Nanometer high-density anti-channeling cement slurry and preparation method thereof

Abstract

This invention proposes a nano-high-density anti-channeling cement slurry and its preparation method. The cement slurry is composed of G-grade oil well cement, silica fume, nano-zinc oxide, nano-magnesium oxide dispersion, a water loss reducing agent, a retarder, a dispersant, an defoamer, and water. The density of the nano-high-density anti-channeling cement slurry of this invention is 1.95–2.60 g / cm³. 3 It also features API water loss of less than 50 mL, zero free liquid, no sedimentation, cement stone permeability of less than 0.01 mD, gas channeling factor SPN value of less than 2, compressive strength of more than 40 MPa, no shrinkage of cement stone, and good anti-channeling effect, which can improve the cementing of ultra-deep wells with high-density cement slurry.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well cementing fluid technology, and in particular to a nano high-density anti-channeling cement slurry and its preparation method. Background Technology

[0002] In existing technologies, high-density anti-gas channeling cement slurries primarily increase their density by adding finely ground iron ore powder and anti-channeling agents such as latex or granules to enhance their anti-channeling performance. However, the high density and large particle size of iron ore powder lead to poor settling stability of the cement slurry. Furthermore, the anti-channeling effect of latex or granule anti-channeling agents is unsatisfactory under complex conditions such as high density in ultra-deep wells. Simultaneously, the shrinkage of the cement stone cannot be controlled, resulting in weak interfacial sealing. Consequently, the cementing quality of this type of slurry in ultra-deep wells is not high.

[0003] Therefore, there is an urgent need to develop a nanoscale anti-channeling cement slurry to improve the cementing quality of high-density cement slurry under complex conditions such as ultra-deep wells. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention proposes a nano-high-density anti-channeling cement slurry and its preparation method.

[0005] In a first aspect, the present invention proposes a nano-high-density anti-channeling cement slurry, the components of which, by mass fraction, include:

[0006]

[0007]

[0008] In a specific embodiment of the present invention, the nano zinc oxide is spherical particles with a particle size distribution of 50nm-300nm.

[0009] In a specific embodiment of the present invention, converter dust from a zinc-steel plant can be used as nano-zinc oxide. This nano-zinc oxide has high purity, spherical particles with a particle size of 50nm-300nm, and exhibits excellent weighting effects in oil well cement slurries. Adding two special nanomaterials, nano-zinc oxide spherical weighting agent and nano-magnesium oxide dispersion, to high-density cement slurries enhances the stability and anti-channeling ability of the cement slurry. The nano-zinc oxide spherical weighting agent has a particle size distribution of 50nm to 300nm, an average particle size of only 200nm, a purity of 99%, and a density of 5.6g / cm³. 3 Replacing conventional iron ore powder with nano-spherical zinc oxide not only effectively improves the stability of cement slurry, but also reduces the amount of cement slurry dispersant due to the "rolling bearing" effect of the spherical material.

[0010] The industry generally considers a density higher than 2.00 g / cm³ to be acceptable. 3The cement slurry is defined as high-density cement slurry, with nano-zinc oxide having a density of 5.6 g / cm³. 3 It can be used as a weighting material and can be used to prepare high-density cement slurry.

[0011] In this invention, the density of the high-density anti-channeling cement slurry is 1.95 g / cm³. 3 The above-mentioned formulations, based on the examples, all have a density of 2.00 g / cm³. 3 The highest density can reach 2.60 g / cm³. 3 It can be used as ultra-high density cement slurry.

[0012] As a specific embodiment of the present invention, the effective solid content of the nano magnesium oxide dispersion is ≥45%, and the particle size distribution range is between 10nm and 300nm.

[0013] As a specific embodiment of the present invention, the preferred formulation of the nano-magnesium oxide dispersion is: a dispersion consisting of 40-45% distilled water, 45-50% nano-magnesium oxide, 0.4-0.6% sodium polynaphthalene sulfonate, 0.05-0.2% disodium ethylenediaminetetraacetate, 2-3.5% ethylene glycol, 0.5-1.5% polyoxyethylene sorbitan fatty acid ester, 0.5-1% dimethyl silicone oil, and 3-5% methacryloxypropyltrimethoxysilane, with a density of 1.45-1.60 g / cm³. 3 The average particle size is 100 nm.

[0014] This is because the gaps between cement particles are on the micrometer scale, while the pore radius of cement stone is on the order of 10-300 nm, with an average radius of 100 nm. The preferred nano-magnesium oxide dispersion has a particle size distribution range of 10 nm to 300 nm, with an average particle size of 100 nm, allowing it to tightly fill the spaces between cement particles and reduce porosity. Using nano-magnesium oxide anti-channeling emulsion instead of latex or granules can prevent a decrease in the anti-channeling ability of cement slurry due to ultra-high temperatures. Simultaneously, nano-magnesium oxide gradually hydrates and expands after the cement stone solidifies, controlling the shrinkage of the cement stone and improving interfacial anti-channeling ability.

[0015] As a specific embodiment of the present invention, the water loss reducing agent is an AMPS-type copolymer, preferably an AMPS-MA-AA terpolymer.

[0016] In a specific embodiment of the present invention, the dispersant is a ketaldehyde condensate, preferably an acetone-formaldehyde condensate.

[0017] In the preparation of high-density cement slurry, the system needs sufficient viscosity and shear strength to suspend nano-zinc oxide to maintain density and prevent sedimentation that could lead to downhole complications. To achieve this, dispersants can be introduced to balance high-temperature sedimentation stability and rheological properties. Dispersants improve the uniformity of cement slurry, reduce the frictional resistance of solid particles, and maintain the sedimentation stability of the system.

[0018] In a specific embodiment of the present invention, the retarder is an organic acid, preferably ethylenediaminetetramethylenephosphonic acid.

[0019] In a specific embodiment of the present invention, the defoamer is an organosilicone oil, preferably dimethyl silicone oil.

[0020] In a specific embodiment of the present invention, the silicon powder is mainly composed of SiO2 and has a particle size range of 80 to 200 mesh.

[0021] In a specific embodiment of the present invention, the density of the cement slurry ranges from 1.95 to 2.60 g / cm³. 3 API water loss < 50 mL, permeability < 0.01 mD, gas channeling factor SPN value < 2.

[0022] In the field of oil and gas well cementing fluid technology, the density generally reaches 2 g / cm³. 3 This is called high-density cement.

[0023] The raw materials mentioned above in this invention can all be prepared in-house or commercially available; this invention does not impose any particular limitations on them.

[0024] Secondly, the present invention provides a method for preparing nano-high-density anti-channeling cement slurry, comprising the following steps:

[0025] S1: Mix and stir water, nano magnesium oxide dispersion, water loss reducing agent, retarder, dispersant, and defoamer to obtain the first mixture;

[0026] S2: Dry-mix G-grade oil well cement, silica fume, and nano zinc oxide to obtain a second mixture;

[0027] S3: Mix the first mixture with the second mixture to obtain nano high-density anti-channeling cement slurry.

[0028] In a specific embodiment of the present invention, in step S3, the first mixture and the second mixture are mixed in a ratio of (0.19 to 0.45):1.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. The nano-high-density anti-channeling cement slurry of the present invention, by adding nano-zinc oxide, has a stronger ability to increase the density of the cement slurry. Under the same cement slurry density requirements, the cement content in the cement slurry system is higher, and the strength of the cement stone is also higher. Compared with the existing iron ore powder weighting agent (average particle size of 100μm-300μm or more), the particle size is finer and the density is higher. The average pore size of the cement stone is 100nm. The nano-magnesium oxide dispersion fills the gaps between cement particles, which has the effect of reducing API water loss and reducing cement stone permeability. At the same time, the nano-magnesium oxide gradually hydrates to form nano-magnesium hydroxide after the cement slurry solidifies. The volume expansion of the nanoparticles can significantly control the shrinkage performance of the cement stone.

[0031] 2. As can be seen from the embodiments of the present invention, the density of the nano-high-density anti-channeling cement slurry of the present invention is 1.95~2.60g / cm³. 3 It also features API water loss of less than 50mL, zero free liquid, no sedimentation, cement stone permeability of less than 0.01mD, compressive strength of greater than 40MPa, gas channeling factor SPN value of less than 2, no shrinkage of cement stone, and has a good anti-channeling effect, which can improve the cementing of ultra-deep wells with high-density cement slurry.

[0032] 3. In actual production, the Sichuan Basin and Tarim Basin contain numerous high-pressure gas layers, and the density of cement slurry in well cementing mainly ranges from 2.05 to 2.35 g / cm³. 3 Using ground iron ore powder (density only 5.0 g / cm³) 3 The traditional method of adding weight to high-density cement slurry results in large, low-density particles, making it difficult to adjust the stability (zero free liquid, no settling) and strength of the slurry. Furthermore, using conventional magnesium oxide or calcium oxide expanding agents to control cement stone shrinkage leads to annular air channeling in some wells after cementing, and annular pressure buildup in others due to the slow seepage of cement stone (permeability 0.3 mD). These issues highlight the safety and environmental protection challenges in oil and gas well production. The technology provided by this invention uses nano-zinc oxide for weighting, making the strength and stability of the cement slurry easier to adjust. It also uses nano-magnesium oxide dispersion to reduce cement stone permeability and control system shrinkage, resulting in excellent anti-channeling effects. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0034] In each embodiment of this invention, the rheological properties, stability properties, water loss, gas channeling factor (SPN) value, and strength testing methods are performed according to the industry standard SY / T 6544-2017, "Performance Requirements of Oil Well Cement Slurry." After the cement slurry is cured into stone, the permeability is measured according to the requirements of the industry standard SY / T6385-2016, "Determination Method of Porosity and Permeability of Rock under Overburden." The expansion rate of the cement slurry is measured using a Trinley high-temperature and high-pressure expansion and contraction meter.

[0035] In the various embodiments of this invention, the nano-zinc oxide used is converter flue dust from a zinc-steel plant, wherein the nano-zinc oxide has a purity >99%, a particle size distribution of 100nm to 300nm, an average particle size of 200nm, and a density of 5.6g / cm³. 3 ;

[0036] Iron ore powder, particle size 200 mesh, purity ≥90%, density 5.0 g / cm³ 3 ;

[0037] Silica powder, 100-200 mesh, purity >99%, density 2.60 g / cm³ 3 ;

[0038] AMPS-AM-AA copolymer, Continental Shelf Petroleum Engineering & Technology, SCFL-180, weight average molecular weight 650,000;

[0039] Acetone-formaldehyde condensate, Continental Shelf Petroleum Engineering Technology Co., Ltd., SCD, weight average molecular weight 81,000;

[0040] Grade G oil well cement, Sichuan Leshan Jiahua Cement Plant;

[0041] Magnesium oxide, Continental Shelf Petroleum Engineering & Technology Company, SCEX, 100 mesh;

[0042] All other reagents are commercially available products from the Continental Shelf Petroleum Engineering Technology Company of the Petroleum Engineering Technology Research Institute of China Petroleum & Chemical Corporation.

[0043] In various embodiments of the present invention, the nano-magnesium oxide dispersion is formulated as follows: 41% distilled water, 50% nano-magnesium oxide, 0.5% sodium polynaphthalene sulfonate, 0.1% disodium ethylenediaminetetraacetate, 2.5% ethylene glycol, 1% polyoxyethylene sorbitan fatty acid ester, 1% dimethyl silicone oil, and 4% methacryloxypropyltrimethoxysilane, with a density of 1.50 g / cm³. 3 The average particle size is 100 nm.

[0044] Example 1

[0045] This embodiment provides a nano-high-density anti-channeling cement slurry and its preparation method. Specific details are as follows, based on 10 cubic meters of cement slurry:

[0046] S1: Add 4.3 tons of tap water, 0.05 tons of dimethyl silicone oil, 1.35 tons of nano magnesium oxide dispersion, 0.27 tons of AMPS-AM-AA copolymer, 0.03 tons of ethylenediaminetetramethylenephosphonic acid, and 0.05 tons of acetone-formaldehyde condensate to storage tanks and circulate them for 3 hours to obtain the liquid for later use.

[0047] S2: 9 tons of G-grade oil well cement, 2.25% silica fume, and 2.7 tons of zinc steel plant converter flue dust are dry-mixed using a dry-mixing equipment, and the resulting dry-mixed material is stored in a cement ash silo for later use.

[0048] S3: The liquid material obtained in step S1 and the dry mixture obtained in step S2 are mixed in a mass ratio of 0.43:1 and then prepared using cementing equipment to obtain nano high-density anti-channeling cement slurry.

[0049] The nano-high-density anti-channeling cement slurry obtained in Example 1 has a density of 2.0 g / cm³. 3 The cement slurry had an API water loss of 42 mL, zero free liquid, no sedimentation density difference, a cement stone permeability of 0.008 mD, an air channeling factor (SPN) value of 1.7, a cement stone expansion rate of 0.6%, and a compressive strength of 52 MPa.

[0050] Example 2

[0051] This embodiment provides a nano-high-density anti-channeling cement slurry and its preparation method. Specific details are as follows, based on 10 cubic meters of cement slurry:

[0052] S1: Add 3.28 tons of tap water, 0.08 tons of dimethyl silicone oil, 1.0 ton of nano magnesium oxide dispersion, 0.39 tons of oil well cement slurry AMPS-AM-AA, 0.05 tons of ethylenediaminetetramethylenephosphonic acid, and 0.08 tons of acetone formaldehyde condensate to the storage tank and pump them, circulate for 2 hours to obtain the liquid for later use.

[0053] S2: Mix 9.8 tons of G-grade oil well cement, 2.94 tons of silica fume, and 5.39 tons of converter dust from a zinc steel plant using a dry mixing equipment to obtain a dry mix, which is then stored in a cement ash silo for later use.

[0054] S3: The liquid material obtained in step S1 and the dry mixture obtained in step S2 are mixed in a mass ratio of 0.27:1 and then prepared using cementing equipment to obtain nano high-density anti-channeling cement slurry.

[0055] The nano-high-density anti-channeling cement slurry obtained in Example 2 has a density of 2.3 g / cm³. 3 API water loss 46mL, zero free liquid, no sedimentation density difference, cement stone permeability 0.009mD, gas channeling factor SPN value 1.8, cement stone expansion rate 0.53%, compressive strength 47MPa.

[0056] Example 3

[0057] This embodiment provides a nano-high-density anti-channeling cement slurry and its preparation method. Specific details are as follows, based on 10 cubic meters of cement slurry:

[0058] S1: 2.66 tons of tap water, 0.09 tons of dimethyl silicone oil, 0.73 tons of nano magnesium oxide dispersion, 0.46 tons of oil well cement slurry AMPS-AM-AA copolymer, 0.06 tons of ethylenediaminetetramethylenephosphonic acid, and 0.06 tons of acetone formaldehyde condensate were respectively added into a storage tank and circulated by pump for 3.5 hours to obtain the material solution for later use;

[0059] S2: Mix 9.1 tons of G-grade oil well cement, 2.7 tons of silica powder, and 10 tons of converter dust from a zinc steel plant using a dry mixing equipment to obtain a dry mix, which is then stored in a cement ash silo for later use.

[0060] S3: The liquid material obtained in step S1 and the dry mixture obtained in step S2 are mixed in a mass ratio of 0.19:1 and then prepared using cementing equipment to obtain nano high-density anti-channeling cement slurry.

[0061] The nano-high-density anti-channeling cement slurry obtained in Example 3 has a density of 2.6 g / cm³. 3 The cement slurry had an API water loss of 32 mL, zero free liquid, no sedimentation density difference, a cement stone permeability of 0.005 mD, an air channeling factor (SPN) value of 1.3, a cement stone expansion rate of 0.73%, and a compressive strength of 41 MPa.

[0062] Comparative Example 1

[0063] This comparative example provides a cement slurry for preventing iron powder from migrating into the cementitious slurry, the specific details of which are as follows:

[0064] 4.55 tons of tap water, 0.05 tons of dimethyl silicone oil, 0.27 tons of AMPS-AM-AA copolymer, 0.03 tons of ethylenediaminetetramethylenephosphonic acid, and 0.05 tons of acetone-formaldehyde condensate were respectively added to a storage tank and circulated by pump for 3 hours to obtain a liquid for later use.

[0065] S2: After dry mixing 9 tons of G-grade oil well cement, 2.25 tons of silica fume and 3.53 tons of iron ore powder using a dry mixing equipment, the resulting dry mixture is stored in a cement ash silo for later use.

[0066] S3: The liquid material obtained in step S1 and the dry mixture obtained in step S2 are mixed in a mass ratio of 0.33:1 and then prepared using cementing equipment to obtain nano high-density anti-channeling cement slurry.

[0067] The density of the nano-high-density anti-channeling cement slurry obtained in Comparative Example 1 was 2.0 g / cm³. 3 The cement slurry lost 56 mL of API water, had 0.7 mL of free liquid, and exhibited a sedimentation density difference of 0.02 g / cm³. 3 The cement stone has a permeability of 0.16 mD, an air channeling factor (SPN) of 2.5, a cement stone expansion rate of 0.2%, and a compressive strength of 38 MPa.

[0068] Comparative Example 2

[0069] This comparative example provides a prior art anti-channeling cement slurry that does not contain nano zinc oxide and nano magnesium oxide dispersions. Specific details are as follows:

[0070] S1: Add 4.95 tons of tap water, 0.08 tons of dimethyl silicone oil, 0.28 tons of AMPS-AM-AA, 0.05 tons of ethylenediaminetetramethylenephosphonic acid, and 0.08 tons of acetone-formaldehyde condensate to the storage tank and pump them, and circulate for 2 hours to obtain the liquid for later use.

[0071] S2: Mix 7 tons of G-grade oil well cement, 2.1 tons of silica fume, 8.19 tons of iron ore powder and 0.27 tons of magnesium oxide using a dry mixing equipment, and store the dry mixture in a cement ash silo for later use.

[0072] S3: The liquid material obtained in step S1 and the dry mixture obtained in step S2 are mixed in a mass ratio of 0.31:1 and then prepared using cementing equipment to obtain nano high-density anti-channeling cement slurry.

[0073] The density of the nano-high-density anti-channeling cement slurry obtained in Comparative Example 2 was 2.3 g / cm³. 3 API loss: 65 mL, free liquid: 1.2 mL, sedimentation density difference: 0.06 g / cm³ 3 The cement stone has a permeability of 0.28 mD, a gas channeling factor (SPN) of 2.8, a cement stone expansion rate of 0.3%, and a compressive strength of 32 MPa.

[0074] Comparative Example 3

[0075] This comparative example provides a cement slurry that prevents cross-linking, without the addition of nano-magnesium oxide dispersion. Specific details are as follows:

[0076] S1: Add 4.3 tons of tap water, 0.05 tons of dimethyl silicone oil, 0.27 tons of AMPS-AM-AA copolymer, 0.03 tons of ethylenediaminetetramethylenephosphonic acid, and 0.05 tons of acetone-formaldehyde condensate to storage tanks and circulate them for 3 hours to obtain a liquid for later use.

[0077] S2: 9 tons of G-grade oil well cement, 2.25% silica fume, and 2.7 tons of zinc steel plant converter flue dust are dry-mixed using a dry-mixing equipment, and the resulting dry-mixed material is stored in a cement ash silo for later use.

[0078] S3: The liquid material obtained in step S1 and the dry mixture obtained in step S2 are mixed in a mass ratio of 0.43:1 and then prepared using cementing equipment to obtain nano high-density anti-channeling cement slurry.

[0079] The density of the nano-high-density anti-channeling cement slurry obtained in Comparative Example 3 was 2.0 g / cm³. 3 The cement slurry lost 52 mL of API water, had 0.3 mL of free liquid, and a sedimentation density difference of 0.04 g / cm³. 3The cement stone permeability is 0.19 mD, the gas channeling factor SPN value is 2.2, the cement stone expansion rate is -0.1%, and the compressive strength is 43 MPa.

[0080] The test data of the cement slurries obtained in Examples 1-3 and Comparative Examples 1-2 were compared, and the results are shown in Table 1:

[0081] Table 1 shows the tests conducted on the cement slurries obtained in Examples 1-3 and Comparative Examples 1-2.

[0082]

[0083] Table 1 shows that the compressive strength and other properties of the iron powder anti-channeling cement slurry in Comparative Example 1 are not as good as the high-density anti-channeling cement slurry with added nano-zinc oxide of the present invention; the anti-channeling cement slurry in Comparative Example 2 does not contain nano-magnesium oxide dispersion and nano-zinc oxide, but adds iron ore powder and magnesium oxide powder, and its effect is far inferior to the cement slurry obtained in the embodiments of the present invention; the anti-channeling cement slurry in Comparative Example 3 does not contain nano-magnesium oxide dispersion, but is otherwise the same as in Example 1, and although its compressive strength is acceptable, its performance is far inferior to that of Example 1. This further illustrates that the present invention, by adding nano-zinc oxide, has a stronger ability to increase the density of the cement slurry; the use of nano-magnesium oxide dispersion to fill the gaps between cement particles has the effect of reducing API water loss and reducing cement stone permeability; both are indispensable.

[0084] In summary, the density of the nano-high-density anti-channeling cement slurry of the present invention is 1.95–2.60 g / cm³. 3 It also features API water loss of less than 50mL, zero free liquid, no sedimentation, cement stone permeability of less than 0.01mD, compressive strength of greater than 40MPa, gas channeling factor SPN value of less than 2, no shrinkage of cement stone, and has a good anti-channeling effect, which can improve the cementing of ultra-deep wells with high-density cement slurry.

[0085] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 50-90, in this specification it means specifically listing values ​​such as 51-89, 52-88… and 69-71 and 70-71, etc. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0086] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A nano-high-density anti-channeling cement slurry, characterized in that, The components, by mass parts, include: 35-45 parts of Grade G oil well cement 10-13 parts of silicon powder 5-38 parts of nano zinc oxide 2.5-7 parts of nano-magnesium oxide dispersion 1.3-1.8 parts of water loss reducer 0.12-0.25 parts of retarder; Dispersant 0.2-0.35 parts, Defoamer 0.2-0.35 parts, 10-22 parts water; The nano zinc oxide is spherical particles with a particle size distribution of 50nm-300nm; The nano-magnesium oxide dispersion is a dispersion composed of 40-45% distilled water, 45-50% nano-magnesium oxide, 0.4-0.6% sodium polynaphthalene sulfonate, 0.05-0.2% disodium ethylenediaminetetraacetate, 2-3.5% ethylene glycol, 0.5-1.5% polyoxyethylene sorbitan fatty acid ester, 0.5-1% dimethyl silicone oil, and 3-5% methacryloxypropyltrimethoxysilane. The particle size distribution range of the nano-magnesium oxide dispersion is 10-300 nm.

2. The nano-high-density anti-channeling cement slurry according to claim 1, characterized in that, The effective solid content of the nano-magnesium oxide dispersion is ≥45%.

3. The nano-high-density anti-channeling cement slurry according to claim 1, characterized in that, The water loss reducing agent is an AMPS-type copolymer.

4. The nano-high-density anti-channeling cement slurry according to claim 3, characterized in that, The water loss reducing agent is an AMPS-MA-AA terpolymer.

5. The nano-high-density anti-channeling cement slurry according to claim 1, characterized in that, The dispersant is a ketaldehyde condensate.

6. The nano-high-density anti-channeling cement slurry according to claim 5, characterized in that, The dispersant is acetone-formaldehyde condensate.

7. The nano-high-density anti-channeling cement slurry according to claim 1, characterized in that, The retarder is an organic acid.

8. The nano-high-density anti-channeling cement slurry according to claim 7, characterized in that, The retarder is ethylenediaminetetramethylenephosphonic acid.

9. The nano-high-density anti-channeling cement slurry according to claim 1, characterized in that, The defoamer is an organosilicone oil.

10. The nano-high-density anti-channeling cement slurry according to claim 9, characterized in that, The defoamer is dimethyl silicone oil.

11. The nano-high-density anti-channeling cement slurry according to claim 1, characterized in that, The silicon powder is mainly composed of SiO2, with a particle size range of 80~200 mesh.

12. The nano-high-density anti-channeling cement slurry according to any one of claims 1-11, characterized in that, The density of this cement grout ranges from 1.95 to 2.60 g / cm³. 3 API water loss < 50 mL, permeability < 0.01 mD, gas channeling factor SPN value < 2.

13. A method for preparing the nano-high-density anti-channeling cement slurry according to any one of claims 1-12, characterized in that, Includes the following steps: S1: Mix and stir water, nano magnesium oxide dispersion, water loss reducing agent, retarder, dispersant, and defoamer to obtain the first mixture; S2: Dry-mix G-grade oil well cement, silica fume, and nano zinc oxide to obtain a second mixture; S3: Mix the first mixture with the second mixture to obtain nano high-density anti-channeling cement slurry.

14. The preparation method according to claim 13, characterized in that, In step S3, the first mixture and the second mixture are mixed at a mass ratio of (0.19~0.45):1.

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