A temperature-resistant composite lightweight material for low-density cementing

Abstract

This invention discloses a low-density cementing material with a heat-resistant composite weight-reducing agent, comprising the following components by weight: 100 parts oil well cement; 20-30 parts reinforcing material; 10-20 parts composite weight-reducing agent; 0.5-1.0 parts suspension stabilizer; 0.5-1.5 parts early-strength agent; 0.3-0.5 parts dispersant; 1.0-2.5 parts fluid loss reducer; 0.5-1.5 parts retarder; and 0.2 parts defoamer. The composite weight-reducing agent is a composite material including expanded perlite powder. Under the premise of controlling costs and reducing cement slurry density, it can ensure the rheological properties and stability of the slurry while improving the mechanical properties of the cement paste.

Description

Technical Field

[0001] This invention relates to the field of cementing materials technology in oil and gas development, and more particularly to low-density cementing, and more specifically to a low-density cementing with a heat-resistant composite lightweighting material. Background Technology

[0002] Low-density cement slurry plays a very important role in the exploration and development of oil and gas resources. During the oil and gas development process, when encountering low-pressure and weak formations, low-density cement slurry is used to seal the formation to prevent it from being squeezed out during cementing, so as to facilitate the smooth progress of subsequent operations.

[0003] With the exploration and development of unconventional and deep oil and gas resources, the geological challenges encountered are increasing. The difficulty of developing high-temperature, thin, and low-pressure formations is constantly raising the technical requirements for low-density cement slurry. In particular, the development of oil and gas in some complex formations and long cementing sections poses a severe test to low-density cement slurry cementing.

[0004] Currently, two main technical methods are used to prepare low-density cement slurry:

[0005] One approach is to incorporate a suitable amount of lightweighting material into the cement slurry. This low-density material replaces part of the solid phase in the slurry, thereby reducing its density. For example, patent application CN104263332A, entitled "A High-Temperature Resistant, High-Strength, Low-Density Cement Slurry," discloses the use of high-performance hollow glass microspheres as a lightweighting material to obtain a low-density cement slurry. Another example is patent application CN109437710A, entitled "A High Water-Cement Ratio, Low-Cost, Low-Density Cement Slurry," which discloses a method for reducing cement slurry density by increasing the water-cement ratio. Yet another example is patent application CN113969152A, entitled "A Low-Cost Nanoscale Low-Density Cement Slurry System," which discloses a method for reducing slurry density using hollow glass microspheres. It is evident that existing technologies typically use materials such as hollow glass microspheres to replace part of the solid phase in the slurry, which does indeed reduce the density of the cement slurry and provides good engineering performance. However, these materials are mostly expensive, increasing the cost of oil and gas development.

[0006] Secondly, increasing the water-cement ratio of the slurry reduces the solid content per unit volume, thereby lowering the slurry density. However, a high water-cement ratio results in poor slurry performance and can even negatively impact later operations. Using relatively inexpensive expanded perlite is a commonly used technique, but excessive use of expanded perlite can cause significant stratification and instability in the slurry, and also negatively affects the mechanical strength of the cementitious stone.

[0007] Therefore, given the shortcomings of existing technologies, further optimization is still needed. Summary of the Invention

[0008] The purpose of this invention is to provide a composite lightweight low-density cementing material that, while controlling costs and reducing cement slurry density, can both ensure the rheological properties and stability of the slurry and improve the mechanical properties of the cement paste.

[0009] This invention is achieved through the following technical solution:

[0010] A heat-resistant composite lightweight low-density cementing material comprises the following components by weight:

[0011] 100 parts of oil well cement;

[0012] 20-30 parts of reinforcing material;

[0013] 10-20 parts of composite light-reducing material;

[0014] Suspension stabilizer 0.5-1.0 parts;

[0015] Early-strength agent 0.5-1.5 parts;

[0016] Dispersant 0.3-0.5 parts;

[0017] 1.0-2.5 parts of water loss reducer;

[0018] 0.5-1.5 parts of retarder;

[0019] 0.2 parts of defoamer

[0020] The composite weight-reducing material is composed of the following components by mass percentage: 30-45% expanded perlite powder, 25-35% ultrafine perlite, 20-30% high softening point modified hard asphalt powder, 3-5% nano silica, 3-5% boromagnesite, and 1-2% vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer powder.

[0021] Furthermore, the oil well cement is either Grade G oil well cement or Grade A oil well cement.

[0022] Furthermore, the reinforcing material is a dry powder mixture of 4-7 parts ultrafine metakaolin, 5-8 parts ultrafine cement, and 5-15 parts microsilica, wherein the particle size of the ultrafine metakaolin is above 500 mesh, the average particle size of the ultrafine cement is 5-10 μm, and the average particle size of the microsilica is 0.1-0.4 μm.

[0023] Furthermore, the expanded perlite powder has a mesh size of 500 or higher and a SiO2 content of 70% or higher; the ultrafine perlite is a deep-processed material of vitrified microspheres, with a mesh size of 200 or higher.

[0024] Furthermore, the high softening point modified hard asphalt powder has a density of 1.1-1.2 g / cm³. 3 Modified hard asphalt powder with ash content <3%, solubility >97.5%, softening point >200℃, flash point >400℃, and sulfur content <0.2%.

[0025] The high softening point modified hard asphalt powder is prepared by the following steps:

[0026] a. Select a density of 1.0-1.2 g / cm³ 3 De-oiled hard asphalt with ash content of 5-8%, solubility of >88%, water content of <3%, softening point of >120℃, flash point of >300℃, and sulfur content of <0.5% is first heated to 130-150℃ for dehydration treatment, with the heating rate controlled at 10℃ / min and the dehydration treatment time being 20min.

[0027] b. Further heat it to 200-220℃ and perform vacuum distillation to remove the light components, wherein the distillation pressure is -50~10KPa, the heating rate is controlled at 5℃ / min, and the vacuum distillation time is 30min;

[0028] c. After vacuum distillation, 3% nano carbon powder and 2% nano silicon carbide are added to the hard asphalt. The mixture is stirred for 90 minutes at a stirring speed of about 500 rpm / min. After stirring evenly, the preliminarily modified hard asphalt is obtained.

[0029] d. Then, the preliminarily modified hard asphalt is placed in a reactor and heated to 180-200°C by controlling the heating rate at 15°C / min. O3 is introduced into the reactor for oxidation treatment. After stirring and oxidation treatment for 60 minutes, SO3 is introduced into the reactor and stirred and sulfonated for 60 minutes to obtain multi-modified hard asphalt.

[0030] e. Finally, the multi-modified hard asphalt from step d is ground to a fineness of 500 mesh or higher to obtain high softening point hard asphalt powder.

[0031] Furthermore, the nano-silica is a white powder with an average particle size of 15-80 nm and a SiO2 content of over 98%; the boromagnesia stone is a fibrous aggregate with a length of 1-2 mm.

[0032] Furthermore, the density of the composite lightweight material ranges from 0.65 to 0.75 g / cm³. 3 It has an upper limit of applicable temperature of 200℃ and a pressure resistance of over 30MPa.

[0033] Furthermore, the vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer is a high molecular weight polymer powder with a particle size of 800 mesh or more.

[0034] Furthermore, the early strength agent is an inorganic salt-based early strength agent; the dispersant is at least one of carboxylates, polystyrene sulfonates, polynaphthalene sulfonates, lignin sulfonates, and ketone-aldehyde condensates; the loss-reducing agent is at least one of polyamides, polyvinyl alcohol, and AMPS polymers; the retarder is at least one of tartrates, citric acid, boric acid, and phosphates; and the defoamer is at least one of polyacryl alcohol, organosilicon compounds, and tributyl phosphate.

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

[0036] 1. In this invention, the raw materials are mainly inorganic materials, which are widely available and easy to prepare into a slurry. The low-density cementing cement of this invention, made from a heat-resistant composite lightweight material, is used to prepare a cement slurry system with a liquid-to-solid ratio of 0.6-0.9. This low-density cementing slurry is suitable for cementing operations in medium-to-high temperature formations at temperatures ranging from 40-150℃, exhibiting good slurry stability and a density range of 1.35-1.55 g / cm³. 3 After hardening, the compressive strength of the cement stone can be greater than 14MPa. The thickening time of the slurry can be adjusted according to the needs of the site, and the thickening time can be controlled within the range of 3-6 hours, which has good application prospects.

[0037] 2. In this invention, guided by the theory of close packing, the different particle sizes of cement particles, reinforcing materials and weight-reducing materials in the system are used to achieve close packing of the solid phase of the system, which not only ensures the rheological properties of the slurry, but also improves the mechanical properties of the cement paste.

[0038] 3. In this invention, by treating the deoiled hard asphalt in a corresponding manner, especially by incorporating nano-carbon powder and nano-silicon carbide, the softening point of the hard asphalt can be increased, and its high-temperature durability, wear resistance, and pressure bearing capacity can be significantly improved. After chemical treatment to change its wettability, it is ensured that it can be fully and uniformly dispersed in the slurry, avoiding uneven suspension and stratification. It also significantly improves the mechanical properties of cement stone, especially by reducing the elastic modulus of cement stone and enhancing its toughness.

[0039] 4. In this invention, the optimized solution utilizes nano-silica (nano-SiO2). Due to its large specific surface area and high surface activity, the borosilicate stone possesses a fibrous three-dimensional spatial structure, and the ultrafine polymer materials exhibit nanoscale characteristics. These materials can generate a weak potential difference to disperse the slurry particles. Therefore, when these materials are used in combination, the slurry can better form a three-dimensional network structure, allowing for better suspension of various particles and enhancing the slurry's stability. Furthermore, it can fill the micropores and cracks in the cement stone to a certain extent, thereby reducing the cement stone's permeability. While reducing the slurry density and ensuring its engineering performance, it also participates in the cement hydration process, making the hardened cement stone more compact and with lower permeability. Simultaneously, all materials possess high temperature resistance, ensuring that the slurry will not become unstable even at higher temperatures. Detailed Implementation

[0040] The technical solution of the present invention will be further described in detail below with reference to the embodiments. It should be noted that the embodiments described below are merely preferred embodiments of the present invention and not all embodiments. Therefore, these embodiments are only described to help understand the present invention and do not constitute a limitation of the present invention.

[0041] This invention proposes a low-density cementing material with a heat-resistant composite lightweighting component, comprising the following components by weight: 100 parts well cement; 20-30 parts reinforcing material; 10-20 parts composite lightweighting material; 0.5-1.0 parts suspension stabilizer; 0.5-1.5 parts early-strength agent; 0.3-0.5 parts dispersant; 1.0-2.5 parts fluid loss reducing agent; 0.5-1.5 parts retarder; and 0.2 parts defoamer.

[0042] The composite weight-reducing material is composed of the following components by mass percentage: 30-45% expanded perlite powder, 25-35% ultrafine perlite, 20-30% high softening point modified hard asphalt powder, 3-5% nano silica, 3-5% boromagnesite, and 1-2% vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer powder.

[0043] In this invention, the oil well cement is either Grade G oil well cement or Grade A oil well cement.

[0044] In this invention, the reinforcing material is a dry powder mixture of 4-7 parts ultrafine metakaolin, 5-8 parts ultrafine cement and 5-15 parts microsilica, wherein the particle size of the ultrafine metakaolin is above 500 mesh, the average particle size of the ultrafine cement is 5-10 μm, and the average particle size of the microsilica is 0.1-0.5 μm.

[0045] In this invention, the expanded perlite powder has a mesh size of 500 or more and a SiO2 content of 70% or more; the ultrafine perlite is a deep-processed material of vitrified microspheres with a mesh size of 200 or more.

[0046] In this invention, the high softening point modified hard asphalt powder has a density of 1.1-1.2 g / cm³. 3 Modified hard asphalt powder with ash content <3%, solubility >97.5%, softening point >200℃, flash point >400℃, and sulfur content <0.2%.

[0047] The high softening point modified hard asphalt powder is prepared by the following steps:

[0048] a. Select a density of 1.0-1.2 g / cm³ 3 De-oiled hard asphalt with ash content of 5-8%, solubility of >88%, water content of <3%, softening point of >120℃, flash point of >300℃, and sulfur content of <0.5% is first heated to 130-150℃ for dehydration treatment, with the heating rate controlled at 10℃ / min and the dehydration treatment time being 20min.

[0049] b. Further heat it to 200-220℃ and perform vacuum distillation to remove the light components, wherein the distillation pressure is -50~10KPa, the heating rate is controlled at 5℃ / min, and the vacuum distillation time is 30min;

[0050] c. After vacuum distillation, 3% nano carbon powder and 2% nano silicon carbide are added to the hard asphalt. The mixture is stirred for 90 minutes at a stirring speed of about 500 rpm / min. After stirring evenly, the preliminarily modified hard asphalt is obtained.

[0051] d. Then, the preliminarily modified hard asphalt is placed in a reactor and heated to 180-200°C by controlling the heating rate at 15°C / min. O3 is introduced into the reactor for oxidation treatment. After stirring and oxidation treatment for 60 minutes, SO3 is introduced into the reactor and stirred and sulfonated for 60 minutes to obtain multi-modified hard asphalt.

[0052] e. Finally, the multi-modified hard asphalt from step d is ground to a fineness of 500 mesh or higher to obtain high softening point hard asphalt powder.

[0053] In this invention, the nano-silica is a white powder with an average particle size of 15-80 nm and a SiO2 content of over 98%; the boromagnesia stone is a fibrous aggregate with a length of 1-2 mm.

[0054] In this invention, the density range of the composite weight-reducing material is 0.65-0.75 g / cm³.3 It has an upper limit of applicable temperature of 200℃ and a pressure resistance of over 30MPa.

[0055] In this invention, the vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer is a high-molecular polymer powder with a particle size of 800 mesh or larger. This ternary polymer is prepared by randomly incorporating bulky trichlorofluoroethylene into the long chains of the vinylidene fluoride-trifluoroethylene polymer. During this random incorporation process, the ordered structure of the binary polymer is disrupted, resulting in the formation of nano-polar domains in the ternary polymer. After being incorporated into the slurry, a slight potential voltage difference is generated within the slurry, which better disperses the micro-solid phase particles and cement particles uniformly, forming a stable three-dimensional structure. This ensures the slurry reduces the suspension of the material and cement particles.

[0056] In this invention, the expanded perlite powder, ultrafine perlite, high softening point modified hard asphalt powder, nano-silica (nano-SiO2), boromagnesite, and vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer are weighed and then dry-mixed evenly to obtain the composite weight-reducing material; the density range of this composite weight-reducing material is 0.65-0.75 g / cm³. 3 It has an applicable temperature limit of 200℃ and a pressure resistance of over 30MPa, which meets the requirements of this solution.

[0057] In this invention, the density control of low-density cement slurry is achieved by adjusting the amount of composite mitigation material added and the liquid-solid ratio, while ensuring the engineering performance of the slurry.

[0058] In this invention, the early strength agent is an inorganic salt-based early strength agent; the dispersant is preferably at least one of carboxylates, polystyrene sulfonates, polynaphthalene sulfonates, lignin sulfonates, and ketone-aldehyde condensates; the loss-reducing agent is preferably at least one of polyamides, polyvinyl alcohol, and AMPS polymers; the retarder is preferably at least one of tartrates, citric acid, boric acid, and phosphates; and the defoamer is preferably at least one of polyacryl alcohol, organosilicon compounds, and tributyl phosphate.

[0059] Example 1

[0060] This embodiment discloses a low-density cementing material with heat-resistant composite weight-reducing material, which comprises the following components by mass: 100 parts oil well cement, 28 parts reinforcing material, 20 parts composite weight-reducing material, 1 part suspension stabilizer, 1.5 parts early strength agent, 0.3 parts dispersant, 2.5 parts fluid loss reducing agent, 1.2 parts retarder, and 0.2 parts defoamer.

[0061] In this embodiment, the oil well cement is Grade G oil well cement (HSR).

[0062] In this embodiment, the reinforcing material is a dry powder mixture of 7 parts ultrafine metakaolin, 8 parts ultrafine cement and 13 parts microsilica, wherein the particle size of the ultrafine metakaolin is above 500 mesh, the ultrafine cement is selected with an average particle size of 5-10 μm, and the microsilica is selected with an average particle size of 0.1-0.5 μm.

[0063] In this embodiment, the composite weight-reducing material is composed of the following components by mass percentage: 40% expanded perlite powder, 28% ultrafine perlite, 24% high softening point modified hard asphalt powder, 3.5% nano-silica (nano-SiO2), 3% boromagnesite, and 1.5% vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer.

[0064] The expanded perlite powder has a mesh size of 500 or more and a SiO2 content of 70% or more; the ultrafine perlite is a deep-processed material for vitrified microspheres, with a mesh size of 200 or more.

[0065] In this embodiment, the high softening point modified hard asphalt micro powder is processed as follows: The deoiled hard asphalt is heated to 130°C for dehydration, then further heated to 220°C for vacuum distillation to remove light components. After vacuum distillation, 3% nano-carbon powder and 2% nano-silicon carbide are added to the hard asphalt and stirred evenly to obtain pre-modified high softening point hard asphalt. The pre-modified hard asphalt is then placed in a reactor and heated to 180°C. O3 is introduced into the reactor for oxidation treatment, with continuous stirring during the oxidation process. After 1 hour of oxidation treatment, SO3 is introduced into the reactor for sulfonation treatment, with continuous stirring during the sulfonation process. After 1 hour of sulfonation treatment, multi-modified hard asphalt is obtained. Finally, the modified hard asphalt is ground to a fineness of 500 mesh or higher to obtain high softening point modified hard asphalt micro powder with a density of 1.1 g / cm³. 3 It has an ash content of 2%, a solubility of 98.5%, a softening point of 230℃, a flash point of 450℃, and a sulfur content of 0.1%.

[0066] In this embodiment, the nano-silica (nano-SiO2) is a white powder, and the nano-silica with an average particle size of 15-80nm and a SiO2 content of over 98% is selected.

[0067] In this embodiment, the boromagnesia stone presents as a fibrous aggregate with a length of 1-2 mm.

[0068] In this embodiment, the vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer is a high molecular polymer material, which is in powder form and has a particle size of 800 mesh or more.

[0069] In this embodiment, the suspension stabilizer is the slurry stabilizer disclosed in invention patent CN113234424A.

[0070] In this embodiment, the early strength agent is HHG-2; the dispersant is polycarboxylic acid; the loss-reducing agent is AMPS polymer; the retarder is tartrate; and the defoamer is polyacryl alcohol.

[0071] In this embodiment, low-density cementing cement is mixed with an appropriate amount of water to obtain cement slurry, and the liquid-to-solid ratio of the low-density cementing cement slurry is 0.9.

[0072] Example 2

[0073] This embodiment discloses a low-density cementing material with heat-resistant composite lightweighting, which comprises the following components by mass: 100 parts oil well cement, 25 parts reinforcing material, 18 parts composite lightweighting material, 0.8 parts suspension stabilizer, 1 part early strength agent, 0.4 parts dispersant, 2 parts fluid loss reducing agent, 1.5 parts retarder, and 0.2 parts defoamer.

[0074] In this embodiment, the oil well cement is Grade G oil well cement (HSR).

[0075] In this embodiment, the reinforcing material is a dry powder mixture of 6 parts ultrafine metakaolin, 7 parts ultrafine cement and 12 parts microsilica, wherein the particle size of the ultrafine metakaolin is above 500 mesh, the average particle size of the ultrafine cement is 5-10 μm, and the average particle size of the microsilica is 0.1-0.5 μm.

[0076] In this embodiment, the composite weight-reducing material is composed of the following components in the system according to the percentage: 42% expanded perlite powder, 25% ultrafine perlite, 25% high softening point modified hard asphalt powder, 4% nano-silica (nano-SiO2), 3% boromagnesite, and 1% vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer.

[0077] In this embodiment, the expanded perlite powder has a mesh size of 500 or higher and a SiO2 content of 70% or higher.

[0078] In this embodiment, the ultrafine pearlescent sand is a deep-processed material of vitrified microspheres, with a mesh size of 200 mesh or higher.

[0079] In this embodiment, the high softening point modified hard asphalt micro powder is processed as follows: The deoiled hard asphalt is heated to 140°C for dehydration, then further heated to 200°C for vacuum distillation to remove light components. After vacuum distillation, 3% nano-carbon powder and 2% nano-silicon carbide are added to the hard asphalt and stirred evenly to obtain pre-modified high softening point hard asphalt. The pre-modified hard asphalt is then placed in a reactor and heated to 180°C. O3 is introduced into the reactor for oxidation treatment, with continuous stirring during the oxidation process. After 1 hour of oxidation treatment, SO3 is introduced into the reactor for sulfonation treatment, with continuous stirring during the sulfonation process. After 1 hour of sulfonation treatment, multi-modified hard asphalt is obtained. Finally, the modified hard asphalt is ground to a fineness of 500 mesh or higher to obtain high softening point modified hard asphalt micro powder with a density of 1.1 g / cm³. 3 It has an ash content of 2%, a solubility of 98.5%, a softening point of 230℃, a flash point of 450℃, and a sulfur content of 0.1%.

[0080] In this embodiment, the nano-silica (nano-SiO2) is a white powder with an average particle size of 15-80 nm and a SiO2 content of over 98%.

[0081] In this embodiment, the boromagnesia stone presents as a fibrous aggregate with a length of 1-2 mm.

[0082] In this embodiment, the vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer is a high molecular polymer material, which is in powder form and has a particle size of 800 mesh or more.

[0083] In this embodiment, the suspension stabilizer is the slurry stabilizer disclosed in invention patent CN113234424A.

[0084] In this embodiment, the early strength agent is HHG-2; the dispersant is a ketaldehyde condensate; the loss-reducing agent is polyvinyl alcohol; the retarder is citrate; and the defoamer is polyacryl alcohol.

[0085] In this embodiment, low-density cementing cement is mixed with an appropriate amount of water to obtain cement slurry, and the liquid-to-solid ratio of the low-density cementing cement slurry is 0.8.

[0086] Example 3

[0087] This embodiment discloses a low-density cementing material with heat-resistant composite lightweighting, which comprises the following components by mass: 100 parts oil well cement, 21 parts reinforcing material, 15 parts composite lightweighting material, 0.7 parts suspension stabilizer, 0.8 parts early strength agent, 0.4 parts dispersant, 1.5 parts fluid loss reducing agent, 1 part retarder, and 0.2 parts defoamer.

[0088] In this embodiment, the oil well cement is Grade G oil well cement (HSR).

[0089] In this embodiment, the reinforcing material is a dry powder mixture of 5 parts ultrafine metakaolin, 6 parts ultrafine cement and 10 parts microsilica, wherein the particle size of the ultrafine metakaolin is above 500 mesh, the average particle size of the ultrafine cement is 5-10 μm, and the average particle size of the microsilica is 0.1-0.5 μm.

[0090] In this embodiment, the composite weight-reducing material is composed of the following components in the system according to the percentage: 35% expanded perlite powder, 35% ultrafine perlite, 22% high softening point modified hard asphalt powder, 3% nano-silica (nano-SiO2), 3.5% boromagnesite, and 1.5% vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer.

[0091] In this embodiment, the expanded perlite powder has a mesh size of 500 or higher and a SiO2 content of 70% or higher.

[0092] In this embodiment, the ultrafine pearlescent sand is a deep-processed material of vitrified microspheres, with a mesh size of 200 mesh or higher.

[0093] In this embodiment, the high softening point modified hard asphalt micro powder is processed as follows: The deoiled hard asphalt is heated to 150°C for dehydration, then further heated to 210°C for vacuum distillation to remove light components. After vacuum distillation, 3% nano-carbon powder and 2% nano-silicon carbide are added to the hard asphalt, and the mixture is stirred evenly to obtain pre-modified high softening point hard asphalt. The pre-modified hard asphalt is then placed in a reactor and heated to 200°C. O3 is introduced into the reactor for oxidation treatment, with continuous stirring during the oxidation process. After 1 hour of oxidation treatment, SO3 is introduced into the reactor for sulfonation treatment, with continuous stirring during the sulfonation process. After 1 hour of sulfonation treatment, multi-modified hard asphalt is obtained. Finally, the modified hard asphalt is ground to a mesh size of 500 or finer to obtain high softening point modified hard asphalt micro powder with a density of 1.1 g / cm³. 3 It has an ash content of 2%, a solubility of 98.5%, a softening point of 230℃, a flash point of 450℃, and a sulfur content of 0.1%.

[0094] In this embodiment, the nano-silica (nano-SiO2) is a white powder with an average particle size of 15-80 nm and a SiO2 content of over 98%.

[0095] In this embodiment, the boromagnesia stone presents as a fibrous aggregate with a length of 1-2 mm.

[0096] In this embodiment, the vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer is a high molecular polymer material, which is in powder form and has a particle size of 800 mesh or more.

[0097] In this embodiment, the suspension stabilizer is the slurry stabilizer disclosed in invention patent CN113234424A.

[0098] In this embodiment, the early strength agent is HHG-2; the dispersant is polystyrene sulfonate; the water loss reducing agent is a polyamide-based water loss reducing agent; the retarder is a phosphate retarder; and the defoamer is tributyl phosphate.

[0099] In this embodiment, low-density cementing cement is mixed with an appropriate amount of water to obtain cement slurry, and the liquid-to-solid ratio of the low-density cementing cement slurry is 0.7.

[0100] Example 4

[0101] This embodiment discloses a low-density cementing material with heat-resistant composite lightweighting, which comprises the following components by mass: 100 parts oil well cement, 30 parts reinforcing material, 12 parts composite lightweighting material, 0.5 parts suspension stabilizer, 0.5 parts early strength agent, 0.5 parts dispersant, 1 part fluid loss reducer, 0.5 parts retarder, and 0.2 parts defoamer.

[0102] In this embodiment, the oil well cement is Grade G oil well cement (HSR).

[0103] In this embodiment, the reinforcing material is a dry powder mixture of 7 parts ultrafine metakaolin, 8 parts ultrafine cement and 15 parts microsilica, wherein the particle size of the ultrafine metakaolin is above 500 mesh, the average particle size of the ultrafine cement is 5-10 μm, and the average particle size of the microsilica is 0.1-0.5 μm.

[0104] In this embodiment, the composite weight-reducing material is composed of the following components in the system according to the percentage: 30% expanded perlite powder, 30% ultrafine perlite, 30% high softening point modified hard asphalt powder, 5% nano-silica (nano-SiO2), 3% boromagnesite, and 2% vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer.

[0105] In this embodiment, the expanded perlite powder has a mesh size of 500 or higher and a SiO2 content of 70% or higher.

[0106] In this embodiment, the ultrafine pearlescent sand is a deep-processed material of vitrified microspheres, with a mesh size of 200 mesh or higher.

[0107] In this embodiment, the high softening point modified hard asphalt micro powder is processed as follows: The deoiled hard asphalt is heated to 130°C for dehydration, then further heated to 220°C for vacuum distillation to remove light components. After vacuum distillation, 3% nano-carbon powder and 2% nano-silicon carbide are added to the hard asphalt and stirred evenly to obtain pre-modified high softening point hard asphalt. The pre-modified hard asphalt is then placed in a reactor and heated to 190°C. O3 is introduced into the reactor for oxidation treatment, with continuous stirring during the oxidation process. After 1 hour of oxidation treatment, SO3 is introduced into the reactor for sulfonation treatment, with continuous stirring during the sulfonation process. After 1 hour of sulfonation treatment, multi-modified hard asphalt is obtained. Finally, the modified hard asphalt is ground to a mesh size of 500 or finer to obtain high softening point modified hard asphalt micro powder with a density of 1.2 g / cm³. 3 It has an ash content of 2%, a solubility of 99%, a softening point of 240℃, a flash point of 465℃, and a sulfur content of 0.1%.

[0108] In this embodiment, the nano-silica (nano-SiO2) is a white powder with an average particle size of 15-80 nm and a SiO2 content of over 98%.

[0109] In this embodiment, the boromagnesia stone presents as a fibrous aggregate with a length of 1-2 mm.

[0110] In this embodiment, the vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer is a high molecular polymer material, which is in powder form and has a particle size of 800 mesh or more.

[0111] In this embodiment, the suspension stabilizer is the slurry stabilizer disclosed in invention patent CN113234424A.

[0112] In this embodiment, the early strength agent is HHG-2; the dispersant is a ketaldehyde condensate; the loss-reducing agent is polyvinyl alcohol; the retarder is citrate; and the defoamer is tributyl phosphate.

[0113] In this embodiment, low-density cementing cement is mixed with an appropriate amount of water to obtain cement slurry, and the liquid-to-solid ratio of the low-density cementing cement slurry is 0.6.

[0114] Example 5

[0115] This embodiment discloses a low-density cementing material with heat-resistant composite lightweighting, which comprises the following components by mass: 100 parts oil well cement, 20 parts reinforcing material, 12 parts composite lightweighting material, 0.5 parts suspension stabilizer, 0.5 parts early strength agent, 0.5 parts dispersant, 1 part fluid loss reducer, 0.5 parts retarder, and 0.2 parts defoamer.

[0116] In this embodiment, the oil well cement is Grade G oil well cement (HSR).

[0117] In this embodiment, the reinforcing material is a dry powder mixture of 6 parts ultrafine metakaolin, 7 parts ultrafine cement and 7 parts microsilica, wherein the particle size of the ultrafine metakaolin is above 500 mesh, the average particle size of the ultrafine cement is 5-10 μm, and the average particle size of the microsilica is 0.1-0.5 μm.

[0118] In this embodiment, the composite weight-reducing material is composed of the following components in the system according to the percentage: 30% expanded perlite powder, 30% ultrafine perlite, 30% high softening point modified hard asphalt powder, 5% nano-silica (nano-SiO2), 3% boromagnesite, and 2% vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer.

[0119] In this embodiment, the expanded perlite powder has a mesh size of 500 or higher and a SiO2 content of 70% or higher.

[0120] In this embodiment, the ultrafine pearlescent sand is a deep-processed material of vitrified microspheres, with a mesh size of 200 mesh or higher.

[0121] In this embodiment, the high softening point modified hard asphalt micro powder is processed as follows: The deoiled hard asphalt is heated to 130°C for dehydration, then further heated to 220°C for vacuum distillation to remove light components. After vacuum distillation, 3% nano-carbon powder and 2% nano-silicon carbide are added to the hard asphalt and stirred evenly to obtain pre-modified high softening point hard asphalt. The pre-modified hard asphalt is then placed in a reactor and heated to 190°C. O3 is introduced into the reactor for oxidation treatment, with continuous stirring during the oxidation process. After 1 hour of oxidation treatment, SO3 is introduced into the reactor for sulfonation treatment, with continuous stirring during the sulfonation process. After 1 hour of sulfonation treatment, multi-modified hard asphalt is obtained. Finally, the modified hard asphalt is ground to a mesh size of 500 or finer to obtain high softening point modified hard asphalt micro powder with a density of 1.2 g / cm³. 3 It has an ash content of 2%, a solubility of 99%, a softening point of 240℃, a flash point of 465℃, and a sulfur content of 0.1%.

[0122] In this embodiment, the nano-silica (nano-SiO2) is a white powder with an average particle size of 15-80 nm and a SiO2 content of over 98%.

[0123] In this embodiment, the boromagnesia stone presents as a fibrous aggregate with a length of 1-2 mm.

[0124] In this embodiment, the vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer is a high molecular polymer material, which is in powder form and has a particle size of 800 mesh or more.

[0125] In this embodiment, the suspension stabilizer is the slurry stabilizer disclosed in invention patent CN113234424A.

[0126] In this embodiment, the early strength agent is HHG-2; the dispersant is polycarboxylic acid; the water loss reducing agent is AMPS polymer-based water loss reducing agent; the retarder is citric acid; and the defoamer is an organosilicon.

[0127] In this embodiment, low-density cementing cement is mixed with an appropriate amount of water to obtain cement slurry, and the liquid-to-solid ratio of the low-density cementing cement slurry is 0.6.

[0128] Comparative Example 1

[0129] The low-density cement slurry prepared in this comparative example is the same as in Example 1, except that hollow glass microspheres are used instead of composite weight-reducing materials, and the liquid-to-solid ratio of the slurry is 0.5.

[0130] Comparative Example 2

[0131] The low-density cement slurry prepared in this comparative example is the same as in Example 3, except that expanded perlite is used instead of composite weight-reducing materials, and the liquid-to-solid ratio of the slurry is 0.7.

[0132] Comparative Example 3

[0133] The low-density cement slurry prepared in this comparative example is the same as in Example 5, except that expanded perlite is used instead of composite weight-reducing materials, and the liquid-to-solid ratio of the slurry is 0.6.

[0134] test

[0135] The low-density cement slurry systems of heat-resistant composite lightweight materials obtained in Examples 1-5 and the low-density cement slurries obtained in Comparative Examples 1-3 were tested and analyzed according to GB / T 19139 "Test Methods for Oil Well Cement". The experimental results are shown in Table 1 below:

[0136] Table 1

[0137]

[0138] As shown in Table 1, the low-density cement slurry in this scheme exhibits good rheological properties. Its fluidity is within a suitable range, its API water loss is less than 50 ml, its thickening time is greater than 4 hours and adjustable, and the maximum density difference between the upper and lower parts of the slurry is only 0.02 g / cm³. 3After 48 hours of curing, the compressive strength of the cement stone was greater than 14 MPa, demonstrating good engineering performance. In contrast, in Comparative Example 1, the use of hollow glass microspheres resulted in poorer slurry fluidity. Although the compressive strength was improved, the use of hollow glass microspheres increased the slurry production cost. Comparative Examples 2 and 3 used relatively inexpensive expanded perlite, but the slurry exhibited instability, with a significant density difference between the upper and lower layers, and the compressive strength of the hardened cement stone also decreased significantly. Therefore, the low-density cement used in this method demonstrates better engineering performance than other technical solutions and can better meet the requirements of on-site construction.

[0139] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A low-density cementing material with heat-resistant composite material and light reduction, characterized in that, The following components are included by mass parts: 100 parts of oil well cement; 20-30 parts of reinforcing material; 10-20 parts of composite light-reducing material; Suspension stabilizer 0.5-1.0 parts; Early-strength agent 0.5-1.5 parts; Dispersant 0.3-0.5 parts; 1.0-2.5 parts of water loss reducer; 0.5-1.5 parts of retarder; 0.2 parts of defoamer; The composite weight-reducing material comprises, by mass percentage,: 30-45% expanded perlite powder, 25-35% ultrafine perlite, 20-30% high softening-point modified hard asphalt powder, 3-5% nano-silica, 3-5% boromagnesite, and 1-2% vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer powder; the vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer powder is produced by adding vinylidene fluoride... It is prepared by randomly incorporating bulky trifluorochloroethylene into the long chain of trifluoroethylene polymer; The high softening point modified hard asphalt powder has a density of 1.1-1.2 g / cm³. 3 Modified hard asphalt powder with ash content <3%, solubility >97.5%, softening point >200℃, flash point >400℃, and sulfur content <0.2%; The high softening point modified hard asphalt powder is prepared by the following steps: a. Select a density of 1.0-1.2 g / cm³ 3 Deoiled hard asphalt with ash content of 5-8%, solubility >88%, water content <3%, softening point >120℃, flash point >300℃, and sulfur content <0.5% is heated to 130-150℃ for dehydration treatment, and then further heated to 200-220℃ for vacuum distillation to remove light components from the product. b. After vacuum distillation, 3% nano carbon powder and 2% nano silicon carbide are added to the hard asphalt. After stirring evenly, a preliminary modified high softening point hard asphalt is obtained. c. Then, the preliminarily modified high softening point hard asphalt is placed into the reactor, heated to 180-200℃, and O3 is introduced into the reactor for oxidation treatment. After stirring and oxidation treatment for 1 hour, SO3 is introduced into the reactor, and after stirring and sulfonation treatment for 1 hour, multi-modified hard asphalt is obtained. d. Grind the multi-modified hard asphalt from step c to a fineness of 500 mesh or higher to obtain high softening point modified hard asphalt powder.

2. The low-density cementing material with heat-resistant composite weight reduction according to claim 1, characterized in that: The oil well cement is either Grade G oil well cement or Grade A oil well cement.

3. The low-density cementing material with heat-resistant composite weight reduction according to claim 1, characterized in that: The reinforcing material is a dry powder mixture of 4-7 parts ultrafine metakaolin, 5-8 parts ultrafine cement and 5-15 parts microsilica, wherein the particle size of the ultrafine metakaolin is above 500 mesh, the average particle size of the ultrafine cement is 5-10 μm, and the average particle size of the microsilica is 0.1-0.5 μm.

4. The low-density cementing material with heat-resistant composite weight reduction according to claim 1, characterized in that: The expanded perlite powder has a mesh size of 500 or higher and a SiO2 content of 70% or higher; the ultrafine perlite is a deep-processed material of vitrified microspheres with a mesh size of 200 or higher.

5. The low-density cementing material with heat-resistant composite weight reduction according to claim 1, characterized in that: The nano-silica is a white powder with an average particle size of 15-80 nm and a SiO2 content of over 98%; the boromagnesia stone is a fibrous aggregate with a length of 1-2 mm.

6. The low-density cementing material with heat-resistant composite weight reduction according to claim 1, characterized in that: The density range of the composite weight-reducing material is 0.65-0.75 g / cm³. 3 It has an upper limit of applicable temperature of 200℃ and a pressure resistance of over 30MPa.

7. The low-density cementing material with heat-resistant composite weight reduction according to claim 1, characterized in that: The vinylidene fluoride-trifluoroethylene-trichlorofluoroethylene copolymer is a high molecular weight polymer powder with a particle size of 800 mesh or more.

8. The low-density cementing material with heat-resistant composite weight reduction according to claim 1, characterized in that: The early-strength agent is an inorganic salt-based early-strength agent; the dispersant is at least one of carboxylates, polystyrene sulfonates, polynaphthalene sulfonates, lignin sulfonates, and ketone-aldehyde condensates; the water loss reducing agent is at least one of polyamides, polyvinyl alcohol, and AMPS polymers; the retarder is at least one of tartrates, citric acid, boric acid, and phosphates; and the defoamer is at least one of polyacryl alcohol, organosilicon compounds, and tributyl phosphate.

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