Corrosion and scale inhibition integrated fracturing fluid

Abstract

The application discloses a kind of corrosion and scale integrated fracturing fluid, and relates to fracturing fluid technical field.The fracturing fluid includes thickening agent, crosslinking agent, composite corrosion and scale inhibitor and water;The composite corrosion and scale inhibitor includes the first component and the second component with mass ratio of 3:0.5~1, wherein the first component is prepared by the reaction of polyethyleneimine, long-chain acrylate monomer, acrylic acid monomer and hydroxyethyl acrylate monomer, and the second component is prepared by imidazole compound containing a primary amine and glyoxylic acid.The corrosion and scale integrated fracturing fluid of the application has good compatibility between components, and at the same time, it has good corrosion and scale inhibition and anti-sloughing performance.

Description

Technical Field

[0001] This invention relates to the field of fracturing fluid technology, specifically to an integrated corrosion and scale inhibitor fracturing fluid. Background Technology

[0002] Fracturing fluid is the working fluid used when fracturing oil and gas reservoirs. Its main function is to use the principle of liquid pressure transmission to inject fracturing fluid with a certain viscosity into the oil reservoir at a pressure greater than the reservoir's absorption capacity, thereby gradually increasing the pressure inside the wellbore, causing the formation to fracture and transport proppant along the fracture.

[0003] However, with the in-depth development of shale reservoirs, a large number of scale-forming ions, such as calcium, magnesium, and carbonate ions, are usually present in the formation water downhole. These ions not only corrode downhole tools but also easily form precipitates with other substances. Simultaneously, other materials, such as sulfides and carbon dioxide, also corrode downhole tools. To address the aforementioned scaling and corrosion problems, scale inhibitors and corrosion inhibitors are typically added to fracturing fluids. Furthermore, when applied to shale reservoirs, existing fracturing fluids also contain anti-collapse inhibitors to prevent hydration of the shale reservoir. When too many materials are added to the drilling fluid, the compatibility between them needs to be considered. For example, some quaternary ammonium salt agents used for anti-collapse and polycarboxylate agents used for scale inhibition have poor compatibility, making it difficult to use them simultaneously in the same fracturing fluid, thus increasing the cost of the fracturing fluid. Summary of the Invention

[0004] In view of the above technical problems, the purpose of this invention is to provide an integrated corrosion and scale inhibitor fracturing fluid to address the shortcomings of the prior art.

[0005] The present invention adopts the following technical solution: an integrated corrosion and scale inhibitor fracturing fluid, comprising, by mass percentage, 0.1~1.0% thickener, 0.1~0.5% crosslinking agent, 0.2~0.8% composite corrosion and scale inhibitor, with the balance being water; the composite corrosion and scale inhibitor comprises a first component and a second component in a mass ratio of 3:0.5~1.

[0006] The preparation method of the first component by mass is as follows: Take 10 parts of branched polyethyleneimine and dissolve it, then add 0.5~1 parts of long-chain acrylate monomer, 4~7 parts of acrylic monomer, and 1~3 parts of hydroxyethyl acrylate monomer, and continue to react for 10~30 hours under the action of an alkaline catalyst. After the reaction is completed, separate and purify it to obtain the product.

[0007] The preparation method of the second component is as follows: a reaction monomer and glyoxylic acid with a molar ratio of 1:1 to 1.2 are subjected to a Schiff base reaction. After the reaction is completed, the mixture is separated and purified to obtain the product. The reaction monomer is an imidazole compound containing a primary amine.

[0008] In the first component mentioned above, the branched polyethyleneimine backbone has multiple amino groups, and its side chains have multiple primary and secondary amine groups. The large number of amino groups gives polyethyleneimine a certain degree of anti-collapse properties. At the same time, amino groups can adsorb onto the metal surface to form a corrosion-inhibiting film, thereby preventing the corrosive medium from corroding the metal, thus having a certain degree of corrosion resistance. Amino groups also have adsorption properties, which can adsorb scale particles in water. They also have a certain degree of chelation, thus having a certain scale inhibition ability.

[0009] Grafting long-chain acrylate monomers, acrylic acid monomers, and hydroxyethyl acrylate monomers significantly improves its performance: acrylic acid monomers contain carboxyl groups, which can chelate with calcium and magnesium ions in water. Simultaneously, the combined action of carboxyl and amino groups forms a more stable adsorption film on the metal surface, thus greatly enhancing its corrosion and scale inhibition performance. Hydroxyethyl acrylate contains hydroxyl and carboxylic acid ester groups, which can further enhance the adsorption effect through hydrogen bonding and coordination bonds; the long-chain acrylate imparts a certain degree of hydrophobicity to the product, increasing the adsorption film's resistance to water erosion and improving its density. Modification of branched polyethyleneimine with these three monomers—long-chain acrylate monomers, acrylic acid monomers, and hydroxyethyl acrylate monomers—significantly enhances its scale and corrosion inhibition performance.

[0010] As for the second component, the imidazole monomers contain two nitrogen atoms, so they can be adsorbed onto the metal surface well. After being modified by glyoxylic acid, the resulting Schiff base further enhances its film-forming properties. At the same time, the carboxyl group in glyoxylic acid gives it better compatibility with the first component.

[0011] One embodiment of the present invention is that the thickener is a guar gum-based thickener, and the crosslinking agent is one of a chromium crosslinking agent or a boron crosslinking agent. Guar gum-based thickeners are common thickeners in the art. Furthermore, when applied to the present invention, common crosslinking agents for guar gum-based thickeners, such as chromium crosslinking agents and borax, can also be used. The composite corrosion and scale inhibitor of the present invention has good compatibility with these crosslinking agents. Although some guar gum fracturing fluids in the prior art do not contain crosslinking agents, their rock-carrying capacity is relatively poor. Therefore, crosslinking agents are usually added to guar gum fracturing fluids.

[0012] In one embodiment of the present invention, the fracturing fluid further includes 0.1-0.5% of a flow-aiding agent, which is a fluorocarbon surfactant. The flow-aiding agent is mainly used to improve reservoir wettability and is a conventional additive in the art; for example, perfluorooctane sulfonate and perfluorooctanoic acid can be used in this invention. Of course, other flow-aiding agents, such as sodium dodecylbenzene sulfonate, can also be used in this invention.

[0013] One embodiment of the present invention is that the long-chain acrylate monomer has the following structural formula: In the formula, R1 is either -H or -CH3, R2 is a straight-chain alkyl group with a carbon chain length of 10 to 18, such as lauryl methacrylate and hexadecyl methacrylate, which are all conventional commercial products; the acrylic monomer is one of acrylic acid, methacrylic acid, sodium acrylate, and sodium methacrylate; the hydroxyethyl acrylate monomer is one of hydroxyethyl acrylate and hydroxyethyl methacrylate.

[0014] In one embodiment of the present invention, during the preparation of the first component, the branched polyethyleneimine solvent is a mixture of ethanol and toluene in a volume ratio of 10:1~2, the reaction temperature is 20~50°C, and the alkaline catalyst is one of triethylamine and sodium ethoxide, with the amount of alkaline catalyst added being 0.5~5 parts. In fact, esterified polyethyleneimine is soluble in ethanol; however, the solubility of long-chain acrylate monomers in ethanol is poor. Therefore, in order to dissolve all materials, this embodiment designs a mixed solvent.

[0015] One embodiment of the present invention is that the separation and purification of the first component includes the following steps: taking the product, removing low-boiling substances, washing it several times with diethyl ether and drying it to obtain the final product.

[0016] In one embodiment of the present invention, the reactant monomer is one of 1-(3-aminopropyl)imidazolium, 2-amino-1-methylimidazolium, or 2-aminomethylimidazolium hydrochloride. In the preparation of the second component, a Schiff base reaction is mainly carried out using the amino group of the reactant monomer and the aldehyde group of glyoxylic acid. The Schiff base reaction is a relatively mature reaction. In this invention, for 1-(3-aminopropyl)imidazolium and 2-amino-1-methylimidazolium, the reaction can be carried out at a temperature of 20-60°C with ethanol as a solvent for 5-24 hours. Alternatively, a small amount of acetic acid can be added during the reaction (to maintain the pH between 4 and 6) as a catalyst. For 2-aminomethylimidazolium hydrochloride, a certain amount of alkali needs to be added to adjust the pH to 7-9, and the reaction is carried out at 20-60°C for 3-10 hours. The second component can be separated and purified by directly removing low-boiling-point substances through vacuum drying.

[0017] The beneficial effects of the present invention are: the integrated corrosion and scale inhibition fracturing fluid of the present invention has a small number of components, good compatibility between the components, and good corrosion and scale inhibition and anti-collapse performance. The corrosion inhibition rate and scale inhibition rate can reach more than 96%, and the rolling recovery rate can reach more than 85%. Detailed Implementation

[0018] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail with reference to the embodiments, but this should not be construed as limiting the scope of implementation of the present invention.

[0019] Unless otherwise specified, the operations described in the following embodiments are conventional operations in the art.

[0020] Unless otherwise specified, the raw materials used in the following embodiments are all conventional commercial products in the art.

[0021] In the following embodiments, unless otherwise specified, the number of parts refers to parts by weight.

[0022] In the following examples, the scale inhibition rate was measured according to the method in GB / T 16632-2019 "Determination of scale inhibition performance of water treatment agents - calcium carbonate deposition method".

[0023] In the following examples, the corrosion inhibition rate was measured using the following method: 2 wt% potassium chloride was added to the fracturing fluid, and the corrosion inhibition rate was measured using the rotating clip method, wherein the clip material was carbon steel, and the test time was 10 days.

[0024] In the following examples, the rolling recovery rate was measured according to the method in SY / T 5621-2018 "Evaluation Method of Shale Inhibitor for Drilling Fluids" at a test temperature of 80°C.

[0025] Example 1: An integrated corrosion and scale inhibitor fracturing fluid comprises 0.45 wt% hydroxypropyl guar gum, 0.2 wt% borax, 0.6 wt% a composite corrosion and scale inhibitor, and 0.2 wt% sodium perfluorooctane sulfonate, which are stirred until homogeneous. The composite corrosion and scale inhibitor consists of a first component and a second component in a mass ratio of 3:0.7.

[0026] The preparation method of the first component is as follows: Take 10 parts by mass of branched polyethyleneimine and dissolve it in a mixture of ethanol and toluene with a volume ratio of 10:1.5. Add 1 part of triethylamine and stir to dissolve it. Under the condition of 35°C, add 0.8 parts of lauryl methacrylate, 5 parts of sodium acrylate (prepared into a solution by adding ethanol), and 2 parts of hydroxyethyl methacrylate dropwise to the aforementioned branched polyethyleneimine solution and continue stirring for 20 hours. After the reaction is completed, remove the low-boiling substances by vacuum distillation, wash the solid phase several times with diethyl ether and dry to obtain the final product.

[0027] The preparation method of the second component is as follows: 1 mole of 2-aminomethylimidazolium hydrochloride is dissolved in ethanol, and 1.1 moles of glyoxylic acid are added. Triethylamine is added to adjust the pH to 8. The reaction is carried out under stirring at 30°C for 6 hours. After the reaction is completed, the low-boiling substances are removed by vacuum distillation to obtain the final product.

[0028] Compared with fracturing fluid without the addition of composite corrosion and scale inhibitor, the scale inhibition rate of the fracturing fluid prepared in this embodiment was 97.4%, the corrosion inhibition rate was 96.1%, and the rolling recovery rate was 85.6%.

[0029] Example 2: An integrated corrosion and scale inhibitor fracturing fluid comprises 0.55 wt% hydroxypropyl guar gum, 0.28 wt% borax, 0.4 wt% a composite corrosion and scale inhibitor, and 0.4 wt% sodium dodecylbenzenesulfonate, which are stirred until homogeneous. The composite corrosion and scale inhibitor consists of a first component and a second component in a mass ratio of 3:0.5.

[0030] The preparation method of the first component is as follows: Take 10 parts by mass of branched polyethyleneimine and dissolve it in a mixture of ethanol and toluene with a volume ratio of 10:1.5. Add 4 parts of triethylamine and stir to dissolve it. Under the condition of 45°C, add 0.6 parts of hexadecyl methacrylate, 6 parts of acrylic acid, and 1.5 parts of hydroxyethyl methacrylate dropwise to the aforementioned branched polyethyleneimine solution and continue stirring for 15 hours. After the reaction is completed, remove the low-boiling substances by vacuum distillation. Then wash the solid phase several times with diethyl ether and dry to obtain the final product.

[0031] The preparation method of the second component is as follows: 1 mole of 1-(3-aminopropyl)imidazolium is dissolved in ethanol, and 1.1 moles of glyoxylic acid are added at the same time. The mixture is stirred continuously at 40°C for 20 hours. After the reaction is completed, the low-boiling substances are removed by vacuum distillation to obtain the final component.

[0032] Compared with fracturing fluid without the addition of composite corrosion and scale inhibitor, the scale inhibition rate of the fracturing fluid prepared in this embodiment was 96.3%, the corrosion inhibition rate was 93.2%, and the rolling recovery rate was 88.1%.

[0033] Example 3: An integrated corrosion and scale inhibitor fracturing fluid, comprising 0.6 wt% guar gum, 0.32 wt% borax, and 0.7 wt% a composite corrosion and scale inhibitor, which are stirred until homogeneous. The composite corrosion and scale inhibitor consists of a first component and a second component in a mass ratio of 3:1.

[0034] The preparation method of the first component is as follows: Take 10 parts by mass of branched polyethyleneimine and dissolve it in a mixture of ethanol and toluene with a volume ratio of 10:1.5. Add 4 parts of triethylamine and stir to dissolve it. Under the condition of 25°C, add 1.0 part of dodecyl methacrylate, 5.5 parts of acrylic acid, and 1.2 parts of hydroxyethyl methacrylate dropwise to the aforementioned branched polyethyleneimine solution and continue stirring for 28 hours. After the reaction is completed, remove the low-boiling substances by vacuum distillation. Then wash the solid phase several times with diethyl ether and dry to obtain the final product.

[0035] The preparation method of the second component is as follows: 1 mole of 1-(3-aminopropyl)imidazolium is dissolved in ethanol, and 1.1 moles of glyoxylic acid are added at the same time. The mixture is stirred continuously at 50°C for 12 hours. After the reaction is completed, the low-boiling substances are removed by vacuum distillation to obtain the final product.

[0036] Compared with fracturing fluid without the addition of composite corrosion and scale inhibitor, the scale inhibition rate of the fracturing fluid prepared in this embodiment was 98.7%, the corrosion inhibition rate was 96.4%, and the rolling recovery rate was 81.0%.

[0037] Comparative Example 1, an integrated corrosion and scale inhibitor fracturing fluid, differs from Example 1 in that the composite corrosion and scale inhibitor contains only the first component, while the rest are the same.

[0038] Compared with fracturing fluid without added composite corrosion and scale inhibitor, the scale inhibition rate of the fracturing fluid prepared in this comparative example was 95.2%, the corrosion inhibition rate was 60.5%, and the rolling recovery rate was 86.5%.

[0039] Comparative Example 2, an integrated corrosion and scale inhibitor fracturing fluid, differs from Example 1 in that lauryl methacrylate was not added during the preparation of the first component, while the rest were the same.

[0040] Compared with fracturing fluid without the addition of composite corrosion and scale inhibitor, the scale inhibition rate of the fracturing fluid prepared in this comparative example was 97.1%, the corrosion inhibition rate was 87.0%, and the rolling recovery rate was 76.5%.

[0041] Comparative Example 3, an integrated corrosion and scale inhibitor fracturing fluid, differs from Example 1 in that hydroxyethyl methacrylate was not added during the preparation of the first component, while the rest were the same.

[0042] Compared with fracturing fluid without added composite corrosion and scale inhibitor, the scale inhibition rate of the fracturing fluid prepared in this comparative example was 90.3%, the corrosion inhibition rate was 92.6%, and the rolling recovery rate was 81.4%.

[0043] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An integrated corrosion and scale inhibitor fracturing fluid, characterized in that, The product comprises, by mass percentage, 0.1-1.0% thickener, 0.1-0.5% crosslinking agent, 0.2-0.8% composite corrosion and scale inhibitor, with the balance being water; the composite corrosion and scale inhibitor comprises a first component and a second component in a mass ratio of 3:0.5-1. The preparation method of the first component by mass is as follows: Take 10 parts of branched polyethyleneimine and dissolve it, then add 0.5~1 parts of long-chain acrylate monomer, 4~7 parts of acrylic monomer, and 1~3 parts of hydroxyethyl acrylate monomer, and continue to react for 10~30 hours under the action of an alkaline catalyst. After the reaction is completed, separate and purify it to obtain the product. The preparation method of the second component is as follows: a reaction monomer and glyoxylic acid with a molar ratio of 1:1 to 1.2 are subjected to a Schiff base reaction. After the reaction is completed, the mixture is separated and purified to obtain the product. The reaction monomer is an imidazole compound containing a primary amine.

2. The integrated corrosion and scale inhibitor fracturing fluid according to claim 1, characterized in that, The thickener is a guar gum-based thickener, and the crosslinking agent is one of a chromium crosslinking agent or a boron crosslinking agent.

3. The integrated corrosion and scale inhibitor fracturing fluid according to claim 1, characterized in that, The fracturing fluid also includes 0.1-0.5% of a flow aid, which is a fluorocarbon surfactant.

4. The integrated corrosion and scale inhibitor fracturing fluid according to claim 1, characterized in that, The structural formula of the long-chain acrylate monomer is shown below: In the formula, R1 is either -H or -CH3, and R2 is a straight-chain alkyl group with a carbon chain length of 10 to 18; the acrylic monomer is one of acrylic acid, methacrylic acid, sodium acrylate, and sodium methacrylate; the hydroxyethyl acrylate monomer is one of hydroxyethyl acrylate and hydroxyethyl methacrylate.

5. The integrated corrosion and scale inhibitor fracturing fluid according to claim 1, characterized in that, In the preparation of the first component, the solvent for branched polyethyleneimine is a mixture of ethanol and toluene with a volume ratio of 10:1~2, the reaction temperature is 20~50℃, the alkaline catalyst is one of triethylamine and sodium ethoxide, and the amount of alkaline catalyst added is 0.5~5 parts.

6. The integrated corrosion and scale inhibitor fracturing fluid according to claim 1, characterized in that, The separation and purification of the first component includes the following steps: take the product, remove low-boiling substances, wash it several times with diethyl ether and dry it to obtain the final product.

7. The integrated corrosion and scale inhibitor fracturing fluid according to claim 1, characterized in that, The reaction monomer is one of 1-(3-aminopropyl)imidazolium, 2-amino-1-methylimidazolium, and 2-aminomethylimidazolium hydrochloride.