CO2 corrosion resistant phosphoaluminate cement based on ion doping and composite modification and application thereof in well cementation

Abstract

The invention discloses CO2 corrosion-resistant phosphoaluminate cement based on ion doping and composite modification and application of the CO2 corrosion-resistant phosphoaluminate cement in well cementation. The cement is prepared from phosphoaluminate cement clinker, alkaline earth metal ion metal oxide, gypsum, an active mineral admixture and a thickening time control agent, the doping amount of the alkaline earth metal ion metal oxide is 0.1 wt%-3.0 wt% of the total mass of the phosphoaluminate cement clinker in terms of metal oxide; the mixing amount of the gypsum is 3.0 wt%-10.0 wt% of the mass of the cement base material in terms of SO3; the mixing amount of the active mineral admixture is 10-40 wt% of the total mass of the cement base material and the gypsum; the mixing amount of the thickening time control agent is 0.1 wt%-1.0 wt% of the mass of the cement base material. The mineral phase composition is effectively regulated and controlled through ion doping, the content of calcium phosphoaluminate (C-A-P-H) in a hydration product is remarkably increased, and early strength development is promoted. The cement has excellent early strength, long-term CO2 corrosion resistance and economical efficiency in a high-temperature environment of 80-150 DEG C, and solves the problems that traditional cement is easy to carbonize and degrade and insufficient in early strength under a corrosive well condition.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building materials, and particularly relates to a special cement material for well cementing engineering in CO2-containing corrosive environments such as oil and gas fields, geothermal fields, and carbon capture, utilization and storage (CCUS), and especially relates to a phosphoaluminate cement with excellent CO2 corrosion resistance and good early mechanical strength, and a preparation method and application thereof by means of specific ion doping technology combined with composite additive modification. BACKGROUND

[0002] In oil and gas exploitation, geothermal development, and CCUS engineering, the downhole cementing cement sheath is exposed to a corrosive environment with high temperature, high pressure, and rich CO2 for a long time. The main hydration products of traditional Portland cement, calcium hydroxide and calcium silicate hydrate (C-S-H), are prone to carbonation by reacting with CO2, generating calcium carbonate and silica gel with low strength and high permeability, which leads to the deterioration of cement sheath structure and sealing failure, and seriously threatens the integrity and long-term safety of the wellbore.

[0003] Phosphoaluminate cement has become one of the research hotspots of CO2 corrosion resistant cementing cement because its main hydration product, calcium phosphoaluminate hydrate (C-A-P-H), is more stable and less likely to react with CO2 than C-S-H of Portland cement in thermodynamics. However, the unmodified phosphoaluminate cement still faces challenges such as insufficient early strength development and relatively high cost in practical application, which limits its reliable application in harsh well conditions. Although ion doping is often used in Portland cement systems to regulate mineral activity, gypsum is added to adjust setting, or industrial waste such as fly ash is added to reduce cost in the prior art, but these means directly transferred to the phosphoaluminate cement system have essential differences in mineral composition, hydration mechanism and product performance from Portland cement, and their effects and mechanisms are not clear and may be completely different. For example, in phosphoaluminate cement, the role of gypsum is not limited to retarding, and the synergistic effect of gypsum and fly ash in high temperature environment and the influence on the formation and stability of key mineral phase calcium phosphoaluminate have not been fully recognized and utilized, especially the systematic research on precisely regulating the mineral composition of phosphoaluminate cement by ion doping to improve the content of key corrosion resistant phase and synergistically promote early strength.

[0004] Therefore, it is urgent to develop a modification technology specially for phosphoaluminate cement system, which can effectively improve the early strength, optimize the long-term CO2 corrosion resistance, and consider the economy, to meet the urgent needs of high-performance cementing cement for various CO2-containing corrosive oil and gas wells, geothermal wells, and carbon storage wells. SUMMARY

[0005] Technical problem: The technical problem solved by the present application is to provide a cementing cement material with high early strength, excellent CO2 corrosion resistance, good economy and applicable to high temperature and high pressure corrosive well conditions, aiming at the problems of early strength to be improved, long-term corrosion resistance to be further optimized and high cost of existing phosphoaluminate cement in CO2-containing corrosive wellbore cementing application.

[0006] In order to achieve the above-mentioned object, the technical scheme adopted by the present application is as follows: The present application precisely controls the mineral phase composition of cement clinker by doping specific ions, significantly increases the content of key corrosion-resistant phase calcium phosphoaluminate (C-A-P) and promotes the development of early strength; utilizes the strength enhancement effect of gypsum in the system to synergistically improve the mechanical properties; and effectively reduces the material cost by adding fly ash, slag and other industrial waste residue admixtures, while utilizing the activity or micro-aggregate effect thereof under high temperature environment to further optimize the density and long-term stability of the cement stone matrix, finally obtaining a cementing cement material with high early strength, excellent CO2 corrosion resistance, good economy and applicable to high temperature and high pressure corrosive well conditions.

[0007] Specifically, the present application provides a CO2 corrosion resistant phosphoaluminate cement based on ion doping and composite modification, characterized by being composed of phosphoaluminate cement clinker, alkaline earth metal ion metal oxide, gypsum, active mineral admixture and setting retarder. The alkaline earth metal ion metal oxide accounts for 0.1 wt% to 3.0 wt% (preferably 0.5 wt% to 1.0 wt%) of the total mass of the phosphoaluminate cement clinker in terms of metal oxide; The gypsum accounts for 3.0 wt% to 10.0 wt% (preferably 5.0 wt% to 8.0 wt%) of the mass of the cement base in terms of SO3; The active mineral admixture accounts for 10 wt% to 40 wt% (preferably 15 wt% to 30 wt%) of the total mass of the cement base and gypsum; The setting retarder accounts for 0.1 wt% to 1.0 wt% of the mass of the cement base.

[0008] Preferably, the main mineral composition of the phosphoaluminate cement clinker accounts for 40% to 80% of calcium phosphoaluminate phase (CAP), 0% to 20% of monocalcium aluminate (CA), 0% to 20% of calcium dialuminate (CA2), 0% to 15% of calcium aluminum yellow longite (C2AS), 0% to 15% of hydroxyapatite and 0% to 8% of other trace components.

[0009] Preferably, the alkaline earth metal ion metal oxide is selected from alkaline earth metal ions Sr2+ , Ba 2+ , Zn 2+ , Mn 2+ or Fe 3+ metal oxide of at least one of the group consisting of Li

[0010] Specifically, the gypsum is selected from at least one of dihydrate gypsum (CaSO4·2H2O), hemihydrate gypsum (CaSO4·0.5H2O) or anhydrite (CaSO4). Gypsum not only adjusts the setting time in the phosphoaluminate system, but more importantly, plays a significant role in strength enhancement.

[0011] Specifically, the active mineral admixture is selected from at least one of fly ash (F or C) and granulated blast furnace slag (GGBS). The active mineral admixture can play the role of pozzolanic activity or micro-aggregate filling effect in the high-temperature cementing environment (such as 80°C), and synergistically improve the late strength and reduce the cost.

[0012] Specifically, the setting regulator is selected from any one of citric acid, organic phosphonate, and polymer-based retarder.

[0013] Specifically, the method for preparing the cement-based material is as follows: Phosphoaluminate cement clinker is obtained by calcining apatite, bauxite and limestone as main raw materials at a temperature of 1350°C to 1500°C (preferably 1400°C to 1500°C), and in this process, a source of alkali metal ion doping is introduced. The obtained clinker is ground to a specific surface area of 350 m 2 / kg to 450 m 2 / kg to obtain the cement-based material.

[0014] Further, the application also claims the use of the above-mentioned phosphoaluminate cement with CO2 corrosion resistance based on ion doping and composite modification in well cementing operations.

[0015] Specifically, the phosphoaluminate cement with CO2 corrosion resistance based on ion doping and composite modification is prepared into a slurry with a water-cement ratio of 0.40 to 0.60, and then used in well cementing engineering of oil and gas wells, geothermal wells or carbon storage wells with CO2 corrosion risk.

[0016] Preferably, the downhole temperature of the well cementing operation is controlled at 80°C to 150°C, showing excellent early compressive strength development and long-term carbonation corrosion resistance.

[0017] Compared with the prior art, the application has the following beneficial effects: First, for the first time in the phosphate-aluminate cement system, through the optimization of specific ion doping technology and the combination of composite additives (gypsum + fly ash), the early strength and long-term corrosion resistance of the cement stone in the high temperature (such as 80°C) CO2 environment are significantly improved, which is designed for CO2 corrosion resistant cementing application. The innovation and advantage of this invention is different from the existing technology (including the related patents of Portland cement system). Although ion doping, gypsum adjustment and fly ash utilization are known means in Portland cement, we creatively apply these means to the phosphate-aluminate cement system which is structurally different, and find a unique performance improvement mechanism and application effect with synergistic effect in this specific system.

[0018] Second, the targeting of ion doping and the uniqueness of phosphate-aluminate system: the introduction of specific doping ions (specific ion species need to be determined according to experimental results, such as Sr 2+ , Ba 2+ , Zn 2+ , Mn 2+ , Fe 3+ , etc.) in phosphate-aluminate cement can effectively control the mineral composition and significantly increase the content of key hydration product calcium phosphate (such as C-A-P-H phase). This is a control target and mineral phase basis that Portland cement system (main product C-S-H) does not have. This optimization of mineral composition is directly related to the significant improvement of early strength observed in experiments, providing key early mechanical support for cementing operations.

[0019] Third, the new role of gypsum in phosphate-aluminate system: the addition of gypsum in phosphate-aluminate cement shows that it not only adjusts the setting time (possible effect), but more importantly, directly improves the mechanical strength of the cement. This is significantly different from the role of gypsum in Portland cement as a retarder to prevent fast setting. This strength enhancement effect, especially in combination with the early strength improvement of ion doping, constitutes a unique performance optimization path for phosphate-aluminate system.

[0020] Fourth, the synergistic benefits of fly ash in high temperature phosphate-aluminate system: the introduction of fly ash as an admixture into this system, my experimental results verify that it not only reduces the cost, but also synergistically improves the final mechanical strength of the cement stone. More importantly, under the simulated 80°C high temperature conditions of cementing, the pozzolanic activity or micro-aggregate effect of fly ash in the phosphate-aluminate environment shows a unique optimization effect, which helps to form a more dense and stronger matrix. This performance synergy at high temperature is an important supplement to the application effect of fly ash in Portland cement system and an advantage in the specific situation of high temperature cementing.

[0021] Fifth, the synergistic effect and the pertinence of CO2 corrosion resistance: the core breakthrough of the patent lies in the systematic integration and optimization of ion doping (improving the content of key mineral phases and early strength), gypsum (enhancing strength) and fly ash (optimizing matrix and reducing cost), which are applied to the phosphate aluminate cement system which has certain acid resistance potential. The experiment is carried out at 80°C to simulate the CCUS environment, and directly aims at the high temperature and high pressure CO2 corrosion challenge faced by well cementing cement. The phosphate aluminate cement matrix is more inert to CO2 than Portland cement, and our composite modification strategy (doping phase + gypsum strong base + fly ash densification) synergistically enhances this innate advantage, aiming to obtain a special well cementing material with fast early strength development, excellent long-term CO2 corrosion resistance and controllable cost. The composite modification scheme designed for specific system (phosphate aluminate), specific problem (CCUS high temperature CO2 corrosion) and specific application (well cementing) and the synergistic effect produced thereby are original contributions that cannot be directly inspired or covered by existing Portland cement system patents. BRIEF DESCRIPTION OF DRAWINGS

[0022] The above and / or other aspects of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which:

[0023] Figure 1 The X-ray diffraction (XRD) pattern of the ion-doped phosphate aluminate cement clinker prepared for Example 1 of the present application shows that the characteristic calcium phosphate aluminate (C-A-P-H) phase peak is significantly enhanced.

[0024] Figure 2 The compressive strength contrast column chart of the cement stone of Examples 1-3 and Comparative Examples of the present application after curing at 80°C for 1 day.

[0025] Figure 3 The strength decline contrast chart of the cement stone of Examples 1-3 and Comparative Examples of the present application before and after corrosion in 80°C saturated CO2 solution for 28 days. DETAILED DESCRIPTION

[0026] The present application can be better understood according to the following examples.

[0027] In order to fully disclose but not limit the present application, the technical solutions are described in detail below in combination with examples. The raw materials in the examples are all industrial grade. The chemical compositions of apatite, bauxite and limestone are shown in Table 1, and the industrial alumina has a purity of >98%.

[0028] Table 1 Chemical composition of raw materials determined by XRF (%) .

[0029] The doping ion source uses carbonate or oxide of the corresponding metal (such as SrCO3, BaCO3, Fe2O3), the gypsum is dihydrate gypsum (CaSO4·2H2O), the fly ash is F-class I, the slag is S95-class, the strength test refers to GB / T 17671, and the corrosion resistance test is carried out in an 80°C curing kettle.

[0030] Example 1

[0031] First, 40 parts of apatite, 30 parts of bauxite, 15 parts of industrial alumina, and 15 parts of limestone are weighed according to the mass ratio, and 1.5 wt% of SrCO3 (providing Sr 2+ doping) corresponding to the mass of clinker is added. After being mixed uniformly, the mixture is placed in a high-temperature furnace and calcined at about 1500°C for 60 minutes, and then cooled to obtain clinker; the mineral composition of the clinker is: CAP phase 68%, CA phase 12%, CA2 phase 8%, C2AS phase 5%, hydroxyapatite 4%, and other trace components 3%. At the same time, the clinker obtained by calcining the sample without Sr 2+ doping is used as a control. The XRD patterns of the clinkers obtained by calcining the two samples are shown in Figure 1 By comparing the X-ray diffraction quantitative analysis data of the sample without Sr doping in Example 1 and the sample with Sr doping in Example 1, it is confirmed that the content of calcium phosphoaluminate phase CAP is significantly increased from 46% to 68% due to Sr doping, and at the same time, the content of calcium aluminate phase CA2 is reduced from 13.53% to 8%, the content of dicalcium alumino-silicate phase C2AS is reduced from 6.99% to 5%, the content of hydroxyapatite phase Ca5(PO4)3OH is reduced from 8.5% to 4%, the content of calcium aluminate phase CA is reduced from 19.05% to 12%, and the content of other trace components is reduced from 5.93% to 3%. The characteristic of this phase reconstruction is the absolute dominance of the CAP phase and the synergistic weakening of the silicate / aluminate phase, and this structural evolution is the core material basis for the improvement of the CO2 corrosion resistance of the cement. The stable phosphorus-oxygen tetrahedral structure in the CAP phase has intrinsic resistance to carbonic acid corrosion, and a large increase in its content forms a dense system with corrosion-resistant CAP as the continuous skeleton; the reduction of CA2, CA, C2AS and other calcium aluminate / silicate phases that can react with CO2 to generate calcium carbonate and expand in volume significantly reduces the chemical corrosion sensitivity and structural degradation risk of the cement stone in a CO2 saturated environment. Sr doping regulates the conversion path of calcium aluminate phase to calcium phosphoaluminate phase through ion replacement effect, realizing the directional optimization of the corrosion-resistant main phase ratio, and this technical means enables the material to have a breakthrough improvement in the ability to resist CO2 corrosion under high temperature and high pressure well cementing conditions, and fundamentally solves the problems of strength attenuation and sealing failure of the cement sheath caused by carbonation in the acidic oil and gas environment. The XRD data confirms the substantial improvement of the Sr doping technology on the corrosion resistance of the cement from the phase composition level, and constitutes the key evidence of the patent innovation.

[0032] The clinker is ground to a specific surface area of 420 m 2 / kg; take 100 parts of the base, add 5.0 parts of dihydrate gypsum (SO3 content of about 3.2 parts, accounting for 3.2 wt% of the mass of the base) and 25 parts of fly ash (accounting for 23.8 wt% of the total mass of the base + gypsum), mix uniformly to obtain the target cement. The slurry is prepared according to the water-cement ratio of 0.44, and after molding, the compressive strength reaches 28.5 MPa (excellent early strength) after 1 day of water curing at 80°C; the compressive strength retention rate is 95.3% after 28 days of corrosion in the 80°C CO2 environment, verifying the corrosion resistance.

[0033] Example 2

[0034] Adjust the doping scheme: the raw materials are the same as in Example 1, but the dopant is replaced by 1.0 wt% BaCO3 (Ba 2+ ) and 0.8 wt% Fe2O3 (Fe 3+ ) complex, calcination temperature 1420°C, grinding fineness 400 m 2 / kg; the mineral composition of the clinker obtained is: CAP phase 72%, CA phase 10%, CA2 phase 6%, C2AS phase 4%, hydroxyapatite 5%, and other trace components 3%. 4.5 parts of hemihydrate gypsum (SO3 about 3.5 parts, accounting for 3.5 wt% of the base) and 30 parts of slag (accounting for 28.6 wt% of the total mass of the base + gypsum) are added to 100 parts of the base. The water-cement ratio of the cement slurry is 0.48, and the strength is 25.8 MPa after 1 day of water curing at 80°C; the strength retention rate is 93.7% after 28 days of CO2 corrosion, confirming the effectiveness of ion complex doping and slag substitution.

[0035] Example 3

[0036] Verify the performance without doping: the raw materials and proportions are the same as in Example 1, but no SrCO3 is added, the calcination temperature is 1500°C, and the mineral composition of the clinker obtained is: CAP phase 35%, CA phase 25%, CA2 phase 15%, C2AS phase 10%, hydroxyapatite 10%, and other trace components 5%. The base is ground; the base is 100 parts + dihydrate gypsum 5.0 parts + fly ash 25 parts. The strength is only 18.2 MPa after 1 day of water curing (a 36% decrease compared to Example 1); the retention rate is 89.5% after 28 days of CO2 corrosion, indicating the key role of ion doping in early strength and corrosion resistance.

[0037] Comparative Example Commercially available G-grade oil well cement (silicate system) is used, and the slurry is prepared under the same conditions (water-cement ratio of 0.44) and tested. The strength is 22.1 MPa after 1 day of water curing at 80°C; the strength retention rate is only 72% after 30 days of CO2 corrosion, highlighting the significant advantages of the present application in high-temperature CO2 environments.

[0038] Figure 2is a comparison of the 1d compressive strength of the cement stones of Examples 1-3 and the comparative example at 80°C. Among them, the 1d strength of the comparative example is measured to be 22.1 MPa, Example 1 exhibits a 1d strength of 28.5 MPa, Example 2 has a strength of 25.8 MPa, and Example 3 has a strength of only 18.2 MPa. This data chain clearly shows that Sr doping modification enables Example 1 to achieve a breakthrough of 28.9% strength improvement over traditional oil well cement, and a 56.6% strength improvement over Example 3 without doping, fully verifying the specific optimization effect of Sr ions on the hydration kinetics and early microstructure formation of phosphoaluminate cement. Although Example 2 is better than the comparative example, it is significantly lower than the results of Example 1, which shows that barium-iron composite doping fails to achieve the synergistic enhancement effect of Sr doping, and this comparison highlights the irreplaceability of Sr doping technology in this system. The substantial increase in early strength has a core value for well cementing engineering, as it directly shortens the waiting-on-cement time, reduces the risk of wellbore static column pressure fluctuation, and improves the first-time forming qualification rate of wellbore structure under harsh conditions. The present application enables phosphoaluminate cement to exceed the existing oil well cement standard in one-day strength at 80°C environment through ion doping, providing a well cementing solution for high CO2-containing oil and gas wells with early strength characteristics and long-term corrosion resistance.

[0039] Figure 3 is the compressive strength of the cement stones of Examples 1-3 and the comparative example before and after corrosion in 80°C saturated CO2 solution. It can be seen that the strength of the comparative example is 39.8 MPa after being watered at 80°C for 28 days, and after CO2 corrosion, it decreases to 28.7 MPa, with a strength retention rate of 72%; the watered strength of Example 1 is 45 MPa, and after corrosion, it remains at 42.9 MPa, with a strength retention rate of 95.3%; the watered strength of Example 2 is 40.4 MPa, and after corrosion, it is 37.8 MPa, with a strength retention rate of 93.7%; the watered strength of Example 3 is 26.5 MPa, and after corrosion, it is 23.7 MPa, with a strength retention rate of 89.5%. This series of data reveals three key conclusions: first, the strength retention rate of Sr-doped Example 1 is 95.3% in a corrosive environment, which is significantly higher than the 72% retention rate of the comparative example, proving that its CO2 corrosion resistance performance fundamentally surpasses traditional oil well cement; second, under the same corrosion conditions, the strength retention rate of Example 1 is 95.3%, which is much higher than the 89.5% of Example 3, confirming the strengthening effect of Sr doping on the intrinsic corrosion resistance of phosphoaluminate cement; third, although Example 2 is better than the comparative example, the strength retention rate of Example 2 is slightly lower than that of Example 1, highlighting the uniqueness of the Sr doping technology route. This high strength corrosion retention capability has a decisive significance for well cementing engineering in CO2-containing oil and gas wells, as it directly guarantees the structural integrity of the downhole cement sheath in the long-term acidic environment, avoiding the increase in permeability and interlayer sealing failure due to carbonation corrosion. The present application enables phosphoaluminate cement to simultaneously achieve strength stability and durability improvement in corrosive conditions through ion doping modification, providing key technical support for the development of high-acidity oil and gas reservoirs.

[0040] The application provides a CO2 corrosion resistant phosphaluminate cement based on ion doping and composite modification and its application in well cementing. The method and approach for realizing the technical scheme are various. The above description is only the preferred embodiment of the application. It should be pointed out that the ordinary skilled in the art can make several improvements and refinements without departing from the principle of the application, and these improvements and refinements should also be regarded as the protection scope of the application. The components not explicitly described in the embodiment can be realized by the prior art.

Claims

1. A CO2-resistant phosphoaluminate cement based on ion doping and composite modification, characterized in that, It is composed of phosphoaluminate cement clinker, alkaline earth metal ion oxides, gypsum, active mineral admixtures, and setting regulators; The cementitious material is composed of phosphoaluminate cement clinker and alkaline earth metal ion oxides; the content of alkaline earth metal ion oxides, calculated as metal oxides, is 0.1 wt% to 3.0 wt% of the total mass of phosphoaluminate cement clinker. The gypsum content, calculated as SO3, is 3.0 wt% to 10.0 wt% of the cementitious base material. The active mineral admixture is added at a rate of 10 wt% to 40 wt% of the total mass of cementitious material and gypsum. The dosage of the setting regulator is 0.1 wt% to 1.0 wt% of the cement base material.

2. The CO2-corrosion-resistant phosphoaluminate cement based on ion doping and composite modification according to claim 1, characterized in that, The main mineral composition of the phosphoaluminate cement clinker, by mass percentage, is as follows: calcium phosphoaluminate phase 40%~80%, monocalcium aluminate 0%~20%, calcium dialuminate 0%~20%, calcium aluminum feldspar 0%~15%, hydroxyapatite 0%~15%, and other trace components 0%~8%.

3. The CO2-corrosion-resistant phosphoaluminate cement based on ion doping and composite modification according to claim 1, characterized in that, The alkaline earth metal ion oxides are selected from those containing alkaline earth metal ions Sr 2+ Ba 2+ Zn 2+ Mn 2+ or Fe 3+ At least one of the metal oxides.

4. The CO2-corrosion-resistant phosphoaluminate cement based on ion doping and composite modification according to claim 1, characterized in that, The gypsum is selected from at least one of dihydrate gypsum, hemihydrate gypsum, or anhydrous gypsum.

5. The CO2-corrosion-resistant phosphoaluminate cement based on ion doping and composite modification according to claim 1, characterized in that, The active mineral admixture is selected from at least one of fly ash and granulated blast furnace slag.

6. The CO2-corrosion-resistant phosphoaluminate cement based on ion doping and composite modification according to claim 1, characterized in that, The setting retarder is selected from any one of citric acid, organophosphonates, and polymeric retarder.

7. The CO2-corrosion-resistant phosphoaluminate cement based on ion doping and composite modification according to claim 1, characterized in that, The method for preparing the cementitious base material is as follows: Phosphatic aluminate cement clinker is obtained by mixing apatite, bauxite, and limestone as main raw materials and calcining them at a temperature of 1350℃ to 1500℃. During this process, an alkaline earth metal ion source is introduced, and the resulting clinker is ground to a specific surface area of ​​350 m². 2 / kg to 450 m 2 / kg yields cementitious base material.

8. The application of CO2 corrosion resistant phosphoaluminate cement based on ion doping and composite modification as described in any one of claims 1 to 7 in cementing operations.

9. The application according to claim 8, characterized in that, The CO2-resistant phosphoaluminate cement based on ion doping and composite modification was prepared into a slurry with a water-cement ratio of 0.40 to 0.60, and then used in well cementing projects for oil and gas wells, geothermal wells or carbon storage wells where there is a risk of CO2 corrosion.

10. The application according to claim 8, characterized in that, The downhole temperature for the cementing operation is controlled between 80°C and 150°C.

Images