Slip gripping mechanism

A slip gripping mechanism for supporting a cylindrical conduit of the type having a central longitudinal axis within the interior bore of a circumscribing conduit in a well bore, comprising:

• an outer body provided as a part of the cylindrical conduit, the outer body having a plurality of circumferentially spaced, longitudinally disposed slots;
• a plurality of circumferentially spaced, axially shiftable slips carried on the outer body of the cylindrical conduit in the longitudinally disposed slots, each slip having a longitudinal axis and opposing side edges which engage mating profiles formed in the longitudinally disposed slots, whereby the slots form guideways for the slips for shifting the slips axially and radially outward relative to the outer body between a set position engaging the circumscribing conduit and an unset position;
• setting means for effecting opposite relative motion between the outer body and the slips;
• and
• wherein each of the axially shiftable slips has a lower surface and an upper gripping surface with a plurality of rows of wicker teeth which run generally transverse to the longitudinal axis of the slip, and wherein at least selected ones of the axially shiftable slips has an upper, gripping surface which is formed on a longitudinal radius drawn from a center point located in a plane parallel to the central longitudinal axis of the cylindrical conduit;
• and
• wherein each of the axially shiftable slips has a slip body with a cross-sectional thickness defined between a generally planar lower surface and the upper gripping surface thereof, the upper gripping surface of each slip being defined between a leading edge and a trailing edge thereof, and wherein the cross-sectional thickness of the slip body increases to a maximum thickness at a point located intermediate the leading and trailing edges of the upper gripping surface.

A slip gripping mechanism for supporting a cylindrical conduit of the type having a central longitudinal axis within the interior bore of a circumscribing conduit in a well bore, comprising:

• an outer body made up as a part of the cylindrical conduit which extends from the surface to a subterranean location within the well bore, the outer body having a plurality of circumferentially spaced, longitudinally disposed slots;
• a plurality of circumferentially spaced, axially shiftable slips carried on the outer body of the cylindrical conduit in the longitudinally disposed slots, each slip having a longitudinal axis and opposing side edges which engage mating profiles formed in the longitudinally disposed slots, whereby the slots form guideways for the slips for shifting the slips axially and radially outward relative to the outer body between a set position engaging the circumscribing conduit and an unset position;
• setting means for effecting opposite relative motion between the outer body and the slips;
• and
• wherein each of the axially shiftable slips has a lower surface and an upper gripping surface defined between a leading edge and a trailing edge thereof, each upper gripping surface having a plurality of rows of wicker teeth which run generally transverse to the longitudinal axis of the slip, each of the slip upper, gripping surfaces being formed on a longitudinal radius drawn from a center point located in a plane parallel to the central longitudinal axis of the cylindrical conduit, whereby each slip has a slip body of variable cross-sectional thickness, the cross-sectional thickness of each slip body increasing to a maximum thickness at a point located on a row of wicker teeth intermediate the leading and trailing edges of the upper gripping surface, whereby the wicker teeth of the intermediate row are first to contact the interior bore of the circumscribing conduit when the slips are shifted axially and radially outward with respect to the outer body.