Retrievable packer for operations in cased wells at high pressures

Abstract

Retrievable packer for operations in wells cased by means of a casing pipe, the packer being applied in operations involving very high pressures, of up to about 15,000 psi, wherein the packer comprises a connecting head for being fixed to a service pipe, an upper mandrel threaded at a lower mandrel, a balancing liner holder concentrically arranged on the upper mandrel so as to form a space of hydraulic pressure between both, within which space one balancing liner is accommodated, designed to apply a downward force on an annular ledge of the upper mandrel, to offset upwards thrust forces that operate on the tool and the service pipe.

1 . Retrievable packer for operations in wells cased by means of a casing pipe, where the packer is one of the type employed to temporarily or permanently seal the annular space between the casing pipe of the well and a service pipe which is inserted into the casing for operations of treatment of one or more sections of the cased well, the packer comprising:
 a head for connection to the service pipe,   an upper mandrel,   a lower mandrel threaded to the upper mandrel,   pistons and clamps for fixing the packer against the casing pipe, arranged to resist the upward and downward forces, respectively,   a set of rubber gaskets to seal said annular space,   a balancing sleeve holder concentrically arranged one such upper mandrel whereby a hydraulic pressure space is defined between the balancing sleeve holder and the upper mandrel,   at least, one balancing sleeve arranged in said hydraulic pressure space,   an annular ledge of the upper mandrel, aligned with and arranged below said at least one balancing sleeve, and wherein said pistons and clamps respectively comprise a piston holder body, and a set of clamps.   
     
     
         2 . Retrievable packer according to  claim 1 , wherein said at least one balancing sleeve comprises an upper balancing sleeve and a lower balancing sleeve. 
     
     
         3 . Retrievable packer according to  claim 2 , wherein said upper balancing sleeve has an upper end including seals, wherein the seals of the upper end of the upper balancing sleeve seal against said sleeve holder, and a lower end abutting against an upper end of said lower balancing sleeve. 
     
     
         4 . Retrievable packer according to  claim 3 , wherein said lower balancing sleeve is slidably mounted between said upper mandrel and a connecting sleeve fixed to said sleeve holder, with the upper end of said lower balancing sleeve having seals sealing against said connecting sleeve, with the connecting sleeve also having seals sealing against a middle portion of said upper balancing sleeve. 
     
     
         5 . Retrievable packer according to  claim 4 , wherein said sleeve holder has at least one balancing hole below said seals of the upper end of the upper balancing sleeve. 
     
     
         6 . Retrievable packer according to  claim 5 , wherein said connecting sleeve has at least one balancing hole below said seals of the upper end of the lower balancing sleeve. 
     
     
         7 . Retrievable packer according to  claim 6 , wherein said sleeve holder has an upper lip, separated from said upper mandrel, for sealing against a seal arranged in said connecting head to seal the space between said lip and the upper mandrel. 
     
     
         8 . Retrievable packer according to  claim 1 , wherein said annular ledge is a star-shape ledge. 
     
     
         9 . Retrievable packer according to  claim 1 , wherein said piston holder body accommodates four sets of securing pistons. 
     
     
         10 . Retrievable packer according to  claim 9 , wherein each securing piston comprises a piston mounted in a radially extensible way within a corresponding housing of the piston holder body, the housing being open towards the interior of the piston holder body and in communication with circulating pressurized fluid inside the piston holder body. 
     
     
         11 . Retrievable packer according to  claim 1 , wherein said set of rubber gaskets comprises four annular rubber gaskets axially arranged one below the other, having two end gaskets and two internal gaskets of different hardness. 
     
     
         12 . Retrievable packer according to  claim 1 , wherein a drag block is arranged concentrically on said lower mandrel, with the drag block being mounted in a radially and elastically compressible way. 
     
     
         13 . Retrievable packer according to  claim 12 , wherein a clamp holder ring is concentrically arranged on a lower section of said upper mandrel, with said set of clamps being mounted in said clamp holder ring, and said clamp holder ring carries attached thereto a screw for limiting each of the clamps, each ring forming a limitation to the movement of each clamp. 
     
     
         14 . Retrievable packer according to  claim 13 , wherein said clamp holder ring holds a J-guide sleeve that has, carved in an inner wall thereof, a J-shaped guide, with a J-guide pin guidably sliding in the J-shaped guide and the pin being part of said lower mandrel.