Definition
Key Seat — A key seat is a narrow groove worn into the wall of the borehole at a dogleg by the rotating drill pipe, into which a larger tool joint or BHA can wedge and stick while tripping out of the hole.
Also known as: key seat, key seating, keyseat
What a key seat is
A key seat is a slot cut sideways into the borehole wall where the drill string rides against a dogleg. As the smaller-diameter drill pipe rotates under tension through the bend, it abrades a narrow groove — the key seat — that is wide enough for the pipe body but too narrow for the larger tool joints or the BHA below. On the way out of the hole, the larger diameter reaches the key seat and wedges, sticking the string even though it moved freely before.
Prevention and remedy
Key seating is favored by high dogleg severity, long open-hole intervals, and abrasive formations. Prevention includes minimizing doglegs, running a key-seat wiper or roller reamer to open the groove, and reaming through problem sections on connections. When stuck in a key seat, the string is usually worked and jarred downward first, since the obstruction is above the stuck point; reaming out the seat may be required before tripping continues.
Why it matters for rentals
Reamers and wipers that prevent and clear key seats are interval-specific tools well suited to rental.
Rent roller reamers and wipers from our BHA components, or contact us to design a BHA for a dogleg-prone well.