Safety joint incorporating means to aid removal of a string stuck in a wellbore

摘要

The present invention relates to safety joints which permit separation of a downhole assembly at the location of the joint. The invention provides a safety joint characterized by the provision of auxiliary interconnecting means on a body (2) for interconnecting said body (2) to an auxiliary shaft after removal of a main shaft (3) from said body (2). Axial loading between the auxiliary shaft and said body (2) may be thereby transferred. Furthermore, torque may also be transferred between the auxiliary shaft and said body (2) in a direction opposite to that in which torque may be transferred from the main shaft (3) to said body (2). Thus, the present invention allows a length of downhole assembly located above said body (2) to be removed from a wellbore by rotation of said length of assembly in a first direction and then allows rotation of said body (2) in the same first direction by means of the auxiliary shaft in an attempt to remove a length of assembly stuck in the wellbore downhole of said body (2).