A carbon capture cement self-repairing agent and its preparation method and application

Abstract

The present invention relates to the field of cement ring self-repair technology, and in particular to a carbon capture cement self-repairing agent, its preparation method, and application. The present invention comprises uniformly mixing a water-based epoxy resin, a surfactant, and water to obtain an epoxy emulsion; adding a tertiary amine curing agent to the epoxy emulsion for reaction to obtain a carbon capture cement self-repairing agent solution; and freeze-drying and then grinding the carbon capture cement self-repairing agent solution to obtain the carbon capture cement self-repairing agent. The carbon capture cement self-repairing agent obtained by the present invention is easy to prepare industrially, is beneficial for improving the rheological properties of cement slurry, and can achieve rapid self-repair of the cement matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of self-repairing of cement rings for well cementing, and in particular to a carbon capture cement self-repairing agent, a preparation method thereof, and applications thereof. Background Art

[0002] Well cementing is a crucial step in oil and gas extraction, directly determining its quality. Cement slurry is injected between the casing and the formation to form a bonded seal, thereby protecting the well casing, extending well life, and increasing oil and gas production. However, cement-based materials are brittle and susceptible to cracking under external loads and environmental changes, leading to a loss of the cement sheath's sealing integrity and a serious threat to oil and gas extraction safety. Considering the effectiveness and cost of repairing cement sheaths, self-healing technologies derived from the biological field are becoming the leading solution to cement sheath cracking.

[0003] Considering the high-temperature and complex environment of cement sheaths, self-repair methods such as those involving the addition of crystallization accelerators to stimulate secondary hydration of unhydrated cement particles in the cement to achieve crack closure have broader applications and better microcrack filling. Gong et al. used calcium carbonate whiskers to induce the formation of calcium carbonate crystals in a high-concentration carbon dioxide environment. After 28 days of self-repair, the volume self-repair rate of cement matrix cracks incorporating calcium carbonate whiskers reached 55.24%. Peng et al. synthesized a permeable crystallization self-repairing agent, CWS. Studies have shown that after 28 days of self-repair, the permeability of the cement matrix incorporating CWS decreased by 97.5%, and the strength recovery rate was 92.7%.

[0004] However, the self-healing products produced by self-healing are primarily calcium carbonate, produced by the carbonation of calcium hydroxide. This still suffers from a slow self-healing rate, typically requiring 14 to 28 days to achieve a high self-healing rate. This limits the application value of self-healing in cementing projects. Therefore, providing a new carbon capture cement self-healing agent that accelerates the absorption of carbon dioxide by the cement matrix, promotes the generation of self-healing products, and significantly increases the self-healing rate of the cement matrix is ​​of great significance to the field of cement sheath self-healing technology. Summary of the Invention

[0005] Based on the above content, the present invention provides a carbon capture cement self-repairing agent and its preparation method and application.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is a method for preparing a carbon capture cement self-repairing agent, comprising the following steps:

[0008] uniformly mixing a water-based epoxy resin, a surfactant and water to obtain an epoxy emulsion;

[0009] adding a tertiary amine curing agent to the epoxy emulsion for reaction to obtain a carbon capture cement self-repairing agent solution;

[0010] The carbon capture cement self-repairing agent solution is freeze-dried and then ground to obtain the carbon capture cement self-repairing agent.

[0011] The second technical solution of the present invention is a carbon capture cement self-repairing agent prepared according to the above-mentioned preparation method.

[0012] The third technical solution of the present invention is the application of the carbon capture cement self-repairing agent in the self-repair of cement rings.

[0013] The fourth technical solution of the present invention is a self-repairing cement-based material, the raw materials of which include the carbon capture cement self-repairing agent and cement.

[0014] The present invention discloses the following technical effects:

[0015] 1. The preparation method of the carbon capture cement self-repairing agent of the present invention is simple and easy to realize industrial production.

[0016] 2. The carbon capture cement self-repairing agent of the present invention has little effect on cement hydration and is beneficial to improving the rheological properties of cement.

[0017] 3. The carbon capture cement self-healing agent of the present invention has excellent carbon capture performance, can accelerate the generation of cement matrix self-healing products, and significantly improve the self-healing ability of the cement matrix. Compared with the blank G-grade oil well cement matrix, the improvement is as much as 516.3%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Scanning electron microscope images and X-ray energy spectrum analysis images of the carbon capture cement self-healing agent prepared in Example 1 in a cement matrix, wherein (a) is a morphology image of the carbon capture cement self-healing agent in the cement matrix, (b) is a local magnified image of the carbon capture cement self-healing agent in the cement matrix, (c) is a C element distribution image, (d) is an O element distribution image, (e) is a N element distribution image, and (f) is a Ca element distribution image;

[0020] Figure 2Thermogravimetric test diagram of the carbon capture cement self-healing agent prepared in Example 1, wherein (a) is the thermogravimetric curve, and (b) is the first-order derivative curve of the thermogravimetric curve;

[0021] Figure 3 This is a carbon dioxide adsorption test graph of the carbon capture cement self-healing agent prepared in Example 1;

[0022] Figure 4 Rheological test graphs of cement matrices prepared in the control example, example 1, example 2, and example 3;

[0023] Figure 5 The hydration heat release test diagrams of the cement matrix prepared in the control example, Example 1, Example 2 and Example 3;

[0024] Figure 6 The super depth of field pictures and the repair rates of the cement matrix prepared in the control example and Example 1 before and after repair, wherein, (a) is the super depth of field picture and the repair rate of the cement matrix prepared in Example 1 before repair, (b) is the super depth of field picture and the repair rate of the cement matrix prepared in Example 1 after 1 day of repair, (c) is the super depth of field picture and the repair rate of the cement matrix prepared in Example 1 after 7 days of repair, (d) is the super depth of field picture and the repair rate of the cement matrix prepared in the control example before repair, (e) is the super depth of field picture and the repair rate of the cement matrix prepared in the control example after 1 day of repair, and (f) is the super depth of field picture and the repair rate of the cement matrix prepared in the control example after 7 days of repair. DETAILED DESCRIPTION

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0029] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0030] A first aspect of the present invention provides a method for preparing a carbon capture cement self-repairing agent, comprising the following steps:

[0031] uniformly mixing a water-based epoxy resin, a surfactant and water to obtain an epoxy emulsion;

[0032] adding a tertiary amine curing agent to the epoxy emulsion for reaction to obtain a carbon capture cement self-repairing agent solution;

[0033] The carbon capture cement self-repairing agent solution is freeze-dried and then ground to obtain the carbon capture cement self-repairing agent.

[0034] In a preferred embodiment of the present invention, the mass fraction of the waterborne epoxy resin in the epoxy emulsion is 50.0%-60.0%; the mass fraction of the surfactant in the epoxy emulsion is 0.5%-0.6%.

[0035] In the present invention, if the surfactant content in the epoxy emulsion is too high, the cost of the carbon capture cement self-healing agent will increase. If the surfactant content is too low, the epoxy resin emulsion will be unstable, and the carbon capture cement self-healing agent solution will react incompletely and unevenly. If the water-based epoxy resin content in the epoxy emulsion is too high, the emulsion will be unstable, the reaction will be uneven, and the tertiary amine group content will be low. If the water-based epoxy resin content is too low, the yield of the carbon capture cement self-healing agent will be too low, and the cost will increase. Therefore, the present invention preferably limits the mass fractions of the water-based epoxy resin and surfactant in the epoxy emulsion to the above parameter ranges.

[0036] In a preferred embodiment of the present invention, the waterborne epoxy resin is a waterborne modified bisphenol A epoxy resin, a waterborne modified bisphenol F epoxy resin or a waterborne modified bisphenol S epoxy resin; and the surfactant is Span-80, Span-60 or Span-85.

[0037] In a preferred embodiment of the present invention, the waterborne epoxy resin has an epoxy value of 0.41-0.51 and an average dispersed particle size in water of 4-8 μm. In a further preferred embodiment of the present invention, the waterborne modified bisphenol A epoxy resin has an epoxy value of 0.51; the waterborne modified bisphenol F epoxy resin has an epoxy value of 0.44; and the waterborne modified bisphenol S epoxy resin has an epoxy value of 0.41.

[0038] In the present invention, if the epoxy value of the water-based epoxy resin is too low, the yield of the carbon capture cement self-healing agent solution will be too low, and the thermal stability of the prepared carbon capture cement self-healing agent will be worse; if the dispersed particle size in water is too high, the carbon capture cement self-healing agent will not be evenly dispersed in the cement matrix, further deteriorating the mechanical properties of the cement matrix and failing to improve the rheological properties of the cement.

[0039] In a preferred embodiment of the present invention, the mass fraction of the tertiary amine curing agent in the epoxy emulsion is 25.0%-30.0%.

[0040] In a preferred embodiment of the present invention, the tertiary amine curing agent is dimethylaminopropylamine, 4-dimethylaminobutylamine or dimethylaminoethylamine.

[0041] In the present invention, the tertiary amine curing agent not only acts as an epoxy resin curing agent, but also provides abundant tertiary amine groups. The carbon capture cement self-healing agent prepared in this way has more carbon dioxide capture sites and better self-healing effect. If other curing agents commonly used in the field, such as triethylenetetramine, m-phenylenediamine, and diaminodiphenyl sulfone, are used, a cross-linked structure will be formed, and after curing, a self-healing agent solution will not be formed, making it difficult to evenly disperse in the cement paste. In addition, the nitrogen content of the carbon capture cement self-healing agent is reduced, and sufficient tertiary amine groups cannot be provided as stable carbon dioxide capture sites, resulting in a decrease in self-healing performance.

[0042] In a preferred embodiment of the present invention, the reaction temperature is 60-80° C. and the reaction time is 4-10 h.

[0043] The present invention does not impose any particular limitation on the freeze-drying parameter settings, and conventional freeze-drying parameter settings in the art may be used.

[0044] The present invention does not impose any particular limitation on the particle size of the ground material, and the particle size conventionally added to cement in the art may be used, such as 10-100 microns.

[0045] A second aspect of the present invention provides a carbon capture cement self-repairing agent prepared according to the above-mentioned preparation method.

[0046] The third aspect of the present invention provides the use of the carbon capture cement self-repairing agent in the self-repair of cement sheaths of well cementing.

[0047] A fourth aspect of the present invention provides a self-repairing cement-based material, the raw materials of which include the carbon capture cement self-repairing agent and cement.

[0048] In a preferred embodiment of the present invention, the mass ratio of the carbon capture cement self-repairing agent to the cement is (1-6):(99-94).

[0049] The self-repairing cement-based material has good self-repairing performance in a high-temperature carbon dioxide environment.

[0050] In some specific implementation cases of the present invention, the cement is Grade G oil well cement.

[0051] Unless otherwise specified, the technical solutions described in the present invention are all conventional solutions in the field, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0052] The G-grade oil well cement used in the embodiments of the present invention comes from Sichuan Jiahua Enterprise Co., Ltd., and the G-grade oil well cement obtained through other channels is also applicable to the present invention.

[0053] The epoxy value of the water-based modified bisphenol A epoxy resin used in the embodiment of the present invention is 0.51, and the average dispersed particle size in water is 4.1 μm; the epoxy value of the water-based modified bisphenol F epoxy resin is 0.44, and the average dispersed particle size in water is 5.3 μm; the epoxy value of the water-based modified bisphenol S epoxy resin is 0.41, and the average dispersed particle size in water is 7.8 μm.

[0054] The test method involved in the present invention is as follows:

[0055] The carbon dioxide adsorption test method is a conventional technical means in this field and is not the focus of patent protection of this invention, so it will not be described in detail here; the rheological test and hydration exothermic test refer to the GB / T 19139-2012 standard.

[0056] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0057] Example 1

[0058] A method for preparing a carbon capture cement self-repairing agent, comprising the following steps:

[0059] (1) Preparation of epoxy emulsion: A water-based modified bisphenol A epoxy resin, Span-80 and water were mixed and stirred at 10,000 rpm to obtain an epoxy emulsion; the mass fraction of the water-based modified bisphenol A epoxy resin in the epoxy emulsion was 50.0%; the mass fraction of Span-80 in the epoxy emulsion was 0.5%.

[0060] (2) Preparation of carbon capture cement self-healing agent solution: Dimethylaminopropylamine was added to the epoxy emulsion (so that the mass fraction of dimethylaminopropylamine in the epoxy emulsion was 25.0%), stirred at 400 rpm, and reacted at 60°C for 4 hours to obtain the carbon capture cement self-healing agent solution.

[0061] (3) Preparation of carbon capture cement self-repairing agent: freeze-dry the carbon capture cement self-repairing agent solution obtained in step (2) and grind it to obtain a dry carbon capture cement self-repairing agent.

[0062] (4) Carbon capture cement self-healing agent, water, and G-grade oil well cement are prepared according to a water-cement ratio of 0.44 and a mass ratio of carbon capture cement self-healing agent to G-grade oil well cement of 3:97, and are prepared according to GB / T 19139-2012 and cured in a curing box at 60°C±2°C for 7 days.

[0063] Figure 1 The scanning electron microscope image and X-ray energy spectrum analysis image of the carbon capture cement self-repairing agent prepared in Example 1 in the cement matrix. Figure 1 As can be seen in (a), the polymer network structure of carbon capture cement self-healing agent appears in the cement matrix; Figure 1 As shown in (b), the carbon capture cement self-repairing agent has good compatibility with the cement matrix, among which the C element ( Figure 1 (c)) mainly comes from carbon capture cement self-repairing agent, O element ( Figure 1 (d) comes from the carbon capture cement self-repairing agent and calcium hydroxide in the cement matrix, and the N element ( Figure 1 (e)) comes from the tertiary amine functional group of the carbon capture cement self-healing agent, the Ca element ( Figure 1 (f)) comes from the cement matrix.

[0064] Figure 2 This is a thermogravimetric test diagram of the carbon capture cement self-repairing agent prepared in Example 1. Figure 2 From (b), we can see that the carbon capture cement self-repairing agent mainly has two main thermal decomposition temperature ranges: 150-200℃ and 350-450℃. Figure 2As shown in (a), the weight loss rate is 4.31% at 150-200°C due to the thermal decomposition of bicarbonate generated by the carbon capture cement self-healing agent capturing carbon dioxide in the air during the synthesis process; and 74.33% at 350-450°C due to the thermal decomposition of the carbon capture cement self-healing agent.

[0065] Figure 3 This is a carbon dioxide adsorption test chart for the carbon capture cement self-healing agent prepared in Example 1. As can be seen from the figure, the carbon capture cement self-healing agent reaches its maximum carbon dioxide adsorption rate of 1.52 mmolCO2 / g at 65 minutes, demonstrating excellent carbon capture performance and facilitating the formation of cement matrix self-healing products.

[0066] Example 2

[0067] The only difference from Example 1 is that the mass ratio of carbon capture cement self-healing agent to G-grade oil well cement is 1:99; the remaining steps and parameters are the same as those in Example 1.

[0068] Example 3

[0069] The only difference from Example 1 is that the mass ratio of carbon capture cement self-healing agent to G-grade oil well cement is 6:94; the remaining steps and parameters are the same as those in Example 1.

[0070] Example 4

[0071] A method for preparing a carbon capture cement self-repairing agent, comprising the following steps:

[0072] (1) Preparation of epoxy emulsion: A water-based modified bisphenol F epoxy resin, Span-60 and water were mixed and stirred at 11,000 rpm to obtain an epoxy emulsion; the mass fraction of the water-based modified bisphenol F epoxy resin in the epoxy emulsion was 55.0%; the mass fraction of Span-60 in the epoxy emulsion was 0.55%.

[0073] (2) Preparation of carbon capture cement self-healing agent solution: 4-dimethylaminobutylamine was added to epoxy emulsion (so that the mass fraction of 4-dimethylaminobutylamine in the epoxy emulsion was 27.5%), stirred at 450 rpm, and reacted at 70°C for 8 h to obtain a carbon capture cement self-healing agent solution.

[0074] (3) Preparation of carbon capture cement self-repairing agent: freeze-dry the carbon capture cement self-repairing agent solution obtained in step (2) and grind it to obtain a dry carbon capture cement self-repairing agent.

[0075] (4) Carbon capture cement self-healing agent, water, and G-grade oil well cement are prepared according to a water-cement ratio of 0.44 and a mass ratio of carbon capture cement self-healing agent to G-grade oil well cement of 3:97, and are prepared according to GB / T 19139-2012 and cured in a curing box at 60°C±2°C for 7 days.

[0076] Example 5

[0077] A method for preparing a carbon capture cement self-repairing agent, comprising the following steps:

[0078] (1) Preparation of epoxy emulsion: A water-based modified bisphenol S epoxy resin, Span-85 and water were mixed and stirred at 12,000 rpm to obtain an epoxy emulsion; the mass fraction of the water-based modified bisphenol A epoxy resin in the epoxy emulsion was 60.0%; the mass fraction of Span-80 in the epoxy emulsion was 0.6%.

[0079] (2) Preparation of carbon capture cement self-healing agent solution: Dimethylaminoethylamine was added to epoxy emulsion (so that the mass fraction of dimethylaminoethylamine in the epoxy emulsion was 30.0%), stirred at 500 rpm, and reacted at 80°C for 10 hours to obtain a carbon capture cement self-healing agent solution.

[0080] (3) Preparation of carbon capture cement self-repairing agent: freeze-dry the carbon capture cement self-repairing agent solution obtained in step (2) and grind it to obtain a dry carbon capture cement self-repairing agent.

[0081] (4) Carbon capture cement self-healing agent, water, and G-grade oil well cement are prepared according to a water-cement ratio of 0.44 and a mass ratio of carbon capture cement self-healing agent to G-grade oil well cement of 3:97, and are prepared according to GB / T 19139-2012 and cured in a curing box at 60°C±2°C for 7 days.

[0082] Control Example

[0083] Construction of a blank cement system: Water and G-grade oil well cement were prepared at a water-cement ratio of 0.44, prepared according to GB / T19139-2012, and cured in a curing box at 60°C ± 2°C for 7 days.

[0084] Figure 4 The rheological test diagrams of the cement matrix prepared in the control example, embodiment 1, embodiment 2 and embodiment 3 are shown in FIG. Figure 4 It can be seen that the addition of carbon capture cement self-healing agent will not change the fluid properties of the cement matrix; with the increase of the addition amount of carbon capture cement self-healing agent, the consistency of the cement matrix decreases and the rheological properties of the cement matrix improve.

[0085] Figure 5 The hydration heat release test diagram of the cement matrix prepared in the control example, embodiment 1, embodiment 2 and embodiment 3. Figure 5 It can be seen that the peak hydration exotherm rate of the blank cement system is 14.81 mW / g; with the increase of the amount of carbon capture cement self-healing agent added, the peak hydration exotherm rate of the cement matrix is ​​slightly delayed, which is because the polymer network structure of the carbon capture cement self-healing agent delays cement hydration; the peak hydration exotherm rate of the cement matrix first increases and then decreases with the increase of the amount of carbon capture cement self-healing agent added, and the peak hydration exotherm rate of Example 1 is the largest, which is 16.91 mW / g.

[0086] Figure 6 The super depth of field pictures and the repair rates of the cement matrix prepared in the control example and Example 1 before and after repair are shown. Figure 6 From (d) to (f), we can see that after 3 or 7 days of repair at 60℃ in a carbon dioxide environment, the 3-day self-repair rate of the control example is only 11.4%, and the 7-day self-repair rate is only 15.3%. Figure 6 From (a) to (c), it can be seen that the 3-day self-repair rate of Example 1 reaches 49.8%, and the 7-day self-repair rate reaches 94.3%, with an improvement of 516.3%. This is because the carbon capture cement self-repair agent accelerates the absorption of carbon dioxide by the cement matrix, promotes the generation of self-repair products, and greatly improves the self-repair ability.

[0087] The self-healing performance test of the cement matrix prepared in Examples 2-5 was carried out, and the test results were similar to those in Example 1. The results showed that the carbon capture cement self-healing agent prepared by the present invention has excellent carbon capture performance, has little effect on the hydration of the cement matrix, and has greatly improved the rheological properties and self-healing performance of the cement matrix.

[0088] In summary, the carbon capture cement self-healing agent of the present invention has a simple preparation process, is easy to realize industrial production, has little effect on cement hydration, is beneficial to improving the rheological properties of cement, and effectively solves the shortcomings of traditional cement self-healing systems that are difficult to industrialize and have slow self-healing speed.

[0089] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. Application of a carbon capture cement self-repairing agent in self-repairing of cement sheath through carbon capture, characterized in that: The following steps are involved: uniformly mixing a water-based epoxy resin, a surfactant and water to obtain an epoxy emulsion; adding a tertiary amine curing agent to the epoxy emulsion for reaction to obtain a carbon capture cement self-repairing agent solution; freeze-drying the carbon capture cement self-repairing agent solution and then grinding it to obtain the carbon capture cement self-repairing agent; The mass fraction of the waterborne epoxy resin in the epoxy emulsion is 50.0%-60.0%; the mass fraction of the surfactant in the epoxy emulsion is 0.5%-0.6%; The waterborne epoxy resin is a waterborne modified bisphenol A epoxy resin, a waterborne modified bisphenol F epoxy resin or a waterborne modified bisphenol S epoxy resin; the epoxy value of the waterborne epoxy resin is 0.41-0.51, and the average dispersed particle size in water is 4-8 μm; the surfactant is Span-80, Span-60 or Span-85; The mass fraction of the tertiary amine curing agent in the epoxy emulsion is 25.0%-30.0%; The tertiary amine curing agent is dimethylaminopropylamine, 4-dimethylaminobutylamine or dimethylaminoethylamine; The reaction temperature is 60-80° C. and the reaction time is 4-10 h.

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