Slip assembly

Abstract

A gripping system is taught for gripping oil well casing, casing string or other string comprising one or more slips cammed against one or more inclined recesses when the gripping system is rotated to maintain gripping engagement of the casing. A further gripping system is taught for gripping oil well casing, casing string or other string comprising one or more slips received into one or more inclined recesses. A method is taught for gripping casing sections or casing strings. The method comprises the steps of providing a gripping system comprising one or more recesses and one or more slips, setting said one or more slips on the casing section and rotating the gripping system to cam said one or more slips against said one or more inclined recesses, wherein camming said one or more slips against said one or more inclined recesses serves to maintain gripping engagement on the casing. A further method is taught for gripping casing sections or casing strings. The method comprises the steps of receiving a slip into each of one or more inclined recesses of a gripping system, setting said one or more slips on the casing section and rotating the gripping system.

1 . A gripping system for gripping oil well casing, casing string or other string comprising one or more slips cammed against one or more inclined recesses when the gripping system is rotated to enhance gripping engagement of the casing. 
     
     
         2 . The gripping system of  claim 1 , wherein the one or more inclined recesses capture at least a portion of the one or more slips. 
     
     
         3 . The gripping system of  claim 2 , wherein at least an axial portion of said one or more inclined recesses surrounds greater than 180 degrees of the one or more slips. 
     
     
         4 . The gripping system of  claim 3 , wherein the one or more slips have a smaller cross section than said one or more inclined recesses. 
     
     
         5 . The gripping system of  claim 4 , wherein rotation of the gripping system serves to rotate a front face of the one or more slips and to cam a rear face of the one or more slips against the one or more inclined recesses. 
     
     
         6 . The gripping system of  claim 2 , wherein one or more recesses have a cross sectional geometry selected from the group consisting of partial circles, partial rectangles, partial squares, partial ovals, partial rhomboids and partial triangles. 
     
     
         7 . The gripping system of  claim 6 , wherein at least a portion of the one or more inclined recesses have a part cylindrical geometry and at least a portion of the one or more slips have a corresponding cylindrical geometry. 
     
     
         8 . The gripping system of  claim 1 , wherein the one or more inclined recesses are housed in a seat. 
     
     
         9 . The gripping system of  claim 8 , wherein the seat has geometry selected from conical and cylindrical. 
     
     
         10 . The gripping systems of  claim 9 , wherein the one or more inclined recesses are uniformly spaced around the seat. 
     
     
         11 . A gripping system for gripping oil well casing, casing string or other string comprising one or more slips received into one or more inclined recesses. 
     
     
         12 . The gripping system of  claim 11 , wherein at least a portion of the one or more slips are captured by the one or more inclined recesses. 
     
     
         13 . The gripping system of  claim 12 , wherein the one or more recesses comprise a cross sectional geometry for at least a portion of the axial length thereof that surrounds greater than 180 degrees of the one or more slips. 
     
     
         14 . The gripping system of  claim 11 , wherein the one or more slips have a smaller cross section than said one or more inclined recesses. 
     
     
         15 . The gripping system of  claim 14 , wherein rotation of the gripping system serves to rotate a front face of the one or more slips and to force a rear face of the one or more slips against the one or more inclined recesses. 
     
     
         16 . The gripping system of  claim 11 , wherein one or more recesses have a cross sectional geometry selected from the group consisting of partial circles, partial rectangles, partial squares, partial ovals, partial rhomboids and partial triangles. 
     
     
         17 . The gripping system of  claim 16 , wherein at least a portion of the one or more inclined recesses have a part cylindrical geometry and at least a portion of the one or more slips have a corresponding cylindrical geometry. 
     
     
         18 . The gripping system of  claim 17 , wherein at least a portion of the axial length of the inclined recess has a cross sectional geometry that is more than a semi-circle. 
     
     
         19 . The gripping system of  claim 11 , wherein the one or more inclined recesses are housed in a seat. 
     
     
         20 . The gripping system of  claim 19 , wherein the seat has geometry selected from conical and cylindrical. 
     
     
         21 . The gripping systems of  claim 20 , wherein the one or more inclined recesses are uniformly spaced around the seat. 
     
     
         22 . A method of gripping casing sections or casing strings, said method comprising the steps of:
 a) providing a gripping system comprising one or more recesses and one or more slips;   b) setting said one or more slips on the casing section; and   c) rotating the gripping system to cam said one or more slips against said one or more inclined recesses,   wherein camming said one or more slips against said one or more inclined recesses serves to enhance gripping engagement on the casing.   
     
     
         23 . The method of  claim 22 , wherein the one or more slips are at least partially captured by the one or more inclined recesses. 
     
     
         24 . The method of  claim 23 , wherein the one or more recesses comprise a cross sectional geometry on at least a portion of the axial length thereof that surrounds greater than 180 degrees of the one or more slips. 
     
     
         25 . The method of  claim 24 , wherein the one or more slips are cylindrical and wherein at least a portion of the axial length of the one or more inclined recesses has a cross sectional geometry that is more than a semi-circle. 
     
     
         26 . The method of  claim 25 , wherein the one or more slips have a smaller cross section than said one or more inclined recesses. 
     
     
         27 . The method of  claim 26 , wherein rotation of the gripping system serves to rotate the one or more slips and to cam a rear face of the one or more slips against the one or more inclined recesses. 
     
     
         28 . A method of gripping casing sections or casing strings, said method comprising the steps of:
 a) receiving a slip into each of one or more inclined recesses of a gripping system;   b) setting said one or more slips on the casing section; and   c) rotating the gripping system.   
     
     
         29 . The method of  claim 28 , wherein the one or more slips are at least partially captured by the one or more inclined recesses. 
     
     
         30 . The method of  claim 29 , wherein the one or more recesses comprise a cross sectional geometry on at least a portion of the axial length thereof that surrounds greater than 180 degrees of an axial surface of the one or more slips. 
     
     
         31 . The method of  claim 30 , wherein the one or more slips are cylindrical and wherein at least a portion of the axial length of the one or more inclined recesses has a cross sectional geometry that is more than a semi-circle. 
     
     
         32 . The method of  claim 31 , wherein the one or more slips have a smaller cross section than said one or more inclined recesses. 
     
     
         33 . The method of  claim 32 , wherein rotation of the gripping system serves to rotate the one or more slips and to cam a rear face of the one or more slips against the one or more inclined recesses.