of the drill string break off downhole (commonly referred to as a "twist-off" or "fishing" situation), it creates a "fish"—a piece of equipment lost in the wellbore. This is a serious, high-cost, and time-sensitive incident that requires immediate action to recover the lost components to avoid abandoning the hole.
Immediate Actions:
Stop Drilling: Stop the rotation immediately to prevent further damage to the drill string, bit, or wellbore.
Ensure Safety: Check on-site crew safety and secure the area.
Identify the Failure: Monitor for signs of a twist-off, such as sudden loss of pump pressure, a decrease in torque, and a sudden change in hook load (weight indicator).
Do Not Force: Avoid excessive pulling or rotating, as this can damage the derrick or further break the pipe.
Recovery Procedures (Fishing Operations):
Overshot: A specialized tool with internal grapples ("Chinese fingercuffs" style) is lowered over the broken pipe to catc
Spear: If the break is inside the pipe, a fishing spear can be inserted to grip the fish from the inside.
Milling: If the top of the broken pipe is jagged or damaged, it may need to be milled (ground down) to a smooth, round shape before an overshot can engage it.
Magnets: For smaller debris or broken bit cones, a magnet can be used to remove the broken parts.
Washpipe: If the fish is stuck, a washover pipe can be used to clear debris from around the pipe to free it.
If Recovery Fails:
If the fish cannot be recovered after several attempts, the hole might need to be "sidetracked," which involves setting cement and drilling around the lost equipment.
Potential Causes:
Twist-off: High torque during directional drilling causes the string to fail.
Fatigue: Cyclic stress, corrosion, or washouts (holes in the pipe).
Tensile Failure: Overpulling when the pipe is stuck.
Stuck Pipe: Accumulated cuttings or geological conditions causing the string to get lodged.
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