Method for forming an isolating plug

Abstract

The invention relates to methods for isolating near-wellbore zones and fractures and can be used for plugging fractures in the near-wellbore zone during the removal of the fracturing fluid, as well as for plugging different kinds of fractures and branches in the casing. The method for forming an isolating-plug includes the injection of a slurry containing dispersed fibers into a well and subsequent formation of a plug to isolate the relevant section of the well and to prevent the fluid penetration. The slurry is admixed with amphiphilic substances, and the fibers used are capable of adsorbing the amphiphilic substances on their surface.

1 . A method for forming an isolating plug, which includes the injection of a slurry containing dispersed fibers into a well and subsequent formation of a plug to isolate a relevant section of the well and to prevent a fluid penetration, wherein the slurry is admixed with amphiphilic substances, and the fibers used are capable of adsorbing the amphiphilic substances on their surface. 
     
     
         2 . A method for forming an isolating plug according to  claim 1 , wherein the fiber material is selected from the group which includes PET fibers, polylactic acid, polyglycol acid, polyether, cotton, silica glass fiber, polyamide, protein, phenol-formaldehyde, polycarbonate, polyanhydride, epoxy resin. 
     
     
         3 . A method for forming an isolating plug according to  claim 1 , wherein the amphiphilic substances are added to the slurry during the preparation of the slurry. 
     
     
         4 . A method for forming an isolating plug according to  claim 1 , wherein the amphiphilic substances are injected into the well before the slurry injection, or in parallel with the slurry injection, or after the slurry injection. 
     
     
         5 . A method for forming an isolating plug according to  claim 1 , wherein surfactants are used as amphiphilic substances. 
     
     
         6 . A method for forming an isolating plug according to  claim 1 , wherein quaternized ammonium salts are used as amphiphilic substances. 
     
     
         7 . A method for forming an isolating plug according to  claim 1 , wherein benzoic acid is used as amphiphilic substances. 
     
     
         8 . A method for forming an isolating plug according to  claim 1 , wherein diblock copolymers with a polyelectrolyte block are used as amphiphilic substances. 
     
     
         9 . A method for forming an isolating plug according to  claim 1 , wherein the amphiphilic substances are added to the slurry in the capsular form to be subsequently released at the plug formation place under the influence of the environmental conditions, such as temperature, or pressure, or flow, or chemical dissolution. 
     
     
         10 . A method for forming an isolating plug according to  claim 1 , wherein the amphiphilic substances used are destroyed under the influence of the environmental conditions, such as the temperature, the flow, or due to chemical reactions. 
     
     
         11 . A method for forming an isolating plug according to  claim 1 , wherein the amphiphilic substances are added by injecting precursors into the well in parallel with the slurry injection, which precursors will be transformed into amphiphilic substances at the plug formation place under the influence of the environmental conditions, such as the temperature or the flow. 
     
     
         12 . A method for forming an isolating plug according to  claim 1 , wherein esters, antihydrides, heterocyclic acetates, amines, amides and other chemically unstable groups are used as precursors.