Aqueous retarded acid solution and methods for use thereof

Patent metadata

Field	Value
Publication number	US-2016298024-A1
Application number	US-201615090747-A
Country	US
Kind code	A1
Filing date	Apr 5, 2016
Priority date	Apr 10, 2015
Publication date	Oct 13, 2016
Grant date	—

Abstract

Methods include combining an amount of water and an acid retarding agent (RA), where the amount of water is present in an amount up to about 5 times the mass of the RA, inclusive, and wherein the RA includes at least one salt compound. An amount of acid is dissolved in the combined amount of water and RA to form a composition, where the amount of acid is a molar ratio of acid:RA of between 4.0 and 0.2, inclusive, and wherein the amount of acid is up to about 36% by weight of total weight of the composition. The composition is injected into a wellbore penetrating a subterranean formation at a pressure, which may be less than the fracture initiation pressure of the subterranean formation in some cases, while in other cases equal to or greater than the fracture initiation pressure.

First claim

What is claimed is:

1 . A method, comprising:
combining an amount of water and an acid retarding agent (RA), wherein the amount of water is present in an amount up to about 5 times the mass of the RA, inclusive, and wherein the RA comprises at least one salt compound; dissolving an amount of acid in the combined amount of water and acid retarding agent to form a composition, wherein the amount of acid comprises a molar ratio of acid:acid retarding agent of between 4.0 and 0.2, inclusive, and wherein the amount of acid comprises up to about 36% by weight of total weight of the composition; and injecting the composition into a wellbore penetrating a subterranean formation at a pressure less than the fracture initiation pressure of the subterranean formation.

2 . The method of claim 1 further comprising forming wormholes in the subterranean formation.

3 . The method of claim 1 , wherein the acid is one or more of hydrogen chloride, hydrogen bromide, hydrogen iodide, hydrogen fluoride, sulfuric acid, nitric acid, phosphoric acid alkanesulfonic acids or arylsulfonic acids.

4 . The method of claim 1 , wherein the acid is one or more of acetic acid, formic acid, alkyl carboxylic acids, acrylic acid, lactic acid, glycolic acid, malonic acid, fumaric acid, citric acid and tartaric acid.

5 . The method of claim 1 , wherein the acid is hydrogen chloride.

6 . The method of claim 1 , wherein the salt compound comprises one or more cations selected from lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, mercury, boron, aluminum, gallium, indium, thallium, tin, ammonium, alkylammonium, dialkylammonium, trialkylammonium and tetraalkylammonium, and one or more anions selected from fluoride, chloride, bromide, iodide, sulfate, bisulfate, sulfite, bisulfite nitrate, alkanesulfonates, arylsulfonates, acetate and formate.

7 . The method of claim 1 , wherein the salt compound is magnesium chloride.

8 . The method of claim 1 , wherein the acid retarding agent has an estimated retardation factor of at least about 3 at a temperature of 200° F.

9 . The method of claim 1 , wherein the acid retarding agent has an estimated retardation factor of at least about 11 at a temperature of 70° F.

10 . The method of claim 1 further comprising dissolving at least a portion of the acid retarding agent in the amount of water during the dissolving the amount of acid into the combined amount of water and acid retarding agent.

11 . The method of claim 1 , wherein the acid is present in an amount of from about 7.5 to about 36 wt % based on the total weight of the composition.

12 . The method of claim 1 , wherein the acid is present in an amount of from about 7.5 to about 28 wt % based on the total weight of the composition.

13 . The method of claim 1 , wherein the acid is present in an amount of from about 7.5 to about 20 wt % based on the total weight of the composition.

14 . The method of claim 1 , wherein the acid retarding agent is present up to about 40 wt % based on the total weight of the composition.

15 . The method of claim 1 , wherein the acid retarding agent is present from about 10 to about 36 wt % based on the total weight of the composition.

16 . The method of claim 1 , wherein the acid retarding agent is present from about 10 to about 30 wt % based on the total weight of the composition.

17 . A method, comprising:
combining an amount of water and an acid retarding agent (RA), wherein the acid retarding agent comprises at least one salt compound; dissolving an amount of acid in the combined amount of water and acid retarding agent to form a composition, wherein the amount of acid comprises up to about 36% by weight of total weight of the composition; and injecting the composition into a wellbore penetrating a subterranean formation with a high pressure pump; wherein the acid retarding agent has an estimated retardation tactor of at lea about 5 at a temperature of 70° F.

18 . The method of claim 1 , wherein the composition is injected into the wellbore at a pressure less than the fracture initiation pressure of the subterranean formation.

19 . The method of claim 1 , wherein the composition is injected into the wellbore at a pressure equal to or greater than the fracture initiation pressure of the subterranean formation.

20 . A method, comprising:
combining an amount of water and an acid retarding agent (RA), wherein the acid retarding agent comprises at least one salt compound and urea; dissolving an amount of acid in the combined amount of water and acid retarding agent to form a composition, wherein the amount of acid comprises at least about 37% by weight of total weight of the composition; and injecting the composition into a wellbore penetrating a subterranean formation.

Assignees

• Schlumberger Technology Corp

Inventors

• Panga Mohan Kanaka Raju
• Daeffler Christopher
• Nevvonen Olga Vladimirovna

Classifications

• C09K8/74 Primary

  combined with additives added for specific purposes · CPC title

• C09K8/845

  containing inorganic compounds · CPC title

• E21B43/27 Primary

  by use of eroding chemicals, e.g. acids · CPC title

• E21B43/26

  by forming crevices or fractures · CPC title

• E21B43/16

  Enhanced recovery methods for obtaining hydrocarbons · CPC title