Description

The kelly is a specialty tubular located on the drilling rig. It is used as a drive bar to lower the drill string into the ground, and also to rotate the drill string during drilling. Each joint of drill pipe is attached to the bottom of the kelly, one at a time, and is lowered into the hole. The kelly is rotated by the kelly drive bushing which is located in the rotary table on the rig floor, and in turn the kelly rotates the entire drill string and drill bit. The working area of the kelly can be either square shaped, or hexagonal shaped. The square or hex shape of a kelly is what enables the kelly to be turned by the rotary table and kelly drive bushing.