What is a small diameter channel worn into the side of a larger diameter wellbore?

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

Answer: (B)

A keyseat is a narrow groove cut or worn into the wall of a larger bore to provide a seating or engagement location for a downhole tool or component. This specific, small-diameter channel is meant to accept a key or to act as a seating surface, helping to position or lock equipment inside the wellbore.

This distinguishes it from a generic groove (any channel), a ledge (a shelf-like protrusion along the bore wall), or a sidetrack (a separate, new bore drilled from the original). The keyseat is the exact term for a small, sidewall channel that serves as an engagement/seat point in the wellbore.