Method for cleaning gravel packs

Abstract

A method for cleaning a plugged gravel pack in a subterranean wellbore is provided. The method comprises the steps of using a pressure pulsating jet and a tangential vortex to deliver a pressure pulsating treatment fluid into the gravel pack wherein soluble plugging materials in the gravel pack are dissolved by the treatment fluid and insoluble plugging materials are moved through the gravel pack and circulated out of the wellbore. The treatment fluid is driven more completely into the gravel pack to obtain a greater coverage in the pack to dissolve soluble fines and displace insoluble fines from the interstitial pore spaces of the gravel pack.

1 . A method of cleaning a plugged or partially plugged gravel pack in a wellbore comprising the steps of: 
 using a tangential vortex to deliver a treatment fluid into the gravel pack;    dissolving soluble fines in the gravel pack with the treatment fluid;    moving insoluble fines through the interstitial pore space of the gravel pack; and    circulating the insoluble fines out of the wellbore.    
   
   
       2 . The method of  claim 1 , wherein the tangential vortex is created by delivering a pressure pulsating jet of the treatment fluid onto a gravel pack screen with one or more jetting nozzles.  
   
   
       3 . The method of  claim 2 , wherein the tangential vortex is created in the region below the one or more nozzles, thereby directing treatment fluid behind the screen and into the gravel pack.  
   
   
       4 . The method of  claim 2 , further comprising orienting the one or more jetting nozzles to provide an axial downward component to the jet direction.  
   
   
       5 . The method of  claim 1 , wherein the treatment fluid is an acid.  
   
   
       6 . The method of  claim 5 , wherein the acid is selected from hydrochloric or hydrofluoric acids.  
   
   
       7 . The method of  claim 1  further comprising cleaning the gravel pack with about 40 liters to about 400 liters of acid per meter of gravel pack.  
   
   
       8 . The method of  claim 2  wherein the pressure pulsating jet is delivered at an impact pressure of about 50 to about 500 psi.  
   
   
       9 . The method of  claim 2 , wherein the pressure pulsating jet is delivered at an impact pressure of about 5 psi to about 850 psi.  
   
   
       10 . The method of  claim 2 , wherein the one or more jetting nozzles are lowered through the gravel pack at a rate ranging from about 0.2 meters per minute to about 10 meters per minute.  
   
   
       11 . A method of washing a gravel pack in a wellbore comprising the steps of: 
 delivering a treatment fluid into the gravel pack with a pressure pulsating jet and a tangential vortex; and    dissolving soluble plugging materials in the gravel pack with the treatment fluid.    
   
   
       12 . The method of  claim 11 , wherein the tangential vortex is created by delivering the pressure pulsating jet of the treatment fluid onto a gravel pack screen with one or more jetting nozzles.  
   
   
       13 . The method of  claim 12 , wherein the tangential vortex is created in the region below the one or more nozzles, thereby directing treatment fluid behind the screen and into the gravel pack.  
   
   
       14 . The method of  claim 12 , further comprising orienting the one or more jetting nozzles to provide an axial downward component to the jet direction.  
   
   
       15 . The method of  claim 11 , wherein the treatment fluid is an acid.  
   
   
       16 . The method of  claim 15 , wherein the acid is selected from hydrochloric or hydrofluoric acids.  
   
   
       17 . The method of  claim 11  further comprising cleaning the gravel pack with about 40 liters to about 400 liters of acid per meter of gravel pack.  
   
   
       18 . The method of  claim 12  wherein the pressure pulsating jet is delivered at an impact pressure of about 50 to about 500 psi.  
   
   
       19 . The method of  claim 12 , wherein the pressure pulsating jet is delivered at an impact pressure of about 5 psi to about 850 psi.  
   
   
       20 . The method of  claim 12 , wherein the one or more jetting nozzles are lowered through the gravel pack at a rate ranging from about 0.2 meters per minute to about 10 meters per minute.  
   
   
       21 . The method of  claim 11 , further comprising moving insoluble fines through the interstitial pore space of the gravel pack and circulating the insoluble fines out of the wellbore.  
   
   
       22 . A method of washing a gravel pack in a wellbore comprising the steps of: 
 delivering a pressure pulsating treatment fluid into the gravel pack with a pressure pulsating jet and a tangential vortex;    moving insoluble plugging materials through the gravel pack with the fluid; and    circulating the insoluble plugging materials out of the wellbore.    
   
   
       23 . The method of  claim 22 , wherein the soluble plugging materials are dissolved in the gravel pack with the treatment fluid.  
   
   
       24 . The method of  claim 22 , wherein the tangential vortex is created by delivering the pressure pulsating jet of the treatment fluid onto a gravel pack screen with one or more jetting nozzles.  
   
   
       25 . The method of  claim 24 , wherein the tangential vortex is created in the region below the one or more jetting nozzles, thereby directing treatment fluid behind the screen and into the gravel pack.  
   
   
       26 . The method of  claim 24 , further comprising orienting the one or more jetting nozzles to provide an axial downward component to the jet direction.