Breakout apparatus for a sectional drill stem

Claim 1

Drilling apparatus comprising: a sectional drill stem composed of a plurality of sections joined together by threaded box and pin tool joints, each said section having a threaded pin at one of its ends and a threaded box at its opposite end; a rotary drivehead including a threaded tool joint component connectable to the drill stem tool joint components which face the drivehead; means for moving the drivehead axially both towards and away from the ground being drilled; and breakout apparatus for forcibly loosening the threaded connection between a given first drill stem section connected to the drivehead and the drill stem section second from the drivehead, said apparatus comprising side located wrench element engaging means on said first stem section, adjacent the end thereof connected to the drivehead, breakout wrench jaw means on said drivehead having wrench surface means which in use at least is spaced radially outwardly from the wrench element engaging means on said first stem section, a torque transferring wrench insert element sized to snugly fill the radial space between said wrench surface of the breakout wrench jaw means and the wrench element engaging means on the first stem section, means for holding the second stem section and restraining it against both rotational and axial movement, and means for rotating said breakout wrench jaw means in a joint loosening direction, resulting in a joint loosening rotational torque being transferred from the breakout wrench jaw means to the first stem section through the torque transferring wrench insert element and a loosening of the threaded joint between the first and second stem sections.