Filtercake removal using exothermic in-situ nitrogen-producing reactants

Abstract

Removal of filtercake particles from a wellbore is achieved by injecting two (2) water-soluble nitrogen-containing salts and an organic acid resulting in the generation of nitrogen gas and elevated temperature.

What is claimed is: 
     
         1 . A method of removing filtercake particles formed in a wellbore extending into a hydrocarbon reservoir, which comprises:
 a. injecting at least two water-soluble nitrogen-containing salts and an organic acid into a wellbore containing a filtercake sufficient to liberate nitrogen gas and generate heat;   b. dissolving the filtercake by the organic acid, the nitrogen gas formed and the heat generated from the reaction between the acid and the nitrogen salts in the borehole.   
     
     
         2 . The method of  claim 1 , wherein the water-soluble nitrogen-containing salts are NH 4 Cl and NaNO 2  and the organic acid is acetic acid. 
     
     
         3 . The method of  claim 2 , wherein the NaNO 2  and the acetic acid are injected separately from the NH 4 Cl. 
     
     
         4 . The method of  claim 2 , wherein the NaNO 2  and the acetic acid are injected through the wellbore's connective tubing and the NH 4 Cl is injected through the wellbore's production tubing. 
     
     
         5 . The method of  claim 2 , wherein the NH 4 Cl is injected at about two times the rate that the NaNO 2  and acetic acid are injected. 
     
     
         6 . The method of  claim 2 , wherein the heat generated is about 75 kcal/mole.