Is a common recovery method in oilfield drilling operations when a part of the drill string or tubular gets stuck or broken off in the wellbore. Here’s a breakdown of how it works and when it’s used:

A taper tap is a fishing tool designed with a gradual external taper and hardened threads that can screw into the internal diameter (ID) of a stuck or lost tubular, such as drill pipe, casing, or tubing.

Taper Tap Used:
When the top of the fish (the object stuck in the well) is hollow and cleanly cut or has an open ID.
Ideal for recovering tubulars like casing, tubing, or drill pipe that broke off and have a clear opening.
Often used when other fishing tools like overshots cannot grip the outer surface due to size constraints or damage.

How Fishing with a Taper Tap Works:

1. Assessment of the Fish:
   Check the dimensions of the fish’s ID, condition of the top, and depth.
   A clean and round top is ideal for taper tap engagement.
2. Run in Hole (RIH)
   The taper tap is made up to the drill string and run into the wellbore.
3. Engagement:
   Once the taper tap reaches the fish, gentle rotation is applied.
   The tapered threads cut into and bite into the ID of the fish.
   Controlled weight and torque help avoid damaging the fish or the tool.
4. Pull Out of Hole (POOH):
   After a firm grip is achieved, upward pulling retrieves the fish from the hole.

Advantage of Using a Taper Tap:
Simple design, easy to use.
Effective for tubulars with clean, open ends.
Can be a cost-effective solution when more complex tools aren’t needed.

Limitations:
Won’t work if the fish ID is too damaged or filled with debris.
Requires good alignment and proper size match with the fish.
Less secure grip compared to other tools like spears or overshots.