Use of sequestering agent in GLDA-based treatments for siliceous formations

1. A method of increasing the permeability of a siliceous subterranean formation comprising:

(a) introducing into a well penetrating a siliceous subterranean formation an acidic fluid containing (i) from about 5 to about 50 weight percent of a glutamic-N,N-diacetic acid, salt or mixture thereof; (ii) from about 0.25 to 20 weight percent of a HF or a HF-generating component; and (iii) between from about 0.25 to about 50 weight percent of an organophosphonate compound, wherein the ratio of glutamic-N,N-diacetic acid or salt to HF concentration in the fluid is from 5:1 to 10:0.1

and wherein either the fluid contains ammonium bifluoride or ammonium fluoride or a combination thereof as the HF-generating component or the organophosphonate of the fluid is of the formula:

wherein R1, R2 and R3 are independently selected from hydrogen, alkyl, aryl, phosphonates, phosphates, acyl, amine, hydroxy and carboxyl groups and R4 and R5 are independently selected from hydrogen, sodium, potassium, ammonium or an organic radical;

(b) dissolving siliceous materials of the formation and generating monovalent ions, divalent ions or a combination thereof; and

(c) forming a complex of the organophosphonate and monovalent ions, divalent ions or a combination thereof after introduction of the acidic fluid into the well.

2. The method of claim 1 , wherein the organophosphonate is of the formula:

3. The method of claim 1 , wherein the acidic fluid contains ammonium bifluoride or ammonium fluoride or a combination thereof as a HF-generating compound and further wherein the organophosphonate is selected from the group consisting of 1-hydroxyethylidine-1,1-diphosphonic acid, diethylene triamine penta(methylene phosphonic acid) and aminotri (methylene phosphonic acid) and mixtures thereof.

4. The method of claim 1 , wherein (i) the pH of the fluid is between from about 1.9 to about 4.8; (ii) the fluid further comprises an organic acid; or (iii) the pH of the fluid is between from about 1.9 to about 4.8 and the fluid further comprises an organic acid.

5. The method of claim 1 , wherein the amount of:

(i) glutamic acid-N,N-diacetic acid, salt or mixture thereof in the acidic fluid is from about 5 to about 20 weight percent;

(ii) HF or HF-generating component in the acidic fluid is from about 0.5 to 10 weight percent; and

(iii) organophosphonate in the acidic fluid is between from about 0.5 to about 6.0 weight percent.

6. The method of claim 1 , wherein a pre-flush is introduced into the well prior to introduction of the acidic fluid.

7. The method of claim 6 , wherein an over-flush is introduced into the well after step (c).

8. The method of claim 1 , wherein an over-flush is introduced into the well after step (c).

9. The method of claim 1 , wherein the acidic fluid comprises a HF-generating component, wherein the HF-generating compound is ammonium bifluoride or ammonium fluoride or a combination thereof.

10. The method of claim 1 , wherein the acidic fluid further comprises a corrosion and/or non-emulsifier, wherein the corrosion inhibitor optionally further comprises a corrosion inhibitor intensifier.

11. The method of claim 1 , wherein the acidic fluid is free of HCl.

12. The method of claim 1 , wherein the glutamic-N,N-diacetic acid, salt or mixture thereof is a glutamic-N,N-diacetic acid sodium salt.

13. The method of claim 12 , wherein the glutamic-N,N-diacetic acid salt is tetrasodium glutamate diacetate.

14. The method of claim 1 , wherein the ratio of glutamic-N,N-diacetic acid or salt to HF concentration in the fluid is from 20:1 to 10:0.1.

15. A method of stimulating production in a siliceous subterranean formation of an oil, gas or geothermal well comprising:

(a) introducing into a well penetrating a siliceous subterranean formation an acidic fluid comprising (i) from about 5 to about 50 weight percent of a glutamic-N,N-diacetic acid or salt or a mixture thereof; (ii) from about 0.25 to 20 weight percent of ammonium bifluoride or ammonium fluoride or a combination thereof as a HF-generating compound; and (iii) between from about 0.25 to about 50 weight percent of an organophosphonate selected from the group consisting of 1-hydroxyethylidine-1,1-diphosphonic acid, diethylene triamine penta(methylene phosphonic acid) and aminotri (methylene phosphonic acid) and mixtures thereof, wherein the ratio of glutamic-N,N-diacetic acid or salt to HF concentration in the fluid is from 5:1 to 10:0.1;

(b) reacting the glutamic-N,N-diacetic acid, salt or mixture thereof and the HF or HF-generating component with the siliceous subterranean formation and generating un-complexed monovalent ions, divalent ions or a combination thereof; and

(c) forming a complex by sequestering the un-complexed monovalent ions, divalent ions or combination thereof with the organophosphonate; and

(d) producing hydrocarbons from the siliceous formation.

16. The method of claim 15 , wherein (i) the pH of the acidic fluid is between from about 1.9 to about 4.8; (ii) the acidic fluid further comprises an organic acid; or (iii) the pH of the acidic fluid is between from about 1.9 to about 4.8 and the acidic fluid further comprises an organic acid.

17. The method of claim 15 , wherein at least one of the following conditions prevail:

(i) a pre-flush is introduced into the well prior to introduction of the acidic fluid;

(ii) an over-flush is introduced into the well after introduction of the acidic fluid and after formation of the complexes of the monovalent ion, divalent ion or combination thereof; or

(iii) the glutamic-N,N-diacetic acid, salt or mixture thereof is a glutamic-N,N-diacetic acid sodium salt.

18. The method of claim 15 , wherein the acidic fluid is free of HCl.

19. A method of remediating a sandstone formation of an oil or gas or geothermal well by:

(a) introducing into the well a buffered HF-acidizing fluid comprising:

(i) from about 5 to about 50 weight percent of a glutamic-N,N-diacetic acid, salt or mixture thereof;

(ii) from about 0.25 to 20 weight percent of HF or a HF generating component or a mixture thereof;

(iii) from about 0.25 to about weight percent of an organophosphonate of the formula:

wherein R1, R2 and R3 are independently selected from hydrogen, alkyl, aryl, phosphonates, phosphates, acyl, amine, hydroxy and carboxyl groups and R4 and R5 are independently selected from hydrogen, sodium, potassium, ammonium or an organic radical

and wherein the ratio of glutamic-N,N-diacetic acid or salt to HF concentration in the fluid is from 5:1 to 10:0.1 and the pH of the acidizing fluid is between from about 1.9 to about 4.8; and

(b) forming complexes of the organophosphonate with monovalent ions, divalent ions or a combination thereof after introduction of the acidizing fluid into the well; and

(c) remediating the well by removing the formed complexes therefrom.

20. The method of claim 19 , wherein at least one of the following conditions prevail:

(i) the acidizing fluid further comprises an organic acid;

(ii) a pre-flush is introduced into the well prior to introduction of the acidizing fluid;

(iii) an over-flush is introduced into the well after introduction of the acidizing fluid and after formation of the complexes of the monovalent ion, divalent ion or combination thereof;

(iv) the acidic fluid comprises the HF-generating component, wherein the HF-generating component is ammonium bifluoride or ammonium fluoride or a combination thereof; or

(v) the glutamic-N,N-diacetic acid, salt or mixture thereof is a glutamic-N,N-diacetic acid sodium salt.