Reinforcing material suitable for carbon sequestration rock interface and preparation method thereof

Abstract

The invention provides a reinforcing material suitable for a carbon sequestration rock interface and a preparation method thereof, and the preparation method comprises the following steps: calcining magnesium oxide powder to obtain active magnesium oxide; uniformly mixing active magnesium oxide with monopotassium phosphate to obtain first mixed powder; the molar ratio of the active magnesium oxide to the monopotassium phosphate is (3-5): 1; adding borax accounting for 5-10% of the mass of the active magnesium oxide into the first mixed powder, and uniformly mixing to obtain second mixed powder; mixing the second mixed powder with mixing water according to a water-material mass ratio of 0.10-0.40, and stirring to obtain magnesium phosphate cement paste; within the initial setting time after the magnesium phosphate cement paste is prepared, the paste is injected into a mold through pressure grouting equipment, and curing carbonization is conducted after the paste and rock are formed. By the adoption of the technical scheme, the interface sealing life is greatly prolonged, and the anti-carbonization performance is remarkably improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of carbon dioxide storage materials, in particular to a reinforcing material suitable for a carbon storage rock interface and a preparation method thereof. BACKGROUND

[0002] With the intensification of global climate change, carbon dioxide (CO2) geological storage technology as the core link of the carbon capture and storage (CCS) technology chain is a key means to mitigate the greenhouse effect, and the core of its storage effect depends on the integrity of the injection well. However, the existing wellbore sealing technology has significant defects in the long-term high-temperature and high-pressure, high-CO2 concentration geological environment, and it is urgent to develop new sealing materials with strong adaptability, high stability and environmental friendliness and construction schemes to ensure the long-term safety of the storage system.

[0003] Traditional wellbore sealing is mainly based on silicate cement-based materials, but such materials are prone to carbonation reaction in the CO2 storage environment: the generated calcium carbonate and silica gel will cause material volume shrinkage and microstructure degradation. Research by the US Department of Energy shows that under high temperature and high pressure conditions, the permeability of traditional cement increases significantly within 3-5 years, the interface shear strength decreases by 40%-60%, and CO2 leakage channels are easily formed, which seriously threatens the safety of storage.

[0004] Although organic polymer materials such as epoxy resin have good short-term sealing performance, they are prone to aging and degradation in a simulated storage environment of 80℃ and 15MPa, and the interface bonding strength decreases by more than 50% within 2 years. Moreover, the curing of these materials requires the addition of organic solvents, which is not in line with the green engineering concept. At the same time, the adaptability of existing materials for construction is insufficient: conventional cement slurry has a slow setting speed (only 70% of the designed strength is reached after 24 hours or more), which makes it difficult to meet the rapid plugging demand; and the compatibility with carbonate rock and other reservoir rocks is poor. Research by the Norwegian University of Science and Technology shows that the microfracture density of the cement-rock interface in a limestone reservoir is 3-5 times higher than that of the bulk material, becoming a major leakage path. In addition, traditional cement production has high energy consumption and large carbon emissions (0.8-1 ton of CO2 is emitted per ton of cement clinker produced), which is contrary to the initial purpose of carbon storage and emission reduction, and the material is difficult to recycle after failure, increasing the environmental burden throughout the life cycle. In recent years, magnesium phosphate cement (MPC) has been concerned by the academic community due to its fast hardening, early strength, micro-expansion, corrosion resistance and other characteristics. However, existing research focuses on the field of building repair, and the optimization of material formulations for CO2 geological storage, the adaptability of construction technology, and the key technologies such as the strengthening mechanism of material-rock interface and long-term stability evaluation are still blank.

[0005] From the perspective of engineering application, the existing plugging technology also has problems such as insufficient lithology adaptability (e.g. lack of research on marble and sandstone adaptability), lack of special formulations for special working conditions (temperature gradient, stress change), and low standardization of construction technology, which seriously restricts the large-scale promotion of carbon storage technology. SUMMARY

[0006] To address the above technical problems, this invention discloses a reinforcing material suitable for the rock interface of carbon sequestration and its preparation method, providing a reliable means to solve the problem of carbon dioxide leakage along the wellbore-rock interface, and has significant environmental benefits and engineering application value in improving sequestration safety and reducing long-term maintenance costs.

[0007] The technical solution adopted by this invention is as follows:

[0008] A method for preparing a reinforcing material suitable for carbon-sequestered rock interfaces includes the following steps:

[0009] Step S1: Calcining magnesium oxide powder to obtain active magnesium oxide;

[0010] Step S2: Mix the active magnesium oxide and potassium dihydrogen phosphate evenly to obtain a mixed powder; wherein the molar ratio of active magnesium oxide to potassium dihydrogen phosphate is 3-5:1.

[0011] Step S3: Add 5-10% by weight of active magnesium oxide and borax as a retarder to the mixed powder, mix evenly, and obtain a method for preparing a reinforcing material suitable for carbon sequestration rock interface.

[0012] The reinforcing material obtained by this technical solution, suitable for the rock interface of carbon sequestration, is mixed with mixing water to obtain a slurry. The slurry is injected into the rock fissures during its initial setting time, and then cured and carbonized after molding. It has good sealing effect, good environmental adaptability, and high construction efficiency. It solves the problems of insufficient interface sealing performance, poor environmental adaptability, and low construction efficiency in existing technologies, and provides an innovative solution for ensuring the long-term safety of CO2 geological sequestration systems.

[0013] As a further improvement of the present invention, in step S1, the calcination temperature is 1000-1200℃.

[0014] As a further improvement of the present invention, the purity of the active magnesium oxide is ≥90%.

[0015] As a further improvement of the present invention, in step S2, the molar ratio of active magnesium oxide to potassium dihydrogen phosphate in the first mixed powder is 4:1.

[0016] As a further improvement of the present invention, in step S3, the mass of the borax is 5% of the mass of the active magnesium oxide.

[0017] This invention discloses a reinforcing material suitable for carbon-sequestrated rock interfaces, which is prepared by any of the above-described methods for preparing reinforcing materials suitable for carbon-sequestrated rock interfaces.

[0018] This invention discloses the application of the reinforcing material described above for carbon sequestration rock interfaces in geological carbon dioxide sequestration. This application also represents a carbon sequestration method for rock interfaces.

[0019] As a further improvement of the present invention, the application includes: mixing the reinforcing material suitable for carbon sequestration rock interface with mixing water at a water-material mass ratio of 0.10-0.40:1, stirring for 1-5 minutes to prepare a magnesium phosphate cement slurry with good fluidity; during the initial setting time after the magnesium phosphate cement slurry is prepared, injecting the slurry into the rock fissures using a pressure grouting device, so that it can be cured and carbonized after being formed with the rock.

[0020] As a further improvement of the present invention, the mass of the mixing water is 15-40% of the mass of the second mixed powder.

[0021] As a further improvement of the present invention, the reinforcing material suitable for carbon sequestration rock interface is mixed with mixing water and then stirred slowly at 135-145 rpm for 60 seconds, and then rapidly stirred at 275-295 rpm for 30 seconds, for a total of 90 seconds.

[0022] As a further improvement of the present invention, in step S5, the environment for carbonization is: temperature 20±2℃, humidity 70±5%, and carbon dioxide concentration 20±1%.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] The technical solution of this invention uses magnesium phosphate cement material to maintain long-term stability in a CO2 environment, which significantly extends the interface sealing life and significantly improves the anti-carbonation performance compared with traditional materials; the slurry can harden within hours, and the strength can reach more than 70% of the final strength in 24 hours, which greatly shortens the construction cycle and enables rapid engineering application; through unique chemical bonding and micro-expansion characteristics, it effectively seals rock pores, reduces the risk of CO2 leakage by more than 90%, enhances the interface sealing effect, reduces energy consumption in the material preparation process by 40%, and releases no harmful substances throughout the process, making it more environmentally friendly. Attached Figure Description

[0025] Figure 1 This is a compositional analysis diagram of heavy magnesium oxide used in the embodiments of the present invention.

[0026] Figure 2 This is a test diagram of the interface strength between magnesium phosphate cement and marble in Example 4 of the present invention.

[0027] Figure 3 This is a test diagram of the interface strength between magnesium phosphate cement and sandstone in Example 5 of the present invention.

[0028] Figure 4 This is a diagram showing the damage at the interface between magnesium phosphate cement and marble in Example 4 of this invention.

[0029] Figure 5 This is a diagram showing the damage at the interface between magnesium phosphate cement and sandstone in Example 5 of this invention.

[0030] Figure 6 This is a comparison diagram of the boundary strength between Embodiment 4 and Embodiment 5 of the present invention. Detailed Implementation

[0031] The preferred embodiments of the present invention will be described in further detail below.

[0032] The specific steps for indoor test simulation of the invention are as follows:

[0033] Example 1

[0034] A method for preparing a reinforcing material suitable for carbon-sequestered rock interfaces includes the following steps:

[0035] Step S1: Calcine magnesium oxide powder at 1000℃ for 2 hours to obtain active magnesium oxide; weigh 720.0g of the magnesium oxide powder, the specific composition of which is as follows: Figure 1 As shown;

[0036] Step S2: Weigh 612.0g of potassium dihydrogen phosphate powder, and mix the active magnesium oxide and potassium dihydrogen phosphate evenly at a molar ratio of 4:1 to obtain a mixed powder.

[0037] Step S3: Weigh 36.0g of borax, which accounts for 0.05% of the mass of magnesium oxide powder; add borax to the mixed powder and mix evenly to obtain a reinforcing material suitable for carbon sequestration rock interfaces.

[0038] The simulation experiment was conducted using the reinforced material prepared above, suitable for carbon-sequestration rock interfaces. The steps included:

[0039] Step S11: Process the target rock into a specimen and fix it in a mold;

[0040] Step S12: Weigh 273.6g of water and mix the second mixed powder with the mixing water. Alternatively, water can be added while stirring. Use a JJ-5 type mortar mixer to first slowly stir at 135-145rpm for 60s, then quickly stir at 275-295rpm for 30s, for a total of 90s, to prepare a magnesium phosphate cement paste with good fluidity.

[0041] Step S13: During the initial setting time of 5-20 minutes after the magnesium phosphate cement slurry is prepared, the slurry is injected into the mold (40×40×160mm) using a pressure grouting device and left to stand. After the slurry and marble are formed, they are cured and carbonized in the following environment: temperature 20±2℃, humidity 70±5%, carbon dioxide concentration 20±1%.

[0042] The obtained magnesium phosphate cement (MPC cement) was tested according to GB / T 1767l-2021, using a NELD-FC300 flexural and compressive strength testing machine with a flexural rate of 50 N / s. The properties are shown in Table 1. It can be seen that the strength initially increases or decreases during the curing process, reaching its maximum strength after 3 days of curing.

[0043] Table 1. Flexural strength (MPa) of MPC cement

[0044] Carbonation curing time 1h 1 day 3 days 7 days 28 days Example 1 4.9 5.5 6.3 6.3 5.5

[0045] Example 2

[0046] Step 1: Remove the marble from the geological formation;

[0047] Step 2: Prepare it into a test block of 40×40×160mm;

[0048] Step 3: First, conduct a flexural strength test, then take out powder from the rock specimen that was damaged after the flexural strength test, and conduct XRF (X-ray fluorescence spectrometry) test and mercury porosimetry test.

[0049] Example 3

[0050] Step 1: Remove the sandstone from the geological formation;

[0051] Step 2: Prepare it into a test block of 40×40×160mm;

[0052] Step 3: First, conduct a flexural strength test, then take out powder from the rock specimen that was damaged after the flexural strength test, and conduct XRF (X-ray fluorescence spectrometry) test and mercury porosimetry test.

[0053] The chemical composition of the marble and sandstone in Examples 2 and 3 is shown in Table 2, and the flexural strength is shown in Table 3.

[0054] Table 2 Chemical composition of raw materials

[0055] Al2O3 SiO2 CaO Fe2O3 CO2 Marble / 0.91 72.71 / 26.29 Sandstone 16.03 69.71 0.61 3.55 /

[0056] Table 3 Flexural strength of marble and sandstone

[0057] Flexural strength Porosity Marble 12.4 MPa 3.9％ Sandstone 4.9 MPa 17.5％

[0058] Example 4

[0059] Based on Example 1, the difference in this example is that in step S4, a 40×40×80mm marble is placed into a mold (40×40×160mm).

[0060] Example 5

[0061] Based on Example 1, the difference in this example is that in step S4, a 40×40×80mm sandstone is placed into a mold (40×40×160mm).

[0062] The molded samples obtained in Examples 4 and 5 were tested, and the test results of the interface strength between magnesium phosphate cement and marble are shown in the figure. Figure 2 As shown in the figure, the test diagram of the interface strength between magnesium phosphate cement and sandstone is as follows. Figure 3 As shown, the failure diagram at the interface between magnesium phosphate cement and marble is as follows. Figure 4 As shown, the failure diagram at the interface between magnesium phosphate cement and sandstone is as follows. Figure 5 As shown, the interface strength tests were conducted on magnesium phosphate cement and marble, and magnesium phosphate cement and sandstone. The tests were conducted according to GB / T1767l-2021, using a NELD-FC300 flexural and compressive strength testing machine with a flexural rate of 50 N / s.

[0063] Boundary strength analysis diagram as shown Figure 6 As shown, MPC-S is a test block at the interface between magnesium phosphate cement and sandstone, and MPC-R is a test block at the interface between magnesium phosphate cement and marble.

[0064] Table 4. Boundary strength test results (MPa)

[0065] Carbonation curing time 1 day 3 days 7 days 28 days Example 4 3.1 3.6 5.4 5.5 Example 5 1.5 2.4 2.5 2.5

[0066] As shown in Table 4, the interface strength between magnesium phosphate cement and marble initially increases and then stabilizes with increasing carbonation curing time. The trend for the interface strength between magnesium phosphate cement and sandstone is similar. The interface strength between magnesium phosphate cement and marble is 5.5 MPa, the same as the strength of magnesium phosphate cement after 28 days of carbonation curing. This is because marble has low porosity, allowing magnesium phosphate cement to adhere to the interface, resulting in an interface strength equal to the flexural strength of the smaller component. The failure mode of magnesium phosphate cement and sandstone leans towards sandstone because sandstone has high porosity, allowing the magnesium phosphate cement slurry to infiltrate into it. Later, as the slurry solidifies and interweaves with the sandstone, the interface strength is related to the amount of slurry intrusion.

[0067] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a reinforcing material suitable for carbon-sequestered rock interfaces, characterized in that, Includes the following steps: Step S1: Calcining magnesium oxide powder to obtain active magnesium oxide; Step S2: Mix the active magnesium oxide and potassium dihydrogen phosphate evenly to obtain a mixed powder; wherein the molar ratio of active magnesium oxide to potassium dihydrogen phosphate is 3-5:

1. Step S3: Add 5-10% by weight of borax, a retarder, to the mixed powder and mix evenly to obtain a reinforcing material suitable for carbon sequestration rock interfaces.

2. The method for preparing a reinforcing material suitable for carbon-sequestration rock interfaces according to claim 1, characterized in that: In step S1, the calcination temperature is 1000-1200℃.

3. The method for preparing a reinforcing material suitable for carbon-sequestration rock interfaces according to claim 1, characterized in that: In step S2, the molar ratio of active magnesium oxide to potassium dihydrogen phosphate in the mixed powder is 4:

1.

4. The method for preparing a reinforcing material suitable for carbon-sequestration rock interfaces according to claim 1, characterized in that: In step S3, the mass of the borax is 5% of the mass of the active magnesium oxide.

5. A reinforcing material suitable for carbon sequestration rock interfaces, characterized in that: It was prepared using the preparation method for reinforcing materials suitable for carbon-sequestrated rock interfaces as described in any one of claims 1 to 4.

6. The application of the reinforcing material for carbon sequestration rock interfaces as described in claim 5, characterized in that: Used in the geological sequestration of carbon dioxide.

7. The application of the reinforcing material for carbon sequestration rock interfaces according to claim 6, characterized in that: include: The reinforcing material suitable for carbon sequestration rock interface is mixed with mixing water at a water-to-material mass ratio of 0.10-0.40:1 and stirred for 1-5 minutes to prepare a magnesium phosphate cement slurry with good fluidity. During the initial setting time after the magnesium phosphate cement slurry is prepared, the slurry is injected into the rock fissures using a pressure grouting device, so that it can be cured and carbonized after it is formed with the rock.

8. The application of the reinforcing material for carbon sequestration rock interfaces according to claim 7, characterized in that: The environment for carbonization maintenance is: temperature 20±2℃, humidity 70±5%, and carbon dioxide concentration 20±1%.

9. The application of the reinforcing material for carbon sequestration rock interfaces according to claim 7, characterized in that: The mass of the mixing water is 15-40% of the mass of the second mixed powder.

Images