A cement slurry for cementing carbon dioxide injection and production wells, its preparation method and application

Abstract

The present invention discloses a cement slurry for cementing carbon dioxide injection and production wells, its preparation method and application. By weight, the cement slurry for cementing comprises the following components: 95 - 105 parts of oil well cement, 44 - 48 parts of water, 4 - 6 parts of polymer emulsion, 4 - 6 parts of self-healing material, 1.5 - 2.5 parts of drag reducer, 0.5 - 1.5 parts of fluid loss reducer and 0.2 - 0.8 parts of defoamer; wherein, the polymer emulsion is an emulsion polymerized from methyl methacrylate, vinyltrimethoxysilane and propylene carbonate as monomers; the self-healing material is a microcapsule embedding Thiobacillus ferrooxidans cells and Bacillus amyloliquefaciens cells. The cement slurry for cementing maintains good strength and low permeability in a carbon dioxide environment, has good corrosion resistance and has self-healing ability.

Description

Technical Field

[0001] The present invention belongs to the technical field of well cementing technology, and particularly relates to a well cementing slurry for carbon dioxide injection and production wells, a preparation method thereof, and an application thereof. Background Art

[0002] During the development of oil and gas fields, well cementing is one of the important processes to ensure the safe and stable operation of oil wells. The main function of well cementing slurry is to fill the annular space between the casing and the wellbore wall, form an effective sealing layer, prevent the interflow of different formation fluids, and ensure the long-term stable production of oil wells. However, in oil and gas wells containing high-concentration carbon dioxide gas, traditional well cementing slurries face a series of severe challenges. Especially in recent years, more and more carbon dioxide enhanced oil recovery and storage (CCUS) projects have been carried out globally, including in China. The leakage problem of carbon dioxide along the cement sheath is an important risk point that cannot be ignored for the safe operation of such projects. The sealing safety of well cementing slurry throughout the life cycle of CCUS projects has become one of the current hot issues of concern.

[0003] The existing well cementing slurries have the following main problems in an environment rich in carbon dioxide:

[0004] Carbonation reaction: Carbon dioxide gas reacts with calcium hydroxide in the cement slurry to form calcium carbonate, resulting in a decrease in the pH value of the cement slurry and a weakening of the alkaline environment.

[0005] Strength reduction and permeability increase: The carbonation reaction not only reduces the pH value of the cement slurry but also weakens the stability of its internal structure, thereby affecting the strength and permeability of the cement sheath and causing sealing failure.

[0006] Lack of self-healing function: During the operation of CCUS projects in carbon dioxide injection and production wells, there are multiple up-and-down processes of tubing in the wellbore, which are extremely likely to impact the casing, generate micro-cracks in the cement sheath, and cause carbon dioxide to leak upward along the micro-cracks. Traditional cement slurries lack self-healing functions and cannot inhibit the expansion of cracks, further exacerbating the aging and damage of the material.

[0007] The combined action of these factors makes it difficult for traditional well cementing slurries to meet the long-term stable sealing and support requirements of oil and gas wells in a high-carbon dioxide environment, increasing the risks and costs of oil well operation.

[0008] "Self-healing microcapsule concrete capable of fixing carbon dioxide" with the application number CN107500589A discloses a kind of self-healing microcapsule concrete, but it is mainly applied in the construction field, which has great differences from the application scenarios and requirements in the oil exploration field. "Self-healing well cement slurry for well cementing at medium and low temperatures upon encountering carbon dioxide and its application" with the application number CN118026608A discloses a kind of self-healing well cement slurry, but its core is to add slag, and adding slag will affect the strength of the well cement slurry to varying degrees, and at the same time has relatively high requirements for the formulation debugging of the system. Summary of the Invention

[0009] Aiming at the defects of the prior art, the present invention provides a well cement slurry for carbon dioxide injection and production wells, which can not only solve the problems of reduced corrosion strength and lack of integrity of the cement sheath in carbon dioxide injection and production wells, but also endow the cement stone with self-healing ability when damaged by carbon dioxide channeling, seal the carbon dioxide gas channeling path, and provide more reliable technical guarantee for well cementing in carbon dioxide injection and production wells. At the same time, the present invention also provides a preparation method and application of the well cement slurry for carbon dioxide injection and production wells.

[0010] A well cement slurry for carbon dioxide injection and production wells, by weight, comprises the following components:

[0011] 95 - 105 parts of oil well cement, 44 - 48 parts of water, 4 - 6 parts of polymer emulsion, 4 - 6 parts of self-healing material, 1.5 - 2.5 parts of drag reducer, 0.5 - 1.5 parts of fluid loss reducer and 0.2 - 0.8 parts of defoamer;

[0012] Wherein, the polymer emulsion is an emulsion polymerized from methyl methacrylate, vinyltrimethoxysilane and propylene carbonate as monomers;

[0013] The self-healing material is a microcapsule embedding Thiobacillus ferrooxidans cells and Bacillus amyloliquefaciens cells.

[0014] Preferably, the polymer emulsion is prepared by the following method: dispersing methyl methacrylate, vinyltrimethoxysilane and propylene carbonate in the dispersion medium water under the action of a dispersion aid, adjusting the pH to 7, then adding an initiator, and stirring and reacting at 55 - 60 °C for 7 - 8 h.

[0015] Preferably, the ratio of methyl methacrylate, vinyltrimethoxysilane, propylene carbonate, dispersion medium, dispersion aid, initiator is (90 - 110) g : (45 - 55) g : (35 - 45) g : 400 mL : (0.8 - 1.2) g : (0.8 - 1.2) g.

[0016] More preferably, the mass ratio of methyl methacrylate, vinyltrimethoxysilane, propylene carbonate is 100 : 50 : 40.

[0017] Preferably, the dispersion aid is sodium dodecylbenzenesulfonate, and the initiator is potassium persulfate.

[0018] Preferably, the self-healing material is prepared by the following method:

[0019] (1) Mix the Thiobacillus ferrooxidans cells and Bacillus amyloliquefaciens cells to obtain a mixed cell mass;

[0020] (2) Mix the mixed cell mass with a sodium alginate solution, extrude it into a CaCl2 solution to form calcium alginate gel beads, let it stand for 30 min, and then add it to a carboxymethyl chitosan solution for curing to obtain the self-healing material.

[0021] Preferably, the concentration of the sodium alginate solution is 1.5 wt%, the concentration of the CaCl2 solution is 2 wt%, the concentration of the carboxymethyl chitosan solution is 1 wt%, and the ratio of the mixed cell mass to the sodium alginate solution is 20 g: 1000 mL.

[0022] Preferably, the mass ratio of the Thiobacillus ferrooxidans cells to the Bacillus amyloliquefaciens cells is 1:2.

[0023] Preferably, the drag reducer is a small molecule polymer; the defoamer is a silicone; the fluid loss reducer is a cellulose and its derivatives.

[0024] More preferably, the cement slurry for cementing carbon dioxide injection-production wells comprises the following components:

[0025] 100 parts of oil well cement, 44 parts of water, 5 parts of polymer emulsion, 5 parts of self-healing material, 2 parts of drag reducer, 1 part of fluid loss reducer, and 0.5 part of defoamer.

[0026] More preferably, the Thiobacillus ferrooxidans cells and Bacillus amyloliquefaciens cells are respectively cultured from Thiobacillus ferrooxidans and Bacillus amyloliquefaciens according to their respective growth conditions.

[0027] The preparation method of the cement slurry for cementing carbon dioxide injection-production wells: After respectively preparing the polymer emulsion and the self-healing material, mix the oil well cement, water, polymer emulsion, self-healing material, drag reducer, fluid loss reducer, and defoamer, and stir evenly.

[0028] The application of the cement slurry in the cementing operation of carbon dioxide injection-production wells: Apply the cement slurry to the cementing operation of carbon dioxide injection-production wells, and the temperature of the application well section is not higher than 60 °C.

[0029] The present invention improves the properties of cement slurry in multiple aspects by adjusting the formula of the well cementing slurry, introducing polymer emulsion and self-healing materials: the polymer emulsion cross-links and combines to form a structure that fills the particle pores and microvoids, making the cement slurry (stone) more dense; when the polymer emulsion is incorporated into the cement slurry, the emulsion forms a polymer film structure on the surface of the original hydration products, which can prevent the alkaline hydration products from being corroded and improve the anti-corrosion performance of the cement slurry in a high carbon dioxide environment; by introducing propylene carbonate into the monomers for synthesizing the polymer emulsion, the properties of the polymer are improved, the bonding strength with the cement hydration products is enhanced, and its stability is improved; a self-healing material that can resist the cross-flow damage of carbon dioxide injection and production wells is introduced to ensure that the cement slurry can automatically repair microcracks when damaged by carbon dioxide injection and production.

[0030] Advantages of the present invention:

[0031] The well cementing slurry provided by the present invention maintains good strength and low permeability in a carbon dioxide environment, has good anti-corrosion performance, not only solves the stability problem of the well cementing annulus in the complex and harsh downhole environment of carbon dioxide injection and production wells, but also endows the cement slurry with self-healing ability under carbon dioxide injection and production conditions, providing a more reliable technical guarantee for the integrity of carbon dioxide injection and production wells. Description of the drawings

[0032] Figure 1 It is a test result diagram of the initial compressive strength of the cement stone for each experimental group;

[0033] Figure 2 It is a test result diagram of the initial permeability of the cement stone for each experimental group. Detailed implementation manners

[0034] The oil well cement used in the present invention is G-class oil well cement, purchased from Jiahua Special Cement Co., Ltd.;

[0035] Acidithiobacillus ferrooxidans is purchased from Mingzhou Biology, and the strain number is B80698; Bacillus amyloliquefaciens is purchased from Taisituo Biology, and the strain number is TS335151; Sarcina pasteurii is Sarcina pasteurii ATCC11859 of the American Type Culture Collection (ATCC);

[0036] The drag reducer and fluid loss reducer are purchased from Weihui Chemical Industry Co., Ltd., with model numbers GD-1 and G301 respectively; the defoamer is purchased from BASF SE, Germany, with model number FoamStar A 38.

[0037] Example 1

[0038] A well cementing slurry for carbon dioxide injection and production wells is composed of the following raw materials: 100 g of oil well cement, 44 g of water, 5 g of polymer emulsion, 5 g of self-healing material, 2 g of drag reducer, 1 g of fluid loss reducer, and 0.5 g of defoamer;

[0039] Among them, the polymer emulsion is prepared by the following method: 100 g of methyl methacrylate, 50 g of vinyltrimethoxysilane, 40 g of propylene carbonate and 1 g of sodium dodecylbenzenesulfonate are dispersed in 400 mL of water, the pH is adjusted to 7.0, and then 1 g of initiator potassium persulfate is added, and the mixture is stirred and reacted at 55 °C for 8 h;

[0040] The self-healing material is prepared by the following method:

[0041] (a) Thiobacillus ferrooxidans is inoculated into MRS liquid medium and fermented and cultured at 30 °C and 160 rpm for 48 h, and then the cells of Thiobacillus ferrooxidans are obtained by centrifugation; Bacillus amyloliquefaciens is inoculated into LB liquid medium and fermented and cultured at 37 °C and 150 rpm for 36 h, and then the cells of Bacillus amyloliquefaciens are obtained by centrifugation; the cells of Thiobacillus ferrooxidans and the cells of Bacillus amyloliquefaciens are mixed evenly according to the mass ratio of 1:2 to obtain a mixed cell mass;

[0042] (b) Weigh 10.0 g of the mixed cell mass and mix it evenly with 500 mL of a 1.5 wt% sodium alginate solution, and use a sterile syringe to inject it into 2000 mL of a 2 wt% CaCl2 solution to form calcium alginate gel beads. After standing and curing for 30 min, the gel beads are transferred to 1000 mL of a 1 wt% carboxymethyl chitosan solution for curing to obtain microcapsules, which are the self-healing material.

[0043] Mix well the well cement, water, polymer emulsion, self-healing material, drag reducer, fluid loss agent, and defoamer, and stir evenly to prepare the cement slurry for carbon dioxide injection and production well cementing.

[0044] Example 2

[0045] A cement slurry for carbon dioxide injection and production well cementing is composed of the following raw materials: 105 g of well cement, 48 g of water, 4 g of polymer emulsion, 6 g of self-healing material, 1.5 g of drag reducer, 1.5 g of fluid loss agent, and 0.2 g of defoamer;

[0046] Among them, the polymer emulsion is prepared by the following method: 110 g of methyl methacrylate, 45 g of vinyltrimethoxysilane, 45 g of propylene carbonate and 1.2 g of sodium dodecylbenzenesulfonate are dispersed in 400 mL of water, the pH is adjusted to 7.0, and then 1.2 g of initiator potassium persulfate is added, and the mixture is stirred and reacted at 60 °C for 7 h;

[0047] The self-healing material is the same as that in Example 1.

[0048] All raw materials are mixed and stirred evenly to prepare the cement slurry for the carbon dioxide injection-production well.

[0049] Example 3

[0050] A cement slurry for the carbon dioxide injection-production well is composed of the following raw materials: 95 g of oil well cement, 45 g of water, 6 g of polymer emulsion, 4 g of self-healing material, 2.5 g of drag reducer, 0.5 g of fluid loss reducer, and 0.8 g of defoamer.

[0051] Among them, the polymer emulsion is prepared by the following method: 90 g of methyl methacrylate, 55 g of vinyltrimethoxysilane, 35 g of propylene carbonate, and 0.8 g of sodium dodecylbenzenesulfonate are dispersed in 400 mL of water, the pH is adjusted to 7.0, and then 0.8 g of initiator potassium persulfate is added, and the mixture is stirred and reacted at 55 °C for 8 h.

[0052] The self-healing material is the same as that in Example 1.

[0053] All raw materials are mixed and stirred evenly to prepare the cement slurry for the carbon dioxide injection-production well.

[0054] Comparative Example 1

[0055] When synthesizing the polymer emulsion, propylene carbonate is replaced by acrylamide, and the others are the same as in Example 1.

[0056] Comparative Example 2

[0057] In the self-healing material, Bacillus amyloliquefaciens cells are replaced by Sarcina pasteurii cells, and the others are the same as in Example 1;

[0058] Among them, the cultivation process of Sarcina pasteurii cells is as follows: Sarcina pasteurii is inoculated into a urea medium (containing 20 g / L urea, 5 g / L ammonium chloride, 1 g / L yeast extract, 75 mmol / L tris buffer, pH 9.0), and fermented and cultured at 30 °C and 100 rpm for 72 h, and then Sarcina pasteurii cells are obtained by centrifugation.

[0059] Comparative Example 3

[0060] The self-healing material is prepared by the following method:

[0061] (a) Thiobacillus ferrooxidans is inoculated into MRS liquid medium and fermented and cultured at 30 °C and 160 rpm for 48 h, and then Thiobacillus ferrooxidans cells are obtained by centrifugation.

[0062] (b) Weigh 10.0 g of Thiobacillus ferrooxidans cells and mix them evenly with 500 mL of a 1.5 wt% sodium alginate solution. Then use a sterile syringe to inject the mixture into 2000 mL of a 2 wt% CaCl₂ solution to form calcium alginate gel beads. After standing for 30 min for solidification, transfer the gel beads to 1000 mL of a 1 wt% carboxymethyl chitosan solution for further solidification to obtain microcapsules, which are the self-healing materials.

[0063] Others are the same as in Example 1.

[0064] Comparative Example 4

[0065] The self-healing material is prepared by the following method:

[0066] (a) Inoculate Bacillus amyloliquefaciens into LB liquid medium and ferment at 37 °C and 150 rpm for 36 h, then centrifuge to obtain Bacillus amyloliquefaciens cells.

[0067] (b) Weigh 10.0 g of Bacillus amyloliquefaciens cells and mix them evenly with 500 mL of a 1.5 wt% sodium alginate solution. Then use a sterile syringe to inject the mixture into 2000 mL of a 2 wt% CaCl₂ solution to form calcium alginate gel beads. After standing for 30 min for solidification, transfer the gel beads to 1000 mL of a 1 wt% carboxymethyl chitosan solution for further solidification to obtain microcapsules, which are the self-healing materials.

[0068] Others are the same as in Example 1.

[0069] Comparative Example 5

[0070] Do not add polymer emulsion and self-healing material, and others are the same as in Example 1.

[0071] Comparative Example 6

[0072] Do not add self-healing material, and others are the same as in Example 1.

[0073] Comparative Example 7

[0074] Do not add polymer emulsion, and others are the same as in Example 1.

[0075] Performance testing

[0076] Prepare cement stones from the well cement slurries provided in Examples 1 - 5 and Comparative Examples 1 - 7 above (referring to the method of GB / T19139 - 2012), detect the initial compressive strength and permeability, and place the prepared cement stones under a carbon dioxide pressure of 6 MPa and carry out a corrosion experiment at 50 °C. Evaluate the corrosion degree of the cement stones after 28 days of corrosion. The corrosion device is an XWL - 18 type carbon dioxide high-temperature and high-pressure reaction kettle.

[0077] The corrosion degree of hardened cement paste is mainly evaluated according to the corrosion depth, the decline rate of compressive strength and the increase rate of permeability. The specific evaluation method for the corrosion depth of hardened cement paste is as follows: Take out the hardened cement paste after being corroded for a certain time under experimental conditions, cut it in half, and evenly apply phenolphthalein reagent on the section. The hydration products of hardened cement paste are alkaline and will turn red when encountering phenolphthalein. However, the alkalinity of the hydration products of hardened cement paste corroded by acidic corrosive media will weaken or even become neutral, and will not change color or turn light red when encountering phenolphthalein. Finally, use a vernier caliper to measure the thickness of multiple places without red at the boundary, and calculate the average value of the measurement results as the corrosion depth of hardened cement paste (hereinafter referred to as corrosion depth);

[0078] The compressive strength measured after the hardened cement paste is cured is used as the initial compressive strength, and the compressive strength after being corroded for a certain time is used as the compressive strength after corrosion. The compressive strength is tested using a YJ-2001 uniform loading pressure testing machine, and the hardened cement paste is cured using a DFC-0722 type pressurized curing autoclave. The greater the decline rate of compressive strength, the more serious the corrosion degree of hardened cement paste. The calculation formula for the decline rate of compressive strength is as follows:

[0079] α = (P - P i ) / P × 100%;

[0080] In the formula, α is the decline rate of compressive strength, with the unit of %; P is the initial compressive strength, with the unit of MPa; P i is the compressive strength after the i-th day of corrosion, with the unit of MPa;

[0081] The permeability measured after the hardened cement paste is cured is used as the initial permeability, and the permeability after the hardened cement paste is corroded for a certain time is used as the permeability after corrosion. The permeability is tested using a CMS300 type computer-controlled automatic measurement system for confining pressure pore permeability. The greater the increase rate of permeability, the greater the corrosion degree of hardened cement paste. The calculation formula for the change rate of permeability is as follows:

[0082] μ = (K i - K) / K × 100%;

[0083] In the formula, μ is the change rate of permeability, with the unit of %; K is the initial permeability, with the unit of mD; K i is the permeability after the i-th day of corrosion, with the unit of mD;

[0084] The self - healing effect of the hardened cement paste is evaluated by the self - healing efficiency. The specific process is as follows: First, a cylindrical specimen is loaded with a pressure of 20 MPa using a pressure testing machine. The internal crack volume is measured using a CT scanner (model METROTOM1) and calibrated as the original crack volume. Then, the sample is placed in a high - temperature and high - pressure carbon dioxide reaction kettle. After corrosion for a certain period of time, it is taken out, and the internal crack volume is measured again using a CT scanner and calibrated as the repaired crack volume. The difference between the two crack volumes divided by the original crack volume is the self - healing efficiency. The calculation formula for the self - healing efficiency is as follows:

[0085] β=(V - V i ) / V×100%;

[0086] In the formula, β is the self - healing efficiency, with the unit of %; V is the initial crack volume, with the unit of mm 3 ; V i is the repaired crack volume after the i - th day of corrosion, with the unit of mm 3 ;

[0087] In this invention, the P i , K i , V i tested are the P 28 , K 28 , V 28 after 28 days respectively. The test results of the initial compressive strength and initial permeability of the hardened cement paste in each experimental group are shown in Figure 1 and Figure 2 , and the relevant corrosion test results are shown in Table 1;

[0088] Table 1 Corrosion depth, compressive strength decay rate, permeability increase rate and self - healing efficiency of each hardened cement paste

[0089] Example / Comparative Example Corrosion Depth (cm) Compressive Strength Degradation Rate (%) Permeability Increase Rate (%) Self-Healing Efficiency (%) Example 1 0.31 3.31 5.10 76.79 Example 2 0.35 4.24 5.64 76.23 Example 3 0.43 4.85 6.05 71.26 Comparative Example 1 1.46 16.20 15.24 56.37 Comparative Example 2 1.25 12.23 13.09 42.33 Comparative Example 3 1.18 11.49 12.56 39.34 Comparative Example 4 1.26 13.58 13.72 37.89 Comparative Example 5 1.74 25.27 21.85 11.62 Comparative Example 6 1.32 14.65 14.34 15.34 Comparative Example 7 1.56 18.68 18.32 51.23 .

[0090] From Figure 1 , Figure 2 it can be seen that after introducing polymer emulsion and self - healing materials in this invention, the compressive strength of the hardened cement paste has increased to a certain extent, and the permeability has decreased;

[0091] As can be seen from Table 1, by introducing polymer emulsion and self-healing material, the corrosion resistance of the well cement is effectively improved in the present invention. Moreover, the selected polymer monomer combination of methyl methacrylate, vinyltrimethoxysilane and propylene carbonate in the present invention has its particularity, which can effectively improve the physical properties of the polymer and enhance its carbon dioxide resistance. By filling the particle pores and microvoids with the polymer macromolecular cross-linking and bonding structure, the cement slurry system can be made more dense; when the polymer emulsion is incorporated into the cement slurry, a polymer film structure is formed on the surface of the original hydration products, which can prevent the alkaline hydration products from being corroded and improve the anti-corrosion performance of the cement slurry in a high-carbon dioxide environment. By introducing propylene carbonate, the performance of the polymer emulsion is improved, the bonding strength with the cement hydration products is enhanced, and its stability is increased. Combining the compressive strength and corrosion resistance evaluation results of Example 1 and Comparative Example 1, it can be seen that propylene carbonate monomer plays an important role in improving the physical properties and anti-corrosion performance of the cement;

[0092] The present invention also combines Thiobacillus ferrooxidans and Bacillus amyloliquefaciens to carry out bioremediation of the cement cracks caused by gas channeling during the carbon dioxide injection and production process through the mineralization reaction of microorganisms. Using the two kinds of bacteria alone is difficult to achieve the effect of combined use. Moreover, although both Bacillus amyloliquefaciens and Sporosarcina pasteurii have the property of producing urease, after replacing Bacillus amyloliquefaciens with Sporosarcina pasteurii, the corrosion resistance and self-healing performance of the cement show a significant downward trend. Based on the above, the present invention believes that Thiobacillus ferrooxidans and Bacillus amyloliquefaciens produce a certain synergistic effect during bioremediation.

[0093] From the above test results, it can be seen that when the polymer emulsion or the self-healing material is added alone, the anti-corrosion effect of the cement stone is weaker than the overall solution of the present invention. This is mainly because the synergistic effect of the two materials is strong. The polymer emulsion of the present invention can limit the expansion of cracks, making the crack scale within the effective range where the self-healing material can act efficiently, and the overall anti-corrosion effect is good.

Claims

1. A cement slurry for well cementing of carbon dioxide injection-production wells, characterized in that: By weight parts, it includes the following components: 95 - 105 parts of oil well cement, 44 - 48 parts of water, 4 - 6 parts of polymer emulsion, 4 - 6 parts of self - healing material, 1.5 - 2.5 parts of drag reducer, 0.5 - 1.5 parts of fluid loss reducer, and 0.2 - 0.8 parts of defoamer; Among them, the polymer emulsion is an emulsion polymerized from methyl methacrylate, vinyltrimethoxysilane, and propylene carbonate as monomers; The self - healing material is a microcapsule embedding Thiobacillus ferrooxidans cells and Bacillus amyloliquefaciens cells; The polymer emulsion is prepared by the following method: Methyl methacrylate, vinyltrimethoxysilane, and propylene carbonate are dispersed in the dispersion medium water under the action of a dispersion aid, the pH is adjusted to 7, and then an initiator is added, and the mixture is stirred and reacted at 55 - 60 °C for 7 - 8 h.

2. The cement slurry for cementing of carbon dioxide injection-production well according to claim 1, wherein: The ratio of methyl methacrylate, vinyltrimethoxysilane, propylene carbonate, dispersion medium, dispersion aid, and initiator is (90 - 110) g : (45 - 55) g : (35 - 45) g : 400 mL : (0.8 - 1.2) g : (0.8 - 1.2) g.

3. The cement slurry for well cementing of carbon dioxide injection and production wells according to claim 2, characterized in that: The dispersion aid is sodium dodecylbenzenesulfonate, and the initiator is potassium persulfate.

4. The cement slurry for well cementing of carbon dioxide injection and production wells according to claim 1, wherein: The self - healing material is prepared by the following method: (1) Mix Thiobacillus ferrooxidans cells and Bacillus amyloliquefaciens cells to obtain a mixed cell mass; (2) Mix the mixed cell mass with sodium alginate solution, extrude it into CaCl2 solution to form calcium alginate gel beads, let it stand for 30 min, and then add it to carboxymethyl chitosan solution for curing to obtain the self - healing material.

5. The cement slurry for cementing of carbon dioxide injection and production well according to claim 4, characterized in that: The concentration of the sodium alginate solution is 1.5 wt%, the concentration of the CaCl2 solution is 2 wt%, the concentration of the carboxymethyl chitosan solution is 1 wt%, and the ratio of the mixed cell mass to the sodium alginate solution is 20 g : 1000 mL.

6. The cement slurry for cementing of carbon dioxide injection-production well according to claim 4, characterized in that: The mass ratio of Thiobacillus ferrooxidans cells to Bacillus amyloliquefaciens cells is 1:

2.

7. The cement slurry for well cementing of carbon dioxide injection-production well according to claim 1, wherein: The drag reducer is a small - molecule polymer type; the defoamer is a silicone type; the fluid loss reducer is a cellulose and its derivative type.

8. The preparation method of the cement slurry for cementing of the carbon dioxide injection and production well according to claim 1, characterized in that: After separately preparing the polymer emulsion and the self - healing material, mix the oil well cement, water, polymer emulsion, self - healing material, drag reducer, fluid loss reducer, and defoamer, and stir evenly.

9. Use of the cement slurry for well cementing in carbon dioxide injection and production wells according to claim 1, characterized in that: The application well section temperature of the well cement slurry is not higher than 60 °C.

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