Which term refers to a small diameter channel worn into the side of a larger diameter wellbore?

• A. Ledge
• B. Keyseat
• C. Groove
• D. Sidetrack

Answer: (B)

In wellbore terminology, features along the bore wall are named to reflect how tools interact with the hole. A small diameter channel worn into the side of a larger diameter wellbore is called a keyseat. This term describes a recessed slot that provides a seat for a tool or component, helping to align or retain it so it sits securely against the wall during downhole operations. The idea is that the shoulder or key of a tool can drop into or rest in that precise channel, preventing unwanted movement.

A ledge is a raised edge or shelf along the wall, not a narrow channel built for seating. A groove is a general term for any channel and isn’t specific to a side-worn seating feature. A sidetrack refers to drilling a separate bore off the main well, rather than a small intrawall channel.