Method of removing inorganic scales

Abstract

The productivity of hydrocarbons from hydrocarbon-bearing calcareous or siliceous formations is enhanced by contacting the formation with a well treatment composition which contains a hydrofluoric acid source, a phosphonate acid, ester or salt thereof, a quaternary ammonium salt and an organosilane and, optionally, a boron-containing compound.

1 . A method for enhancing the productivity of a hydrocarbon-bearing calcareous or siliceous formation comprising:
 (A) pumping into the wellbore penetrating the formation a well treatment composition comprising:
 a) a phosphonate acid, ester or salt thereof, wherein the phosphonate is of the formula: 
   
       
         
           
           
               
               
           
         
         
           wherein R1, R2 and R3 are independently selected from hydrogen, alkyl, aryl, phosphonic, phosphonate, phosphate, aminophosphonic acid, aminophosphonate, acyl, amine, hydroxy or carboxyl groups or R4 and R5 are independently selected from hydrogen, sodium, potassium, ammonium or an organic radical; 
           (b) a hydrofluoric acid source; 
           (c) a quaternary ammonium salt; and 
           (d) an organosilane; and 
         
         (B) preventing the formation or inhibiting the formation of inorganic fluoride scales in the wellbore and/or formation. 
       
     
     
         2 . The method of  claim 1 , wherein the pH of the well treatment composition is between from about 0 to about 3. 
     
     
         3 . The method of  claim 1 , wherein the amount of quaternary ammonium salt in the aqueous well treating composition is between from about 0.01 to about 10 percent by volume based on the total volume of the well treatment composition. 
     
     
         4 . The method of  claim 1 , wherein the amount of the organosilane in the well treatment composition is between from about 0.01 to about 10 percent by volume based on the total volume of the well treatment composition. 
     
     
         5 . The method of  claim 1 , wherein the inorganic or siliceous scales are selected from the group consisting of calcium fluoride, magnesium fluoride, sodium fluorosilicate, potassium fluorosilicate and fluoroaluminate. 
     
     
         6 . The method of  claim 1 , wherein the amount of phosphonate acid, ester or salt thereof in the aqueous well treating composition is between from about 0.1 to about 10 percent by volume based on the total volume of (a) and (b) and water. 
     
     
         7 . The method of  claim 1 , wherein the aqueous well treating composition further comprises a boron containing compound selected from the group consisting of (i.) fluoroboric acid and/or (ii.) boron compounds capable of forming a BF 4   −  complex when exposed to F 4   −  or a hydrofluoric acid source and further comprising forming a BF 4   −  complex. 
     
     
         8 . The method of  claim 7 , wherein the boron containing compound is of the formula R 6 R 7 R 8 BO 3  wherein each of R 6 , R 7  and R 8  are independently hydrogen or a unsubstituted or substituted alkyl or alkylene group. 
     
     
         9 . The method of  claim 7 , wherein the boron containing compound is of the formula: 
       
         
           
           
               
               
           
         
       
       wherein each of R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15  and R 16  is independently selected from hydrogen or a substituted or unsubstituted alkyl or alkenyl group. 
     
     
         10 . The method of  claim 7 , wherein the amount of boron containing compound in the aqueous well treatment composition is that sufficient to render between from about 0.5 to about 10 g BF 4   −  complex per 100 cc of (a), (b) and water. 
     
     
         11 . The method of  claim 1 , wherein the aqueous well treatment composition is introduced into the wellbore during a fracturing, remedial workover or matrix acidizing operation. 
     
     
         12 . The method of  claim 1 , wherein the quaternary ammonium salt is represented by the formula:
   N(R 6 )(R 7 )(R 8 )(R 9 )Y −     
       wherein each of R 6 , R 7 , R 8  and R 9  are selected from the group consisting of hydrogen, a C 1 -C 6  alkyl group or a hydroxyalkyl group, provided not all of R 6 , R 7 , R 8  and R 9  are hydrogen; and Y −  is a halide, perchlorate, thiocyanate, cyanate, a C 1 -C 6  carboxylate, an alkyl sulfate, methanesulfonate, BX 4   − , PF 6   − , AsF 6   − , SbF 6   − , NO 2   − , NO 3   −  or SO 4   − . 
     
     
         13 . The method of  claim 12 , wherein Y is —Cl. 
     
     
         14 . The method of  claim 12 , wherein the cation of the quaternary ammonium salt is N,N,N-trimethylethanolammonium. 
     
     
         15 . The method of  claim 1 , wherein the quaternary ammonium salt has repeating units selected from the group consisting of: 
       
         
           
           
               
               
           
         
       
       wherein R and R 3  are independently selected from the group consisting of an alkylene group having from about 2 to about 4 carbon atoms; R 1 , R 2 , R 4 , R 5 , R 7 , R 8   3   n  d R 9  are independently selected from the group consisting of methyl or ethyl; R 6  is selected from the group consisting of an unsubstituted alkylene group having from about 2 to 4 carbon atoms and a substituted alkylene group having from about 2 to about 4 carbon atoms and containing a hydroxy group; X is an anion selected from the group consisting of a halogen, methyl sulfate, sulfate, and nitrate; v represents the valency of the anion represented by X; and, s is an integer equal to the number of said anions required to maintain electronic neutrality. 
     
     
         16 . The method of  claim 15 , wherein the quaternary ammonium salt is of the formula: 
       
         
           
           
               
               
           
         
       
     
     
         17 . The method of  claim 1 , wherein the organosilane is at least one of the following:
 (a) a silane-based compound of the formula:   
       
         
           
           
               
               
           
         
       
       wherein X is a halogen, R 1  is an organic radical having from 1 to about 50 carbon atoms, and R 2  and R 3  are the same or different halogens or organic radicals having from 1 to about 50 carbon atoms;
 (b) a silane-based compound of the formula
   R—Si(OR′) 3  
 
 
 
       wherein R is branched or linear aliphatic carbon chain that is saturated or unsaturated, and that has from about 1 to about 10 carbon atoms; and wherein each R′ is independently branched or linear carbon chain that is saturated or unsaturated, and that has from about 1 to about 4 carbon atoms; or
 (c) a siloxane-based compound of the formula:
   R—Si(OR′) 2 —O—Si(OR″) 2 —R
 
 
 
       wherein R is a branched or linear aliphatic carbon chain that is saturated or unsaturated, and that has from about 1 to about 10 carbon atoms; and wherein each R′ and each R″ is independently a branched or linear carbon chain that may be saturated or unsaturated and that has from about 1 to about 4 carbon atoms. 
     
     
         18 . The method of  claim 17 , wherein the organosilane is an aminoalkyl siloxane. 
     
     
         19 . A method of preventing and/or inhibiting the swelling of clay within a subterranean formation penetrated by a wellbore which comprises:
 (A) pumping into the wellbore an aqueous well treatment composition comprising:
 a) a phosphonate acid, ester or salt thereof, wherein the phosphonate is of the formula: 
   
       
         
           
           
               
               
           
         
         
           wherein R1, R2 and R3 are independently selected from hydrogen, alkyl, aryl, phosphonic, phosphonate, phosphate, aminophosphonic acid, aminophosphonate, acyl, amine, hydroxy or carboxyl groups and R4 and R5 are independently selected from hydrogen, sodium, potassium, ammonium or an organic radical; 
           (c) a hydrofluoric acid source; 
           (d) a quaternary ammonium salt; and 
           (e) an organosilane; and 
         
         (B) minimizing or eliminating the amount of clay swelled in the formation. 
       
     
     
         20 . The method of  claim 19 , wherein the pH of the well treatment composition is between from about 0 to about 3, the amount of quaternary ammonium salt in the aqueous well treating composition is between from about 0.01 to about 10 percent by volume based on the total volume of the well treatment composition, and the amount of the organosilane in the well treatment composition is between from about 0.01 to about 10 percent by volume based on the total volume of the well treatment composition. 
     
     
         21 . The method of  claim 19  wherein the aqueous well treating composition further comprises a boron containing compound selected from the group consisting of (i.) fluoroboric acid and/or (ii.) boron compounds capable of forming a BF 4   −  complex when exposed to F 4   −  or a hydrofluoric acid source and further comprising forming a BF 4   −  complex. 
     
     
         22 . The method of  claim 19 , wherein the quaternary ammonium salt is represented by the formula:
   N(R 6 )(R 7 )(R 8 )(R 9 )Y −     
       wherein R 6 , R 7 , R 8  and R 9  are independently a C 1 -C 6  alkyl group or a hydroxyalkyl group wherein the alkyl group is preferably a C 1 -C 6  alkyl; and Y −  is a halide, perchlorate, thiocyanate, cyanate, a C 1 -C 6  carboxylate, an alkyl sulfate, methanesulfonate, BX 4   − , PF 6   − , AsF 6   − , SbF 6   − , NO 2   − , NO 3   −  or SO 4   − . 
     
     
         23 . The method of  claim 22 , wherein Y is —Cl. 
     
     
         24 . The method of  claim 22 , wherein the cation of the quaternary ammonium salt is N,N,N-trimethylethanolammonium. 
     
     
         25 . The method of  claim 19 , wherein the quaternary ammonium salt has repeating units selected from the group consisting of: 
       
         
           
           
               
               
           
         
       
       wherein R and R 3  are independently selected from the group consisting of an alkylene group having from about 2 to about 4 carbon atoms; R 1 , R 2 , R 4 , R 5 , R 7 , R 8 , and R 9  are independently selected from the group consisting of methyl or ethyl; R 6  is selected from the group consisting of an unsubstituted alkylene group having from about 2 to 4 carbon atoms and a substituted alkylene group having from about 2 to about 4 carbon atoms and containing a hydroxy group; X is an anion selected from the group consisting of a halogen, methyl sulfate, sulfate, and nitrate; v represents the valency of the anion represented by X; and, s is an integer equal to the number of said anions required to maintain electronic neutrality. 
     
     
         26 . The method of  claim 25 , wherein the quaternary ammonium salt is of the formula: 
       
         
           
           
               
               
           
         
       
     
     
         27 . The method of  claim 19 , wherein the organosilane is at least one of the following:
 (a) a silane-based compound of the formula:   
       
         
           
           
               
               
           
         
         wherein X is a halogen, R 1  is an organic radical having from 1 to about 50 carbon atoms, and R 2  and R 3  are the same or different halogens or organic radicals having from 1 to about 50 carbon atoms; 
         (b) a silane-based compound of the formula
   R—Si(OR′) 3  
 
 
         wherein R is branched or linear aliphatic carbon chain that is saturated or unsaturated, and that has from about 1 to about 10 carbon atoms; and wherein each R′ is independently branched or linear carbon chain that is saturated or unsaturated, and that has from about 1 to about 4 carbon atoms; or 
         (c) a siloxane-based compound of the formula:
   R—Si(OR′) 2 —O—Si(OR″) 2 —R
 
 
         wherein R is a branched or linear aliphatic carbon chain that is saturated or unsaturated, and that has from about 1 to about 10 carbon atoms; and wherein each R′ and each R″ is independently a branched or linear carbon chain that may be saturated or unsaturated and that has from about 1 to about 4 carbon atoms. 
       
     
     
         28 . The method of  claim 27 , wherein the organosilane is an aminoalkyl siloxane. 
     
     
         29 . A method of removing calcium fluoride, magnesium fluoride, sodium fluorosilicate, potassium fluorosilicate and/or fluoroaluminate scales from hydrocarbon-producing wellbores and minimizing or eliminating the swelling of clay within a subterranean formation penetrated by the wellbore, the method comprising:
 (A) pumping into the wellbore a well treatment composition having a pH between from about 0 to about 3.0 and comprising:
 a) a phosphonate acid, ester or salt thereof, wherein the phosphonate is of the formula: 
   
       
         
           
           
               
               
           
         
         
           wherein R1, R2 and R3 are independently selected from hydrogen, alkyl, aryl, phosphonic, phosphonate, phosphate, aminophosphonic acid, aminophosphonate, acyl, amine, hydroxy or carboxyl groups and R4 and R5 are independently selected from hydrogen, sodium, potassium, ammonium or an organic radical; 
           (b) a hydrofluoric acid source; 
           (c) a quaternary ammonium salt of the formula:
   N(R 6 )(R 7 )(R 8 )(R 9 )Y −   
 
           wherein R 6 , R 7 , R 8  and R 9  are independently a C 1 -C 6  alkyl group or a hydroxyalkyl group wherein the alkyl group is preferably a C 1 -C 6  alkyl; and 
           (d) an aminoalkyl siloxane; and 
         
         (B) removing inorganic or siliceous scales from the wellbore wherein the amount of quaternary ammonium salt and the amount of the organosilane in the well treatment composition is each between from about 0.01 to about 10 percent by volume based on the total volume of the well treatment composition. 
       
     
     
         30 . The method of  claim 29 , wherein the cation of the quaternary ammonium salt is N,N,N-trimethylethanolammonium. 
     
     
         31 . The method of  claim 29  wherein the aqueous well treating composition further comprises a boron containing compound selected from the group consisting of (i.) fluoroboric acid and/or (ii.) boron compounds capable of forming a BF 4   −  complex when exposed to F 4   −  or a hydrofluoric acid source and further comprising forming a BF 4   −  complex.