阅读说明：本技术 用于受控地输送酸的组合物和方法 (Compositions and methods for controlled delivery of acids ) 是由 A·J·凯恩斯 K·L·赫尔 M·赛义德 于 2018-04-05 设计创作，主要内容包括：本申请描述了用于将酸受控地输送到期望位置,例如到地层的组合物和方法。(Compositions and methods for controlled delivery of acid to a desired location, such as to a subterranean formation, are described.)

1. A method of in situ acid stimulation of a formation containing a hydrocarbon reservoir, the method comprising contacting the formation with an aqueous fluid comprising (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidant capable of oxidizing the ammonium salt, wherein the ammonium salt and oxidant in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃ at 1 atmosphere.

2. The method of claim 1, wherein the layer comprises a carbonate.

3. The method of claim 1, wherein the layer comprises sandstone.

4. The method of claim 1, wherein the layer comprises shale.

5. The method of any one of claims 1 to 4, wherein the ammonium salt comprises a salt selected from the group consisting of: ammonium halides, ammonium sulfate, ammonium nitrate, ammonium phosphate, ammonium carbonate, and mixtures thereof.

6. The method of any one of claims 1 to 5, wherein the ammonium salt comprises ammonium chloride.

7. The method of any one of claims 1 to 5, wherein the ammonium salt comprises ammonium persulfate.

8. The method of any one of claims 1 to 7, wherein the oxidizing agent comprises an agent selected from the group consisting of: peroxides, persulfates, permanganates, bromates, perbromates, chlorates, perchlorates, iodates, periodates, and mixtures thereof.

9. The method of any one of claims 1 to 8, wherein the oxidizing agent comprises a bromate salt.

10. The method of any one of claims 1 to 9, wherein the oxidizing agent comprises sodium bromate.

11. The method of any one of claims 1 to 10, wherein the aqueous fluid further comprises a chelating agent.

12. The method of claim 11, wherein the layer comprises a carbonate.

13. The method of claim 12, wherein the ammonium salt comprises a salt selected from the group consisting of: ammonium persulfate, ammonium sulfate, ammonium bisulfate (ammonium hydrogen sulfate), ammonium thiosulfate, ammonium bisulfate (ammonium bisulfate), ammonium phosphate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphite, ammonium nitrite, and mixtures thereof.

14. The method of any one of claims 11-13, wherein the chelating agent is selected from the group consisting of: 1, 2-cyclohexanediaminetetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethanol-diglycine (EDG), ethylenediaminetetraacetic acid (EDTA), N' -bis (carboxymethyl) glycine (NTA), L-glutamic acid N, N-diacetic acid, tetrasodium salt (GLDA), HEDTA (N-hydroxyethyl-ethylenediaminetriacetic acid), hydroxyaminocarboxylic acid (HACA), hydroxyethylidene iminodiacetate (HEIDA), and Sodium Hexametaphosphate (SHMP), and derivatives and mixtures thereof.

15. The method of any one of claims 11-14, wherein the chelating agent is sodium hexametaphosphate and the ammonium salt comprises ammonium persulfate.

16. The method of any one of claims 1-15, wherein the ammonium salt is present in the aqueous fluid at a concentration of 0.001M to saturation.

17. The method of any one of claims 1-16, wherein the oxidizing agent is present in the aqueous fluid at a concentration of 0.001M to saturation.

18. The method of any one of claims 1-17, wherein the ammonium salt and oxidant in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 80 ℃ at 1 atmosphere.

19. The method of any one of claims 1-17, wherein the ammonium salt and an oxidizing agent in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 100 ℃ at 1 atmosphere.

20. The method of any of claims 1-17, wherein the aqueous fluid has a pH greater than 5 at 1 atmosphere and a temperature less than 65 ℃.

21. The method of any one of claims 1 to 20, wherein the aqueous fluid is free of free tertiary amine salts or compounds that react to form free tertiary amine salts in situ.

22. The method of any one of claims 1 to 21, wherein the contacting step comprises introducing the aqueous fluid into the layer by means of coiled tubing or extrusion in production tubing.

23. The method of any one of claims 1 to 21, wherein the contacting step comprises introducing the aqueous fluid of the ammonium salt and the aqueous fluid of the oxidant into the layer through the same conduit and allowing the aqueous fluid to form in situ within the conduit, within the layer, or within a region surrounding the wellbore.

24. The method of any one of claims 1 to 21, wherein the contacting step comprises introducing the aqueous fluid of the ammonium salt and the aqueous fluid of the oxidant into the layer in separate stages and allowing the aqueous fluids to form in situ within the layer.

25. An aqueous fluid for in situ acid stimulation of a formation containing a hydrocarbon reservoir, wherein the aqueous fluid comprises (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidant capable of oxidizing the ammonium salt, wherein, at 1 atmosphere, the ammonium salt and oxidant in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃.

26. A method of in situ acid treatment of a subterranean formation selected from the group consisting of a water injection well, a gas injection well, a water treatment well and a cuttings treatment well, the method comprising contacting the formation with an aqueous fluid comprising (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidant capable of oxidizing the ammonium salt, wherein, at 1 atmosphere, the ammonium salt and oxidant in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃.

27. An aqueous fluid for the in situ acid treatment of a formation selected from the group consisting of water injection wells, gas injection wells, water treatment wells and cuttings treatment wells, wherein the aqueous fluid comprises (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidant capable of oxidizing the ammonium salt, wherein the ammonium salt and oxidant in the aqueous fluid react to produce an acid only at a temperature of 65 ℃ or higher at 1 atmosphere.

Technical Field

The present application relates to compositions and methods for controlled delivery of acids to, for example, subterranean formations.

Background

It is estimated that a significant portion of the world's oil and gas reserves are located in carbonate reservoirs with values of 60% and 40%, respectively (schrenbach market analysis, 2007). The minerals of these heterogeneous carbonate formations consist primarily of calcite, dolomite, or combinations thereof. Stimulation methods typically rely on the use of suitable acid stimulation techniques as they have been shown to successfully and effectively solubilize calcium and magnesium based carbonates. Several acid platforms have been widely used by oil and gas operators to stimulate carbonate formations. These acid platforms include, but are not limited to, the use of strong mineral acids (e.g., hydrochloric acid, HCl), gelled and emulsified acids, organic acids (e.g., formic acid (CH))₂O₂) And acetic acid (C)₂H₄O₂) ) and combinations thereof. While these techniques are effective, improvements are needed to allow, for example, deeper penetration of the acid into the reservoir, or to minimize the amount of acid used, or both.

Brief description of the invention

Not only the oil and gas industry, but also other industries such as the biomedical and semiconductor industry require controlled delivery of acids (of inorganic or organic nature) to a site at a specific location to address various challenges associated with the corrosive nature of the acids, etc., as well as the difficulties and safety issues associated with handling the acids. As noted above, the oil and gas industry uses acid systems to stimulate hydrocarbon reservoirs (e.g., carbonate reservoirs). Acid systems are commonly used to create a more conductive flow path for oil or gas to flow through by dissolving the formation to create wormholes or by reducing damage to the near-wellbore region caused by drilling.

Strong mineral acids (e.g., HCl) are typically used to stimulate carbonate formations consisting of calcite, dolomite, and the like. In situ, treatment with HCl is generally preferred because it reacts with calcite and dolomite to produce water-soluble products, which are less damaging to the formation. In addition, the HCl acid system is very cost effective and therefore economically advantageous. However, this treatment causes serious problems in terms of durability and practical application due to the corrosiveness and the rapid consumption of the live acid due to the rapid reaction kinetics (rock-HCl). The result is that a large amount of acid is required, even so, the live acid does not penetrate deeper into the reservoir. Other disadvantages of this approach include various safety issues associated with the transfer and disposal of corrosive acids at the well site, and the occurrence of undesirable acid reactions near the wellbore that can lead to corrosion of the drilling equipment, tubing and casing. Various alternative approaches have been proposed to address these problems, including but not limited to the use of: (1) organic synthetic acid, (2) gelling acid, (3) emulsifying acid and (4) producing enzyme.

In one aspect, the present application describes techniques directed to compositions and methods for controlled delivery of acids to specific locations, thereby minimizing certain challenges described herein. In some embodiments, the composition for controlled delivery of an acid to a specific location comprises a composition capable of generating an acid in situ at a desired location or time. In some embodiments, the compositions comprise a combination of one or more oxidizing agents, one or more salts, and optionally one or more chelating agents, as described herein. In some embodiments, the methods described herein include controlled delivery of an acid to a formation containing a hydrocarbon reservoir, such as a carbonate layer, a sandstone layer, or a shale layer. In some embodiments, the controlled delivery of acid to a formation containing a hydrocarbon reservoir reduces the occurrence of corrosion of drilling equipment, tubing, and casing associated with acid treatment. In some embodiments, controlled delivery of acid to a formation containing a hydrocarbon reservoir enables the acid to penetrate deeper into the layer than would otherwise be possible.

In some embodiments, controlled delivery of acid to a formation containing a hydrocarbon reservoir may mitigate zonal damage caused during drilling. In some embodiments, the layer damage caused during the drilling process may be filter cake damage. Filter cake damage can result in reduced permeability in the near wellbore region, resulting in reduced production. In some embodiments, to restore permeability, the damaged area is treated by controlled delivery of acid according to the methods described herein. In some embodiments, the method is used to eliminate (dissolve) filter cake damage that has passed into the depth of a hydrocarbon reservoir. In some embodiments, filter cake damage is caused by a carbonate layer. In some embodiments, filter cake damage is caused by calcium carbonate. In some embodiments, the present application describes a method of controlled delivery of acid to a subterranean formation to treat drilling-induced formation damage. In some embodiments, the treatment of drilling-induced formation damage involves filter cake solvation. In some embodiments, the treatment of drilling-induced formation damage increases filter cake permeability. In some embodiments, the treatment of drilling-induced formation damage involves filter cake removal.

There is described a method of in situ acid stimulation of a formation containing a hydrocarbon reservoir, the method comprising contacting the formation with an aqueous fluid comprising (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidant capable of oxidizing the ammonium salt, wherein the ammonium salt and oxidant in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃ at 1 atmosphere.

Wherein the application further describes a method of in situ acid treatment of a subterranean formation selected from the group consisting of a water injection well, a gas injection well, a water treatment well and a cuttings treatment well, the method comprising contacting the formation with an aqueous fluid comprising (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidant capable of oxidizing the ammonium salt, wherein the ammonium salt and oxidant in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃ at 1 atmosphere.

Wherein the application also describes an aqueous fluid for in situ acid treatment of a formation containing a hydrocarbon reservoir, the aqueous fluid comprising (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidant capable of oxidizing the ammonium salt, wherein, at 1 atmosphere, the ammonium salt and oxidant in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃.

Wherein the application further describes an aqueous fluid for use in the in situ acid treatment of a formation selected from the group consisting of water injection wells, gas injection wells, water treatment wells and cuttings treatment wells, wherein the aqueous fluid comprises (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidant capable of oxidizing the ammonium salt, wherein the ammonium salt and oxidant in the aqueous fluid react to produce an acid only at a temperature of 65 ℃ or higher at 1 atmosphere.

Various embodiments of the subject matter described in this application are set forth in the following detailed description and claims.

Detailed Description

It is contemplated that the systems, apparatus, methods, and processes of the present application include variations and adaptations developed using information from the embodiments described below. Adaptations and/or modifications of the films, methods, and processes described below may be made by one of ordinary skill in the relevant art.

Throughout the specification, when a composition, compound or product is described as having, including or comprising a particular component, or when a process or method is described as having, including or comprising a particular step, it is contemplated that there also exist articles, devices and systems of the application that consist essentially of, or consist of, the component, and there exist processes and methods of the application that consist essentially of, or consist of, the process step.

It will be understood that the order of steps or order of performing certain actions is immaterial so long as the operability of the described methods is maintained. Further, two or more steps or actions may be performed simultaneously.

The reference to any publication in this application (e.g., in the background section) is not an admission that the publication is available as prior art against any claims that are presented. The background section is presented for clarity and is not a description of any prior art with respect to the claims. The subheadings are provided for the convenience of the reader and are not intended to limit the claimed subject matter.

As described herein, there is a need in various industries for controlled delivery of acids, whether inorganic or organic, to a site at a particular location in such a way as to address various challenges associated with, for example, the corrosiveness of the acid, as well as the difficulties and safety issues involved in handling the acid. One way to controllably deliver acid to a site at a particular location is by generating the acid in situ. As used herein, "in situ" acid generation generally refers to the generation of acid in the "one pot" where the reaction is to take place, as opposed to the generation of acid in one vessel and its transfer to another, separate vessel for reaction. In some embodiments, generating the acid in situ includes generating the acid at a desired location where the acid is desired to react, e.g., in a subterranean reservoir downhole, rather than generating the acid at the surface and transferring it to the subterranean reservoir downhole. Accordingly, the present application particularly describes methods of using compositions comprising a combination of one or more oxidizing agents, one or more salts, and optionally one or more chelating agents as described herein to generate (e.g., by in situ generation) an acid.

In some embodiments, the compositions described herein may be used in oil and gas applications, for example, for stimulating a subterranean formation. In some embodiments, the in situ method may include generating an acid upon or after reaching the layer, for example, delivering an agent described herein into the layer by way of coiled tubing or plunging in production tubing (depending on whether the application is acid-fracturing or matrix-acidizing, respectively). In some embodiments, the acid is generated within the layer itself.

In some embodiments, the formation contains a hydrocarbon reservoir. In some embodiments, the formation comprises carbonate. In some embodiments, the formation comprises sandstone. In some embodiments, the formation comprises clastic sedimentary rock. For example, in some embodiments, the subterranean formation comprises shale.

In some embodiments, the compositions and methods described herein may be used to acidify a well formation (e.g., a water injection well or a treatment well) or an injection well, for example, to improve injectability. The injection well may be a water injection well or a gas injection well. The disposal well may be a water disposal well or a drill cuttings disposal well.

Since the compositions and methods described herein can be used in a variety of applications where controlled delivery of acids (e.g., by in situ generation) is desired, the applications of the compositions and methods described herein are not limited to the oil and gas industry or other industries contemplated in this application.

Composition comprising a metal oxide and a metal oxide

The present application describes, inter alia, compositions for controlled delivery of acids comprising a combination of one or more oxidizing agents, one or more salts, and optionally one or more chelating agents as described herein. Exemplary oxidizing agents, salts, and optional components are further described below.

In some embodiments, a composition comprises an aqueous fluid for controlled delivery of an acid, wherein the aqueous fluid comprises (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidizing agent capable of oxidizing the ammonium salt, wherein, at 1 atmosphere, the ammonium salt and the oxidizing agent in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃.

In some embodiments, a composition comprises an aqueous fluid for in situ acid stimulation of a formation containing a hydrocarbon reservoir, wherein the aqueous fluid comprises (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidizing agent capable of oxidizing the ammonium salt, wherein, at 1 atmosphere, the ammonium salt and the oxidizing agent in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃.

In some embodiments, the compositions described herein do not contain tertiary amines or compounds that react to form tertiary amine salts in situ. For example, in certain embodiments, the compositions described herein do not comprise trialkylamines (e.g., trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine), dimethyldodecylamine (dimethyldodecylamine), or dimethyltetradecylamine (dimethyldodecylamine).

Oxidizing agent

The compositions described herein for controlled delivery of acids (e.g., by in situ generation) comprise one or more oxidizing agents. In some embodiments, the one or more oxidizing agents are present in the aqueous fluid.

In some embodiments, the oxidizing agent comprises any agent capable of oxidizing an ammonium salt. In some embodiments, the oxidizing agent is an inorganic oxidizing agent. In some embodiments, the oxidizing agent comprises an agent selected from the group consisting of: peroxides, persulfates, permanganates, bromates, perbromates, chlorates, perchlorates, iodates, periodates, and mixtures thereof. In certain embodiments, the oxidizing agent is a bromate salt, such as an alkali metal bromate salt. In certain embodiments, the oxidizing agent is or comprises sodium bromate. In some embodiments, the oxidizing agent is an organic oxidizing agent. In some embodiments, the oxidizing agent comprises an agent selected from the group consisting of: peracetic acid and performic acid.

In some embodiments, the oxidizing agent is present in the aqueous fluid at a concentration ranging from 0.001M to saturation (the concentration measured at 20 ℃). In some embodiments, the oxidizing agent is present in the aqueous fluid at a concentration in the range of 0.05M to 1.0M, or 0.05M to 0.5M, or 0.05M to 0.4M, or 0.05M to 0.3M, or 0.1M to 0.3M. In some embodiments, the oxidizing agent is present in the aqueous fluid at a concentration in a range from 0.5M to 10.0M, or from 0.5M to 9.5M, or from 0.5M to 9.0M, or from 1.0M to 9.0M, or from 2.0M to 9.0M, or from 3.0M to 9.0M, or from 4.0M to 9.0M, or from 5.0M to 9.0M, or from 6.0M to 8.0M, or from 6.5M to 7.5M. In some embodiments, the oxidizing agent is present in the aqueous fluid at a concentration in the range of 1.0M to 4.0M, or 1.0M to 3.0M, or 1.5M to 3.0M, or 2.0M to 3.0M.

In some embodiments, the oxidizing agent comprises a bromate salt, such as sodium bromate, and is present in the aqueous fluid at a concentration in the range of 0.001M to 2.4M. In some embodiments, the oxidizing agent comprises sodium bromate and is present in the fluid at a concentration in the range of 0.01M to 2.4M, or 0.01M to 2.2M, or 0.01M to 1.8M, or 0.01M to 1.6M, or 0.01M to 1.4M, or 0.01M to 1.2M, or 0.01M to 1.0M, or 0.01M to 0.8M, or 0.01M to 0.6M, or 0.01M to 0.4M, or 0.01M to 0.2M, or 0.01M to 0.1M, or 0.01M to 0.09M, or 0.02M to 0.09M, or 0.03M to 0.09M, or 0.04M to 0.09M, or 0.05M to 0.09M, or 0.06M to 0.08M. In some embodiments, the oxidizing agent comprises sodium bromate and is present in the aqueous fluid at a concentration in the range of 0.1M to 0.5M, or 0.1M to 0.4M, or 0.1M to 0.2M, or 0.3M to 0.4M, or 0.15M to 0.25M.

In some embodiments, the oxidizing agent is provided in capsule form, e.g., to delay its release. Encapsulated oxidizing agents are commercially available and known to those of ordinary skill in the art. Exemplary such oxidizing agents include sodium persulfate, potassium bromate, and the like.

In some embodiments, the oxidizing agent is characterized in that it requires a threshold temperature to react with a salt of a composition described herein. For example, in some embodiments, an oxidizing agent requires a threshold temperature of at least 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, or 140 ℃ at 1 atmosphere to react with a salt of a composition described herein. In some embodiments, an oxidizing agent at 1 atmosphere is characterized in that it requires a threshold temperature in the range of 65 ℃ to 250 ℃ to react with a salt of a composition described herein. In some embodiments, an oxidizing agent at 1 atmosphere is characterized in that it requires a threshold temperature above ambient temperature to react with a salt of a composition described herein.

In some embodiments, the threshold temperature may be lowered by, for example, adding an amount of acid to the composition.

Salt (salt)

The compositions described herein for controlled delivery of acids (e.g., by in situ generation) comprise one or more salts that provide a source of hydrogen. In some embodiments, the one or more salts are present in an aqueous fluid.

In some embodiments, the salt comprises an ammonium salt. In some embodiments, the ammonium salt comprises an anion, which is an antioxidant anion. In some embodiments, the anion of the ammonium salt is selected based on its reactivity, which is measured at a temperature that enables the resulting ammonium salt to react with a particular oxidizing agent.

In some embodiments, the ammonium salt is selected based on the intended application. For example, in embodiments where the intended application is to stimulate a carbonate layer, it may be desirable to generate highly water-soluble HCl as an in situ acid. In this case, ammonium chloride may be selected as the ammonium salt. In other embodiments where the intended application is stimulation of a sandstone formation, it may be desirable to generate an acid other than HCl in situ, for example and/or additionally by selecting one or more of ammonium fluoride and ammonium chloride as the ammonium salt.

In some embodiments, the ammonium salt comprises an ammonium halide. In some embodiments, the ammonium halide comprises ammonium fluoride, ammonium chloride, ammonium bromide, ammonium iodide, and mixtures thereof. In some embodiments, the ammonium salt comprises ammonium fluoride. In some embodiments, the ammonium salt comprises ammonium bifluoride. In some embodiments, the ammonium salt comprises ammonium chloride.

In some embodiments, the ammonium salt comprises an anion, which is also an oxidizing agent. For example, in some embodiments, the ammonium salt comprises ammonium persulfate.

In some embodiments, the ammonium salt comprises polyatomic anions such as sulfate, bisulfate, thiosulfate, nitrite, nitrate, phosphite, phosphate, monobasic phosphate, dibasic phosphate, carbonate, and combinations thereof. Other similar polyatomic anions are known to those skilled in the chemical arts.

In some embodiments, the ammonium salt comprises one or more N-substituted ammonium salts. In some embodiments, the N-substituted ammonium salt is mono-or di-substituted, for example, with one or two alkyl groups. In some embodiments, the N-substituted ammonium salt is tri-substituted, e.g., substituted with three alkyl groups. Exemplary alkyl groups include methyl, ethyl, propyl, butyl, and the like. In some embodiments, the ammonium salt is not a tri-substituted ammonium salt. In some embodiments, the ammonium salt is not a tetra-substituted ammonium salt.

In some embodiments, the salt is present in the aqueous fluid at a concentration ranging from 0.001M to saturation (the concentration measured at 20 ℃). In some embodiments, the salt is present in the aqueous fluid at a concentration ranging from 0.1M to 1.0M, or from 0.2M to 0.9M, or from 0.3M to 0.8M, or from 0.4M to 0.7M, or from 0.5M to 0.6M. In some embodiments, the salt is present in the aqueous fluid at a concentration ranging from 0.1M to 10.0M, or from 0.5M to 10.0M, or from 1.0M to 10.0M, or from 1.5M to 10.M, or from 2.0M to 10.0M, or from 2.5M to 9.5M, or from 3.0M to 9.0M, or from 3.5M to 8.5M, or from 4.0M to 8.5M, or from 4.5M to 8.5M, or from 5.0M to 8.5M, or from 5.5M to 8.5M, or from 6.0M to 8.5M, or from 6.5M to 8.5M, or from 7.0M to 8.0M.

Chelating agents

The compositions for controlled delivery of acids (e.g., by in situ generation) described herein optionally comprise one or more chelating agents. In some embodiments, the one or more chelating agents are present in an aqueous fluid.

In some embodiments, the chelating agent includes any agent capable of chelating one or more salts formed during controlled delivery of the acid (e.g., by in situ generation).

In some embodiments, the chelating agent is an organic chelating agent.

In some embodiments, the chelating agent is an inorganic chelating agent.

Exemplary chelating agents include, but are not limited to, 1, 2-cyclohexanediaminetetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethanol-diglycine (EDG), ethylenediaminetetraacetic acid (EDTA), L-glutamic acid N, N-diacetic acid, tetrasodium salt (GLDA), hydroxyaminocarboxylic acid (HACA), HEDTA (N-hydroxyethyl-ethylenediaminetriacetic acid), hydroxyethylidene iminodiacetate (HEIDA), N' -bis (carboxymethyl) glycine (NTA), Sodium Hexametaphosphate (SHMP), tetraammonium EDTA, and derivatives and mixtures thereof. In certain embodiments, the chelating agent comprises SHMP.

In some embodiments, the chelating agent is selected based on the particular type of ammonium salt present in the composition. For example, in some embodiments, the ammonium salt comprises a polyatomic phosphorus-or sulfur-containing counterion, and the chelating agent is selected from chelating agents known in the art to solubilize salts comprising polyatomic phosphorus-or sulfur-containing counterions. Exemplary such ammonium salts containing polyatomic phosphorus-or sulfur-containing counterions include, but are not limited to, ammonium persulfate, ammonium sulfate, ammonium bisulfite, ammonium phosphate, and the like. Exemplary chelating agents that may be used in compositions comprising such ammonium salts include inorganic chelating agents such as SHMP. In some embodiments, chelating agents may be used to chelate metal cations. For example, in some embodiments, chelating agents are particularly good at chelating calcium salts, such as calcium salts produced in the step of contacting a carbonate layer with the compositions described herein. In some embodiments, the chelating agent is particularly adept at chelating magnesium salts, such as those produced in the step of contacting the carbonate layer with the compositions described herein. In some embodiments, chelating agents are particularly good at chelating iron, for example, to control iron levels and help mitigate corrosion associated therewith. In some embodiments, the composition comprising the chelate is used to treat a formation containing a hydrocarbon reservoir, such as a carbonate layer. In some such embodiments, the ammonium salt is ammonium persulfate and the oxidizing agent is sodium bromate. In some such embodiments, it has been surprisingly found that SHMP exhibits a synergistic effect in that it not only chelates calcium salts to minimize precipitation, but also promotes additional dissolution of calcium carbonate, as compared to a composition without a chelating agent.

In some embodiments, the chelating agent is present in the aqueous fluid at a concentration ranging from 0.001M to saturation (the concentration measured at 20 ℃). In some embodiments, the chelating agent is present in the aqueous fluid at a concentration in the range of 0.005 to 0.01, or 0.005M to 0.09M, or 0.005M to 0.08M, or 0.005M to 0.07M, or 0.005M to 0.06M, or 0.005M to 0.05M, or 0.01M to 0.04M, or 0.02M to 0.04M, or 0.025M to 0.04M, or 0.03M to 0.04M.

In some embodiments, the chelating agent ranges from 1lb chelating agent/1000 gallons aqueous fluid to 300

The concentration of lb/1000 gallons of aqueous fluid, or 5lb of chelant/1000 gallons of aqueous fluid to 300lb/1000 gallons of aqueous fluid, 25lb of chelant/1000 gallons of aqueous fluid to 300lb/1000 gallons of aqueous fluid, or 50lb of chelant/1000 gallons of aqueous fluid to 300lb/1000 gallons of aqueous fluid, or 100lb of chelant/1000 gallons of aqueous fluid to 300lb/1000 gallons of aqueous fluid, or 200lb of chelant/1000 gallons of aqueous fluid to 300lb/1000 gallons of aqueous fluid is present in the aqueous fluid.

In some embodiments, the aqueous fluid comprises up to 50 wt% chelating agent. In some embodiments, the aqueous fluid comprises up to 45 wt% chelating agent. In some embodiments, the aqueous fluid comprises up to 40 wt% chelating agent. In some embodiments, the aqueous fluid comprises up to 35 wt% chelating agent. In some embodiments, the aqueous fluid comprises up to 30 wt% chelating agent. In some embodiments, the aqueous fluid comprises up to 25 wt% chelating agent. In some embodiments, the aqueous fluid comprises up to 20 wt% chelating agent. In some embodiments, the aqueous fluid comprises up to 15 wt% chelating agent. In some embodiments, the aqueous fluid comprises up to 10 wt% chelating agent. In some embodiments, the aqueous fluid comprises up to 5 wt% chelating agent.

Method for controlled delivery of acids

In some embodiments, the present disclosure describes a method for controlled delivery of an acid, the method comprising providing an aqueous fluid comprising (a) an ammonium salt that is capable of being oxidized to produce an acid and (b) an oxidizing agent that is capable of oxidizing the ammonium salt, wherein, at 1 atmosphere, the ammonium salt and the oxidizing agent in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃.

In some embodiments, the present invention provides a method for in situ acid generation, the method comprising providing an aqueous fluid comprising (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidizing agent capable of oxidizing the ammonium salt, wherein, at 1 atmosphere, the ammonium salt and the oxidizing agent in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃.

In some embodiments, the present invention provides a method of in situ acid stimulation of a formation containing a hydrocarbon reservoir, the method comprising contacting the layer with an aqueous fluid comprising (a) an ammonium salt capable of being oxidized to produce an acid and (b) an oxidizing agent capable of oxidizing the ammonium salt, wherein the ammonium salt and the oxidizing agent in the aqueous fluid react to produce an acid only at a temperature equal to or greater than 65 ℃ at 1 atmosphere.

In some embodiments, the contacting step comprises introducing the aqueous fluid into the layer by way of coiled tubing or extrusion in production tubing.

In some embodiments, the method is as described herein, wherein the contacting step comprises introducing the aqueous fluid of the ammonium salt and the aqueous fluid of the oxidant into the formation through the same conduit (e.g., the same coiled tubing) and allowing the aqueous fluid to form in situ within the conduit, within the formation, or within a region surrounding the wellbore.

Alternatively, in some embodiments, the method is as described herein, wherein the contacting step comprises introducing the aqueous fluid of the ammonium salt and the aqueous fluid of the oxidant into the layer (optionally through the same or different conduits, e.g., the same or different coiled tubing) in separate stages and allowing the aqueous fluid to form in situ within the layer. In some embodiments, the aqueous fluid of the ammonium salt is first introduced into the layer. In some embodiments, the aqueous fluid of the oxidizing agent is first introduced into the layer.

Temperature of

In some embodiments, the controlled delivery of acid using the compositions and methods described herein comprises controlling the temperature at which the acid is generated. For example, in some embodiments, the compositions described herein (i.e., the components are selected) are designed such that they require a certain desired threshold temperature for the oxidizing agent to react with the salt to produce the acid. In some embodiments, the ammonium salt and the oxidizing agent react to produce the acid only at a temperature equal to or greater than 65 ℃ at 1 atmosphere. For example, in some embodiments, at 1 atmosphere, the compositions described herein require a temperature of at least 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, or 140 ℃ to produce the acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 65 ℃ to 250 ℃ at 1 atmosphere to generate acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 65 ℃ to 200 ℃ at 1 atmosphere to generate acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 65 ℃ to 175 ℃ at 1 atmosphere to generate acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 65 ℃ to 150 ℃ at 1 atmosphere to generate acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 65 ℃ to 125 ℃ at 1 atmosphere of pressure to generate the acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 70 ℃ to 125 ℃ at 1 atmosphere of pressure to generate the acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 75 ℃ to 125 ℃ at 1 atmosphere to generate acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 75 ℃ to 120 ℃ at 1 atmosphere to generate acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 75 ℃ to 115 ℃ at 1 atmosphere to generate acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 75 ℃ to 110 ℃ at 1 atmosphere to generate acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 75 ℃ to 105 ℃ at 1 atmosphere to generate acid. In some embodiments, the compositions described herein require a threshold temperature in the range of 80 ℃ to 100 ℃ at 1 atmosphere to generate acid.

In some embodiments, the heat required to generate an acid using the compositions and methods described herein is naturally present at the location where acid generation is desired. For example, in some embodiments, the heat is from a formation, such as limestone, sandstone, or shale. It should be understood that at 1 atmosphere, the actual threshold temperature for acid generation within the layer (the pressure in the layer is greater than 1 atmosphere) may be less than the temperature described herein.

Other parameters

In some embodiments, the method (or composition) is as described herein, wherein the aqueous fluid has a pH greater than 5 at 1 atmosphere and a temperature less than 65 ℃. In some embodiments, the pH is greater than 6. In some embodiments, the pH is greater than 7. In some embodiments, the pH is greater than 8.

In some embodiments, the present application describes methods for in situ acid stimulation of a formation containing a hydrocarbon reservoir, wherein the layer comprises a carbonate. In some embodiments, the present application describes methods for in situ acid stimulation of a formation containing a hydrocarbon reservoir, wherein the layer comprises sandstone. In some embodiments, the present application describes methods of in situ acid stimulation of a formation containing a hydrocarbon reservoir, wherein the layer comprises shale.

In some embodiments, the method (or composition) is as described herein, wherein the ammonium salt comprises a salt selected from the group consisting of: ammonium halides, ammonium sulfate, ammonium nitrate, ammonium phosphate, ammonium carbonate, and mixtures thereof. In some embodiments, the ammonium salt comprises ammonium chloride. In some embodiments, the ammonium salt comprises ammonium persulfate. In some similar embodiments, the ammonium salt is present in the aqueous fluid at a concentration of 0.001M to saturation.

In some embodiments, a method (or composition) is as described herein, wherein the oxidizing agent comprises an agent selected from the group consisting of: peroxides, persulfates, permanganates, bromates, and mixtures thereof. In some embodiments, the oxidizing agent comprises a bromate salt. In some embodiments, the oxidizing agent comprises sodium bromate. In some embodiments, the oxidizing agent is present in the aqueous fluid at a concentration of 0.001M to saturation.

In some embodiments, the method (or composition) is as described herein, wherein the aqueous fluid further comprises a chelating agent. Exemplary such chelating agents are described above. In some embodiments, the chelating agent is used to sequester calcium salts, such as those generated upon in situ acid stimulation of a calcium carbonate layer. In some embodiments, the ammonium salt comprises a salt selected from the group consisting of: ammonium persulfate, ammonium sulfate, ammonium bisulfate (ammonium bisulfate), ammonium phosphate, and mixtures thereof. In some embodiments, the chelating agent is selected from the group consisting of: 1, 2-cyclohexanediaminetetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), ethanol-diglycine (EDG), ethylenediaminetetraacetic acid (EDTA), N' -bis (carboxymethyl) glycine (NTA), L-glutamic acid N, N-diacetic acid, tetrasodium salt (GLDA), HEDTA (N-hydroxyethyl-ethylenediaminetriacetic acid), hydroxyaminocarboxylic acid (HACA), hydroxyethylidene iminodiacetate (HEIDA), and Sodium Hexametaphosphate (SHMP), and derivatives and mixtures thereof.

In certain embodiments, the chelating agent is Sodium Hexametaphosphate (SHMP) and the ammonium salt comprises ammonium persulfate.

In some embodiments, the method (or composition) is as described herein, wherein the aqueous fluid is free of a free tertiary amine salt or a compound capable of reacting to form a free tertiary amine salt in situ. For example, in some embodiments, the aqueous fluid does not comprise a trialkylamine such as trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, dimethyldodecylamine (dimethyldodecylamine), or dimethyltetradecylamine (dimethylradodecylamine).

Examples

In order that the application may be more fully understood, the following examples are set forth. It should be understood that these examples are for illustrative purposes only and should not be construed as being limiting in any way.