Low-temperature early-strength low-density cement-based material for deepwater cementing and preparation method thereof

Abstract

The application discloses a low-temperature early-strength low-density cement-based material for deepwater cementing and a preparation method thereof, and the cement-based material comprises 54-70wt% of cementitious material, 20wt% of active material, 3-6wt% of strength enhancing material, 5-15wt% of density adjusting material, 1-3wt% of fluid loss additive and 1-2wt% of dispersant in percentage by weight; the cementitious material is prepared by mixing G-grade oil well cement and superfine portland cement at a mass ratio of 7:3; and the active material is prepared by mixing metakaolin and microsilica at a mass ratio of 1:1. The application is prepared by using solid waste as raw material, which helps to reduce environmental pressure, has the characteristics of green environmental protection, low cost and the like. The cement-based material prepared by the application has good engineering performance in a low-temperature environment, fast early-strength development, micro-expansibility, short setting time and strong anti-channeling capacity.

Description

Technical Field

[0001] This invention relates to the field of oil and gas resource development technology, specifically to a low-temperature early-strength low-density cement-based material for deep-water cementing and its preparation method. Background Technology

[0002] As the focus of oil and gas exploration and extraction gradually shifts from onshore to offshore, deep water holds abundant oil and gas resources, making the research and development of deepwater oil and gas extraction technologies particularly important. However, deepwater cementing faces a series of problems. In low-temperature environments, the hydration of cement in oil wells is extremely slow, which severely affects the development of cement stone strength and increases the risk of annular flow. Furthermore, due to the low fracture pressure, low-density cement slurry systems are typically chosen. Currently, most solutions involve adding early-strength agents to the cement slurry to improve its early strength development. However, conventional early-strength agents often suffer from severe thickening problems, especially commonly used novel early-strength agents containing calcium ions and nanomaterials, which significantly impact the workability of the cement slurry.

[0003] Significant progress has been made in addressing the challenges of deep-water cryogenic cementing, but limited consideration has been given to the comprehensive performance of cryogenic cement slurries. Therefore, a cryogenic, early-strength, low-density cement-based material with rapid early strength development, gas channeling prevention, and good workability is needed. Summary of the Invention

[0004] To overcome the above-mentioned technical difficulties, the present invention provides a low-temperature early-strength low-density cement-based material for deep-water cementing and its preparation method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] On one hand, the present invention provides a low-temperature early-strength low-density cement-based material for deep-water cementing, comprising the following raw materials by weight percentage:

[0007] Cementitious materials: 54-70 wt%;

[0008] Active material: 20wt%;

[0009] Strength-reinforcing materials: 3-6 wt%;

[0010] Density regulating material: 5-15 wt%;

[0011] Water loss reducing agent: 1-3 wt%;

[0012] Dispersant: 1-2 wt%;

[0013] The cementing material is a mixture of Grade G oil well cement and ultrafine silicate cement in a mass ratio of 7:3; the active material is a mixture of metakaolin and microsilica in a mass ratio of 1:1.

[0014] Furthermore, the metakaolin has a SiO2 content of 48–54 wt%, an Al2O3 content of 40–45 wt%, and a powder particle size of less than 600 mesh.

[0015] Furthermore, the microsilicon has a SiO2 content of 96 wt% and a particle size of 0.05–0.30 μm.

[0016] Furthermore, the density-adjusting material is hollow glass microspheres with a density of 0.44–0.48 g / cm³. 3 The median particle size is 40 μm, and the compressive strength is >4000 psi.

[0017] Furthermore, the strength-enhancing material is prepared by mixing active component A, active component B, and reinforcing component in a mass ratio of 1:3:1, and the preparation method is as follows:

[0018] Sa1. Mix the active component A and the reinforcing component to obtain powder A;

[0019] Sa2. Place active component B in a ball mill jar and ball mill at 500 rpm for 6 hours to obtain powder B;

[0020] Sa3. Powder A and powder B are pneumatically mixed to obtain a strength-enhancing material.

[0021] The strength-enhancing material of this invention provides an alkaline environment for the initial hydration reaction of cement, thus promoting the cement hydration reaction on the one hand; and on the other hand, activating the activity of active component B, promoting the activation and decomposition of solid waste residue in active component B, and promoting the Si 4+ Al 3+ and Ca 2+ Plasma release accelerates the formation of hydration products. Furthermore, in this invention, active component A acts as a seed crystal for hydrated calcium silicate and hydrated calcium aluminosilicate in the early stages of hydration, providing a good nucleation effect during cement hydration, inducing the formation of hydrated calcium silicate and hydrated calcium aluminosilicate during cement hydration, promoting cement hydration, and thus improving the early strength of cement.

[0022] Furthermore, the active component A is prepared by mixing carbide slag, biomass slag, and aerated concrete waste in a mass ratio of 5:4:1, as follows:

[0023] Sb1. Carbide slag, biomass slag and aerated concrete waste were placed in a ball mill jar at a mass ratio of 5:4:1 and a liquid-to-material ratio of 1.0. The mixture was ball milled at 400 rpm for 72 hours to obtain slurry A.

[0024] Sb2. Place slurry A in a sealed mixing tank, add 1 wt% of the dispersant and stabilizer from the solid phase of slurry A and stir. The stirring temperature is 80℃ and the stirring time is 72h to obtain slurry B.

[0025] Sb3. Place slurry B in a centrifuge for liquid-solid separation, and dry the solid phase at the bottom of the liquid-solid separation into dry powder to obtain active component A;

[0026] Preferably, the carbide slag has a CaO content of 65-70 wt% and a pH of 12-13; the biomass slag has a SiO2 content of ≥65 wt%, an Al2O3 content of ≥15 wt%, and a particle size of less than 325 mesh; the aerated concrete waste is composed of tobermorite, semi-crystalline CSH(I), CSH gel, and silica, and is pulverized and ground to a powder fineness of less than 600 mesh; the dispersing stabilizer is a mixture of ketal-aldehyde condensate and microcrystalline cellulose.

[0027] The active component A of this invention utilizes carbide slag, biomass slag, and aerated concrete waste under wet grinding conditions to generate hydrated calcium silicate and hydrated calcium aluminosilicate. The aerated concrete waste contains a large amount of tobermorite, which can serve as nucleation sites for calcium silicate and hydrated calcium aluminosilicate, greatly accelerating the formation of hydrated calcium silicate and hydrated calcium aluminosilicate and promoting the cement hydration reaction.

[0028] Furthermore, the active component B is composed of modified zirconium silicon slag, silicomanganese slag, phosphorus slag, and alkali slag mixed in a mass ratio of 3:2:1:1. The modified zirconium silicon slag is made into slurry C from zirconium silicon slag. Slurry C is neutralized, washed with water, and impurity removed, and then subjected to solid-liquid separation. The product is obtained by high-temperature drying and grinding.

[0029] Preferably, the modified zirconium silicon slag has a SiO2 content ≥90wt%, a neutral pH, and a powder particle size less than 325 mesh; the ferrosilicon manganese slag has a powder particle size less than 325 mesh, a SiO2 content of 35-40wt%, an Al2O3 content of 9-12wt%, a CaO content of 25-28wt%, and a MgO content of 6-11wt%; the phosphorus slag has a SiO2 content of 35-40wt% and a CaO content of 42-48wt%; and the alkali slag has a CaCO3 content of 40-45wt%, a CaSO4 content of 7-10wt%, and a CaCl2 content of 10-14wt%.

[0030] The active component B of this invention contains a large number of amorphous SiO2 particles, which are highly active and can quickly react with the cement hydration product Ca(OH)2 to accelerate cement hydration. At the same time, the active component B also contains a small amount of MgO and CaSO4, which can promote the crystallization of ettringite through synergistic effect with the reinforcing component, and can also form Mg(OH)2 during cement hydration, thereby enhancing the bonding and sealing properties of the cementing stone and improving the anti-channeling ability of the cementing stone.

[0031] Furthermore, the reinforcing component is composed of lithium silicate and aluminum sulfate mixed in a mass ratio of 1:2; preferably, the purity of the lithium silicate is greater than 98 wt%, and the purity of the aluminum sulfate is greater than 98 wt%.

[0032] The reinforcing component of this invention can react with free hydroxide ions (OH-). - ) and calcium ions (Ca) in the system 2+ The reaction produces silicate cement and calcium silicate, which fill the micropores and gaps in the hydration products, thereby increasing the matrix density. The generated silicate cement and calcium silicate, through a synergistic effect with active component A, further promote the formation of hydrated calcium silicate and hydrated calcium aluminosilicate; the reinforcing component also works with various ions released by active component B to promote the crystallization of ettringite. Due to the large amount of Si in the system... 4+ Al 3+ and Ca 2+ The consumption of plasma further promotes cement hydration and the dissociation and release of active component B, thereby promoting early strength formation. In addition, the Li released by lithium silicate... + It accelerates the destruction of the early hydration product film on cement particles, speeding up the hydration process; and the formed cement hydration product Ca(OH)2 can activate the activity of solid waste-based reinforcing materials for cementing cement and react with them, promoting the occurrence of hydration reaction.

[0033] Furthermore, the water loss reducing agent is a copolymer of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) / acrylamide (AM); the dispersant is a sulfonated acetone-formaldehyde condensate.

[0034] On the other hand, the present invention provides a method for preparing a low-temperature early-strength low-density cement-based material for deep-water cementing, comprising: mixing cementitious materials, active materials, strength-enhancing materials, density-regulating materials, fluid loss reducing agents and dispersants in a uniform weight ratio to form a dry powder, thereby obtaining the low-temperature early-strength low-density cement-based material for deep-water cementing.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The density-adjusting material of the present invention can achieve a density of 1.3 to 1.5 g / cm³.3 It exhibits good engineering performance under low-temperature conditions, rapid early strength development, micro-expansion, short setting time, and strong anti-channeling ability. This invention uses solid waste as raw material, which helps reduce environmental pressure and is characterized by its green and environmentally friendly nature and low cost.

[0037] 2. The strength-enhancing material of this invention provides an alkaline environment for the initial hydration reaction of cement, which on the one hand promotes the cement hydration reaction; on the other hand, it stimulates the activity of active components, accelerates the dissolution of active ions, and reacts with the SO4 dissolved from the active components themselves. 2- Together, they promote the formation of hydration products such as ettringite. In addition, the small amount of MgO present in the strength-enhancing material forms Mg(OH)2 during cement hydration, which interacts with the generated ettringite, giving the cement slurry a certain degree of micro-expansion. This synergistically enhances the bonding and sealing properties of the cementing stone, thereby improving the anti-channeling ability of the cementing stone.

[0038] 3. The strength-enhancing material of this invention can act as a seed crystal for hydrated calcium silicate and hydrated calcium aluminosilicate in the early stage of hydration, and the reinforcing component can react with free hydroxide ions (OH-) in the system. - ) and calcium ions (Ca 2+ The reaction generates silicate cement and calcium silicate, which provide a good nucleation effect during cement hydration, induce the formation of hydrated calcium silicate and hydrated calcium aluminosilicate during cement hydration, promote cement hydration and thus improve the early strength of cement. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] The following examples all demonstrate the preparation of cement slurry according to GB / T19139 standard. The G-grade oil well cement and ultrafine silicate cement were provided by Jiahua Special Cement Co., Ltd. The water loss reducing agent was AMPS / AM copolymer, and the dispersant was sulfonated acetone formaldehyde condensate.

[0041] Example 1

[0042] As a preferred embodiment of the present invention, the specific composition of the low-temperature early-strength low-density cement-based material for deep-water cementing in this embodiment is shown in Table 1 below:

[0043] Table 1

[0044] raw material Weight percentage (wt%) cementing materials 54 Active materials 20 Strength-enhancing materials 6 Density adjustment materials 15 Water loss reducer 3 dispersant 2

[0045] In this embodiment, the cementing material is a mixture of Grade G oil well cement and ultrafine silicate cement in a mass ratio of 7:3.

[0046] In this embodiment, the active material is a mixture of metakaolin and microsilica in a mass ratio of 1:1.

[0047] In this embodiment, the strength-enhancing material active component A, active component B and reinforcing component are mixed in a mass ratio of 1:3:1.

[0048] In this embodiment, the density-adjusting material is hollow glass microspheres with a density of 0.44–0.48 g / cm³. 3 The median particle size is 40 μm, and the compressive strength is >4000 psi.

[0049] The cementitious material, active material, strength-enhancing material, density-regulating material, fluid loss reducing agent and dispersant are mixed evenly according to the weight ratio in Table 1 to form a dry powder, thus obtaining low-temperature early-strength low-density cement-based material 1# for deep water cementing.

[0050] Cement slurry was prepared according to GB / T19139 standard with a water-cement ratio of 0.6. Cement slurry system 1# was obtained by using low-temperature early-strength low-density cement-based material 1# for deep water cementing.

[0051] Example 2

[0052] As a preferred embodiment of the present invention, the specific composition of the low-temperature early-strength low-density cement-based material for deep-water cementing in this embodiment is shown in Table 2 below:

[0053] Table 2

[0054] raw material Weight percentage (wt%) cementing materials 62 Active materials 20 Strength-enhancing materials 4.5 Density adjustment materials 10 Water loss reducer 2 dispersant 1.5

[0055] In this embodiment, the cementing material is a mixture of Grade G oil well cement and ultrafine silicate cement in a mass ratio of 7:3.

[0056] In this embodiment, the active material is a mixture of metakaolin and microsilica in a mass ratio of 1:1.

[0057] In this embodiment, the strength-enhancing material active component A, active component B and reinforcing component are mixed in a mass ratio of 1:3:1.

[0058] In this embodiment, the density-adjusting material is hollow glass microspheres with a density of 0.44–0.48 g / cm³. 3 The median particle size is 40 μm, and the compressive strength is >4000 psi.

[0059] The cementitious material, active material, strength-enhancing material, density-regulating material, fluid loss reducer and dispersant are mixed evenly according to the weight ratio in Table 2 to form a dry powder, thus obtaining low-temperature early-strength low-density cement-based material 2# for deep water cementing.

[0060] Cement slurry was prepared according to GB / T19139 standard with a water-cement ratio of 0.6. Cement slurry system 2# was obtained by using low temperature early strength low density cement-based material 2# for deep water cementing.

[0061] Example 3

[0062] As a preferred embodiment of the present invention, the specific composition of the low-temperature early-strength low-density cement-based material for deep-water cementing in this embodiment is shown in Table 3 below:

[0063] Table 3

[0064] raw material Weight percentage (wt%) cementing materials 70 Active materials 20 Strength-enhancing materials 3 Density adjustment materials 5 Water loss reducer 1 dispersant 1

[0065] In this embodiment, the cementing material is a mixture of Grade G oil well cement and ultrafine silicate cement in a mass ratio of 7:3.

[0066] In this embodiment, the active material is a mixture of metakaolin and microsilica in a mass ratio of 1:1.

[0067] In this embodiment, the strength-enhancing material active component A, active component B and reinforcing component are mixed in a mass ratio of 1:3:1.

[0068] In this embodiment, the density-adjusting material is hollow glass microspheres with a density of 0.44–0.48 g / cm³. 3 The median particle size is 40 μm, and the compressive strength is >4000 psi.

[0069] The cementitious material, active material, strength-enhancing material, density-regulating material, fluid loss reducing agent and dispersant are mixed evenly according to the weight ratio in Table 3 to form a dry powder, thus obtaining low-temperature early-strength low-density cement-based material 3# for deep water cementing.

[0070] Cement slurry was prepared according to GB / T19139 standard with a water-cement ratio of 0.6. Cement slurry system 3# was obtained by using low temperature early strength low density cement-based material 3# for deep water cementing.

[0071] Example 4

[0072] As a preferred embodiment of the present invention, the specific composition of the low-temperature early-strength low-density cement-based material for deep-water cementing in this embodiment is shown in Table 4 below:

[0073] Table 4

[0074] raw material Weight percentage (wt%) cementing materials 67 Active materials 20 Strength-enhancing materials 6 Density adjustment materials 5 Water loss reducer 1 dispersant 1

[0075] In this embodiment, the cementing material is a mixture of Grade G oil well cement and ultrafine silicate cement in a mass ratio of 7:3.

[0076] In this embodiment, the active material is a mixture of metakaolin and microsilica in a mass ratio of 1:1.

[0077] In this embodiment, the strength-enhancing material active component A, active component B and reinforcing component are mixed in a mass ratio of 1:3:1.

[0078] In this embodiment, the density-adjusting material is hollow glass microspheres with a density of 0.44–0.48 g / cm³. 3 The median particle size is 40 μm, and the compressive strength is >4000 psi.

[0079] The cementitious material, active material, strength-enhancing material, density-regulating material, fluid loss reducing agent and dispersant are mixed evenly according to the weight ratio in Table 4 to form a dry powder, thus obtaining low-temperature early-strength low-density cement-based material 4# for deep water cementing.

[0080] Cement slurry was prepared according to GB / T19139 standard with a water-cement ratio of 0.6. Cement slurry system 4# was obtained by using low-temperature early-strength low-density cement-based material 4# for deep water cementing.

[0081] Example 5

[0082] As a preferred embodiment of the present invention, the specific composition of the low-temperature early-strength low-density cement-based material for deep-water cementing in this embodiment is shown in Table 5 below:

[0083] Table 5

[0084]

[0085]

[0086] In this embodiment, the cementing material is a mixture of Grade G oil well cement and ultrafine silicate cement in a mass ratio of 7:3.

[0087] In this embodiment, the active material is a mixture of metakaolin and microsilica in a mass ratio of 1:1.

[0088] In this embodiment, the strength-enhancing material active component A, active component B and reinforcing component are mixed in a mass ratio of 1:3:1.

[0089] In this embodiment, the density-adjusting material is hollow glass microspheres with a density of 0.44–0.48 g / cm³. 3 The median particle size is 40 μm, and the compressive strength is >4000 psi.

[0090] The cementitious material, active material, strength-enhancing material, density-regulating material, fluid loss reducing agent and dispersant are mixed evenly according to the weight ratio in Table 5 to form a dry powder, thus obtaining low-temperature early-strength low-density cement-based material 5# for deep water cementing.

[0091] Cement slurry was prepared according to GB / T19139 standard with a water-cement ratio of 0.6. Cement slurry system 5# was obtained by using low-temperature early-strength low-density cement-based material 5# for deep water cementing.

[0092] Comparative Example 1

[0093] This comparative example is identical to Example 1 except that the cementitious material does not contain ultrafine silicate cement.

[0094] Comparative Example 2

[0095] This comparative example is identical to Example 1 except that it does not contain any strength-enhancing material.

[0096] Comparative Example 3

[0097] This comparative example is identical to Example 1 except that the strength-enhancing material is replaced with a commercially available early-strength agent.

[0098] Test case

[0099] Referring to GB / T19139 Oil Well Cement Test Method, the cement slurry systems prepared by Comparative Examples 1 to 3 and Examples 1 to 5 were tested for engineering properties such as density, water loss, fluidity, anti-channeling coefficient (SPN value), thickening time, and compressive strength at different curing temperatures. The results are shown in Tables 6 and 7.

[0100] Table 6

[0101]

[0102] Based on the data in Table 6, it can be concluded that the cement slurry systems prepared in Examples 1 to 5 can well meet the construction requirements in terms of water loss, fluidity, and thickening time, and the density of the slurry ranges from 1.30 to 1.55 g / cm³. 3 Between these components, the cement slurry exhibits excellent anti-channeling properties, significantly shortening the setting time. Compared to Example 1, the thickening time of the cement slurry systems in Comparative Examples 1 to 3 is significantly prolonged, and the anti-channeling ability of the slurry is greatly reduced.

[0103] Table 7

[0104]

[0105] As shown in Table 7, the cement slurry systems prepared in Examples 1 to 5 exhibit a compressive strength > 3.5 MPa after curing at 10°C for 24 hours, meeting the requirements for cementing operations. The cement stone formed by the cement slurry systems in Comparative Examples 1 to 3 shows a significantly lower compressive strength than that in Example 1, indicating a substantial decrease in compressive strength.

[0106] As can be seen from the above embodiments, the technical solution of the present invention does not affect the construction performance of cement slurry, and can significantly promote the early hydration process of cement, greatly improve the strength development rate of cement slurry, improve the early strength of cement stone, and help prevent low-temperature shallow water and gas channeling, thereby improving the cementing quality.

[0107] 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 low-temperature, early-strength, low-density cement-based material for deep-water cementing, characterized in that, Including the following raw materials by weight percentage: Cementitious materials: 54~70wt% Active material: 20wt% Strength-reinforcing material: 3~6wt%; Density adjustment material: 5~15wt%; Water loss reducer: 1~3wt%; Dispersant: 1~2wt%; The cementing material is a mixture of Grade G oil well cement and ultrafine silicate cement in a mass ratio of 7:3; the active material is a mixture of metakaolin and microsilica in a mass ratio of 1:

1. The strength-enhancing material is composed of active component A, active component B and reinforcing component mixed in a mass ratio of 1:3:1; The active component A is composed of calcium carbide slag, biomass slag and aerated concrete waste in a mass ratio of 5:4:

1. The active component B is composed of modified zirconium silicon slag, silicomanganese slag, phosphorus slag, and alkali slag mixed in a mass ratio of 3:2:1:1; The reinforcing component is composed of lithium silicate and aluminum sulfate mixed in a mass ratio of 1:

2.

2. The low-temperature early-strength low-density cement-based material for deep-water cementing according to claim 1, characterized in that, The metakaolin has a SiO2 content of 48-54 wt%, an Al2O3 content of 40-45 wt%, and a powder particle size of less than 600 mesh.

3. The low-temperature early-strength low-density cement-based material for deep-water cementing according to claim 1, characterized in that, The microsilicon has a SiO2 content of 96 wt% and a particle size of 0.05~0.30 μm.

4. The low-temperature early-strength low-density cement-based material for deep-water cementing according to claim 1, characterized in that, The density-adjusting material is hollow glass microspheres with a density of 0.44~0.48 g / cm³. 3 The median particle size is 40 μm, and the compressive strength is >4000 psi.

5. The low-temperature early-strength low-density cement-based material for deep-water cementing according to claim 1, characterized in that, The method for preparing the strength-enhancing material is as follows: Sa1. Mix the active component A and the reinforcing component to obtain powder A; Sa2. Place active component B in a ball mill jar and ball mill at 500 rpm for 6 hours to obtain powder B; Sa3. Powder A and powder B are pneumatically mixed to obtain a strength-enhancing material.

6. The low-temperature early-strength low-density cement-based material for deep-water cementing according to claim 1, characterized in that, The preparation method of the active component A is as follows: Sb1. Carbide slag, biomass slag and aerated concrete waste were placed in a ball mill jar at a mass ratio of 5:4:1 and a liquid-to-material ratio of 1.

0. The mixture was ball milled at 400 rpm for 72 hours to obtain slurry A. Sb2. Place slurry A in a sealed mixing tank, add 1 wt% of the dispersant and stabilizer from the solid phase of slurry A and stir. The stirring temperature is 80℃ and the stirring time is 72h to obtain slurry B. Sb3. Place slurry B in a centrifuge for liquid-solid separation, and dry the solid phase at the bottom of the liquid-solid separation into dry powder to obtain active component A.

7. The low-temperature early-strength low-density cement-based material for deep-water cementing according to claim 6, characterized in that, The carbide slag has a CaO content of 65-70 wt% and a pH of 12-13; the biomass slag has a SiO2 content of ≥65 wt%, an Al2O3 content of ≥15 wt%, and a particle size of less than 325 mesh; the aerated concrete waste is composed of tobermorite, semi-crystalline CSH(I), CSH gel, and silica, and is pulverized and ground to a powder fineness of less than 600 mesh; the dispersing stabilizer is a mixture of ketaldehyde condensate and microcrystalline cellulose.

8. The low-temperature early-strength low-density cement-based material for deep-water cementing according to claim 1, characterized in that, The modified zirconium silicon slag is made into slurry C from zirconium silicon slag. Slurry C is neutralized, washed with water, and impurity removed, then subjected to solid-liquid separation, and finally dried and ground at high temperature to obtain the product.

9. A low-temperature early-strength, low-density cement-based material for deep-water cementing according to claim 1, characterized in that, The modified zirconium silicon slag has an SiO2 content ≥90wt%, a neutral pH, and a powder particle size of less than 325 mesh; the ferrosilicon manganese slag has a powder particle size of less than 325 mesh, an SiO2 content of 35~40wt%, an Al2O3 content of 9~12wt%, a CaO content of 25~28wt%, and a MgO content of 6~11wt%; the phosphorus slag has an SiO2 content of 35~40wt% and a CaO content of 42~48wt%; the alkali slag has a CaCO3 content of 40~45wt%, a CaSO4 content of 7~10wt%, and a CaCl2 content of 10~14wt%.

10. A low-temperature early-strength, low-density cement-based material for deep-water cementing according to claim 1, characterized in that, The purity of the lithium silicate is greater than 98 wt%, and the purity of the aluminum sulfate is greater than 98 wt%.

11. A low-temperature early-strength, low-density cement-based material for deep-water cementing according to claim 1, characterized in that, The water loss reducing agent is a 2-acrylamido-2-methylpropanesulfonic acid / acrylamide copolymer; the dispersant is a sulfonated acetone-formaldehyde condensate.

12. A method for preparing a low-temperature early-strength, low-density cement-based material for deep-water cementing according to any one of claims 1 to 11, characterized in that, include: The cementitious material, active material, strength-enhancing material, density-regulating material, fluid loss reducing agent and dispersant are mixed evenly in each weight ratio to form a dry powder, which yields a low-temperature early-strength low-density cement-based material for deep-water cementing.

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