Borehole plug with spiral cut slip and integrated sealing element

Abstract

A tapered mandrel is advanced into a spirally cut sleeve having a corresponding taper to the mandrel. The outer surface of the sleeve conforms to the surrounding borehole and features an exterior recess in which a sealing element is mounted. The sleeve diameter expands as the tapered mandrel is axially advanced. Axial cuts in the spiral sleeve further reduce the force needed for setting. A leading nose is provided for the uphole end of the sealing element to allow high treatment flow rate while the sealing element is protected from the erosive effects of high velocities.

We claim: 
     
         1 . A plug assembly for borehole use, comprising:
 a mandrel;   a slip sleeve assembly having opposed uphole and downhole ends and externally supporting a sealing element assembly axially spaced from said uphole end such that said sealing assembly and said slip sleeve assembly move in tandem relative to an external taper on said mandrel from a run in position to wedge said sealing assembly to the borehole in a set position.   
     
     
         2 . The plug assembly of  claim 1 ; wherein:
 said uphole end further comprises an external taper.   
     
     
         3 . The plug assembly of  claim 2 , wherein:
 said sealing element assembly comprising a tapered uphole end substantially aligned with said external taper of said uphole end of said slip sleeve assembly.   
     
     
         4 . The plug assembly of  claim 3 , wherein:
 said tapered uphole end of said sealing element is coincident with said external taper of said slip sleeve assembly.   
     
     
         5 . The plug assembly of  claim 1 ; wherein:
 said slip sleeve assembly further comprises at least one spiral cut extending substantially over the axial distance between said uphole and downhole ends of said slip sleeve assembly.   
     
     
         6 . The plug assembly of  claim 1 , wherein:
 said slip sleeve assembly comprises an outer cylindrical surface with a plurality of wickers and an external groove, said sealing element assembly extending radially outside of said groove and beyond said wickers in said run in position.   
     
     
         7 . The plug assembly of  claim 6 , wherein:
 said sealing element assembly is bonded, molded or 3D printed to said external groove.   
     
     
         8 . The plug assembly of  claim 5 , wherein:
 said slip sleeve assembly retaining an external cylindrical shape without gaps while engaging a borehole wall in said set position to act as an extrusion barrier for said sealing element assembly.   
     
     
         9 . The plug assembly of  claim 1 , wherein:
 said mandrel comprising a seat surrounding an axial passage therethrough, said seat accepting an object to close said passage to allow pressure on the object to be communicated to a formation about the borehole.   
     
     
         10 . The plug assembly of  claim 9 , wherein:
 said object and said mandrel selectively removable without intervention.   
     
     
         11 . The plug assembly of  claim 2 , wherein:
 said external taper shielding said sealing element assembly from erosion and swabbing effects from fluid under high flow rates flowing around the plug when pushing the assembly in horizontal section of the wellbore   
     
     
         12 . A plug assembly for borehole use, comprising:
 a mandrel;   a slip sleeve assembly having opposed uphole and downhole ends and supporting a sealing element assembly such that said sealing assembly and said slip sleeve assembly move in tandem relative to an external taper on said mandrel from a run in position to a set position where said sealing assembly is wedged against the borehole;   said slip sleeve assembly further comprising a spiral cut.   
     
     
         13 . The plug assembly of  claim 12 , wherein:
 said spiral cut extending over a substantial length of said slip sleeve assembly between said uphole and said downhole ends.   
     
     
         14 . The plug assembly of  claim 12 , wherein:
 said slip sleeve assembly retaining an external cylindrical shape without gaps while engaging a borehole wall in said set position to act as an extrusion barrier for said sealing element assembly.   
     
     
         15 . The plug assembly of  claim 12 , wherein:
 said sealing element assembly mounted externally on said slip sleeve assembly and below said uphole end.   
     
     
         16 . The plug assembly of  claim 15 , wherein:
 said sealing element assembly mounted in a groove on said slip sleeve assembly.   
     
     
         17 . The plug assembly of  claim 16 , wherein:
 said uphole end further comprises an external taper;   said sealing element assembly comprising a tapered uphole end substantially aligned with said external taper of said uphole end of said slip sleeve assembly.   
     
     
         18 . The plug assembly of  claim 17 , wherein:
 said external taper shielding said sealing element assembly from erosion and swabbing effects from fluid under high flow rates delivered around the frac plug assembly while pushing it in the horizontal section of the wellbore.   
     
     
         19 . The plug assembly of  claim 12 , wherein:
 said mandrel comprising a seat surrounding an axial passage therethrough, said seat accepting an object to close said passage to allow pressure on the object to be communicated to a formation about the borehole said object, said mandrel and at least in part said slip sleeve assembly selectively removable without intervention.   
     
     
         20 . The plug assembly of  claim 5 , wherein:
 said slip sleeve assembly further comprises at least one internal or external axially oriented score.   
     
     
         21 . The plug assembly of  claim 12 , wherein:
 said slip sleeve assembly further comprises at least one internal or external axially oriented score.   
     
     
         22 . The plug assembly of  claim 1 , further comprising:
 an internal seal disposed between said slip sleeve and said mandrel.   
     
     
         23 . The plug assembly of  claim 12 , further comprising:
 an internal seal disposed between said slip sleeve and said mandrel.   
     
     
         24 . A borehole treatment method, comprising:
 applying pressure against the plug assembly of  claim 1  when the plug assembly is in said set position to direct a material to a formation about the borehole for the treatment.   
     
     
         25 . The method of  claim 24 , comprising:
 fracturing the formation as said treatment.   
     
     
         26 . A borehole treatment method, comprising:
 applying pressure against the plug assembly of  claim 12  when the plug assembly is in said set position to direct a material to a formation about the borehole for the treatment.   
     
     
         27 . The method of  claim 26 , comprising:
 fracturing the formation as said treatment.