Acid liquor prepared on site and acid fracturing method of acid liquor

Abstract

The invention discloses acid liquor prepared on site. The acid liquor comprises first acid liquor, water, an acid liquor instant thickening agent, an acid liquor tackifying accelerant, a corrosion inhibitor, a demulsifying agent, a discharge aiding agent and an iron ion stabilizer, wherein the mass fraction of the first acid liquor is 60 to 63 percent, the mass fraction of the water is 30 to 33 percent, the mass fraction of the acid liquor instant thickening agent is 0.15 to 0.80 percent, the mass fraction of the acid liquor tackifying accelerant is 0.01 to 0.2 percent, the mass fraction of the corrosion inhibitor is 1 to 3 percent, the mass fraction of the demulsifying agent is 1 to 2 percent, the mass fraction of the cleanup additive is 1 to 2 percent, and the mass fraction of the iron ion stabilizer is 1 to 2 percent. The viscosity of the acid liquid is rapidly improved by using the acid liquid instant thickening agent and the acid liquid tackifying accelerant, online injection and continuous mixing of the first acid liquid, the water and the additive are achieved, and the online prepared acid liquid has good temperature resistance and shear resistance and meets the requirements of online acid fracturing operation of different scales.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas well reservoir transformation, in particular to an acid solution prepared on site and an acid fracturing method of the acid solution. Background Art

[0002] Acid fracturing refers to injecting acid into the formation at a pressure higher than the rock fracture pressure to form cracks in the formation. The acid dissolves the material on the crack wall unevenly to form cracks with high conductivity. Acid fracturing is one of the key technologies for increasing the production of carbonate oil and gas reservoirs. my country's carbonate rocks mainly include cave-type, fracture-cave-type, fracture-hole-type reservoirs, etc. Statistics show that the cumulative production of a single well is not strongly correlated with the scale of acid fracturing. During the acid fracturing process, there is a large amount of designed liquid volume that has not been completed but has not been connected to the reservoir, or the designed liquid volume has not been completed but has been connected. The precise design of the amount of acid is difficult.

[0003] In order to improve the effect of carbonate rock acid fracturing, online acid preparation and acid fracturing methods are developed to achieve on-site preparation, inject the required amount of acid into the formation, judge the communication effect in real time, and stop the pump in time. The difficulty of online acid fracturing lies in the online preparation of acid, and the acid must meet the requirements of resistance reduction and corrosion retardation.

[0004] At present, the commonly used acid systems for acid fracturing include gelling acid, cross-linking acid, variable viscosity acid, steering acid, etc. These acids need to be prepared in advance in the acid tank before use. The preparation process is as follows: add water according to the preparation amount in the hydrochloric acid in the preparation tank, then add corrosion inhibitor, vacuum inhale thickener under stirring conditions, stir for 20-30 minutes to make it sticky, and the viscosity is required to reach more than 80% of the indoor preparation viscosity. Add drainage aids, demulsifiers, iron ion stabilizers or other functional additives, and mix and stir for 30-40 minutes. The viscosity of the prepared acid is generally greater than 12mPa·s. The preparation time of the commonly used acid on site is about 50-70 minutes, and it does not have an online preparation function.

[0005] Therefore, how to realize online configuration of acid has become a technical problem that needs to be solved urgently. Summary of the invention

[0006] The present invention aims to provide an online prepared acid solution and an acid fracturing method for the acid solution, which uses an acid solution instant thickener and an acid solution viscosity increasing promoter to quickly increase the viscosity of the acid solution, thereby realizing online injection and continuous mixing of hydrochloric acid, water and additives. The online prepared acid solution has good temperature resistance and shear resistance, and can meet the needs of online acid fracturing operations of different scales.

[0007] To achieve the above object, the present invention provides an acid solution prepared on site, the acid solution comprising: a first acid solution, water, an acid solution instant thickener, an acid solution viscosity increasing promoter, a corrosion inhibitor, a demulsifier, a drainage aid and an iron ion stabilizer;

[0008] Among them, the mass fractions of the first acid solution, the water, the acid solution quick-dissolving thickener, the acid solution viscosity-increasing promoter, the corrosion inhibitor, the demulsifier, the drainage agent and the iron ion stabilizer are: 60-63%, 30-33%, 0.15-0.80%, 0.01-0.2%, 1-3%, 1-2%, 1-2% and 1-2%, respectively.

[0009] Optionally, the first acid solution includes one or more of the following: hydrochloric acid, formic acid and acetic acid; wherein the mass concentration of hydrochloric acid is 28-31%.

[0010] Optionally, the water includes one or more of the following: fresh water, salt water; wherein the concentration of calcium ions and magnesium ions in the salt water is ≤2000 mg / L.

[0011] Optionally, the acid liquid fast-soluble thickener includes one or more of the following: polyacrylamide and modified polyacrylamide; wherein the particle size range of the acid liquid fast-soluble thickener is 70-300 mesh.

[0012] Optionally, the acid solution viscosity increasing promoter is a mixture of sodium polyacrylate, polyoxyethylene and polyvinyl pyrrolidone.

[0013] Optionally, the corrosion inhibitor includes at least one of the following: a mixture of cinnamaldehyde and aniline, an aldehyde-ketoamine condensate, an imidazoline derivative and a copolymer of a quaternary ammonium salt of quaternary ammonium salt.

[0014] Optionally, the demulsifier includes: a nitrogen-containing polyoxyethylene-polyoxypropylene block copolymer.

[0015] Optionally, the drainage aid includes one or more of the following: a polyether surfactant, a quaternary ammonium salt surfactant, a fluorocarbon surfactant and a polyether carboxylate surfactant.

[0016] Optionally, the iron ion stabilizer is a mixture of fatty alkyl quaternary ammonium salts and fatty aryl alkyl quaternary ammonium salts.

[0017] Optionally, the acid solution is an acid solution whose viscosity is increased to 15 mPa·s-45 mPa·s within 60s-600s.

[0018] The present invention also provides an acid fracturing method for acid solution, the method comprising:

[0019] Prepare the first acid solution, water, acid solution instant thickener, acid solution viscosity increasing accelerator, corrosion inhibitor, demulsifier, drainage aid and iron ion stabilizer;

[0020] Inject the prepared first acid solution, water, acid solution quick-dissolving thickener, acid solution viscosity enhancing agent, corrosion inhibitor, demulsifier, drainage aid and iron ion stabilizer into the formation to complete acid fracturing;

[0021] Among them, the mass fractions of the injected first acid solution, the water, the acid solution quick-dissolving thickener, the acid solution viscosity-increasing promoter, the corrosion inhibitor, the demulsifier, the drainage agent and the iron ion stabilizer are: 60-63%, 30-33%, 0.15-0.80%, 0.01-0.2%, 1-3%, 1-2%, 1-2% and 1-2%, respectively.

[0022] The present invention also provides a method for applying the above method to a carbonate reservoir.

[0023] Technical effects and advantages of the present invention:

[0024] The invention provides an acid solution prepared on site, comprising: a first acid solution, water, an acid solution quick-dissolving thickener, an acid solution viscosity-increasing promoter, a corrosion inhibitor, a demulsifier, a drainage aid and an iron ion stabilizer; wherein the mass fractions of the first acid solution, the water, the acid solution quick-dissolving thickener, the acid solution viscosity-increasing promoter, the corrosion inhibitor, the demulsifier, the drainage aid and the iron ion stabilizer are 60-63%, 30-33%, 0.15-0.80%, 0.01-0.2%, 1-3%, 1-2%, 1-2% and 1-2%, respectively.

[0025] Compared with the prior art, the beneficial effects of the present invention include: (1) The acid solution involved in the present invention can be prepared online, which simplifies the acid solution preparation process. The first acid solution, water, acid solution instant thickener, acid solution viscosity promoter, corrosion inhibitor, demulsifier, drainage agent and iron ion stabilizer are mixed online according to the proportion to obtain the online prepared acid solution. (2) The method involved in the present invention can be prepared on-site, the amount of acid solution required for injection into the formation can be determined in real time, the communication effect can be judged in real time, and the pump can be stopped in time, so as to realize online acid fracturing.

[0026] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flow chart of the method for preparing the acid solution. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings provided by the present invention, and the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0030] In order to solve the deficiencies of the prior art, the present invention discloses an acid solution prepared on site, the acid solution comprising: a first acid solution, water, an acid solution quick-dissolving thickener, an acid solution viscosity-increasing promoter, a corrosion inhibitor, a demulsifier, a drainage aid and an iron ion stabilizer; wherein the mass fractions of the first acid solution, the water, the acid solution quick-dissolving thickener, the acid solution viscosity-increasing promoter, the corrosion inhibitor, the demulsifier, the drainage aid and the iron ion stabilizer are 60-63%, 30-33%, 0.15-0.80%, 0.01-0.2%, 1-3%, 1-2%, 1-2% and 1-2%, respectively.

[0031] The present invention uses an acid liquid instant thickener and an acid liquid viscosity-increasing promoter to quickly increase the viscosity of the acid liquid, thereby achieving online injection and continuous mixing of hydrochloric acid, water and additives. The online prepared acid liquid has good temperature resistance and shear resistance, and meets the needs of online acid fracturing operations of different scales.

[0032] In order to better explain this solution, the following is a detailed explanation of the acid prepared on site:

[0033] The acid solution prepared on site includes: first acid solution, water, acid solution instant thickener, acid solution viscosity accelerator, corrosion inhibitor, demulsifier, drainage aid and iron ion stabilizer;

[0034] Among them, the mass fractions of the first acid solution, the water, the acid solution quick-dissolving thickener, the acid solution viscosity-increasing promoter, the corrosion inhibitor, the demulsifier, the drainage agent and the iron ion stabilizer are: 60-63%, 30-33%, 0.15-0.80%, 0.01-0.2%, 1-3%, 1-2%, 1-2% and 1-2%, respectively.

[0035] Specifically, the first acid solution includes one or more of the following: hydrochloric acid, formic acid and acetic acid; wherein the mass concentration of hydrochloric acid is 28-31%.

[0036] Specifically, the water includes one or more of the following: fresh water, salt water; wherein the concentration of calcium ions and magnesium ions in the salt water is ≤2000 mg / L.

[0037] Specifically, the acid liquid fast-dissolving thickener includes one or more of the following: polyacrylamide and modified polyacrylamide; wherein the particle size range of the acid liquid fast-dissolving thickener is 70-300 meshes.

[0038] Specifically, the acid solution viscosity increasing promoter is a mixture of sodium polyacrylate, polyoxyethylene and polyvinyl pyrrolidone.

[0039] Specifically, the corrosion inhibitor is a copolymer of aldehyde, ketone and amine condensation products, imidazoline derivatives and quaternary ammonium salts of quaternary ammonium salts.

[0040] Specifically, the demulsifier is a nitrogen-containing polyoxyethylene-polyoxypropylene block copolymer.

[0041] Specifically, the drainage aid includes one or more of the following: polyether surfactant, quaternary ammonium salt surfactant, fluorocarbon surfactant and polyether carboxylate surfactant.

[0042] Specifically, the iron ion stabilizer is a mixture of fatty alkyl quaternary ammonium salt and fatty aryl alkyl quaternary ammonium salt.

[0043] Specifically, the acid solution prepared online refers to an acid solution whose viscosity increases to 15 mPa·s-45 mPa·s between 60s-600s.

[0044] The present invention provides an acid solution prepared on site, the acid solution comprising: a first acid solution, water, an acid solution instant thickener, an acid solution viscosity promoter, a corrosion inhibitor, a demulsifier, a drainage aid and an iron ion stabilizer; wherein the mass fractions of the first acid solution, the water, the acid solution instant thickener, the acid solution viscosity promoter, the corrosion inhibitor, the demulsifier, the drainage aid and the iron ion stabilizer are 60-63%, 30-33%, 0.15-0.80%, 0.01-0.2%, 1-3%, 1-2%, 1-2% and 1-2% respectively. The present invention uses an acid solution instant thickener and an acid solution viscosity promoter to quickly increase the viscosity of the acid solution, realize online injection and continuous mixing of the first acid solution, water and additives, and the online prepared acid solution has good temperature resistance and shear resistance, and meets the needs of online acid fracturing operations of different scales.

[0045] The present invention provides an acid fracturing method of an acid solution, such as Figure 1The method comprises: preparing a first acid solution, water, an acid solution quick-dissolving thickener, an acid solution viscosity-enhancing agent, a corrosion inhibitor, a demulsifier, a drainage aid and an iron ion stabilizer; injecting the prepared first acid solution, water, an acid solution quick-dissolving thickener, an acid solution viscosity-enhancing agent, a corrosion inhibitor, a demulsifier, a drainage aid and an iron ion stabilizer into the formation to complete acid fracturing; wherein the mass fractions of the injected first acid solution, the water, the acid solution quick-dissolving thickener, the acid solution viscosity-enhancing agent, the corrosion inhibitor, the demulsifier, the drainage aid and the iron ion stabilizer are 60-63%, 30-33%, 0.15-0.80%, 0.01-0.2%, 1-3%, 1-2%, 1-2% and 1-2%, respectively.

[0046] Specifically, the first acid solution includes one or more of the following: hydrochloric acid, formic acid and acetic acid; wherein the mass concentration of hydrochloric acid is 28-31%.

[0047] Specifically, the water includes one or more of the following: fresh water, salt water; wherein the concentration of calcium ions and magnesium ions in the salt water is ≤2000 mg / L.

[0048] Specifically, the acid liquid fast-dissolving thickener includes one or more of the following: polyacrylamide and modified polyacrylamide; wherein the particle size range of the acid liquid fast-dissolving thickener is 70-300 meshes.

[0049] Specifically, the acid solution viscosity increasing promoter is a mixture of sodium polyacrylate, polyoxyethylene and polyvinyl pyrrolidone.

[0050] Specifically, the corrosion inhibitor is a copolymer of aldehyde, ketone and amine condensation products, imidazoline derivatives and quaternary ammonium salts of quaternary ammonium salts.

[0051] Specifically, the demulsifier is a nitrogen-containing polyoxyethylene-polyoxypropylene block copolymer.

[0052] Specifically, the drainage aid includes one or more of the following: polyether surfactant, quaternary ammonium salt surfactant, fluorocarbon surfactant and polyether carboxylate surfactant.

[0053] Specifically, the iron ion stabilizer is a mixture of fatty alkyl quaternary ammonium salt and fatty aryl alkyl quaternary ammonium salt.

[0054] Specifically, the acid solution prepared online refers to an acid solution whose viscosity increases to 15 mPa·s-45 mPa·s between 60s-600s.

[0055] Specifically, the injection and displacement of the first acid solution, water, acid solution instant thickener, acid solution viscosity accelerator, corrosion inhibitor, demulsifier, drainage aid and iron ion stabilizer are all 6m 3 / min.

[0056] The present invention also provides an application of the acid fracturing method to carbonate reservoirs.

[0057] In order to make this solution more substantial, the present invention also provides embodiments.

[0058] Example 1

[0059] An online acid preparation and acid fracturing method, the method comprising the following steps:

[0060] 1. Prepare sufficient 31% hydrochloric acid (density 1.1 g / cm 3 ), water, acid instant thickener, acid viscosity increasing promoter, corrosion inhibitor, demulsifier, drainage aid, iron ion stabilizer.

[0061] 2. The prepared hydrochloric acid, water, acid instant thickener, acid viscosity accelerator, corrosion inhibitor, demulsifier, drainage aid, and iron ion stabilizer are injected into the formation simultaneously through a pump according to 61, 31.6, 0.3, 0.1, 2, 2, 2, and 1 parts by weight respectively; the injection displacement is 6m 3 / min.

[0062] 3. When the cumulative injection is 180m 3 Finally, it is determined that the construction pressure has reached the reservoir level, so injection is stopped, the acid fracturing construction is completed, and the remaining materials are transferred to other well sites.

[0063] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An acid solution prepared on site, characterized in that: The acid solution comprises: a first acid solution, water, an acid solution quick-dissolving thickener, an acid solution viscosity-increasing accelerator, a corrosion inhibitor, a demulsifier, a drainage aid and an iron ion stabilizer; Among them, the mass fractions of the first acid solution, the water, the acid solution quick-dissolving thickener, the acid solution viscosity-increasing promoter, the corrosion inhibitor, the demulsifier, the drainage agent and the iron ion stabilizer are: 60-63%, 30-33%, 0.15-0.80%, 0.01-0.2%, 1-3%, 1-2%, 1-2% and 1-2%, respectively.

2. The acid solution according to claim 1, characterized in that The first acid solution includes one or more of the following: hydrochloric acid, formic acid and acetic acid; wherein the mass concentration of hydrochloric acid is 28-31%.

3. The acid solution according to claim 1, characterized in that The water includes one or more of the following: fresh water, salt water; wherein the concentration of calcium ions and magnesium ions in the salt water is ≤2000 mg / L.

4. The acid solution according to claim 1, characterized in that The acid liquid fast-dissolving thickener comprises one or more of the following: polyacrylamide and modified polyacrylamide; wherein the particle size range of the acid liquid fast-dissolving thickener is 70-300 meshes.

5. The acid solution according to claim 1, characterized in that The acid solution viscosity increasing promoter is a mixture of sodium polyacrylate, polyoxyethylene and polyvinyl pyrrolidone.

6. The acid solution according to claim 1, characterized in that The corrosion inhibitor comprises at least one of the following: a mixture of cinnamaldehyde and aniline, an aldehyde ketone amine condensate, an imidazoline derivative and a copolymer of a quaternary ammonium salt of quaternary ammonium salt.

7. The acid solution according to claim 1, characterized in that The demulsifier comprises: a nitrogen-containing polyoxyethylene-polyoxypropylene block copolymer.

8. The acid solution according to claim 1, characterized in that The drainage aid includes one or more of the following: polyether surfactant, quaternary ammonium salt surfactant, fluorocarbon surfactant and polyether carboxylate surfactant.

9. The acid solution according to claim 1, characterized in that The iron ion stabilizer is a mixture of fatty alkyl quaternary ammonium salt and fatty aryl alkyl quaternary ammonium salt.

10. The acid solution according to claim 1, characterized in that The acid solution is an acid solution whose viscosity is increased to 15 mPa·s-45 mPa·s within 60s-600s.

11. A method for acid fracturing based on the acid solution according to any one of claims 1 to 10, characterized in that: The method comprises: Prepare the first acid solution, water, acid solution instant thickener, acid solution viscosity increasing accelerator, corrosion inhibitor, demulsifier, drainage aid and iron ion stabilizer; Inject the prepared first acid solution, water, acid solution quick-dissolving thickener, acid solution viscosity enhancing agent, corrosion inhibitor, demulsifier, drainage aid and iron ion stabilizer into the formation to complete acid fracturing; Among them, the mass fractions of the injected first acid solution, the water, the acid solution quick-dissolving thickener, the acid solution viscosity-increasing promoter, the corrosion inhibitor, the demulsifier, the drainage agent and the iron ion stabilizer are: 60-63%, 30-33%, 0.15-0.80%, 0.01-0.2%, 1-3%, 1-2%, 1-2% and 1-2%, respectively.

12. The acid fracturing method of claim 11, further characterized in that: The method is applied to carbonate reservoirs.

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