Downhole Seal

Abstract

A downhole seal ( 10 ) comprises an inflatable structure ( 14 ) which receives a volume of swellable particles ( 18 ) at a downhole location. The seal ( 10 ) is adapted to permit the swellable particles ( 18 ) to become exposed to an activator to initiate selling of said particles ( 18 ) to inflate the inflatable structure ( 14 ).

1 . A downhole seal comprising an inflatable structure adapted to receive a volume of swellable particles at a downhole location. 
     
     
         2 . The downhole seal according to  claim 1 , wherein the downhole seal is adapted to permit the swellable particles to become exposed to an activator to initiate swelling of said particles. 
     
     
         3 . The downhole seal according to  claim 1 , wherein the inflatable structure is adapted to permit fluid communication of an activator fluid therethrough to expose the swellable particles to said activator fluid. 
     
     
         4 . The downhole seal according to  claim 1 , wherein at least a portion of the inflatable structure is permeable. 
     
     
         5 . The downhole seal according to  claim 1 , wherein the inflatable structure comprises an osmotic membrane adapted to establish fluid communication across said membrane by osmotic action. 
     
     
         6 . The downhole seal according to  claim 1 , wherein the inflatable structure defines at least one fluid port. 
     
     
         7 . The downhole seal according to  claim 1 , further comprising a store of a swelling activator, wherein the inflatable structure is adapted to receive the swelling activator from said store. 
     
     
         8 . The downhole seal according to  claim 7 , wherein the store of swelling activator is provided at surface level and/or in the region of the inflatable structure. 
     
     
         9 . The downhole seal according to  claim 1 , further comprising a store of swellable particles, wherein the inflatable structure is adapted to receive swellable particles from said store. 
     
     
         10 . The downhole seal according to  claim 9 , wherein the store of swellable particles is provided remotely from the inflatable structure and/or located adjacent the inflatable structure. 
     
     
         11 . The downhole seal according to  claim 9 , further comprising a communication passage between the inflatable structure and the store of swellable particles. 
     
     
         12 . The downhole seal according to  claim 9  further comprising a displacing arrangement adapted to displace swellable particles from the store towards the inflatable structure. 
     
     
         13 . The downhole seal according to  claim 1 , further comprising a tubular body, wherein the inflatable structure is mounted on the tubular body. 
     
     
         14 . The downhole seal according to  claim 13 , wherein the tubular body comprises a store of swellable particles, such that swellable particles contained within the tubular body may be delivered to the inflatable structure to inflate said inflatable structure. 
     
     
         15 . The downhole seal according to  claim 14 , further comprising a displacing arrangement mounted within the tubular body and adapted to displace swellable particles from the store towards the inflatable structure. 
     
     
         16 . The downhole seal according to  claim 15 , wherein the displacing arrangement is adapted to be configured to permit circulation of a fluid through the tubular body and past the displacing arrangement. 
     
     
         17 . The downhole seal according to  claim 16 , wherein the displacing arrangement comprises a piston, and the tubular body comprises a region of increased diameter, wherein location of the piston within said region of increased diameter permits by-pass of fluid. 
     
     
         18 . The downhole seal according to  claim 1 , further comprising a slurry of swellable particles adapted to be delivered to the inflatable structure, wherein the slurry is formed by a volume of swellable particles mixed with a fluid. 
     
     
         19 . The downhole seal according to  claim 18 , wherein the fluid is selected to prevent swelling of the swellable particles. 
     
     
         20 . The downhole seal according to  claim 18 , wherein the slurry fluid comprises a high salinity fluid. 
     
     
         21 . The downhole seal according to  claim 18  wherein the inflatable structure is adapted to permit release of the slurry fluid, thus permitting the swellable particles to become exposed to a swell activating medium. 
     
     
         22 . The downhole seal according to  claim 1 , wherein the inflatable structure comprises a swellable material. 
     
     
         23 . A method of establishing a downhole seal, said method comprising the steps of:
 locating an inflatable structure within a wellbore; and   inflating said inflatable structure with swellable particles.   
     
     
         24 . The method according to  claim 23 , further comprising the step of exposing at least a portion of the swellable particles to a swell-activating medium. 
     
     
         25 . The method according to  claim 23 , comprising the step of running the inflatable structure through a wellbore restriction, and then inflating said inflatable structure.