Dual retarded acid system for well stimulation

• US 9,234,126 B2
• Filed: 05/06/2013
• Issued: 01/12/2016
• Est. Priority Date: 05/06/2013
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Karale, Chaitanya M
• Primary Examiner(s): Li, Aiqun
• Application Number:
  US13/887,462
• Publication Number:
  US 20140329725A1
• Time in Patent Office: 981 Days
• Field of Search: 507/221, 507/225, 507/271, 507/937, 166/305.1
• US Class Current: 1/1
• CPC Class Codes: C09K 2208/32 Anticorrosion additives
• CPC Class Codes: C09K 8/72 Eroding chemicals, e.g. acids
• CPC Class Codes: C09K 8/725 Compositions containing polymers
• CPC Class Codes: C09K 8/82 Oil-based compositions C09K8/64 takes precedence

Abstract

A composition in the form of an emulsion having: (i) a continuous oil phase comprising: (a) an oil; (b) an emulsifier; and (ii) an internal aqueous phase comprising: (a) water; (b) acid such that the aqueous phase has an initial pH of less than about 2; (c) a viscosity-increasing agent; and (d) a crosslinker, wherein the crosslinker is selected or controlled to crosslink the viscosity-increasing agent at a pH range somewhere in a range of about 1.5 to about 6.5 and that is at least higher than the initial pH of the aqueous phase. A method of acidizing a treatment zone of a subterranean formation in a well includes the steps of: (A) forming a treatment fluid comprising such a composition; and (B) introducing the treatment fluid into a well.

Claims

1. A method of acidizing a treatment zone of a subterranean formation in a well, the method comprising the steps of:

(A) forming a treatment fluid in the form of an emulsion, the treatment fluid comprising;

(i) a continuous oil phase comprising;

(a) an oil; and

(b) an emulsifier; and

(ii) an internal aqueous phase comprising;

(a) water;

(b) acid such that the aqueous phase has an initial pH of less than about 2;

(c) a viscosity-increasing agent; and

(d) a crosslinker, wherein the crosslinker is selected or controlled to crosslink the viscosity-increasing agent at a pH range somewhere in a range of about 1.5 to about 6.5 and that is at least higher than the initial pH of the aqueous phase; and

(B) introducing the treatment fluid into a well, wherein a design temperature in the subterranean formation is at least about 121°

C. (about 250°

F.).

2. The method according to claim 1, wherein the oil of the external oil phase comprises an oil selected from the group consisting of petroleum, diesel, kerosene, or synthetic oil.

3. The method according to claim 1, wherein the emulsifier is a cationic amine.

4. The method according to claim 1, wherein the acid comprises a strong acid.

5. The method according to claim 4, wherein the strong acid comprises hydrochloric acid in a concentration of at least 5% by weight of water of the internal aqueous phase.

6. The method according to claim 4, wherein the strong acid comprises hydrochloric acid in a concentration in the range of about 24% to about 28% by weight of water of the internal aqueous phase.

7. The method according to claim 1, wherein the viscosity-increasing agent comprises a polyacrylamide based-polymer.

8. The method according to claim 1, wherein the crosslinker comprises ferric chloride.

9. The method according to claim 1, additionally comprising a corrosion inhibitor.

10. The method according to claim 9, additionally comprising a corrosion inhibitor intensifier.

11. The method according to claim 1, wherein the subterranean formation is a carbonate formation.