CO2 corrosion resistant high thermal conductivity material for cementing cement and preparation method thereof

Abstract

The present application relates to geothermal resource development technical field, specifically to a kind of high heat-conducting material resistant to CO2 corrosion for cementing and its preparation method, the material includes 45wt. 70wt. 20wt. 40wt. 10wt. 15wt. By weight percentage Heat-conducting material, corrosion-resistant material and toughening material, heat-conducting material is formed by heat-conducting reinforced material and reinforcing material by mass ratio (8-12):(6-9) Mixed, the corrosion-resistant material is formed by nano-molybdenum trioxide, chlorite powder and acidified serpentine powder by mass ratio (9-12):(4-6):(4-5) Mixed.The high heat-conducting material resistant to CO2 corrosion for cementing of the present application has the properties of high temperature resistance, toughening, gas channeling prevention, corrosion resistance and heat conduction by mutual cooperation and mutual cooperation between components.

Description

Technical Field

[0001] This invention relates to the field of geothermal resource development technology, specifically to a CO2-resistant, high thermal conductivity material for well cementing and its preparation method. Background Technology

[0002] In the process of geothermal energy extraction, there is a layer of cementing material between the reservoir and the heat exchange device. Its heat transfer performance is an important factor affecting the heat transfer capacity of the wellbore. To improve heat extraction efficiency, cementing materials with high thermal conductivity are usually used. For high thermal conductivity cementing materials, thermally conductive fillers play a key role in improving the material's thermal conductivity. Based on the current research status, thermally conductive fillers can be divided into two types: non-metallic and metallic.

[0003] In addition, factors affecting geothermal extraction efficiency also include the heat extraction medium, with water and CO2 being the two most commonly used. When water is used as a heat extraction medium, it undergoes physicochemical reactions with the rocks and minerals in the formation, disrupting reservoir stability. Dissolved minerals in the water can also cause scaling on wellbores, surface equipment, and various pipelines, affecting equipment lifespan. Supercritical CO2, when used for geothermal resource extraction, exhibits superior properties compared to water, improving extraction efficiency and increasing economic benefits, making it significant for the development of hot dry rock. However, when using supercritical CO2, the cement sheath is subject to acid corrosion, leading to a decline in cement stone performance.

[0004] In order to improve the efficiency of heat extraction and utilization and increase economic benefits, it is particularly important to develop a cementing material that is resistant to high temperature, high thermal conductivity and corrosion. Summary of the Invention

[0005] To overcome the problems of CO2 corrosion and reduced heat extraction efficiency in geothermal resource extraction using supercritical CO2 as the heat extraction medium, this invention provides a CO2-resistant, high thermal conductivity material for well cementing and its preparation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A CO2-resistant and highly thermally conductive cementing material for well cementing comprises the following raw materials by weight percentage:

[0008] Thermally conductive material 45 wt.% to 70 wt.%;

[0009] Corrosion-resistant materials: 20 wt.% to 40 wt.%;

[0010] Toughening material 10 wt.% to 15 wt.%;

[0011] The thermally conductive material is composed of a thermally conductive strengthening material and a reinforcing material mixed in a mass ratio of (8-12):(6-9); the corrosion-resistant material is composed of nano-molybdenum trioxide, chlorite powder and acidified serpentine powder mixed in a mass ratio of (9-12):(4-6):(4-5).

[0012] The CO2-resistant and thermally conductive cementitious material of the present invention has the characteristics of high temperature resistance, CO2 corrosion resistance, high thermal conductivity, good toughness, and micro-expansion.

[0013] In some embodiments, a CO2-resistant, high thermal conductivity material for cementing comprises the following raw materials by weight percentage:

[0014] Thermally conductive material 50wt.%~60wt.%;

[0015] Corrosion-resistant materials: 20 wt.% to 30 wt.%;

[0016] Toughening material 10 wt.% to 12 wt.%;

[0017] The thermally conductive material is composed of a thermally conductive strengthening material and a reinforcing material mixed in a mass ratio of (8-10):(6-8); the corrosion-resistant material is composed of nano-molybdenum trioxide, chlorite powder and acidified serpentine powder mixed in a mass ratio of (10-12):(5-6):(4-5).

[0018] Furthermore, the nano-molybdenum trioxide has a purity ≥99wt.% and an average particle size of 50-100nm; the chlorite powder has a SiO2 content ≥55.0wt.%, an Al2O3 content ≥12wt.%, and an MgO content ≥9wt.%, with a purity ≥99wt.% and an average particle size of 800 mesh; the acidified serpentine powder has an MgO content ≥40.0wt.%, a SiO2 content ≥40.0wt.%, and an average particle size of 325 mesh.

[0019] Further, the acidified serpentine powder is prepared by the following steps: step a, drying the serpentine powder; step b, placing the dried serpentine powder in a dilute sulfuric acid solution for acidification treatment; step c, vacuum filtering the acidified serpentine powder and then drying it to obtain the acidified serpentine powder.

[0020] Further, in step a, the drying heating temperature is preferably 120°C, and the drying time is preferably 24 hours; in step b, the dilute sulfuric acid is a mixture of water and 98% sulfuric acid at a volume ratio of 1:19, and the acidification treatment time is preferably 2 hours; in step c, the re-drying heating temperature is preferably 120°C, and the drying time is preferably 2 hours.

[0021] Furthermore, the toughening material is made by melt blending polyetherimide and polybenzimidazole fiber in a mass ratio of 9:1, followed by granulation, cooling, pulverization, and then low-temperature plasma modification.

[0022] The polyetherimide, after being crushed and ground, has an average particle size ≤45μm; the polybenzimidazole has an effective substance content >98wt.% and an average particle size ≤45μm.

[0023] This invention modifies polyetherimide by adding polybenzimidazole fibers, which possess strong toughness and good compatibility, effectively improving its toughness, temperature resistance, and hydrophilicity. On one hand, the polybenzimidazole fibers act as heterogeneous nucleation agents, enhancing the toughness and temperature resistance of the polyetherimide; on the other hand, polar groups such as ether bonds, imidazole bonds, and amide bonds increase interfacial compatibility with cement hydration products, improving bonding strength. Furthermore, the toughening material and modified expanded graphite work synergistically, dispersing and interpenetrating to form a tough structure, further enhancing the material's toughness.

[0024] Furthermore, the thermally conductive strengthening material is a mixture formed by mixing molybdenum disilicide, tungsten diboride, zirconium diboride, and titanium diboride in a mass ratio of 5:2:2:1 and then modifying it.

[0025] The molybdenum disilicide has an effective material content of >99 wt.% and an average particle size of 15 μm; the tungsten diboride has an effective material content of >99 wt.% and an average particle size of 50 nm; the zirconium diboride has an effective material content of >99 wt.% and an average particle size of 50 nm; and the titanium diboride has an effective material content of >99 wt.% and an average particle size of 15 μm.

[0026] Further, the thermally conductive strengthening material is prepared by the following steps: Step A, molybdenum disilicide, tungsten diboride, zirconium diboride, and titanium diboride are mixed and ground in a mass ratio of 5:2:2:1 to form mixture A; Step B, mixture A is placed in a 3wt.% to 8wt.% tetraethyl orthosilicate ethanol solution, mechanically stirred and ultrasonically dispersed, and then placed in a constant temperature water bath for stirring and reaction; Step C, the product after the reaction is completed is centrifuged and washed repeatedly with anhydrous ethanol 2 to 5 times, and then vacuum dried to obtain the thermally conductive strengthening material.

[0027] Furthermore, the reinforcing material is composed of graphite quartz schist, andalusite, and modified expanded graphite mixed in a mass ratio of 6:1:3;

[0028] The graphite-quartz schist is flaky, with a graphite content of 15wt.%–20wt.%, a SiO2 content of 50wt.%–60wt.%, and a mica content of 10wt.%–20wt.%. After crushing and grinding, the average particle size of the graphite-quartz schist is ≤45μm.

[0029] The andalusite contains Al2O3 content ≥ 50 wt.%, SiO2 content ≥ 40 wt.%, and the average particle size of andalusite ≤ 45 μm;

[0030] The modified expanded graphite is formed by low-temperature plasma modification of expanded graphite, and the average particle size of the modified expanded graphite is ≤74μm.

[0031] The modified expanded graphite has a loose, porous, worm-like structure with a large surface area and flexibility. On the one hand, the large surface area provides a large number of crystallization points for hydration products, promoting hydration. After modification, the hydrophilicity is improved, enhancing the bonding between the graphite and hydration products. On the other hand, its flexibility allows for the relative dispersion of stress, reducing the brittleness of cement stone and enhancing its flexibility. Furthermore, the excellent thermal conductivity of graphite materials can be combined with thermally conductive reinforcing materials to further enhance thermal conductivity.

[0032] The present invention also provides a method for preparing a CO2-resistant and thermally conductive material for cementing, comprising weighing thermally conductive material, corrosion-resistant material and toughening material in various mass ratios and then mixing them thoroughly to obtain the CO2-resistant and thermally conductive material for cementing.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The CO2-resistant, high thermal conductivity cementitious material of this invention features a rationally designed thermally conductive material. Raw materials such as molybdenum disilicide, tungsten diboride, zirconium diboride, titanium diboride, and expanded graphite inherently possess excellent thermal conductivity and strong temperature resistance. Furthermore, the thermally conductive reinforcing material, reinforcing material, and cement particles reduce gaps through small size and particle size distribution effects, increasing the density of the cement stone structure. This mitigates the decrease in thermal conductivity caused by pores, reduces cement stone permeability, and improves corrosion resistance. Simultaneously, modification enhances the bonding strength between the material and cement hydration products, reducing porosity and further improving thermal conductivity.

[0035] The CO2-resistant, high thermal conductivity cementitious material of this invention comprises nano-molybdenum trioxide, chlorite powder, and acidified serpentine powder as its corrosion-resistant material. The main components of the corrosion-resistant and reinforcing materials are SiO2 and Al2O3. Their synergistic effect effectively reduces the calcium-silicon ratio (Ca / Si) of the cement, decreases the use of siliceous raw materials, and prevents the cement stone strength from declining under high-temperature conditions. On the one hand, chlorite powder and acidified serpentine powder have high MgO content, which expands in volume after participating in the hydration reaction. This effectively compensates for the volume shrinkage of the cement system caused by high temperature and the use of ultrafine materials, reducing the gap between the cement sheath and the formation. This not only improves the bonding strength between the cement sheath and the formation and prevents gas channeling, but also enhances the thermal conductivity and corrosion resistance of the cement stone. On the other hand, chlorite powder and acidified serpentine powder can participate in and promote the hydration reaction, reducing the easily carbonized substances in the hydration products and inhibiting and interfering with the formation and growth of calcium carbonate. In addition, the alkaline environment formed after the hydration of cement, chlorite powder, and serpentine powder promotes the reaction of nano-molybdenum trioxide with the hydration products to form insoluble calcium molybdate, which coats the surface of the hydration products. This prevents CO2 from reacting with the hydration products, thereby improving corrosion resistance through a synergistic effect.

[0036] The CO2-resistant and thermally conductive cementitious material of the present invention has properties such as high temperature resistance, toughening, gas channeling prevention, corrosion resistance and thermal conductivity through the mutual cooperation and interaction of its components. Attached Figure Description

[0037] Figure 1 The graph shows the weight loss curves of the solidified products of cement slurry systems No. 1 to No. 10 after 28 days of corrosion. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0039] The following examples all demonstrate the preparation of cement slurry according to GB / T19139 standard. The G-grade oil well cement was provided by Jiahua Special Cement Co., Ltd., the high-temperature retarder was an AMPS polymer, and the high-temperature water loss reducer was a 2-acrylamido-2-methylpropanesulfonic acid polymer.

[0040] The nano-molybdenum trioxide used in this embodiment of the invention has a purity ≥99wt.% and an average particle size of 50-100nm; the chlorite powder used has a SiO2 content ≥55.0wt.%, an Al2O3 content ≥12wt.%, and an MgO content ≥9wt.%, with a purity ≥99wt.% and an average particle size of 800 mesh; the acidified serpentine powder used has an MgO content ≥40.0wt.%, a SiO2 content ≥40.0wt.%, and an average particle size of 325 mesh.

[0041] The acidified serpentine powder used in this embodiment of the invention is prepared by the following steps: Step a, placing the serpentine powder in a 120°C oven for 24 hours; Step b, placing the dried serpentine powder in a dilute sulfuric acid solution for acidification treatment for 2 hours, wherein the dilute sulfuric acid is a mixture of water and 98% sulfuric acid at a volume ratio of 1:19; Step c, after the acidification treatment, the serpentine powder is vacuum filtered and then placed in a 120°C oven for 2 hours to obtain the acidified serpentine powder.

[0042] The toughening material used in the embodiments of the present invention is made by melt blending polyetherimide and polybenzimidazole fiber in a mass ratio of 9:1, followed by granulation, cooling, pulverization, and then low-temperature plasma modification.

[0043] The polyetherimide used has an average particle size ≤45μm after crushing and grinding; the polybenzimidazole used has an effective substance content >98wt.% and an average particle size ≤45μm.

[0044] The thermally conductive strengthening material used in the embodiments of the present invention is a mixture formed by mixing molybdenum disilicide, tungsten diboride, zirconium diboride and titanium diboride in a mass ratio of 5:2:2:1 and then modifying it.

[0045] The effective material content of molybdenum disilicide used is >99 wt.%, and the average particle size is 15 μm; the effective material content of tungsten diboride used is >99 wt.%, and the average particle size is 50 nm; the effective material content of zirconium diboride used is >99 wt.%, and the average particle size is 50 nm; the effective material content of titanium diboride used is >99 wt.%, and the average particle size is 15 μm.

[0046] The thermally conductive strengthening material used in this embodiment of the invention is prepared by the following steps: Step A: Molybdenum disilicide, tungsten diboride, zirconium diboride, and titanium diboride are mixed in a ball mill at a mass ratio of 5:2:2:1 for 30 min to form mixture A; Step B: Mixture A is placed in a 6 wt.% tetraethyl orthosilicate ethanol solution, mechanically stirred and ultrasonically dispersed for 20 min, and then placed in a 60℃ constant temperature water bath for stirring and reaction for 10 h; Step C: After the reaction is completed, the product is centrifuged at 1200 r / min for 5 min, then washed three times with anhydrous ethanol, and vacuum dried for 24 h to obtain the thermally conductive strengthening material.

[0047] The reinforcing material used in the embodiments of the present invention is a mixture of graphite quartz schist, andalusite, and modified expanded graphite in a mass ratio of 6:1:3;

[0048] The graphite quartz schist used is flaky, with a graphite content of 15wt.% to 20wt.%, a SiO2 content of 50wt.% to 60wt.%, and a mica content of 10wt.% to 20wt.%. The average particle size of the graphite quartz schist after crushing and grinding is ≤45μm.

[0049] The andalusite used contains Al2O3 content ≥ 50 wt.% and SiO2 content ≥ 40 wt.%, with an average particle size of andalusite ≤ 45 μm;

[0050] The modified expanded graphite used is expanded graphite modified by low-temperature plasma, and the average particle size of the modified expanded graphite is ≤74μm.

[0051] Example 1

[0052] As a preferred embodiment of the present invention, the specific composition of the CO2 corrosion-resistant and high thermal conductivity material used in this embodiment for cementing is shown in Table 1:

[0053] Table 1

[0054]

[0055]

[0056] In this embodiment, the thermally conductive material used is a mixture of thermally conductive reinforcing material and reinforcing material in a mass ratio of 8:9.

[0057] In this embodiment, the corrosion-resistant material used is a mixture of nano-molybdenum trioxide, chlorite powder and acidified serpentine powder in a mass ratio of 9:6:5.

[0058] After mixing the above proportions of thermally conductive material, corrosion-resistant material, and toughening material in a powder mixer for 10 minutes, CO2 corrosion-resistant high thermal conductivity material #1 for well cementing is obtained.

[0059] According to the formula: 80wt.% Grade G oil well cement + 20wt.% CO2 corrosion resistant and high thermal conductivity cement material No. 1, and 1.5wt.% high temperature retarder and 4wt.% high temperature water loss reducer, the cement slurry is prepared according to GB / T19139 standard with a water-cement ratio of 0.44, resulting in cement slurry system No. 1.

[0060] Example 2

[0061] As a preferred embodiment of the present invention, the specific composition of the CO2 corrosion-resistant and high thermal conductivity material used in this embodiment for cementing is shown in Table 2:

[0062] Table 2

[0063] Components Weight percentage (wt.%) thermal conductive materials 58 Corrosion-resistant materials 30 toughening materials 12

[0064] In this embodiment, the thermally conductive material used is a mixture of thermally conductive reinforcing material and reinforcing material in a mass ratio of 8:9.

[0065] In this embodiment, the corrosion-resistant material used is a mixture of nano-molybdenum trioxide, chlorite powder and acidified serpentine powder in a mass ratio of 9:6:5.

[0066] After mixing the above proportions of thermally conductive material, corrosion-resistant material, and toughening material in a powder mixer for 10 minutes, CO2 corrosion-resistant high thermal conductivity material #2 for cementing is obtained.

[0067] According to the formula: 80wt.% Grade G oil well cement + 20wt.% CO2 corrosion resistant and high thermal conductivity cement material No. 2, and 1.5wt.% high temperature retarder and 4wt.% high temperature water loss reducer, the cement slurry was prepared according to GB / T19139 standard with a water-cement ratio of 0.44, resulting in cement slurry system No. 2.

[0068] Example 3

[0069] As a preferred embodiment of the present invention, the specific composition of the CO2 corrosion-resistant and high thermal conductivity material used in this embodiment for cementing is shown in Table 3:

[0070] Table 3

[0071] Components Weight percentage (wt.%) thermal conductive materials 70 Corrosion-resistant materials 20 toughening materials 10

[0072] In this embodiment, the thermally conductive material used is a mixture of thermally conductive reinforcing material and reinforcing material in a mass ratio of 8:9.

[0073] In this embodiment, the corrosion-resistant material used is a mixture of nano-molybdenum trioxide, chlorite powder and acidified serpentine powder in a mass ratio of 9:6:5.

[0074] After mixing the above proportions of thermally conductive material, corrosion-resistant material, and toughening material in a powder mixer for 10 minutes, CO2 corrosion-resistant high thermal conductivity material #3 for cementing is obtained.

[0075] According to the formula: 80wt.% Grade G oil well cement + 20wt.% CO2 corrosion resistant and high thermal conductivity cement material No. 3, and 1.5wt.% high temperature retarder and 4wt.% high temperature water loss reducer, the cement slurry is prepared according to GB / T19139 standard with a water-cement ratio of 0.44, resulting in cement slurry system No. 3.

[0076] Example 4

[0077] As a preferred embodiment of the present invention, the specific composition of the CO2 corrosion-resistant and high thermal conductivity material used in this embodiment for cementing is shown in Table 4:

[0078] Table 4

[0079] Components Weight percentage (wt.%) thermal conductive materials 58 Corrosion-resistant materials 30 toughening materials 12

[0080] In this embodiment, the thermally conductive material used is a mixture of thermally conductive reinforcing material and reinforcing material in a mass ratio of 5:4.

[0081] In this embodiment, the corrosion-resistant material used is a mixture of nano-molybdenum trioxide, chlorite powder and acidified serpentine powder in a mass ratio of 2:1:1.

[0082] After mixing the above proportions of thermally conductive material, corrosion-resistant material, and toughening material in a powder mixer for 10 minutes, CO2 corrosion-resistant high thermal conductivity material #4 for well cementing is obtained.

[0083] According to the formula: 80wt.% Grade G oil well cement + 20wt.% CO2 corrosion resistant and high thermal conductivity cement material No. 4, as well as 1.5wt.% high temperature retarder and 4wt.% high temperature water loss reducer, the cement slurry is prepared according to GB / T19139 standard with a water-cement ratio of 0.44, resulting in cement slurry system No. 4.

[0084] Example 5

[0085] As a preferred embodiment of the present invention, the specific composition of the CO2 corrosion-resistant and high thermal conductivity material used in this embodiment for cementing is shown in Table 5:

[0086] Table 5

[0087] Components Weight percentage (wt.%) thermal conductive materials 58 Corrosion-resistant materials 30 toughening materials 12

[0088] In this embodiment, the thermally conductive material used is a mixture of thermally conductive reinforcing material and reinforcing material in a mass ratio of 2:1.

[0089] In this embodiment, the corrosion-resistant material used is a mixture of nano-molybdenum trioxide, chlorite powder and acidified serpentine powder in a mass ratio of 3:1:1.

[0090] After thoroughly mixing the above proportions of thermally conductive material, corrosion-resistant material, and toughening material in a powder mixer for 10 minutes, CO2 corrosion-resistant high thermal conductivity material #5 for cementing is obtained.

[0091] According to the formula: 80wt.% Grade G oil well cement + 20wt.% CO2 corrosion resistant and high thermal conductivity cement material No. 5, and 1.5wt.% high temperature retarder and 4wt.% high temperature water loss reducer, the cement slurry is prepared according to GB / T19139 standard with a water-cement ratio of 0.44, resulting in cement slurry system No. 5.

[0092] Comparative Example 1

[0093] According to the formula: 100wt.% Grade G oil well cement + 1.5wt.% high temperature retarder + 4wt.% high temperature fluid loss reducer, cement slurry was prepared according to GB / T19139 standard with a water-cement ratio of 0.44, resulting in No. 6 cement slurry system.

[0094] Comparative Example 2

[0095] In this comparative example, except that the thermally conductive material does not contain reinforcing materials, the other proportions and conditions are the same as in Example 1, resulting in Cementing Slurry System No. 7.

[0096] Comparative Example 3

[0097] In this comparative example, except that the corrosion-resistant material does not contain nano-molybdenum trioxide, the other proportions and conditions are the same as in Example 1, resulting in Cementing Slurry System No. 8.

[0098] Comparative Example 4

[0099] In this comparative example, except that the corrosion-resistant material does not contain chlorite powder and acidified serpentine powder, the other proportions and conditions are the same as in Example 1, resulting in Cementing Slurry System No. 9.

[0100] Comparative Example 5

[0101] In this comparative example, except that the toughening material does not contain polybenzimidazole fiber, the other proportions and conditions are the same as in Example 1, resulting in Cementing Slurry System No. 10.

[0102] The engineering performance of the cementing slurry systems obtained in Examples 1-5 and Comparative Examples 1-5 was tested in accordance with GB / T19139 Oil Well Cement Test Method. The test results are shown in Table 6.

[0103] Table 6

[0104]

[0105] Based on the experimental data in Table 6, it can be concluded that the water loss of the cement slurry prepared in Examples 1-5 is <35ml, and the fluidity and free fluid both meet the construction requirements. The thickening time is controllable, and all engineering performances are good. Furthermore, the CO2-resistant high thermal conductivity material and additives of this invention have good compatibility, and their performance is superior to that of the No. 6 cement slurry system in Comparative Example 1. The test data from Comparative Examples 2-5 show that the engineering performance of the No. 7-10 cement slurry systems in Comparative Examples 2-5 is superior to that of the No. 6 cement slurry system in Comparative Example 1, but inferior to that of the No. 1-5 cement slurry systems in Examples 1-5. This indicates that the components of the CO2-resistant high thermal conductivity material of this invention have a synergistic effect; the absence of any one of them would prevent the achievement of the expected results of this invention.

[0106] The cement slurry obtained in Examples 1-5 and Comparative Examples 1-5 was poured into molds to form cement stone, and then placed in a high-temperature and high-pressure corrosion reactor for curing. The curing temperature was 150℃, the CO2 pressure was 5MPa, the total pressure was 10MPa, and the N2 partial pressure was 7d and 28d respectively. The compressive strength was tested using an NYSQ-2017 pressure testing machine. Core samples were taken from the cured cement stone, and then triaxial mechanical property tests were performed. The mechanical testing standard for cement stone was based on GB / T50266-2013 "Standard for Test Methods of Engineering Rock Mass", and the experimental equipment used was an RTR-1000 triaxial rock mechanics tester. The permeability of the cement stone formed in Examples 1-5 and Comparative Examples 1-5 was measured according to the standard SY / T6466-2000 "Evaluation Method for High Temperature Resistance of Oil Well Cement Stone". The thermal conductivity of cement stone was tested using a DRE-2C thermal conductivity tester and the transient planar heat source method. The test results are shown in Table 7.

[0107] Table 7

[0108]

[0109]

[0110] As shown in Table 7, the compressive strength of cement slurries No. 1 to No. 5 did not decline after a certain corrosion period, but increased slightly, indicating that the high-temperature resistance of the CO2 corrosion-resistant and high-thermal-conductivity cement slurry provided by the technical solution of this invention is good. The 28-day permeability is slightly higher than that of the 7-day permeability, but is still less than 0.03mD, the elastic modulus is ≤6.1GPa, and the thermal conductivity is >1.4W / (m·K), all of which are far superior to the No. 6 cement slurry. The data of cement slurries No. 7 to No. 10 are all better than the No. 6 cement slurry but worse than the No. 1 to No. 5 cement slurries, indicating that the components of the CO2 corrosion-resistant and high-thermal-conductivity material of this invention have a synergistic effect, and the absence of any one of them would prevent the achievement of the expected effect of this application.

[0111] Thermogravimetric analysis was performed on the solidified products of the cement slurry systems of Examples 1-5 and Comparative Examples 1-5. Figure 1 These are the weight loss curves of cement slurry from wells 1 to 10 after 28 days of corrosion. Thermogravimetric analysis of the samples was conducted on a thermal analysis instrument manufactured by Mettle Toledo, with a heating rate of 10℃ / min and nitrogen protection.

[0112] pass Figure 1 The experimental results show that the corrosion resistance of the cured products of cement slurry systems 1-5 is much greater than that of the cured product of cement slurry system 6. This indicates that the CO2-resistant, high thermal conductivity material of the present invention has excellent corrosion resistance and can significantly improve the corrosion resistance of cementing cement.

[0113] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A CO2-resistant, high thermal conductivity material for cementing, characterized in that, Including the following raw materials by weight percentage: Thermally conductive material 45wt.%~70wt.%; Corrosion-resistant materials 20wt.%~40wt.%; Toughening material 10wt.%~15wt.%; The thermally conductive material is composed of thermally conductive reinforcing material and reinforcing material mixed in a mass ratio of (8~12):(6~9); the corrosion-resistant material is composed of nano molybdenum trioxide, chlorite powder and acidified serpentine powder mixed in a mass ratio of (9~12):(4~6):(4~5); The toughening material is made by melt blending polyetherimide and polybenzimidazole fiber in a mass ratio of 9:1, followed by granulation, cooling, pulverization, and then low-temperature plasma modification. The polyetherimide, after being crushed and ground, has an average particle size ≤45μm; the polybenzimidazole has an effective substance content >98wt.% and an average particle size ≤45μm. The thermally conductive strengthening material is a mixture of molybdenum disilicide, tungsten diboride, zirconium diboride, and titanium diboride in a mass ratio of 5:2:2:1, which is then modified. The molybdenum disilicide has an effective material content >99 wt.% and an average particle size of 15 μm; the tungsten diboride has an effective material content >99 wt.% and an average particle size of 50 nm; the zirconium diboride has an effective material content >99 wt.% and an average particle size of 50 nm; the titanium diboride has an effective material content >99 wt.% and an average particle size of 15 μm. The thermally conductive strengthening material is prepared by the following steps: Step A, molybdenum disilicide, tungsten diboride, zirconium diboride, and titanium diboride are mixed and ground in a mass ratio of 5:2:2:1 to form mixture A; Step B, mixture A is placed in an ethanol solution of tetraethyl orthosilicate with a concentration of 3wt.%~8wt.%, mechanically stirred and ultrasonically dispersed, and then placed in a constant temperature water bath for stirring and reaction; Step C, the product after the reaction is completed is centrifuged and washed repeatedly with anhydrous ethanol 2~5 times, and then vacuum dried to obtain the thermally conductive strengthening material.

2. The CO2-resistant and high thermal conductivity material for cementing as described in claim 1, characterized in that, Including the following raw materials by weight percentage: Thermal conductive material 50wt.%~60wt.%; Corrosion-resistant materials 20wt.%~30wt.%; Toughening material 10wt.%~12wtwt.%; The thermally conductive material is composed of thermally conductive reinforcing material and reinforcing material mixed in a mass ratio of (8~10):(6~8); the corrosion-resistant material is composed of nano molybdenum trioxide, chlorite powder and acidified serpentine powder mixed in a mass ratio of (10~12):(5~6):(4~5).

3. A CO2-resistant, high thermal conductivity material for cementing as described in claim 1 or 2, characterized in that, The nano-molybdenum trioxide has a purity ≥99wt.% and an average particle size of 50~100nm; the chlorite powder has a SiO2 content ≥55.0wt.%, an Al2O3 content ≥12wt.%, and an MgO content ≥9wt.%, with a purity ≥99wt.% and an average particle size of 800 mesh; the acidified serpentine powder has an MgO content ≥40.0wt.%, a SiO2 content ≥40.0wt.%, and an average particle size of 325 mesh.

4. A CO2-resistant, high thermal conductivity material for cementing as described in claim 1 or 2, characterized in that, The acidified serpentine powder is prepared by the following steps: Step a, drying the serpentine powder; Step b, placing the dried serpentine powder in a dilute sulfuric acid solution for acidification treatment; Step c, vacuum filtering the acidified serpentine powder and then drying it to obtain the acidified serpentine powder.

5. The CO2-resistant and high thermal conductivity material for cementing as described in claim 4, characterized in that, In step a, the drying temperature is 120°C and the drying time is 24 hours; in step b, the dilute sulfuric acid is a mixture of water and 98% sulfuric acid at a volume ratio of 1:19, and the acidification treatment time is 2 hours; in step c, the re-drying temperature is 120°C and the drying time is 2 hours.

6. A CO2-resistant, high thermal conductivity material for cementing as described in claim 1 or 2, characterized in that, The reinforcing material is composed of graphite quartz schist, andalusite, and modified expanded graphite in a mass ratio of 6:1:3; The graphite-quartz schist is flaky, with a graphite content of 15wt.%~20wt.%, a SiO2 content of 50wt.%~60wt.%, and a mica content of 10wt.%~20wt.%; the average particle size of the graphite-quartz schist after crushing and grinding is ≤45μm. The andalusite contains Al2O3 content ≥ 50 wt.%, SiO2 content ≥ 40 wt.%, and the average particle size of andalusite ≤ 45 μm; The modified expanded graphite is formed by low-temperature plasma modification of expanded graphite, and the average particle size of the modified expanded graphite is ≤74μm.

7. A method for preparing a CO2-resistant, high thermal conductivity material for cementing according to any one of claims 1 to 6, characterized in that, The process involves weighing out thermally conductive materials, corrosion-resistant materials, and toughening materials in various mass ratios and then thoroughly mixing them to obtain the CO2-resistant, high-thermal-conductivity cementitious material for well cementing.

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