Shoe for a tubular element in a wellbore

Abstract

A well casing or liner shoe ( 10 ) comprises a partially of fully openable central fluid channel ( 13 ) which is connected to at least one small width nozzle ( 46 ) and an additional large width fluid outlet ( 49 ), which is closed by a thin walled closure device arranged to open at a selected fluid overpressure in the fluid channel ( 13 ), and which has a flow area larger than each nozzle ( 46 ) to permit fluid circulation when the nozzles ( 46 ) are clogged and clearance of clogging debris through the additional large width additional fluid outlet ( 49 ).

1 . A shoe for a tubular element in a borehole extending into an earth formation, the shoe comprising:
 a body adapted to be connected to a downhole end of the tubular element, the body being provided with:   
       a fluid channel; 
       at least one nozzle for jetting fluid into the borehole, each nozzle being in fluid communication with the fluid channel and 
       an additional fluid outlet for pumping fluid from the fluid channel into the borehole, the fluid outlet being closed by a closure device arranged to open at a selected fluid overpressure in the fluid channel relative to a fluid pressure in the borehole; 
       characterized in that the additional fluid outlet has a flow area larger than each nozzle. 
     
     
         2 . The shoe of  claim 1 , wherein the closure device includes a section of reduced wall thickness of the body, which section is arranged to shear off from the body upon the fluid pressure in the fluid channel reaching the selected overpressure. 
     
     
         3 . The shoe of  claim 2 , wherein the section of reduced wall thickness comprises a burst plate. 
     
     
         4 . The shoe of  claim 1 , wherein the fluid outlet has a flow area between about 2 to 3 square inch (12 to 20 cm 2 ). 
     
     
         5 . The shoe of  claim 1 , wherein the total flow area of said at least one nozzle is less than 1 square inch (6.5 cm 2 ). 
     
     
         6 . The shoe of  claim 1 , wherein the fluid channel is provided with a seat for receiving a plug for closing the fluid channel. 
     
     
         7 . The shoe of  claim 6 , wherein the fluid channel is provided with locking means for locking the plug in the fluid channel. 
     
     
         8 . The shoe of  claim 7 , wherein the locking means comprises a recess formed in a selected one of the fluid channel and the plug, and wherein the other of the fluid channel and the plug is provided with a locking member arranged to snap into the recess upon the plug landing on the seat. 
     
     
         9 . The shoe of  claim 8 , wherein the recess comprises an annular groove formed in the fluid channel, and wherein the locking member comprises a lock ring provided to the plug. 
     
     
         10 . The shoe of  claim 6 , wherein the body is provided with a chamber arranged to receive debris from the fluid channel, and wherein the plug is adapted to move the debris from the fluid channel into the chamber. 
     
     
         11 . The shoe of  claim 1 , wherein the body includes a flange provided with at least one radially extending rib, each rib being arranged to prevent rotation of the flange during drilling-out of the shoe in the borehole. 
     
     
         12 . The shoe of  claim 1 , wherein the body includes a reamer for reaming the borehole during lowering of the tubular element into the borehole. 
     
     
         13 . The shoe of  claim 12 , wherein each nozzle is positioned at the reamer. 
     
     
         14 . The shoe of  claim 12 , wherein the reamer has a nose section arranged eccentrically relative to a central longitudinal axis of the tubular element when the shoe is connected to the tubular element. 
     
     
         15 . The shoe of  claim 12 , wherein the reamer is provided with at least one cutter blade for cutting rock particles during reaming of the borehole, each cutter blade being arranged to prevent rotation of the reamer during drilling-out of the shoe in the borehole. 
     
     
         16 . The shoe of  claim 1 , wherein the closure device comprises a section of reduced wall thickness of the body. 
     
     
         17 . The shoe of  claim 16 , wherein the section is arranged to shear off from the body upon fluid pressure in the fluid channel reducing the selected fluid overpressure. 
     
     
         18 . The shoe of  claim 16 , wherein the section comprises a burst plate. 
     
     
         19 . The shoe of  claim 16 , wherein the section of reduced wall thickness is integral part of the body.