What are drill slips and how are they used?

• A. Drill slips are used to anchor the drill bit to the rig floor.
• B. Drill slips are used to secure the drill string or casing during tripping operations; they consist of tapered wedges that grip the drill pipe when weight is applied, preventing it from slipping while allowing for safe handling and positioning of the string.
• C. Drill slips are used to seal casing joints.
• D. Drill slips are used for mud mixing.

Answer: (B)

Drill slips are the devices used to grip and hold the drill string or casing on the rig floor during tripping operations. Their purpose is to secure the pipe so it won’t move downward or drop while connections are being made or broken.

They work as a set of tapered wedges with gripping teeth. When the weight of the string is applied and the slips are centered around the pipe, the wedges bite into the pipe, creating a firm grip. This holds the string in place and allows safe handling, positioning, and connection or disconnection of joints without the risk of the string slipping or falling.

These slips are engaged specifically during times when the string isn’t being rotated to move it in or out of the hole, and they are released by lifting the pipe so the wedges loosen their grip. They are not used to anchor the drill bit, seal casing joints, or mix mud.