Mandrel Arrangement and Method of Operating Same

Abstract

A mandrel arrangement is for use in a wellbore tubing. A method is for using the same. A mandrel body houses at least one piston, the at least one piston being movable in relation to the mandrel body between a first position and a second position by a fluid force acting on the piston. A cavity is arranged adjacent the piston for communicating wellbore fluid pressure between the wellbore tubing and the piston. The cavity is provided with drainage means for facilitating removal of any particles present in at least a lower portion of the cavity.

1 . A mandrel arrangement for use in a wellbore tubing, the arrangement comprising:
 a mandrel body housing at least one piston, the at least one piston being movable in relation to the mandrel body between a first position and a second position by a fluid force acting on the piston; and   a cavity arranged adjacent the piston for communicating wellbore fluid pressure between the wellbore tubing, and the piston, wherein the cavity is provided with drainage means comprising an opening arranged for communicating fluid between the cavity and the wellbore tubing, thereby facilitating removal of any particles present in at least a lower portion of the cavity.   
     
     
         2 . The mandrel arrangement according to  claim 1 , wherein the opening is inclined downwards in a direction from the cavity towards a wellbore centerline. 
     
     
         3 . The mandrel, arrangement according to  claim 1 , wherein the cavity is a recess open to the wellbore fluid, the recess being defined by a tint portion, a second portion, and as side portion bridging said first portion and second portion, the second portion including the surface of the piston or a fluid pressure transition element extending from the cavity to the piston. 
     
     
         4 . The mandrel arrangement according to  claim 3 , wherein the first portion of the recess is inclined away from the second portion in a direction from the side portion of the recess towards the wellbore centerline. 
     
     
         5 . The mandrel arrangement according to  claim 3 , wherein the second portion of the recess is provided with a surface inclined away from the first portion in a direction towards the wellbore centerline. 
     
     
         6 . The mandrel arrangement according to  claim 1 , wherein the mandrel body comprises an outer mandrel portion and an inner mandrel portion, the inner mandrel portion facing the fluid in the wellbore, and wherein the piston is arranged between the outer mandrel portion and the inner mandrel portion. 
     
     
         7 . The mandrel arrangement according to  claim 1 , wherein the piston is provided with sealing means arranged for sealing off an annulus between the piston and the mandrel body. 
     
     
         8 . The mandrel arrangement according to  claim 1 , wherein the piston is provided with a scraper ring arranged for sealing off an annulus between the piston and the mandrel body in order to prevent impurities from entering between the piston or the fluid pressure transition element(s) and the fixed mandrel body. 
     
     
         9 . The mandrel arrangement according to  claim 3 , wherein the at least one thud pressure transition element is provided with a scraper cap facing the fluid in the cavity. 
     
     
         10 . A method for facilitating operation of a mandrel arrangement for use in a. wellbore tubing, wherein the arrangement comprises: a mandrel body housing at least one piston, the at least one piston being movable in relation to the mandrel body between a first position and a second position by a fluid force acting on the piston; and a cavity arranged adjacent the piston for communicating wellbore fluid, pressure between the wellbore tubing and the piston, the method comprising providing the cavity with drainage means flowing removal of any particles present in at least a lower portion of the cavity. 
     
     
         11 . The method according to  claim 10 , further comprising moving the piston by means of at least one fluid pressure transition element extending between the cavity and the piston. 
     
     
         12 . The method according to  claim 11 , further comprising adjusting the three from the fluid acting on the piston by adding or removing the number of fluid pressure transition elements extending between the cavity and the piston.