Two-stage filter cake removal composition for drilling fluids and method of use thereof

Abstract

Disclosed is a two-stage filter cake removal composition, and method of use thereof, for use in a wellbore for controlled removal of a filter cake present in a target production zone. The two-stage filter cake removal composition may include an enzyme present in an amount of between about 1% and 20%, and a mixture of hydrochloric acid and an organic acid present in amounts of between about 0.1% and 5% and about 0.1% and 10%, respectively, by weight. The two-stage filter cake removal composition, when the enzyme is applied to the filter cake in the target production zone in a first stage and the mixture of the hydrochloric acid and the organic acid is applied to the filter cake in the target production zone in a second stage, is operable to remove the filter cake in the target production zone over an extended reaction time.

What is claimed is: 
     
         1 . A two-stage filter cake removal composition for use in a wellbore for controlled removal of a filter cake present in a target production zone, the two-stage filter cake removal composition comprising:
 an enzyme; and   a mixture of hydrochloric acid and an organic acid,   wherein the two-stage filter cake removal composition, when the enzyme is applied to the filter cake in the target production zone in a first stage and the mixture of the hydrochloric acid and the organic acid is applied to the filter cake in the target production zone in a second stage, is operable to remove the filter cake in the target production zone over an extended reaction time.   
     
     
         2 . The two-stage filter cake removal composition of  claim 1 , wherein the enzyme is selected from the group consisting of an α-amylase enzyme, a β-amylase enzyme, and a γ-amylase enzyme, the enzyme being present in an amount of between about 1 to about 20% by weight. 
     
     
         3 . The two-stage filter cake removal composition of  claim 2 , wherein the enzyme comprises the α-amylase enzyme present in an amount of about 10% by weight. 
     
     
         4 . The two-stage filter cake removal composition of  claim 1 , wherein the hydrochloric acid is present in an amount of between about 0.1% and 5% by weight. 
     
     
         5 . The two-stage filter cake removal composition of  claim 1 , wherein the organic acid comprises a carboxylic acid present in an amount of between about 0.1% and 10% by weight. 
     
     
         6 . The two-stage filter cake removal composition of  claim 1 , wherein the organic acid is selected from the group consisting of formic acid, lactic acid, and malonic acid. 
     
     
         7 . The two-stage filter cake removal composition of  claim 1 , wherein the organic acid comprises one of formic acid and lactic acid present in an amount of about 4% by weight. 
     
     
         8 . The two-stage filter cake removal composition of  claim 1 , wherein the filter cake removal composition comprises the mixture of the hydrochloric acid present in an amount of between about 1% and 2% by weight and the organic acid present in an amount of about 4% by weight. 
     
     
         9 . The two-stage filter cake removal composition of  claim 1 , wherein the enzyme is applied to the filter cake in the target production zone in the first stage for a predetermined period of time based on one of a characteristic of the filter cake, an enzyme type, a concentration of the enzyme, and a thermal stability of the enzyme. 
     
     
         10 . The two-stage filter cake removal composition of  claim 1 , wherein the enzyme is applied to the filter cake in the target production zone in the first stage for about 1 to 4 days, and the mixture of the hydrochloric acid and the organic acid is applied to the filter cake in the target production zone in the second stage for about 18 hours at about 250° F. 
     
     
         11 . A method for the controlled removal of a filter cake from a target production zone of a wellbore using a two-stage filter cake removal composition, the method comprising:
 delivering the two-stage filter cake removal composition to the target production zone,   wherein the two-stage filter cake removal composition contacts the filter cake for an extended reaction time during which extended time the two-stage filter cake removal composition acts to remove the filter cake and after which extended time the two-stage filter cake removal composition acts to control fluid loss from the wellbore into the target production zone, and   wherein the delivering comprises applying an enzyme of the two-stage filter cake removal composition to the filter cake in the target production zone in a first stage and applying a mixture of hydrochloric acid and an organic acid of the two-stage filter cake removal composition to the filter cake in the target production zone in a second stage.   
     
     
         12 . The method of  claim 11 , wherein the enzyme is selected from the group consisting of an α-amylase enzyme, a β-amylase enzyme, and a γ-amylase enzyme, the enzyme being present in an amount of between about 1 to about 20% by weight. 
     
     
         13 . The method of  claim 12 , wherein the delivering further comprises applying the α-amylase enzyme present in the amount of about 10% by weight to the filter cake in the target production zone for about 1-4 days. 
     
     
         14 . The method of  claim 11 , wherein the delivering further comprises applying the enzyme present in an amount of between about 1% and 20% by weight to the filter cake in the target production zone for a predetermined period of time based on one of a characteristic of the filter cake, an enzyme type, a concentration of the enzyme, and a thermal stability of the enzyme. 
     
     
         15 . The method of  claim 11 , wherein the delivering further comprises applying the mixture of the hydrochloric acid present in an amount of between about 0.1% and 5% by weight and the organic acid present in an amount of between about 0.1% and 10% by weight. 
     
     
         16 . The method of  claim 15 , wherein the organic acid comprises one of formic acid and lactic acid present in an amount of about 4% by weight. 
     
     
         17 . The method of  claim 11 , wherein the delivering further comprises applying the mixture of the hydrochloric acid present in the amount of about 1% to 2% by weight and the organic acid present in the amount of about 4% by weight. 
     
     
         18 . The method of  claim 11 , wherein the applying the enzyme comprises applying the enzyme of the two-stage filter cake removal composition to the filter cake in the target production zone for a first predetermined period of time based on one of a characteristic of the filter cake, an enzyme type, a concentration of the enzyme, and a thermal stability of the enzyme, wherein the enzyme concentration of the two-stage filter cake removal composition is between about 1% and 20% by weight, and
 wherein the applying the mixture comprises soaking, after applying the enzyme, the filter cake in the target production zone with the mixture of the hydrochloric acid and the organic acid for a second predetermined period of time, wherein the concentrations of the hydrochloric acid and the organic acid are between about 0.1% and 5% and about 0.1% and 10%, respectively, by weight.   
     
     
         19 . The method of  claim 18 , wherein the concentration of the enzyme is about 10%, the concentration of the hydrochloric acid is about 2%, and the concentration of the organic acid is 4% by weight, for the filter cake removal composition. 
     
     
         20 . The method of  claim 18 , wherein the first predetermined period of time is about 1-4 days and the second predetermined period of time is about 16-24 hours.