Lightening materials based on high-strength and low-density cement slurry systems

Abstract

The present invention discloses a lightening material based on a high-strength, low-density cement slurry system, belonging to the field of oilfield chemical technology. The lightening material preparation method comprises preparing reinforced foam glass particles by compounding waste glass and a reinforcing material; then modifying the surfaces of the reinforced foam glass particles by double-coating to obtain modified foam glass particles; and then dissolving methyl vinyl polyoxyethylene ether, alkyl glycoside, hydroxypropyl methylcellulose, and nano-silica in deionized water, adding the modified foam glass particles, and stirring to prepare a pre-slurry solution to obtain the lightening material based on a high-strength, low-density cement slurry system. The lightening material based on a high-strength, low-density cement slurry system of the present invention has a low density and good compressive strength.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and in particular relates to a lightening material based on a high-strength and low-density cement slurry system. Background Art

[0002] In the process of oilfield development, cementing operations are a crucial link. The main purpose of cementing is to isolate oil, gas, and water layers, prevent fluid cross-contamination between layers, protect the oil layers, and provide good wellbore conditions for subsequent production operations. Cement slurry is a key material used in cementing operations, and its performance directly affects the quality of cementing. Traditional cement slurry usually has a high density, but it can cause serious problems under some special geological conditions. For example, when cementing in low-pressure and leaky formations, high-density cement slurry will generate a large liquid column pressure. When this pressure exceeds the fracture pressure of the formation, it will cause the formation to be compressed and leaked, resulting in a large amount of cement slurry loss. This will not only result in a waste of cementing materials and increase operating costs, but will also seriously affect the quality of cementing.

[0003] To prevent formation leaks, reducing the density of cement slurry is an effective method. However, simply reducing the density of cement slurry can introduce new problems, namely insufficient strength and unstable strength development. At low density, the solid content in the cement slurry is relatively reduced, the spacing between cement particles increases, and the extent and speed of the hydration reaction are affected, making it difficult for the cement stone to achieve sufficient strength after solidification, making it impossible to effectively isolate the formation and support the casing. Moreover, due to the unstable hydration reaction, the strength development of the cement stone may fluctuate, with inconsistent strength growth over different time periods, which is very detrimental to long-term cementing results. During the production process of the oil well, as downhole pressure and temperature change, insufficiently strong and unstable cement stone may crack and damage, leading to cementing failure.

[0004] Currently, some lightening materials for reducing cement slurry density are available on the market, such as perlite and fly ash. While these materials can reduce cement slurry density to a certain extent, they struggle to ensure sufficient strength at low densities. Therefore, the present invention develops a lightening material based on a high-strength, low-density cement slurry system to address the existing technical issues of cement slurry during cementing operations: excessively high cement slurry density can easily cause leaks in the formation, while low density can lead to insufficient strength and unstable development. Summary of the Invention

[0005] The purpose of the present invention is to provide a lightening material based on a high-strength, low-density cement slurry system to solve the technical problems in the prior art of cementing operations in which the cement slurry density is too high and easily causes leaks in the formation, while the strength is insufficient and the development is unstable under low density.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The preparation method of the lightening material based on the high-strength and low-density cement slurry system comprises the following steps:

[0008] (1) Reinforced foam glass particles are prepared by compounding waste glass, special glass, slag, reinforcing fiber and nano-montmorillonite;

[0009] (2) Modified foam glass particles are obtained by performing double-layer coating modification on the surface of the reinforced foam glass particles;

[0010] (3) Methyl vinyl polyoxyethylene ether, alkyl glycoside, hydroxypropyl methylcellulose and nano-silica are dissolved in deionized water respectively, modified foam glass particles are added, stirred and prepared into a pre-slurry liquid to obtain a lightening material based on a high-strength and low-density cement slurry system.

[0011] Preferably, in step (3), the mass ratio of methyl alkylene polyoxyethylene ether, alkyl glycoside, hydroxypropyl methylcellulose, nano-silica, modified foam glass particles and deionized water is 0.6-1:0.1-0.3:0.1-0.3:1-2:35-45:40-50, the stirring speed is 30-60 rpm, and the time is 10-15 min.

[0012] The lightening material based on the high-strength, low-density cement slurry system, step (1) includes the following process:

[0013] S1. After cleaning the waste glass and special glass, crush them separately and then use ball mill to obtain waste glass powder and special glass powder; magnetically separate and grind the slag to obtain micro slag;

[0014] S2, mixing waste glass powder, special glass powder and slag powder, stirring, adding foaming agent and foam stabilizer 1, continuing to stir, mixing evenly, and then adding reinforcing fiber and nano-montmorillonite in sequence, stirring while adding, to obtain a reinforced mixed powder;

[0015] S3. The enhanced mixed powder is loaded into a mold, and the initial temperature is raised, the foaming agent is decomposed, the second foam stabilizer is added, foaming and annealing are performed in sequence to obtain foam glass blocks, which are crushed and sieved to obtain enhanced foam glass particles.

[0016] Preferably, the crushed particle size in S1 is less than 1 mm, the particle size of the waste glass powder, special glass powder and micro slag is 50-200 μm, the slag is blast furnace slag, and the special glass is borate glass.

[0017] Preferably, the stirring speed in S2 is 300-500r / min, the stirring time is 15-30min, and the stirring is continued for 10-20min. The stirring speed when the reinforcing fiber is added is 200-300r / min, and the stirring time is 20-30min. The stirring speed when the nano-montmorillonite is added is 300-500r / min, and the stirring time is 15-30min. The reinforcing fiber is one or more of glass fiber, carbon fiber and basalt fiber, and the fiber length is 3-6mm; waste glass The mass ratio of glass powder, special glass powder, micro slag, reinforcing fiber, nano-montmorillonite, foaming agent and foam stabilizer 1 is 100:10-20:20-30:2-6:1-2.5:4-6:2; the waste glass is bottle or construction waste glass, the special glass is borate glass, the foaming agent is a mixture of calcium carbonate and silicon carbide in a mass ratio of 4-5:1-2, the foam stabilizer 1 is a mixture of boric acid and borax, the foam stabilizer 2 is sodium phosphate, and the mass ratio of boric acid, borax and sodium phosphate is 1.5:0.5:0.5.

[0018] Preferably, the charging height in S3 is 2 / 3-3 / 4 of the mold height, the heating rate in the initial heating stage of heating and foaming is 5-10°C / min, heating to 300-400°C, and the holding time is 10-20min; the heating rate in the foaming agent decomposition stage is 2-5°C / min, heating to 600-700°C, and the holding time is 15-30min; the heating rate in the foaming stage is 3-5°C / min, heating to 800-950°C, and the holding time is 10-30min; the cooling rate in the initial stage of annealing is 1-5°C / min, cooling to 400-500°C, and the holding time is 2-4h, and the cooling rate in the post-annealing stage is 5-10°C / h, cooling to room temperature. The temperature should be kept evenly decreased throughout the annealing process to avoid rapid temperature changes that cause cracking of the foam glass; the sieved particle size is 1-3mm.

[0019] The lightening material based on the high-strength, low-density cement slurry system, step (2) includes the following process:

[0020] Q1. Wash the reinforced foam glass particles, dry them to constant weight, soak them in aluminum dihydrogen phosphate solution, remove them, drain them, dry and solidify them to obtain phosphate-coated foam glass particles;

[0021] Q2. Add phosphate-coated foam glass particles to deionized water containing a dispersant, stir evenly to obtain a suspension, add the hybrid emulsion to the foam glass particle suspension while stirring, stir to react, filter, and dry to obtain modified foam glass particles.

[0022] Preferably, the concentration of the aluminum dihydrogen phosphate solution in Q1 is 10-20 wt %, the drying temperature is 105-110° C., the soaking time is 1-2 h, the drying and curing temperature is 150-200° C., and the drying and curing time is 2-4 h.

[0023] Preferably, the hybrid emulsion in Q2 is obtained by adding nano-montmorillonite modified with 0.8-1.5wt% of KH-550 silane coupling agent to a composite emulsion and ultrasonically dispersing the nano-montmorillonite, and the volume ratio of the composite emulsion to the nano-montmorillonite is 100:3-4; the composite emulsion is prepared from acrylic emulsion, vinyl acetate emulsion, polyurethane emulsion, styrene-acrylic emulsion, ZW-2 and silica fume in a dosage ratio of 40-50mL:35-40mL:25-30mL:10-12mL:0.3-0.5g:0.35-0.6g; the stirring reaction time is 1-2h, and the drying temperature is 60-80°C.

[0024] By combining the components of the hybrid emulsion, modified foam glass particles with better comprehensive performance are prepared. Acrylic emulsion has good weather resistance and water resistance, vinyl acetate emulsion has good adhesion, polyurethane emulsion has high elasticity and wear resistance, and styrene acrylic emulsion has excellent chemical resistance. Nano-montmorillonite can interact with the polymer molecules in the composite emulsion to enhance the stability and adhesion of the emulsion, thereby improving the interfacial bonding force between the modified foam glass particles and the cement slurry.

[0025] The present application provides a lightening material based on a high-strength, low-density cement slurry system, which adopts the following technical solution: the lightening material based on a high-strength, low-density cement slurry system is prepared according to any of the above-mentioned methods for preparing a lightening material based on a high-strength, low-density cement slurry system.

[0026] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0027] 1. The present invention makes full use of waste glass for multi-stage material compounding and surface coating modification to prepare modified foam glass particles, which are used as components of the cement slurry system. This not only achieves the recycling of waste, reduces the pollution of waste glass to the environment, and reduces the cost of raw materials, but also ensures the strength of the material while reducing the density, thereby meeting the needs of a high-strength, low-density cement slurry system.

[0028] 2. The present invention prepares foamed glass particles by compounding multiple-level materials such as waste glass powder, borate glass powder, micro-slag, reinforcing fiber and nano-montmorillonite, and synergizing them. The fibers form a network structure inside the foamed glass, which can effectively prevent crack propagation, enhance the compression and impact resistance of the particles, and thus enhance the mechanical properties of the cement slurry system. The slag and nano-montmorillonite particles can fill the tiny pores in the material, further improving the density of the material. In addition, the optimized foaming and bubble stabilization system can produce uniform and fine bubbles during the heating process, and stabilize the morphology of the bubbles to prevent the bubbles from breaking and merging, thereby forming a uniform porous structure inside the foamed glass, which not only reduces the density of the material, but also gives the material good mechanical properties, making it more suitable for application in high-strength and low-density cement slurry systems.

[0029] 3. The present invention utilizes phosphate coating and hybrid emulsion modification on the surface of foam glass particles. The modified material not only protects the internal structure but also better bonds with the cement slurry matrix, thereby enhancing the mechanical properties of the cement slurry system. The phosphate coating acts as an insulator, reducing direct contact between the foam glass particles and the external environment and improving the chemical stability of the particles, thereby ensuring the long-term stability of the cement slurry system. The hybrid emulsion is composed of a composite of acrylic emulsion, vinyl acetate emulsion, polyurethane emulsion, styrene acrylic emulsion, and nano-montmorillonite. The synergistic effect of these components enhances the overall performance of the cement slurry system. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] Example 1:

[0032] This embodiment provides a method for preparing a lightening material based on a high-strength, low-density cement slurry system, comprising the following steps:

[0033] (1) Reinforced foam glass particles are prepared by compounding waste glass, special glass, slag, reinforcing fiber and nano-montmorillonite;

[0034] (2) Modified foam glass particles are obtained by performing double-layer coating modification on the surface of the reinforced foam glass particles;

[0035] (3) 6 g of methyl vinyl polyoxyethylene ether, 1 g of alkyl glycoside, 1 g of hydroxypropyl methylcellulose and 10-20 g of nano-silica were dissolved in 400 g of deionized water, 350 g of modified foam glass particles were added, and the mixture was stirred at a speed of 30 rpm for 10 min to prepare a pre-slurry liquid to obtain a lightening material based on a high-strength, low-density cement slurry system.

[0036] The method for preparing the lightening material based on the high-strength and low-density cement slurry system, step (1) includes the following process:

[0037] S1. After cleaning, waste glass and borate glass are crushed to a particle size of less than 1 mm, and then ball-milled to obtain waste glass powder and borate glass powder; blast furnace slag is magnetically separated and ground to obtain micro slag;

[0038] S2, 100g waste glass powder, 10g borate glass powder and 20g slag powder were mixed and stirred at a stirring speed of 300r / min and a stirring time of 15min. 4g calcium carbonate, 1g silicon carbide, 1.5g boric acid and 0.5g borax were added and stirred for 10min. Mixed evenly, 2g reinforcing fiber and 1g nano-montmorillonite were added in sequence. The reinforcing fiber was glass fiber with a fiber length of 3mm. The mixture was stirred while added. The stirring speed when the reinforcing fiber was added was 200r / min and the stirring time was 20min. The stirring speed when the nano-montmorillonite was added was 300r / min and the stirring time was 15min. Reinforced mixed powder was obtained.

[0039] S3. The enhanced mixed powder is loaded into a mold with a loading height of 2 / 3 of the mold height, and the initial heating, foaming agent decomposition, 0.5g sodium phosphate is added, foaming, and annealing are performed in sequence to obtain foam glass blocks, which are crushed and sieved to obtain a particle size of 1mm. The heating rate in the initial heating stage is 10℃ / min, and the temperature is increased to 300℃, and the holding time is 10min; the heating rate in the foaming agent decomposition stage is 5℃ / min, and the temperature is increased to 600℃, and the holding time is 15min; the heating rate in the foaming stage is 5℃ / min, and the temperature is increased to 800℃, and the holding time is 10min; the cooling rate in the initial annealing stage is 5℃ / min, and the temperature is decreased to 400℃, and the holding time is 2h. The cooling rate in the post-annealing stage is 10℃ / h, and the temperature is decreased to room temperature to obtain enhanced foam glass particles.

[0040] Wherein, the preparation method of the lightening material based on the high-strength and low-density cement slurry system, step (2) includes the following process:

[0041] Q1. The reinforced foam glass particles were washed and dried to constant weight at a drying temperature of 105°C for 1 hour, and then immersed in a 10 wt% aluminum dihydrogen phosphate solution. The particles were taken out, drained, and dried and solidified at a drying and solidification temperature of 150°C for 2 hours to obtain phosphate-coated foam glass particles.

[0042] Q2. Phosphate-coated foam glass particles are added to deionized water containing a dispersant and stirred evenly to obtain a suspension. Under stirring, the hybrid emulsion is added to the foam glass particle suspension. The hybrid emulsion is obtained by adding nano-montmorillonite modified with 0.8wt% of KH-550 silane coupling agent to a composite emulsion and ultrasonically dispersing the nano-montmorillonite. The volume ratio of the composite emulsion to the nano-montmorillonite is 100:3. The composite emulsion is prepared from acrylic emulsion, vinyl acetate emulsion, polyurethane emulsion, styrene-acrylic emulsion, ZW-2 and silica fume in a dosage ratio of 40mL:35mL:25mL:10mL:0.3g:0.35g. The stirring reaction time is 1h, and the mixture is filtered and dried at a drying temperature of 60°C to obtain modified foam glass particles.

[0043] Example 2:

[0044] This embodiment provides a method for preparing a lightening material based on a high-strength, low-density cement slurry system, comprising the following steps:

[0045] (1) Reinforced foam glass particles are prepared by compounding waste glass, special glass, slag, reinforcing fiber and nano-montmorillonite;

[0046] (2) Modified foam glass particles are obtained by performing double-layer coating modification on the surface of the reinforced foam glass particles;

[0047] (3) 8 g of methyl vinyl polyoxyethylene ether, 2 g of alkyl glycoside, 2 g of hydroxypropyl methylcellulose and 15 g of nano-silica were dissolved in 450 g of deionized water, 400 g of modified foam glass particles were added, and stirred at a speed of 50 rpm for 13 min to prepare a pre-slurry liquid to obtain a lightening material based on a high-strength and low-density cement slurry system.

[0048] The method for preparing the lightening material based on the high-strength and low-density cement slurry system, step (1) includes the following process:

[0049] S1. After cleaning, waste glass and borate glass are crushed to a particle size of less than 1 mm, and then ball-milled to obtain waste glass powder and borate glass powder; blast furnace slag is magnetically separated and ground to obtain micro slag;

[0050] S2, 100g waste glass powder, 15g borate glass powder and 25g slag powder were mixed and stirred at a stirring speed of 400r / min and a stirring time of 20min. 4g calcium carbonate, 1.5g silicon carbide, 1.5g boric acid and 0.5g borax were added and stirred for 14min. The mixture was uniformly mixed and then 4g reinforcing fiber and 1.3g nano-montmorillonite were added in sequence. The reinforcing fiber was basalt fiber with a fiber length of 4mm. The mixture was stirred while added. The stirring speed when the reinforcing fiber was added was 250r / min and the stirring time was 25min. The stirring speed when the nano-montmorillonite was added was 400r / min and the stirring time was 20min. The reinforced mixed powder was obtained.

[0051] S3. The enhanced mixed powder is loaded into a mold with a loading height of 3 / 4 of the mold height, and initial heating, foaming agent decomposition, addition of 0.5 g of sodium phosphate, foaming, and annealing are performed in sequence to obtain foam glass blocks, which are crushed and sieved to obtain a particle size of 2 mm. The heating rate in the initial heating stage is 8°C / min, heating to 350°C, and keeping warm for 15 min; the heating rate in the foaming agent decomposition stage is 3°C / min, heating to 650°C, and keeping warm for 20 min; the heating rate in the foaming stage is 4°C / min, heating to 850°C, and keeping warm for 20 min; the cooling rate in the initial annealing stage is 3°C / min, cooling to 450°C, and keeping warm for 3 h; the cooling rate in the post-annealing stage is 7°C / h, cooling to room temperature, and obtaining enhanced foam glass particles.

[0052] Wherein, the preparation method of the lightening material based on the high-strength and low-density cement slurry system, step (2) includes the following process:

[0053] Q1. The reinforced foam glass particles were washed and dried to constant weight at a drying temperature of 108°C for 1.5 hours, and then immersed in a 15 wt% aluminum dihydrogen phosphate solution. The particles were taken out, drained, and dried and solidified at a drying and solidification temperature of 170°C for 3 hours to obtain phosphate-coated foam glass particles.

[0054] Q2. Add phosphate-coated foam glass particles to deionized water containing a dispersant and stir evenly to obtain a suspension. Under stirring, add the hybrid emulsion to the foam glass particle suspension. The hybrid emulsion is obtained by adding nano-montmorillonite modified with 1.2wt% of KH-550 silane coupling agent to the composite emulsion and ultrasonically dispersing it. The volume ratio of the composite emulsion to the nano-montmorillonite is 100:3.5; the composite emulsion is prepared from acrylic emulsion, vinyl acetate emulsion, polyurethane emulsion, styrene-acrylic emulsion, ZW-2 and silica fume in a dosage ratio of 45mL:38mL:28mL:11mL:0.4g:0.5g. The stirring reaction time is 1.5h, and the mixture is filtered and dried at a drying temperature of 70°C to obtain modified foam glass particles.

[0055] Example 3:

[0056] This embodiment provides a method for preparing a lightening material based on a high-strength, low-density cement slurry system, comprising the following steps:

[0057] (1) Reinforced foam glass particles are prepared by compounding waste glass, special glass, slag, reinforcing fiber and nano-montmorillonite;

[0058] (2) Modified foam glass particles are obtained by performing double-layer coating modification on the surface of the reinforced foam glass particles;

[0059] (3) Dissolve 10 g of methyl vinyl polyoxyethylene ether, 3 g of alkyl glycoside, 3 g of hydroxypropyl methylcellulose and 20 g of nano-silica in 500 g of deionized water, add 450 g of modified foam glass particles, and stir at a speed of 60 rpm for 15 min to prepare a pre-slurry liquid to obtain a lightening material based on a high-strength, low-density cement slurry system.

[0060] The method for preparing the lightening material based on the high-strength and low-density cement slurry system, step (1) includes the following process:

[0061] S1. After cleaning, waste glass and borate glass are crushed to a particle size of less than 1 mm, and then ball-milled to obtain waste glass powder and borate glass powder; blast furnace slag is magnetically separated and ground to obtain micro slag;

[0062] S2, 100g waste glass powder, 20g borate glass powder and 30g slag powder are mixed, and stirring is carried out at a stirring speed of 500r / min, and the stirring time is 30min. 4g calcium carbonate, 2g silicon carbide, 1.5g boric acid and 0.5g borax are added, and stirring is continued for 20min. Mix well, then 6g reinforcing fiber and 1.5g nano-montmorillonite are added in sequence. Reinforcing fiber is carbon fiber, and fiber length is 6mm. Stirring is added while adding. The stirring speed when adding reinforcing fiber is 300r / min, and the stirring time is 30min. The stirring speed when adding nano-montmorillonite is 500r / min, and the stirring time is 30min. Reinforced mixed powder is obtained.

[0063] S3. The enhanced mixed powder is loaded into a mold with a loading height of 3 / 4 of the mold height, and the initial heating, foaming agent decomposition, 0.5g sodium phosphate is added, foaming, and annealing are performed in sequence to obtain foam glass blocks, which are crushed and sieved to obtain a particle size of 3mm. The heating rate in the initial heating stage is 5°C / min, and the temperature is increased to 400°C, and the holding time is 20min; the heating rate in the foaming agent decomposition stage is 2°C / min, and the temperature is increased to 700°C, and the holding time is 30min; the heating rate in the foaming stage is 3°C / min, and the temperature is increased to 950°C, and the holding time is 30min; the cooling rate in the initial annealing stage is 1°C / min, and the temperature is decreased to 500°C, and the holding time is 4h. The cooling rate in the post-annealing stage is 5°C / h, and the temperature is decreased to room temperature to obtain enhanced foam glass particles.

[0064] Wherein, the preparation method of the lightening material based on the high-strength and low-density cement slurry system, step (2) includes the following process:

[0065] Q1. The reinforced foam glass particles were washed and dried to constant weight at a drying temperature of 110°C for 2 hours, and then immersed in a 1.5 wt% aluminum dihydrogen phosphate solution. The particles were taken out, drained, and dried and solidified at a drying and solidification temperature of 200°C for 4 hours to obtain phosphate-coated foam glass particles.

[0066] Q2. Phosphate-coated foam glass particles are added to deionized water containing a dispersant and stirred evenly to obtain a suspension. Under stirring, a hybrid emulsion is added to the foam glass particle suspension. The hybrid emulsion is obtained by adding nano-montmorillonite modified with 20wt% of KH-550 silane coupling agent to a composite emulsion and ultrasonically dispersing the nano-montmorillonite. The volume ratio of the composite emulsion to the nano-montmorillonite is 100:4. The composite emulsion is prepared from acrylic emulsion, vinyl acetate emulsion, polyurethane emulsion, styrene-acrylic emulsion, ZW-2 and silica fume in a dosage ratio of 50mL:40mL:30mL:12mL:0.5g:0.6g. The stirring reaction time is 2h, and the mixture is filtered and dried at a drying temperature of 60-80°C to obtain modified foam glass particles.

[0067] Comparative Example 1:

[0068] Comparative Example 1 Compared with Example 3, in the preparation process of the modified foam glass particles in Comparative Example 1, no phosphate coating modification was performed, and other conditions remained unchanged.

[0069] Comparative Example 2:

[0070] Comparative Example 2 Compared with Example 3, in the preparation process of the modified foam glass particles in Comparative Example 2, no hybrid emulsion was added for modification, and other conditions remained unchanged.

[0071] Comparative Example 3:

[0072] Comparative Example 3 Compared with Example 3, in the preparation process of the lightening material based on the high-strength and low-density cement slurry system, no reinforcing fiber is added in Comparative Example 3, and other conditions remain unchanged.

[0073] Experimental example:

[0074] Slowly add silicate cement to the pre-slurry prepared in Examples 1-3 and Comparative Examples 1-3 and stir at a speed of 500 rpm for 12 min to uniformly disperse the cement particles to prepare 1.6 g / cm 3 , 1.5g / cm 3 and 1.4 g / cm 3 Three different densities of lightening material cements based on a high-strength, low-density cement slurry system were used. According to the national standard GB / T19139-2012, the lightening material cements based on the high-strength, low-density cement slurry system prepared in Examples 1-3 and Comparative Examples 1-3 were tested for sedimentation stability and thickening time. The test results are shown in Table 1:

[0075] Table 1

[0076]

[0077] The test results in Table 1 indicate that the lightening material cements based on the high-strength, low-density cement slurry system prepared in Examples 1-3 of the present invention exhibit good settling stability and a short thickening time. A comparison of Comparative Examples 1-3 with Examples 1-3 demonstrates that the addition of phosphate coating modification, hybrid emulsion modification, and reinforcing fibers can enhance the settling stability and shorten the thickening time of oil well cement.

[0078] According to ISO679:2009 standard, the density is 1.4g / cm 3 The new oil well cement lightening material cement samples prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to 48h compressive strength test. The test results are shown in Table 2:

[0079] Table 2

[0080]

[0081] The test results in Table 2 indicate that the lightening material cements based on the high-strength, low-density cement slurry system prepared in Examples 1-3 of the present invention exhibit good compressive strength. A comparison of Comparative Examples 1-3 with Examples 1-3 demonstrates that the addition of phosphate coating modification, hybrid emulsion modification, and reinforcing fibers can enhance the compressive strength of oil well cement.

[0082] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

[0083] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. Lightening material based on high-strength and low-density cement slurry system, characterized in that: The preparation method comprises the following steps: (1) Reinforced foam glass particles are prepared by compounding waste glass, special glass, slag, reinforcing fiber and nano-montmorillonite; (2) Modified foam glass particles are obtained by performing double-layer coating modification on the surface of the reinforced foam glass particles; (3) dissolving methyl vinyl polyoxyethylene ether, alkyl glycoside, hydroxypropyl methylcellulose and nano-silica in deionized water respectively, adding modified foam glass particles, stirring, and preparing a pre-slurry liquid to obtain a lightening material based on a high-strength and low-density cement slurry system; Step (1) includes the following process: S1. After cleaning, waste glass and special glass are crushed separately, and then ball-milled to obtain waste glass powder and special glass powder; slag is magnetically separated and ground to obtain micro slag; S2. Mixing waste glass powder, special glass powder, and slag powder, stirring, adding a foaming agent and a foam stabilizer, continuing to stir until evenly mixed, and then sequentially adding reinforcing fiber and nano-montmorillonite, stirring while adding, to obtain a reinforced mixed powder; wherein the waste glass is bottle or construction waste glass, the slag is blast furnace slag, and the special glass is borate glass; S3, loading the enhanced mixed powder into a mold, sequentially performing initial heating, decomposition of the foaming agent, addition of the second foam stabilizer, foaming, annealing to obtain foam glass blocks, crushing, and sieving to obtain enhanced foam glass particles; The mass ratio of waste glass powder, special glass powder, micro slag, reinforcing fiber, nano-montmorillonite, foaming agent and foam stabilizer 1 in S2 is 100:10-20:20-30:2-6:1-2.5:4-6:2; the foaming agent is a mixture of calcium carbonate and silicon carbide in a mass ratio of 4-5:1-2, the foam stabilizer 1 is a mixture of boric acid and borax, and the foam stabilizer 2 is sodium phosphate, and the mass ratio of boric acid, borax and sodium phosphate is 1.5:0.5:0.5; Step (2) includes the following process: Q1. Wash the reinforced foam glass particles, dry them to constant weight, soak them in aluminum dihydrogen phosphate solution, remove them, drain them, dry and solidify them to obtain phosphate-coated foam glass particles; Q2. Adding phosphate-coated foam glass particles to deionized water containing a dispersant and stirring uniformly to obtain a suspension. While stirring, adding the hybrid emulsion to the foam glass particle suspension, stirring to react, filtering, and drying to obtain modified foam glass particles; The hybrid emulsion in Q2 is prepared by adding nano-montmorillonite modified with 0.8-1.5wt% of KH-550 silane coupling agent to a composite emulsion and ultrasonically dispersing the nano-montmorillonite. The volume ratio of the composite emulsion to the nano-montmorillonite is 100:3-4. The composite emulsion is prepared by using acrylic emulsion, vinyl acetate emulsion, polyurethane emulsion, styrene-acrylic emulsion, ZW-2 and silica fume in the ratio of 40-50mL:35-40mL:25-30mL:10-12mL:0.3-0.5g:0.35-0.6g. In step (3), the mass ratio of methyl olefin polyoxyethylene ether, alkyl glycoside, hydroxypropyl methylcellulose, nano-silica, modified foam glass particles and deionized water is 0.6-1:0.1-0.3:0.1-0.3:1-2:35-45:40-50.

2. The lightening material based on the high-strength and low-density cement slurry system according to claim 1, characterized in that: The crushed particle size in S1 is less than 1mm, and the particle size of waste glass powder, special glass powder and micro slag is 50-200μm.

3. The lightening material based on high-strength and low-density cement slurry system according to claim 1, characterized in that: The reinforcing fibers in S2 are one or more of glass fibers, carbon fibers and basalt fibers, and the fiber length is 3-6 mm.

4. The lightening material based on high-strength and low-density cement slurry system according to claim 1, characterized in that: The heating rate in the initial heating stage of S3 is 5-10°C / min, the temperature is raised to 300-400°C, and the holding time is 10-20min; the heating rate in the foaming agent decomposition stage is 2-5°C / min, the temperature is raised to 600-700°C, and the holding time is 15-30min; the heating rate in the foaming stage is 3-5°C / min, the temperature is raised to 800-950°C, and the holding time is 10-30min; the cooling rate in the initial annealing stage is 1-5°C / min, the temperature is lowered to 400-500°C, and the holding time is 2-4h, and the cooling rate in the post-annealing stage is 5-10°C / h.

5. The lightening material based on high-strength and low-density cement slurry system according to claim 1, characterized in that: The concentration of the aluminum dihydrogen phosphate solution in Q1 is 10-20wt%.

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