High-temperature enhanced micro-expansive well cementation cement slurry system as well as preparation method and application thereof

Abstract

The invention discloses a high-temperature reinforced micro-expansive well cementation cement slurry system as well as a preparation method and application thereof, and belongs to the technical field of well cementation materials for oil and gas well engineering. The high-temperature enhanced micro-expansion well cementation cement slurry system comprises: 100 parts of low-heat Portland cement; 10-15 parts of a reinforced anti-recession I type material; 10-20 parts of a reinforced anti-recession type II material; 15-25 parts of a reinforced anti-recession III type material; 2-8 parts of a high-temperature expansion material; 5-15 parts of a suspension fluid loss material; 6-8 parts of a high-temperature fluid loss agent; and 2-4 parts of a high-temperature retarder. The invention further discloses a preparation method of the high-temperature reinforced micro-expansion well cementing cement slurry system and application of the high-temperature reinforced micro-expansion well cementing cement slurry system as a well cementing material of oil and gas well engineering. According to the invention, by creatively changing the reaction sequence and mode between the hydration product and the enhanced admixture, the effects of crystal form stability and compactness of the high-temperature hydration product are achieved, so that the strength of the set cement is stably increased without declining.

Description

Technical Field

[0001] This invention belongs to the field of cementing materials technology for oil and gas well engineering, and more specifically relates to a high-temperature enhanced micro-expansion cement slurry system, its preparation method and application. Background Technology

[0002] With the strategic shift of my country's oil and gas exploration and development towards deeper formations, the number of deep and ultra-deep well projects has increased significantly. Against this backdrop, cementing operations, as a core component ensuring the long-term integrity of the wellbore, face severe challenges posed by high-temperature and high-pressure (HTHP) conditions. Cement slurry systems used for sealing are prone to a series of performance degradation issues under such harsh environments: increased filtration loss under high pressure threatens slurry stability; decreased suspension stability leads to stratification and sedimentation of solid particles, affecting uniformity; and thickening time is difficult to adjust, making it hard to precisely match construction requirements. More importantly, after the cement slurry hardens to form a cement sheath, the high-temperature environment often induces significant volume shrinkage (including chemical shrinkage, drying shrinkage, and temperature drop shrinkage) and long-term strength degradation. These defects directly weaken the sealing ability of the cement sheath, easily leading to the formation of micro-annular gaps at the interface between the cement sheath and the casing or formation, ultimately causing sustained annular pressure (SAP) and interlayer fluid flow, seriously endangering wellbore integrity and production safety. Therefore, achieving long-term and synergistic control over the working performance (such as rheology, filtration loss, stability, and thickening) of high-temperature cement slurry systems and the key mechanical properties of hardened cement stone (such as resistance to volume shrinkage and compressive strength stability) has become an urgent need to ensure successful cementing of ultra-deep wells.

[0003] To address these challenges, existing technologies primarily rely on the compounding and application of functional admixtures. Controlling high-temperature performance generally depends on organic polymer additives (such as fluid loss reducers, dispersants, and retarders). For the issues of volume shrinkage and strength degradation in cement paste, mainstream solutions focus on the external addition of crystalline inorganic expansive agents (such as calcium oxide, magnesium oxide, and specific minerals) and reinforcing agents (such as various fibers, whiskers, or rigid microparticles). For example, patent CN 111978028A, "A Cementing Slurry System and Its Application," discloses a system comprising cement, a high-temperature stabilizer, a brittleness reducer, a high-temperature resistant expansive agent, and other optional additives (such as fluid loss reducers and dispersants). The cement slurry system formulated by this invention not only reduces the elastic modulus of cement paste, improves its brittleness, enhances its deformation capacity under stress, improves its impact toughness, and maintains high strength, but also compensates for various shrinkages of the cement paste and enhances the bonding ability of the cement annulus interface. For example, patent CN111454032A, entitled "Toughening and Expanding Agent for Cementing Slurry and Tough Micro-expansion Cement Slurry System," discloses a toughening and expanding agent for cementing slurry and a tough micro-expansion cement slurry system, comprising the following components: 35-55 wt% calcium carbonate whiskers, 30-38 wt% alumina, 15-22 wt% calcium oxide, 1-3 wt% magnesium oxide, a fluid loss reducing agent, a dispersant, and a defoamer. The toughening and expanding agent for cementing slurry prepared by this invention can significantly improve the mechanical properties and volume shrinkage of cement stone, reduce the brittleness of cement stone, decrease the degree of volume shrinkage, and enhance the anti-channeling performance. For example, patent CN 112299757A, entitled "A Cement Slurry System and Its Preparation Method," discloses a cement slurry system whose components include: Grade G high-strength cement, a large temperature difference retarder, a large temperature difference water loss reducing agent, a high-temperature resistant elastic material, a high-temperature resistant toughening material, a high-temperature expansion agent, a high-temperature strength stabilizing material, a weighting agent, an early-strength agent, a dispersant, and water. The cement slurry system can prevent the top cement slurry from being over-retarded, enhance the high-temperature strength stability of the cement stone, compensate for the shrinkage of the cement stone itself, and improve the sealing integrity of the cement ring.

[0004] For example, patent CN 117658507A, entitled "A Wide-Temperature-Band Cementing Expansive Agent and a Cementing Expansive Slurry System Containing the Same," discloses a wide-temperature-band cementing expansive agent and a cementing expansive slurry system containing the same. The main components include: halloysite 5-20%, magnesium raw materials 20-50%, calcium raw materials 10-40%, modified materials 5-10%, and carbonaceous raw materials 10-30%. The expansive cement slurry system provided by this invention has a wide applicable temperature range, good bonding performance, improves the expansion performance and compressive strength of cement stone, prevents cement stone shrinkage and cracking, and ensures long-term bonding and sealing performance of the cement stone.

[0005] Overall, while existing technologies using various additives (especially expanding agents and reinforcing agents) have made some progress in addressing high-temperature cementing issues, significant limitations remain. They rarely consider the cement hydration reaction when addressing cement stone reinforcement and anti-fading issues. This leads to a lack of proper integration between the high-temperature reinforcing admixtures and cement hydration products, thus affecting the reinforcement effect. Furthermore, when addressing cement stone volume shrinkage, directly adding expanding agents makes it difficult to control the timing of expansion and the synergistic effect of the cement hydration reaction. Especially under high-temperature conditions, the effective components of the expanding agent are prone to premature release, resulting in loss of expansion performance, making it difficult to ensure long-term sealing performance of the cement sheath throughout the wellbore's lifespan. Summary of the Invention

[0006] One of the objectives of this invention is to provide a high-temperature enhanced micro-expansion cement slurry system that solves the key problems in the prior art of insufficient strength growth and easy decline of cement stone in high-temperature cementing, as well as the difficulty in synchronizing the expansion timing of the expansion agent with the cement hydration rate, while also taking into account the stable control of other properties of the slurry.

[0007] The cement slurry system of this invention is based on the cement-based hydration reaction mechanism and achieves its objective under high-temperature conditions through the following pathways:

[0008] (1) Optimize the hydration reaction path: By regulating the reaction order and mode between hydration products and reinforcing admixtures, the high-temperature hydration products can form a stable crystal structure and improve their density, thereby ensuring the continuous and stable growth of cement stone strength and avoiding decline.

[0009] (2) Achieve synergistic expansion: By using techniques such as lattice solid solution and core-shell structure encapsulation, the expansion components are synergistically reacted with the cement hydration process, thereby achieving controllable micro-expansion in the cement cementitious system.

[0010] The second objective of this invention is to provide a method for preparing the high-temperature enhanced micro-expansion cement slurry system.

[0011] The third objective of this invention is to provide the application of this high-temperature enhanced micro-expansion cementing slurry system.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] The first aspect of this invention discloses a high-temperature enhanced micro-expansion cement slurry system, which comprises the following components by weight: 100 parts of low-heat silicate cement; 10-15 parts of enhanced anti-fading type I material; 10-20 parts of enhanced anti-fading type II material; 15-25 parts of enhanced anti-fading type III material; 2-8 parts of high-temperature expansion material; 5-15 parts of suspension filtration reduction material; 6-8 parts of high-temperature water loss reduction agent; and 2-4 parts of high-temperature retarder.

[0014] Among them, the enhanced anti-decay type I material is a mixture of quartz sand and metakaolin in a mass ratio of (60-80):(20-40);

[0015] The enhanced anti-fading type II material comprises the following components in parts by weight: 60-80 parts of low-heat silicate cement, 15-30 parts of quartz sand, and 5-10 parts of meta-high terephthalic acid; its preparation method includes: mixing the components in proportion, making slurry, molding and curing, drying, and grinding to obtain the final product.

[0016] The enhanced anti-fading type III material comprises the following components in parts by weight: 60-80 parts of low-heat silicate cement and 20-40 parts of quartz sand; its preparation method includes: mixing the components in proportion, making slurry, molding and curing, drying, and grinding to obtain the final product;

[0017] The high-temperature expansion material comprises the following components by weight: 30-40 parts dolomite, 10-20 parts serpentine, 5-10 parts calcium iron pyroxene, 5-10 parts calcium zeolite, 25-35 parts quicklime powder, and 5-10 parts quartz powder. Its preparation method includes: mixing dolomite, serpentine, calcium iron pyroxene, and calcium zeolite, then crushing, grinding, and calcining them; then mixing and grinding them with the remaining raw materials, pressing them into tablets, and drying them; followed by calcination and grinding to obtain the final product.

[0018] In some embodiments of the present invention, the low-heat silicate cement has a C2S content ≥ 47 wt.% and a specific surface area of ​​280–310 m². 2 / kg, 7d heat of hydration ≤245kJ / kg.

[0019] In some embodiments of the present invention, the quartz sand SiO2 content in the enhanced anti-aging type I material and the enhanced anti-aging type II material is ≥99wt.%, and the powder fineness is ≥200 mesh;

[0020] The metakaolin content of Al2O3 in the enhanced anti-degradation type I material and the enhanced anti-degradation type II material is ≥45wt.%, the content of SiO2 is ≥45wt.%, and the fineness of the powder is ≥800 mesh.

[0021] In some embodiments of the present invention, the particle fineness requirements for the enhanced anti-aging type II material are Dx(10)≤4μm, Dx(50)≤17μm, and Dx(90)≤35μm;

[0022] Preferably, in the preparation method of the enhanced anti-aging type II material, after mixing the components in proportion, 40 to 50 parts of water are added to make a slurry, more preferably 44 parts of water;

[0023] More preferably, the curing conditions in the preparation method of the enhanced anti-aging type II material are: 55-65℃ and normal pressure curing for 26-30 days; more preferably, 60℃ and normal pressure curing for 28 days.

[0024] Preferably, the cured cement stone is placed in a vacuum drying oven at 55-65°C and dried for 24-60 hours; more preferably, it is placed in a vacuum drying oven at 60°C and dried for 48 hours.

[0025] In some embodiments of the present invention, the particle fineness requirements for the enhanced anti-aging type III material are Dx(10)≤3μm, Dx(50)≤9μm, and Dx(90)≤18μm;

[0026] Preferably, the quartz sand in the enhanced anti-aging type III material has a SiO2 content ≥99wt.% and a powder fineness ≥325 mesh;

[0027] Preferably, in the preparation method of the enhanced anti-aging type III material, after mixing the components in proportion, 40 to 50 parts of water are added to make a slurry, more preferably 44 parts of water;

[0028] More preferably, the curing conditions for the enhanced anti-aging type III material are curing in a pressurized curing autoclave at 145–155°C for 6–8 days; more preferably, curing at 150°C under normal pressure for 7 days.

[0029] Preferably, the cured cement stone is placed in a vacuum drying oven at 55-65°C and dried for 24-60 hours; more preferably, it is placed in a vacuum drying oven at 60°C and dried for 48 hours.

[0030] In some embodiments of the present invention, the particle fineness requirements of the high-temperature expansion material are Dx(10)≤4μm, Dx(50)≤10μm, and Dx(90)≤20μm;

[0031] Preferably, the composition of the high-temperature expansion material is as follows: 13 wt.% < MgO < 23 wt.%, 38 wt.% < CaO < 55 wt.%, 18 wt.% < SiO2 < 32 wt.%, Al2O3 < 3.5 wt.%, Fe2O3 < 1 wt.%.

[0032] Preferably, in the preparation method of the high-temperature expansion material, dolomite, serpentine, calcium iron pyroxene and calcium zeolite are mixed and then crushed, and the crushing ratio is controlled to be 60-75.

[0033] Preferably, the crushed mixture is ground into fine powder, and the grinding ratio is controlled at 700-850.

[0034] Preferably, the pulverized mixed fines are fed into a high-temperature calcining furnace for calcination at a temperature of 950°C to 1000°C, with a heating time of 25 to 35 minutes and a holding time of 100 to 140 minutes; more preferably, the heating time is controlled at 30 minutes and the holding time is controlled at 120 minutes.

[0035] Preferably, the tableting conditions are: peak pressure controlled at 120-150 kN, loading speed at 4-6 kN / s, more preferably 5 kN / s;

[0036] Preferably, the sample tablets after compression and drying are placed in a high-temperature calcination furnace for calcination. The calcination process is carried out in two stages: the first stage calcination temperature is 850-950℃, the heating time is 25-35 min, and the holding time is 8-12 min; the second stage calcination temperature is 1300-1350℃, the heating time is 35-45 min, and the holding time is 100-140 min; more preferably, the first stage calcination temperature is 900℃, the heating time is 30 min, and the holding time is 10 min; the second stage calcination temperature is 1300-1350℃, the heating time is 40 min, and the holding time is 120 min.

[0037] In some embodiments of the present invention, the purity of dolomite in the high-temperature expansion material is ≥95%, and its chemical composition content is: MgO > 20 wt.% and CaO > 28 wt.%.

[0038] Serpentine purity ≥ 95%, its chemical composition content is: MgO > 40 wt.%, SiO2 > 40 wt.%;

[0039] The purity of calcium iron pyroxene is ≥90%, and its chemical composition is: CaO > 20 wt.%, SiO2 > 43 wt.%, FeO > 26 wt.%.

[0040] The purity of calcium zeolite is ≥90%, and its chemical composition is: CaO > 12 wt.%, Al2O3 > 23 wt.%, SiO2 > 41 wt.%.

[0041] The fineness of quicklime powder is ≥325 mesh, and its chemical composition content is: CaO > 74 wt.%.

[0042] Quartz powder with a fineness ≥325 mesh and a chemical composition content of SiO2 >98wt.%.

[0043] In some embodiments of the present invention, the suspended filtration loss reducing material is a mixture of palygorskite powder, sepiolite powder and ultrafine calcium carbonate in a mass ratio of (15-25):(15-25):(50-70);

[0044] Preferably, the purity of palygorskite powder is ≥90 wt.%, and the fineness of the powder is ≥500 mesh;

[0045] Preferably, the purity of sepiolite powder is ≥90 wt.%, and the fineness of the powder is ≥600 mesh;

[0046] Preferably, the purity of the ultrafine calcium carbonate is ≥95wt.%, and the fineness of the powder is ≥800 mesh.

[0047] In some embodiments of the present invention, the high-temperature water loss reducing agent is an AMPS anionic polymer;

[0048] Preferably, the high-temperature retarder is an AMPS copolymer system.

[0049] The second aspect of this invention discloses a method for preparing the above-mentioned high-temperature enhanced micro-expansion cement slurry system, which includes the following steps: preparing low-heat silicate cement, enhanced anti-fading type I material, enhanced anti-fading type II material, enhanced anti-fading type III material, high-temperature expansion material, suspension filtration loss reducing material, high-temperature water loss reducing agent and high-temperature retarder in proportion, mixing them evenly, adding water to make slurry, and thus obtaining the slurry.

[0050] In some embodiments of the present invention, the amount of water added during pulping is 59 to 64 parts.

[0051] The third aspect of this invention discloses the application of the above-mentioned high-temperature enhanced micro-expansion cement slurry system as a cementing material for oil and gas well engineering, and preferably as a sealing material for deep wells and / or ultra-deep wells.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) The present invention is scientifically designed and ingeniously conceived. It creatively changes the reaction order and mode between hydration products and reinforcing admixtures to achieve the effect of stable crystal form and density of high-temperature hydration products, thereby ensuring that the strength of cement stone increases steadily without decline.

[0054] In conventional sand-added cement grout systems under high-temperature curing conditions, hydrated calcium silicate reacts rapidly with calcium hydroxide and quartz sand before it can form a stable gel structure. This excessively rapid reaction rate easily leads to decalcification of the hydration products, resulting in coarsening of the hard calcium silicate crystals formed later, increased porosity within the cement stone, and ultimately, a decline in mechanical properties. This is currently considered the main cause of its mechanical property degradation.

[0055] To address this challenge, this invention starts with the cement-based hydration reaction mechanism and develops three types of reinforcing and anti-fading materials. By altering the reaction mode between hydration products and reinforcing admixtures, stable strength growth of cement stone is achieved at high temperatures. The Type I reinforcing and anti-fading material of this invention is primarily composed of silica and aluminosilicate minerals. Its function is twofold: firstly, it balances the calcium-silica ratio in the system (controlled at around 1.0), preventing the formation of high-calcium hydrated silicate mineral phases, which would affect the strength of the cement stone; secondly, it maintains the metastable state of the aluminate-tobermorite generated during high-temperature hydration, slowing down the grain coarsening process when its crystal form transforms into hard calcium silicate, thereby delaying the decline in cement stone strength. The Type II reinforcing and anti-fading material of this invention is mainly composed of hydrated calcium silicate, calcium hydroxide, and unreacted filled quartz sand (silica). During the low-temperature curing stage, this material preferentially forms a dense hydrated calcium silicate cementitious structure. During the high-temperature hydration reaction, the hydrated calcium silicate in this pre-stabilized dense structure undergoes a secondary hydration reaction with calcium hydroxide and the silica encapsulated within both structures. This sequence, from low-temperature stable formation of dense hydration products to high-temperature secondary hydration, ensures a controllable reaction rate and facilitates the formation of a stable and dense hard calcium silicate structure, significantly improving cement stone strength and inhibiting degradation. The main component of the enhanced anti-degradation Type III material of this invention is aluminum-derived torob mullite. Under high-temperature conditions, it can fill the pores created by the coarsening of hard calcium silicate. When a high-temperature crystal transformation occurs, the stable aluminum-derived torob mullite transforms into dense hard calcium silicate, tightly cementing with the original hard calcium silicate pore interface. This not only enhances the filling degree of the original coarsened pores but also possesses self-healing capabilities, effectively improving the packing density of the cementitious structure within the cement stone, thus achieving the effect of enhanced anti-degradation.

[0056] In summary, the three reinforcing and anti-fading materials work synergistically in the cement matrix to optimize the hydration reaction process from different dimensions, jointly ensuring the continuous and stable growth of the compressive strength of high-temperature cement stone and successfully solving the problem of strength fading.

[0057] (2) The high-temperature expansion material used in this invention contains a large amount of Ca2SiO4 minerals, utilizing Mg 2+ With Ca 2+ The similar compatibility of Mg, under high-temperature calcination, promotes Mg through lattice distortion. 2+ Partially replaces Ca 2+ Lattice sites, forming Ca 2- x Mg x SiO4 solid solution; and after solution treatment, the lattice parameters only undergo slight shrinkage, and the structure remains stable. When high-temperature cementing slurry passes through the slow setting period and enters the rapid hydration stage, it benefits from Ca... 2-x Mg xThe SiO4 solid solution and the main cement minerals (Ca3SiO5, Ca2SiO4) are highly similar in structure and chemical composition, and their hydration processes are synchronized, producing a significant synergistic effect. During this process, Ca... 2-x Mg x Mg is released from the hydration decomposition of SiO4 solid solution. 2+ The rapid formation of Mg(OH)2 causes volume expansion, and its expansion effect is exactly applied to the plastic development stage of cement, that is, the key period of cementitious structure formation. This avoids the ineffective loss of expansion efficiency when the slurry is in a liquid state, and also avoids damage to the internal structure of cement stone after solid hardening, thus effectively improving the molding quality and structural stability of cement products.

[0058] (3) In the preparation method of the high-temperature expansion material of the present invention, before high-temperature sintering (i.e., below 1000℃), MgO particles are uniformly dispersed in the Ca2SiO4 mineral precursor (a mixture of CaO and SiO2) by ball milling and mixing. When entering the high-temperature sintering and heat preservation stage, the Ca2SiO4 crystals will encapsulate the unreacted MgO particles during the growth process, forming an encapsulation structure with MgO core and Ca2SiO4 shell. When the high-temperature cement slurry undergoes rapid hydration reaction, since the outer shell of this encapsulation structure is consistent with the main mineral of cement, its hydration reaction will proceed synergistically with the main mineral. After the outer shell is hydrolyzed and destroyed, the MgO particles in the core structure are rapidly released and form Mg(OH)2, causing volume expansion, achieving the effect of synergistic reaction between its expansion component and cement hydration, and thus achieving effective expansion under the cement cementitious structure.

[0059] (4) The suspension filtration loss reduction material of the present invention has two main functions: On the one hand, by utilizing the characteristics of inorganic functional materials such as small particle size, strong adsorption, high surface activity and thermal stability, it can play a role in high-temperature suspension stability by shortening the spacing between solid particles in cement slurry and forming a three-dimensional network interwoven structure, thereby achieving a spatial steric hindrance effect; On the other hand, by utilizing the principle of particle gradation, it can improve the pore size distribution of cement filter cake through methods such as "colloidal network formation and film formation" and "particle mechanical locking", forming a thin and dense filter cake to achieve the purpose of reducing filtration loss.

[0060] (5) The present invention limits and optimizes the chemical composition, fineness and purity of each material in the system. On the one hand, it ensures that the cement slurry system obtained after the materials are compounded meets the expected performance requirements in all aspects. On the other hand, it can improve the compounding success rate of the cement slurry system and give full play to the best performance of each material. Attached Figure Description

[0061] Figure 1 This is a microscopic morphology diagram of cement stone formed by the cement slurry system of Embodiment 1 of the present invention under high temperature curing environment. Detailed Implementation

[0062] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0063] The following examples all demonstrate the preparation of cement slurry according to GB / T 19139-2012 standard. In the cement slurry systems listed in the examples, the low-heat silicate cement was provided by Jiahua Special Cement Co., Ltd., and the raw materials used in the enhanced anti-fading type I material and the suspension filtration reduction material were all available from the market. The high-temperature water loss reducing agent and the high-temperature retarder were provided by Puyang Zhenghe Petroleum Engineering Technology Co., Ltd. The liquid-solid ratio of the cement slurry system was 0.44.

[0064] Unless otherwise specified, all parts mentioned in the embodiments of the present invention refer to parts by weight.

[0065] Example 1

[0066] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature enhanced micro-expansion cement slurry system, the raw materials of which are: 100 parts of low-heat silicate cement, 10 parts of enhanced anti-fading type I material, 20 parts of enhanced anti-fading type II material, 15 parts of enhanced anti-fading type III material, 2 parts of high-temperature expansion material, 5 parts of suspension filtration reduction material, 6 parts of high-temperature water loss reduction agent, 2 parts of high-temperature retarder, and 59 parts of water.

[0067] The preparation method is as follows: prepare low-heat silicate cement, type I reinforcing anti-fading material, type II reinforcing anti-fading material, type III reinforcing anti-fading material, high-temperature expansion material, suspension filtration loss reducing material, high-temperature water loss reducing agent and high-temperature retarder in proportion, mix them evenly, add water to make slurry, and the product is obtained.

[0068] In this embodiment, the raw materials of the high-temperature enhanced micro-expansion cement slurry system are:

[0069] (1) The C2S content of low-heat silicate cement is ≥47wt.%, and the specific surface area is controlled at 280~310m². 2 / kg, 7d heat of hydration ≤245kJ / kg.

[0070] (2) The enhanced anti-fading type I material is a mixture of quartz sand and metakaolin at a mass ratio of 60:40. The quartz sand has a SiO2 content ≥99wt.% and a powder fineness ≥200 mesh; the metakaolin has an Al2O3 content ≥45wt.% and a SiO2 content ≥45wt.% and a powder fineness ≥800 mesh.

[0071] (3) The suspended filtration loss reducing material is a mixture of palygorskite powder, sepiolite powder and ultrafine calcium carbonate in a mass ratio of 15:15:70. Among them, the purity of palygorskite powder is ≥90wt.% and the fineness of the powder is ≥500 mesh; the purity of sepiolite powder is ≥90wt.% and the fineness of the powder is ≥600 mesh; the purity of ultrafine calcium carbonate is ≥95wt.% and the fineness of the powder is ≥800 mesh.

[0072] (4) The high-temperature water loss reducing agent is an AMPS anionic polymer;

[0073] (5) The high-temperature retarder is an AMPS copolymer system.

[0074] (6) The raw materials for the enhanced anti-fading type II material are: 60 parts low-heat silicate cement, 30 parts quartz sand, and 10 parts metakaolin. The low-heat silicate cement has a C2S content ≥47wt.% and a specific surface area controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg; quartz sand SiO2 content ≥99wt.%, powder fineness ≥200 mesh; metakaolin Al2O3 content ≥45wt.%, SiO2 content ≥45wt.%, powder fineness ≥800 mesh.

[0075] In this embodiment, the enhanced anti-aging type II material is prepared by the following method:

[0076] 60 parts of low-heat silicate cement, 30 parts of quartz sand and 10 parts of high-temperature tertiary soil were mixed evenly. After the mixture was evenly mixed, 44 parts of distilled water were added. According to the requirements of GB / T 10238-2015 on slurry preparation, the prepared cement slurry was put into the compressive strength mold and placed in a 60℃ normal pressure curing box for 28 days. Then the cured cement stone was placed in a 60℃ vacuum drying oven for 48 hours. Finally, the dried cement stone was put into a ball mill for grinding. The particle fineness was controlled to be Dx(10)≤4μm, Dx(50)≤17μm, and Dx(90)≤35μm. After grinding evenly, the enhanced anti-fading type II material was obtained.

[0077] (7) The raw materials for the enhanced anti-fading type III material are: 80 parts of low-heat silicate cement and 20 parts of quartz sand. The C2S content of the low-heat silicate cement is ≥47wt.%, and the specific surface area is controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg; the composition of quartz sand contains SiO2 ≥99wt.%, and the fineness of the powder is ≥325 mesh.

[0078] In this embodiment, the enhanced anti-aging type III material is obtained through the following steps:

[0079] 80 parts of low-heat silicate cement and 20 parts of quartz sand were mixed evenly. After the mixture was evenly mixed, 44 parts of distilled water were added. According to the requirements of GB / T 10238-2015 on slurry preparation, the prepared cement slurry was put into the compressive strength mold and placed in a 150℃ pressure curing kettle for 7 days. Then the cured cement stone was placed in a 60℃ vacuum drying oven for 48 hours. Finally, the dried cement stone was put into a ball mill for grinding. The particle fineness was controlled to be Dx(10)≤3μm, Dx(50)≤9μm, and Dx(90)≤18μm. After grinding evenly, the enhanced anti-fading type III material was obtained.

[0080] (8) The raw materials for the high-temperature expansion material are: 30 parts dolomite, 10 parts serpentine, 10 parts calcium iron pyroxene, 10 parts calcium zeolite, 35 parts quicklime powder, and 5 parts quartz powder.

[0081] In this embodiment, the high-temperature expansion material is prepared by the following method:

[0082] S1. Mix 30 parts dolomite, 10 parts serpentine, 10 parts calcium iron pyroxene, and 10 parts calcium zeolite evenly. After mixing evenly, crush the mixture, controlling the crushing ratio at 60. Grind the crushed mixture into fine powder, controlling the grinding ratio at 700. Send the fine powder to a high-temperature calcining furnace for calcination, controlling the calcination temperature at 950℃, the heating time at 30 minutes, and the holding time at 120 minutes. After calcination, the mixture is rapidly cooled to room temperature by an air-cooled refrigerator, controlling the cooling time at 10 minutes. After cooling, type A mixture is obtained.

[0083] S2. The type A mixture prepared in step S1 is mixed and ground evenly with 35 parts of quicklime powder and 5 parts of quartz powder in a ball mill to obtain type B mixture. Type B mixture is then compressed into tablets. When the pressure reaches the peak pressure, the pressure is immediately released to obtain type B mixture test pieces. The tableting conditions are: peak pressure controlled at 120 kN, loading speed at 5 kN / s. The type B mixture test pieces are then placed in a box-type blower for drying. The oven temperature is controlled at 100℃, and the drying time is 24 hours.

[0084] S3. Place the dried B-type mixture test pieces into a high-temperature calcining furnace for calcination. The calcination conditions are as follows: the calcination process is carried out in two stages. The first stage calcination temperature is controlled at 900℃, the heating time is controlled at 30 min, and the holding time is controlled at 10 min. The second stage calcination temperature is controlled at 1300℃, the heating time is controlled at 40 min, and the holding time is controlled at 120 min. After calcination, the test pieces are rapidly cooled to room temperature using an air-cooled refrigerator. The cooling time is controlled at 10 min. After cooling and pulverizing, the C-type mixture is obtained.

[0085] S4. Place the C-type mixture into a ball mill for grinding, and control the particle fineness to be Dx(10)≤4μm, Dx(50)≤10μm, and Dx(90)≤20μm. After grinding evenly, the high-temperature expansion material is obtained.

[0086] The chemical composition requirements for the above-mentioned high-temperature expansion materials are: 13 wt.% < MgO < 23 wt.%, 38 wt.% < CaO < 55 wt.%, 18 wt.% < SiO2 < 32 wt.%, Al2O3 < 3.5 wt.%, Fe2O3 < 1 wt.%.

[0087] To achieve the chemical composition requirements of the aforementioned high-temperature expansion material, this embodiment achieves this by limiting the purity and chemical composition of dolomite, serpentine, calcium iron pyroxene, calcium zeolite, quicklime powder, and quartz powder, specifically through the selection of these materials.

[0088] The purity requirement for dolomite is ≥95wt.%, and its chemical composition requirement is: MgO >20wt.%, CaO >28wt.%.

[0089] The purity requirement for serpentine is ≥95wt.%, and its chemical composition requirement is: MgO > 40wt.% and SiO2 > 40wt.%.

[0090] The purity requirement for calcium iron pyroxene is ≥90wt.%, and its chemical composition requirement is: CaO >20wt.%, SiO2 >43wt.%, FeO >26wt.%.

[0091] The purity requirement for calcium zeolite is ≥90 wt.%, and its chemical composition requirement is: CaO > 12 wt.%, Al2O3 > 23 wt.%, SiO2 > 41 wt.%.

[0092] In quicklime powder, the powder fineness is required to be ≥325 mesh, and its chemical composition is required to be: CaO > 74 wt.%.

[0093] For quartz powder, the powder fineness is required to be ≥325 mesh, and its chemical composition is required to be: SiO2 > 98 wt.%.

[0094] Example 2

[0095] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature enhanced micro-expansion cement slurry system, the raw materials of which are: 100 parts of low-heat silicate cement, 11 parts of enhanced anti-fading type I material, 18 parts of enhanced anti-fading type II material, 17 parts of enhanced anti-fading type III material, 4 parts of high-temperature expansion material, 7 parts of suspension filtration reduction material, 6.5 parts of high-temperature water loss reduction agent, 2.5 parts of high-temperature retarder, and 60 parts of water.

[0096] The preparation method is as follows: prepare low-heat silicate cement, type I reinforcing anti-fading material, type II reinforcing anti-fading material, type III reinforcing anti-fading material, high-temperature expansion material, suspension filtration loss reducing material, high-temperature water loss reducing agent and high-temperature retarder in proportion, mix them evenly, add water to make slurry, and the product is obtained.

[0097] In this embodiment, the raw materials of the high-temperature enhanced micro-expansion cement slurry system are:

[0098] (1) The C2S content of low-heat silicate cement is ≥47wt.%, and the specific surface area is controlled at 280~310m². 2 / kg, 7d heat of hydration ≤245kJ / kg.

[0099] (2) The enhanced anti-fading type I material is a mixture of quartz sand and metakaolin at a mass ratio of 65:35. The quartz sand has a SiO2 content ≥99wt.% and a powder fineness ≥200 mesh; the metakaolin has an Al2O3 content ≥45wt.% and a SiO2 content ≥45wt.% and a powder fineness ≥800 mesh.

[0100] (3) The suspended filtration loss reducing material is a mixture of palygorskite powder, sepiolite powder and ultrafine calcium carbonate in a mass ratio of 20:20:60. Among them, the purity of palygorskite powder is ≥90wt.% and the fineness of the powder is ≥500 mesh; the purity of sepiolite powder is ≥90wt.% and the fineness of the powder is ≥600 mesh; the purity of ultrafine calcium carbonate is ≥95wt.% and the fineness of the powder is ≥800 mesh.

[0101] (4) The high-temperature water loss reducing agent is an AMPS anionic polymer;

[0102] (5) The high-temperature retarder is an AMPS copolymer system.

[0103] (6) The raw materials for the enhanced anti-fading type II material are: 65 parts low-heat silicate cement, 27 parts quartz sand, and 8 parts metakaolin. Among them, the C2S content of the low-heat silicate cement is ≥47wt.%, and the specific surface area is controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg; quartz sand SiO2 content ≥99wt.%, powder fineness ≥200 mesh; metakaolin Al2O3 content ≥45wt.%, SiO2 content ≥45wt.%, powder fineness ≥800 mesh.

[0104] In this embodiment, the enhanced anti-aging type II material is prepared by the following method:

[0105] 65 parts of low-heat silicate cement, 27 parts of quartz sand and 8 parts of high-temperature tertiary soil were mixed evenly. After the mixture was evenly mixed, 44 parts of distilled water were added. According to the requirements of GB / T 10238-2015 on slurry preparation, the prepared cement slurry was put into the compressive strength mold and placed in a 60℃ normal pressure curing box for 28 days. Then the cured cement stone was placed in a 60℃ vacuum drying oven for 48 hours. Finally, the dried cement stone was put into a ball mill for grinding. The particle fineness was controlled to be Dx(10)≤4μm, Dx(50)≤17μm, and Dx(90)≤35μm. After grinding evenly, the enhanced anti-fading type II material was obtained.

[0106] (7) The raw materials for the enhanced anti-fading type III material are: 75 parts of low-heat silicate cement and 25 parts of quartz sand. The C2S content of the low-heat silicate cement is ≥47wt.%, and the specific surface area is controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg; the composition of quartz sand contains SiO2 ≥99wt.%, and the fineness of the powder is ≥325 mesh.

[0107] In this embodiment, the enhanced anti-aging type III material is obtained through the following steps:

[0108] 75 parts of low-heat silicate cement and 25 parts of quartz sand were mixed evenly. After the mixture was evenly mixed, 44 parts of distilled water were added. According to the requirements of GB / T 10238-2015 on slurry preparation, the prepared cement slurry was put into the compressive strength mold and placed in a 150℃ pressure curing kettle for 7 days. Then the cured cement stone was placed in a 60℃ vacuum drying oven for 48 hours. Finally, the dried cement stone was put into a ball mill for grinding. The particle fineness was controlled to be Dx(10)≤3μm, Dx(50)≤9μm, and Dx(90)≤18μm. After grinding evenly, the enhanced anti-fading type III material was obtained.

[0109] (8) The raw materials for the high-temperature expansion material are: 32 parts dolomite, 12 parts serpentine, 8 parts calcium iron pyroxene, 8 parts calcium zeolite, 33 parts quicklime powder, and 7 parts quartz powder.

[0110] In this embodiment, the high-temperature expansion material is prepared by the following method:

[0111] S1. Mix 32 parts dolomite, 12 parts serpentine, 8 parts calcium iron pyroxene, and 8 parts calcium zeolite evenly. After mixing evenly, crush the mixture, controlling the crushing ratio at 62. Grind the crushed mixture into fine powder, controlling the grinding ratio at 750. Send the fine powder to a high-temperature calcining furnace for calcination, controlling the calcination temperature at 960℃, the heating time at 30 minutes, and the holding time at 120 minutes. After calcination, the mixture is rapidly cooled to room temperature by an air-cooled refrigerator, controlling the cooling time at 11 minutes. After cooling, type A mixture is obtained.

[0112] S2. The type A mixture prepared in step S1 is mixed and ground evenly with 33 parts of quicklime powder and 7 parts of quartz powder in a ball mill to obtain type B mixture. Type B mixture is then compressed into tablets. When the pressure reaches the peak pressure, the pressure is immediately released to obtain type B mixture test pieces. The tableting conditions are: peak pressure controlled at 130 kN, loading speed at 5 kN / s. The type B mixture test pieces are then placed in a box-type blower for drying. The oven temperature is controlled at 100℃, and the drying time is 24 hours.

[0113] S3. Place the dried B-type mixture test pieces into a high-temperature calcining furnace for calcination. The calcination conditions are as follows: the calcination process is carried out in two stages. The first stage calcination temperature is controlled at 900℃, the heating time is controlled at 30 min, and the holding time is controlled at 10 min. The second stage calcination temperature is controlled at 1310℃, the heating time is controlled at 40 min, and the holding time is controlled at 120 min. After calcination, the test pieces are rapidly cooled to room temperature using an air-cooled refrigerator. The cooling time is controlled at 12 min. After cooling and pulverizing, the C-type mixture is obtained.

[0114] S4. Place the C-type mixture into a ball mill for grinding, and control the particle fineness to be Dx(10)≤4μm, Dx(50)≤10μm, and Dx(90)≤20μm. After grinding evenly, the high-temperature expansion material is obtained.

[0115] The chemical composition requirements for the above-mentioned high-temperature expansion materials are: 13 wt.% < MgO < 23 wt.%, 38 wt.% < CaO < 55 wt.%, 18 wt.% < SiO2 < 32 wt.%, Al2O3 < 3.5 wt.%, Fe2O3 < 1 wt.%.

[0116] To achieve the chemical composition requirements of the aforementioned high-temperature expansion material, this embodiment achieves this by limiting the purity and chemical composition of dolomite, serpentine, calcium iron pyroxene, calcium zeolite, quicklime powder, and quartz powder, specifically through the selection of these materials. Specifically:

[0117] The purity requirement for dolomite is ≥95wt.%, and its chemical composition requirement is: MgO >20wt.%, CaO >28wt.%.

[0118] The purity requirement for serpentine is ≥95wt.%, and its chemical composition requirement is: MgO > 40wt.% and SiO2 > 40wt.%.

[0119] The purity requirement for calcium iron pyroxene is ≥90wt.%, and its chemical composition requirement is: CaO >20wt.%, SiO2 >43wt.%, FeO >26wt.%.

[0120] The purity requirement for calcium zeolite is ≥90 wt.%, and its chemical composition requirement is: CaO > 12 wt.%, Al2O3 > 23 wt.%, SiO2 > 41 wt.%.

[0121] In quicklime powder, the powder fineness is required to be ≥325 mesh, and its chemical composition is required to be: CaO > 74 wt.%.

[0122] For quartz powder, the powder fineness is required to be ≥325 mesh, and its chemical composition is required to be: SiO2 > 98 wt.%.

[0123] The preparation method of the high-temperature enhanced micro-expansion cement slurry system in this embodiment is as follows: prepare low-heat silicate cement, enhanced anti-fading type I material, enhanced anti-fading type II material, enhanced anti-fading type III material, high-temperature expansion material, suspension filtration loss reducing material, high-temperature water loss reducing agent and high-temperature retarder in proportion, mix them evenly, add water to make slurry, and the slurry is obtained.

[0124] Example 3

[0125] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature enhanced micro-expansion cement slurry system, the raw materials of which are: 100 parts of low-heat silicate cement, 12 parts of enhanced anti-fading type I material, 16 parts of enhanced anti-fading type II material, 20 parts of enhanced anti-fading type III material, 5 parts of high-temperature expansion material, 10 parts of suspension filtration reduction material, 7 parts of high-temperature water loss reduction agent, 3 parts of high-temperature retarder, and 62 parts of water.

[0126] The preparation method is as follows: prepare low-heat silicate cement, type I reinforcing anti-fading material, type II reinforcing anti-fading material, type III reinforcing anti-fading material, high-temperature expansion material, suspension filtration loss reducing material, high-temperature water loss reducing agent and high-temperature retarder in proportion, mix them evenly, add water to make slurry, and the product is obtained.

[0127] In this embodiment, the raw materials of the high-temperature enhanced micro-expansion cement slurry system are:

[0128] (1) The C2S content of low-heat silicate cement is ≥47wt.%, and the specific surface area is controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg;

[0129] (2) The enhanced anti-degradation type I material is a mixture of quartz sand and metakaolin at a mass ratio of 70:30. The quartz sand has a SiO2 content ≥99wt.% and a powder fineness ≥200 mesh; the metakaolin has an Al2O3 content ≥45wt.% and a SiO2 content ≥45wt.% and a powder fineness ≥800 mesh.

[0130] (3) The suspended filtration loss reducing material is a mixture of palygorskite powder, sepiolite powder, and ultrafine calcium carbonate in a mass ratio of 25:25:50. Among them, the purity of palygorskite powder is ≥90wt.%, and the fineness of the powder is ≥500 mesh; the purity of sepiolite powder is ≥90wt.%, and the fineness of the powder is ≥600 mesh; the purity of ultrafine calcium carbonate is ≥95wt.%, and the fineness of the powder is ≥800 mesh.

[0131] (4) The high-temperature water loss reducing agent is an AMPS anionic polymer;

[0132] (5) The high-temperature retarder is an AMPS copolymer system.

[0133] (6) The raw materials for the enhanced anti-fading type II material are: 70 parts low-heat silicate cement, 25 parts quartz sand, and 5 parts metakaolin. The low-heat silicate cement has a C2S content ≥47wt.% and a specific surface area controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg; SiO2 content in quartz sand ≥99wt.%, powder fineness ≥200 mesh; Al2O3 content in metakaolin ≥45wt.%, SiO2 content ≥45wt.%, powder fineness ≥800 mesh.

[0134] The preparation method of the enhanced anti-aging type II material in this embodiment is as follows:

[0135] 70 parts of low-heat silicate cement, 25 parts of quartz sand and 5 parts of high-temperature tertiary soil were mixed evenly. After the mixture was evenly mixed, 44 parts of distilled water were added. According to the requirements of GB / T 10238-2015 on slurry preparation, the prepared cement slurry was put into the compressive strength mold and placed in a 60℃ normal pressure curing box for 28 days. Then the cured cement stone was placed in a 60℃ vacuum drying oven for 48 hours. Finally, the dried cement stone was put into a ball mill for grinding. The particle fineness was controlled to be Dx(10)≤4μm, Dx(50)≤17μm, and Dx(90)≤35μm. After grinding evenly, the enhanced anti-fading type II material was obtained.

[0136] (7) The raw materials for the enhanced anti-fading type III material are: 70 parts of low-heat silicate cement and 30 parts of quartz sand. The C2S content of the low-heat silicate cement is ≥47wt.%, and the specific surface area is controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg; SiO2 content in quartz sand ≥99wt.%, powder fineness ≥325 mesh.

[0137] The preparation method of the enhanced anti-aging type III material in this embodiment is as follows:

[0138] 70 parts of low-heat silicate cement and 30 parts of quartz sand were mixed evenly. After the mixture was evenly mixed, 44 parts of distilled water were added. According to the requirements of GB / T 10238-2015 on slurry preparation, the prepared cement slurry was put into the compressive strength mold and placed in a 150℃ pressure curing kettle for 7 days. Then the cured cement stone was placed in a 60℃ vacuum drying oven for 48 hours. Finally, the dried cement stone was put into a ball mill for grinding. The particle fineness was controlled to be Dx(10)≤3μm, Dx(50)≤9μm, and Dx(90)≤18μm. After grinding evenly, the enhanced anti-fading type III material was obtained.

[0139] (8) The raw materials for the high-temperature expansion material are: 35 parts dolomite, 15 parts serpentine, 5 parts calcium iron pyroxene, 5 parts calcium zeolite, 30 parts quicklime powder, and 10 parts quartz powder.

[0140] In this embodiment, the high-temperature expansion material is prepared by the following method:

[0141] S1. Mix 35 parts dolomite, 15 parts serpentine, 5 parts calcium iron pyroxene, and 5 parts calcium zeolite evenly. After mixing evenly, crush the mixture, controlling the crushing ratio at 65. Grind the crushed mixture into fine powder, controlling the grinding ratio at 800. Send the fine powder to a high-temperature calcining furnace for calcination, controlling the calcination temperature at 970℃, the heating time at 30 minutes, and the holding time at 120 minutes. After calcination, the mixture is rapidly cooled to room temperature by an air-cooled refrigerator, controlling the cooling time at 12 minutes. After cooling, type A mixture is obtained.

[0142] S2. The type A mixture prepared in step S1 is mixed and ground evenly with 30 parts of quicklime powder and 10 parts of quartz powder in a ball mill to obtain type B mixture. Type B mixture is then compressed into tablets. When the pressure reaches the peak pressure, the pressure is immediately released to obtain type B mixture test pieces. The tableting conditions are: peak pressure controlled at 135 kN, loading speed at 5 kN / s. The type B mixture test pieces are then placed in a box-type blower for drying. The oven temperature is controlled at 100℃, and the drying time is 24 hours.

[0143] S3. Place the dried B-type mixture test pieces into a high-temperature calcining furnace for calcination. The calcination conditions are as follows: the calcination process is carried out in two stages. The first stage calcination temperature is controlled at 900℃, the heating time is controlled at 30 min, and the holding time is controlled at 10 min. The second stage calcination temperature is controlled at 1330℃, the heating time is controlled at 40 min, and the holding time is controlled at 120 min. After calcination, the test pieces are rapidly cooled to room temperature using an air-cooled refrigerator. The cooling time is controlled at 13 min. After cooling and pulverizing, the C-type mixture is obtained.

[0144] S4. Place the C-type mixture into a ball mill for grinding, and control the particle fineness to be Dx(10)≤4μm, Dx(50)≤10μm, and Dx(90)≤20μm. After grinding evenly, the high-temperature expansion material is obtained.

[0145] The chemical composition requirements for the above-mentioned high-temperature expansion materials are: 13 wt.% < MgO < 23 wt.%, 38 wt.% < CaO < 55 wt.%, 18 wt.% < SiO2 < 32 wt.%, Al2O3 < 3.5 wt.%, Fe2O3 < 1 wt.%.

[0146] In order to achieve the chemical composition requirements of the high-temperature expansion material mentioned above, this embodiment is achieved by limiting the purity and chemical composition of dolomite, serpentine, calcium iron pyroxene, calcium zeolite, quicklime powder and quartz powder, that is, by selecting dolomite, serpentine, calcium iron pyroxene, calcium zeolite, quicklime powder and quartz powder materials. Specifically, the purity requirement for dolomite is ≥95 wt.%, and its chemical composition is required to be: MgO > 20 wt.% and CaO > 28 wt.%; the purity requirement for serpentine is ≥95 wt.%, and its chemical composition is required to be: MgO > 40 wt.% and SiO2 > 40 wt.%; the purity requirement for hedonic iron pyroxene is ≥90 wt.%, and its chemical composition is required to be: CaO > 20 wt.% and SiO2 > 43 wt.% and FeO > 26 wt.%; the purity requirement for calcium zeolite is ≥90 wt.%, and its chemical composition is required to be: CaO > 12 wt.% and Al2O3 > 23 wt.% and SiO2 > 41 wt.%; the fineness requirement for quicklime powder is ≥325 mesh, and its chemical composition is required to be: CaO > 74 wt.%; the fineness requirement for quartz powder is ≥325 mesh, and its chemical composition is required to be: SiO2 > 98 wt.%.

[0147] Example 4

[0148] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature enhanced micro-expansion cement slurry system, the raw materials of which are: 100 parts of low-heat silicate cement, 14 parts of enhanced anti-fading type I material, 13 parts of enhanced anti-fading type II material, 23 parts of enhanced anti-fading type III material, 6 parts of high-temperature expansion material, 12 parts of suspension filtration reduction material, 7.5 parts of high-temperature water loss reduction agent, 3.5 parts of high-temperature retarder, and 63 parts of water.

[0149] The preparation method is as follows: prepare low-heat silicate cement, type I reinforcing anti-fading material, type II reinforcing anti-fading material, type III reinforcing anti-fading material, high-temperature expansion material, suspension filtration loss reducing material, high-temperature water loss reducing agent and high-temperature retarder in proportion, mix them evenly, add water to make slurry, and the product is obtained.

[0150] In this embodiment, the raw materials of the high-temperature enhanced micro-expansion cement slurry system are:

[0151] (1) The C2S content of low-heat silicate cement is ≥47wt.%, and the specific surface area is controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg;

[0152] (2) The enhanced anti-fading type I material is a mixture of quartz sand and metakaolin at a mass ratio of 75:25; wherein the quartz sand contains ≥99wt.% SiO2 and has a fineness of ≥200 mesh; and the metakaolin contains ≥45wt.% Al2O3 and ≥45wt.% SiO2 and has a fineness of ≥800 mesh.

[0153] (3) The suspended filtration loss reducing material is a mixture of palygorskite powder, sepiolite powder and ultrafine calcium carbonate in a mass ratio of 17:18:65. Among them, the purity of palygorskite powder is ≥90wt.% and the fineness of the powder is ≥500 mesh; the purity of sepiolite powder is ≥90wt.% and the fineness of the powder is ≥600 mesh; the purity of ultrafine calcium carbonate is ≥95wt.% and the fineness of the powder is ≥800 mesh.

[0154] (4) The high-temperature dehydration agent is an AMPS anionic polymer.

[0155] (5) The high-temperature retarder is an AMPS copolymer system.

[0156] (6) The raw materials for the enhanced anti-fading type II material are: 75 parts low-heat silicate cement, 20 parts quartz sand, and 5 parts metakaolin. The low-heat silicate cement has a C2S content ≥47wt.% and a specific surface area controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg; SiO2 content in quartz sand ≥99wt.%, powder fineness ≥200 mesh; Al2O3 content in metakaolin ≥45wt.%, SiO2 ≥45wt.%, powder fineness ≥800 mesh.

[0157] In this embodiment, the enhanced anti-aging type II material is prepared by the following method:

[0158] 75 parts of low-heat silicate cement, 20 parts of quartz sand and 5 parts of high-temperature tertiary soil were mixed evenly. After the mixture was evenly mixed, 44 parts of distilled water were added. According to the requirements of GB / T 10238-2015 on slurry preparation, the prepared cement slurry was put into the compressive strength mold and placed in a 60℃ normal pressure curing box for 28 days. Then the cured cement stone was placed in a 60℃ vacuum drying oven for 48 hours. Finally, the dried cement stone was put into a ball mill for grinding. The particle fineness was controlled to be Dx(10)≤4μm, Dx(50)≤17μm, and Dx(90)≤35μm. After grinding evenly, the enhanced anti-fading type II material was obtained.

[0159] (7) The raw material composition of the enhanced anti-fading type III material is: 65 parts low-heat silicate cement and 35 parts quartz sand. The C2S content of the low-heat silicate cement is ≥47 wt.%, and the specific surface area is controlled between 280 and 310 m². 2 / kg, 7d heat of hydration ≤245kJ / kg; SiO2 content in quartz sand ≥99wt.%, powder fineness ≥325 mesh.

[0160] In this embodiment, the enhanced anti-aging type III material is obtained through the following steps:

[0161] 65 parts of low-heat silicate cement and 35 parts of quartz sand were mixed evenly. After the mixture was evenly mixed, 44 parts of distilled water were added. According to the requirements of GB / T 10238-2015 on slurry preparation, the prepared cement slurry was put into the compressive strength mold and placed in a 150℃ pressure curing kettle for 7 days. Then the cured cement stone was placed in a 60℃ vacuum drying oven for 48 hours. Finally, the dried cement stone was put into a ball mill for grinding. The particle fineness was controlled to be Dx(10)≤3μm, Dx(50)≤9μm, and Dx(90)≤18μm. After grinding evenly, the enhanced anti-fading type III material was obtained.

[0162] (8) The raw material composition of the high temperature expansion material is: 38 parts dolomite, 18 parts serpentine, 6 parts calcium iron pyroxene, 8 parts calcium zeolite, 25 parts quicklime powder, and 5 parts quartz powder.

[0163] In this embodiment, the high-temperature expansion material is prepared by the following method:

[0164] S1. Mix 38 parts dolomite, 18 parts serpentine, 6 parts calcium iron pyroxene, and 8 parts calcium zeolite evenly. After mixing evenly, crush the mixture, controlling the crushing ratio at 70. Grind the crushed mixture into fine powder, controlling the grinding ratio at 820. Send the fine powder to a high-temperature calcining furnace for calcination, controlling the calcination temperature at 985℃, the heating time at 30 minutes, and the holding time at 120 minutes. After calcination, the mixture is rapidly cooled to room temperature by an air-cooled refrigerator, controlling the cooling time at 14 minutes. After cooling, type A mixture is obtained.

[0165] S2. The type A mixture prepared in step S1 is mixed and ground evenly with 25 parts of quicklime powder and 5 parts of quartz powder in a ball mill to obtain type B mixture. Type B mixture is then compressed into tablets. When the pressure reaches the peak pressure, the pressure is immediately released to obtain type B mixture test pieces. The tableting conditions are: peak pressure controlled at 140 kN, loading speed at 5 kN / s. The type B mixture test pieces are then placed in a box-type blower for drying. The oven temperature is controlled at 100℃, and the drying time is 24 hours.

[0166] S3. Place the dried B-type mixture test pieces into a high-temperature calcining furnace for calcination. The calcination conditions are as follows: the calcination process is carried out in two stages. The first stage calcination temperature is controlled at 900℃, the heating time is controlled at 30 min, and the holding time is controlled at 10 min. The second stage calcination temperature is controlled at 1340℃, the heating time is controlled at 40 min, and the holding time is controlled at 120 min. After calcination, the test pieces are rapidly cooled to room temperature using an air-cooled refrigerator. The cooling time is controlled at 14 min. After cooling and pulverizing, the C-type mixture is obtained.

[0167] S4. Place the C-type mixture into a ball mill for grinding, and control the particle fineness to be Dx(10)≤4μm, Dx(50)≤10μm, and Dx(90)≤20μm. After grinding evenly, the high-temperature expansion material is obtained.

[0168] The chemical composition requirements for the above-mentioned high-temperature expansion materials are: 13 wt.% < MgO < 23 wt.%, 38 wt.% < CaO < 55 wt.%, 18 wt.% < SiO2 < 32 wt.%, Al2O3 < 3.5 wt.%, Fe2O3 < 1 wt.%.

[0169] To achieve the chemical composition requirements of the aforementioned high-temperature expansion material, this embodiment achieves this by limiting the purity and chemical composition of dolomite, serpentine, calcium iron pyroxene, calcium zeolite, quicklime powder, and quartz powder, namely, the selection of dolomite, serpentine, calcium iron pyroxene, calcium zeolite, quicklime powder, and quartz powder materials. Specifically, the purity requirement for dolomite is ≥95 wt.%, and its chemical composition is required to be: MgO > 20 wt.% and CaO > 28 wt.%; the purity requirement for serpentine is ≥95 wt.%, and its chemical composition is required to be: MgO > 40 wt.% and SiO2 > 40 wt.%; the purity requirement for hedonic iron pyroxene is ≥90 wt.%, and its chemical composition is required to be: CaO > 20 wt.% and SiO2 > 43 wt.% and FeO > 26 wt.%; the purity requirement for calcium zeolite is ≥90 wt.%, and its chemical composition is required to be: CaO > 12 wt.% and Al2O3 > 23 wt.% and SiO2 > 41 wt.%; the fineness requirement for quicklime powder is ≥325 mesh, and its chemical composition is required to be: CaO > 74 wt.%; the fineness requirement for quartz powder is ≥325 mesh, and its chemical composition is required to be: SiO2 > 98 wt.%.

[0170] Example 5

[0171] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature enhanced micro-expansion cement slurry system, the raw material composition of which is: 100 parts of low-heat silicate cement, 15 parts of enhanced anti-fading type I material, 10 parts of enhanced anti-fading type II material, 25 parts of enhanced anti-fading type III material, 8 parts of high-temperature expansion material, 15 parts of suspension filtration reduction material, 8 parts of high-temperature water loss reduction agent, 4 parts of high-temperature retarder, and 64 parts of water.

[0172] The preparation method is as follows: prepare low-heat silicate cement, type I reinforcing anti-fading material, type II reinforcing anti-fading material, type III reinforcing anti-fading material, high-temperature expansion material, suspension filtration loss reducing material, high-temperature water loss reducing agent and high-temperature retarder in proportion, mix them evenly, add water to make slurry, and the product is obtained.

[0173] In this embodiment, the raw materials of the high-temperature enhanced micro-expansion cement slurry system are:

[0174] (1) The C2S content of low-heat silicate cement is ≥47wt.%, and the specific surface area is controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg.

[0175] (2) The enhanced anti-degradation type I material is a mixture of quartz sand and metakaolin at a mass ratio of 80:20. The quartz sand contains ≥99wt.% SiO2 and has a fineness of ≥200 mesh; the metakaolin contains ≥45wt.% Al2O3 and ≥45wt.% SiO2 and has a fineness of ≥800 mesh.

[0176] (3) The suspended filtration loss reducing material is a mixture of palygorskite powder, sepiolite powder, and ultrafine calcium carbonate in a mass ratio of 20:15:65. Among them, the purity of palygorskite powder is ≥90wt.%, and the fineness of the powder is ≥500 mesh; the purity of sepiolite powder is ≥90wt.%, and the fineness of the powder is ≥600 mesh; the purity of ultrafine calcium carbonate is ≥95wt.%, and the fineness of the powder is ≥800 mesh.

[0177] (4) The high-temperature water loss reducing agent is an AMPS anionic polymer;

[0178] (5) The high-temperature retarder is an AMPS copolymer system.

[0179] (6) The raw material composition of the enhanced anti-degradation type II material package is: 80 parts low-heat silicate cement, 15 parts quartz sand, and 5 parts metakaolinite. The low-heat silicate cement has a C2S content ≥47wt.% and a specific surface area controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg; SiO2 content in quartz sand ≥99wt.%, powder fineness ≥200 mesh; Al2O3 content in metakaolin ≥45wt.%, SiO2 content ≥45wt.%, powder fineness ≥800 mesh.

[0180] In this embodiment, the enhanced anti-aging type II material is prepared by the following method:

[0181] 80 parts of low-heat silicate cement, 15 parts of quartz sand and 5 parts of high-temperature tertiary soil were mixed evenly. After mixing evenly, 44 parts of distilled water were added. According to the requirements of GB / T 10238-2015 on slurry preparation, the prepared cement slurry was put into the compressive strength mold and placed in a 60℃ normal pressure curing box for 28 days. Then, the cured cement stone was placed in a 60℃ vacuum drying oven for 48 hours. Finally, the dried cement stone was put into a ball mill for grinding. The particle fineness was controlled to be Dx(10)≤4μm, Dx(50)≤17μm, and Dx(90)≤35μm. After grinding evenly, the enhanced anti-fading type II material was obtained.

[0182] (7) The raw material composition of the enhanced anti-fading type III material is: 60 parts of low-heat silicate cement and 40 parts of quartz sand. The C2S content of the low-heat silicate cement is ≥47wt.%, and the specific surface area is controlled between 280 and 310m². 2 / kg, 7d heat of hydration ≤245kJ / kg; SiO2 content in quartz sand ≥99wt.%, powder fineness ≥325 mesh.

[0183] In this embodiment, the enhanced anti-aging type III material is obtained through the following steps:

[0184] 60 parts of low-heat silicate cement and 40 parts of quartz sand were mixed evenly. After the mixture was evenly mixed, 44 parts of distilled water were added. According to the requirements of GB / T 10238-2015 on slurry preparation, the prepared cement slurry was put into the compressive strength mold and placed in a 150℃ pressure curing kettle for 7 days. Then the cured cement stone was placed in a 60℃ vacuum drying oven for 48 hours. Finally, the dried cement stone was put into a ball mill for grinding. The particle fineness was controlled to be Dx(10)≤3μm, Dx(50)≤9μm, and Dx(90)≤18μm. After grinding evenly, the enhanced anti-fading type III material was obtained.

[0185] (8) The high-temperature expansion material includes the following components by weight: 40 parts dolomite, 20 parts serpentine, 5 parts calcium iron pyroxene, 5 parts calcium zeolite, 25 parts quicklime powder, and 5 parts quartz powder.

[0186] In this embodiment, the high-temperature expansion material is prepared by the following method:

[0187] S1. Mix 40 parts dolomite, 20 parts serpentine, 5 parts calcium iron pyroxene, and 5 parts calcium zeolite evenly. After mixing evenly, crush the mixture, controlling the crushing ratio at 75. Grind the crushed mixture into fine powder, controlling the grinding ratio at 850. Send the fine powder to a high-temperature calcining furnace for calcination, controlling the calcination temperature at 1000℃, the heating time at 30 minutes, and the holding time at 120 minutes. After calcination, the mixture is rapidly cooled to room temperature by an air-cooled refrigerator, controlling the cooling time at 15 minutes. After cooling, type A mixture is obtained.

[0188] S2. The type A mixture prepared in step S1 is mixed and ground evenly with 25 parts of quicklime powder and 5 parts of quartz powder in a ball mill to obtain type B mixture. Type B mixture is then compressed into tablets. When the pressure reaches the peak pressure, the pressure is immediately released to obtain type B mixture test pieces. The tableting conditions are: peak pressure controlled at 150 kN, loading speed at 5 kN / s. The type B mixture test pieces are then placed in a box-type blower for drying. The oven temperature is controlled at 100℃, and the drying time is 24 hours.

[0189] S3. Place the dried B-type mixture test pieces into a high-temperature calcining furnace for calcination. The calcination conditions are as follows: the calcination process is carried out in two stages. The first stage calcination temperature is controlled at 900℃, the heating time is controlled at 30 min, and the holding time is controlled at 10 min. The second stage calcination temperature is controlled at 1350℃, the heating time is controlled at 40 min, and the holding time is controlled at 120 min. After calcination, the test pieces are rapidly cooled to room temperature using an air-cooled refrigerator. The cooling time is controlled at 15 min. After cooling and pulverizing, the C-type mixture is obtained.

[0190] S4. Place the C-type mixture into a ball mill for grinding, and control the particle fineness to be Dx(10)≤4μm, Dx(50)≤10μm, and Dx(90)≤20μm. After grinding evenly, the high-temperature expansion material is obtained.

[0191] The chemical composition requirements for the above-mentioned high-temperature expansion materials are: 13 wt.% < MgO < 23 wt.%, 38 wt.% < CaO < 55 wt.%, 18 wt.% < SiO2 < 32 wt.%, Al2O3 < 3.5 wt.%, Fe2O3 < 1 wt.%.

[0192] To achieve the chemical composition requirements of the aforementioned high-temperature expansion material, this embodiment achieves this by limiting the purity and chemical composition of dolomite, serpentine, calcium iron pyroxene, calcium zeolite, quicklime powder, and quartz powder, namely, the selection of dolomite, serpentine, calcium iron pyroxene, calcium zeolite, quicklime powder, and quartz powder materials. Specifically, the purity requirement for dolomite is ≥95 wt.%, and its chemical composition is required to be: MgO > 20 wt.% and CaO > 28 wt.%; the purity requirement for serpentine is ≥95 wt.%, and its chemical composition is required to be: MgO > 40 wt.% and SiO2 > 40 wt.%; the purity requirement for hedonic iron pyroxene is ≥90 wt.%, and its chemical composition is required to be: CaO > 20 wt.% and SiO2 > 43 wt.% and FeO > 26 wt.%; the purity requirement for calcium zeolite is ≥90 wt.%, and its chemical composition is required to be: CaO > 12 wt.% and Al2O3 > 23 wt.% and SiO2 > 41 wt.%; the fineness requirement for quicklime powder is ≥325 mesh, and its chemical composition is required to be: CaO > 74 wt.%; the fineness requirement for quartz powder is ≥325 mesh, and its chemical composition is required to be: SiO2 > 98 wt.%.

[0193] Comparative Example 1

[0194] Compared with Example 1, the cement slurry system in this comparative example does not contain any reinforcing anti-fading type I, II, or III materials, and is replaced with commercially available quartz sand. The formula is as follows: 100 parts low-heat silicate cement, 45 parts quartz sand, 2 parts high-temperature expansion material, 5 parts suspension filtration loss reducing material, 6 parts high-temperature water loss reducing agent, 2 parts high-temperature retarder, and 59 parts water.

[0195] Comparative Example 2

[0196] Compared with Example 2, the cement slurry system in this comparative example does not contain the type I reinforcing anti-fading material, and is replaced with commercially available quartz sand. The formula is as follows: 100 parts of low-heat silicate cement, 11 parts of quartz sand, 18 parts of type II reinforcing anti-fading material, 17 parts of type III reinforcing anti-fading material, 4 parts of high-temperature expansion material, 7 parts of suspension filtration loss reducing material, 6.5 parts of high-temperature water loss reducing agent, 2.5 parts of high-temperature retarder, and 60 parts of water.

[0197] Comparative Example 3

[0198] Compared with Example 3, the cement slurry system in this comparative example does not contain the type II reinforcing anti-fading material, and is replaced with commercially available quartz sand. The formula is as follows: 100 parts of low-heat silicate cement, 12 parts of type I reinforcing anti-fading material, 16 parts of quartz sand, 20 parts of type III reinforcing anti-fading material, 5 parts of high-temperature expansion material, 10 parts of suspension filtration loss reducing material, 7 parts of high-temperature water loss reducing agent, 3 parts of high-temperature retarder, and 62 parts of water.

[0199] Comparative Example 4

[0200] Compared with Example 4, the cement slurry system in this comparative example does not contain the type III reinforcing anti-fading material, and is replaced with commercially available quartz sand. The formula is as follows: 100 parts of low-heat silicate cement, 14 parts of type I reinforcing anti-fading material, 13 parts of type II reinforcing anti-fading material, 23 parts of quartz sand, 6 parts of high-temperature expansion material, 12 parts of suspension filtration loss reducing material, 7.5 parts of high-temperature water loss reducing agent, 3.5 parts of high-temperature retarder, and 63 parts of water.

[0201] Comparative Example 5

[0202] Compared with Example 5, the cement slurry system in this comparative example does not contain high-temperature expansion materials. The formula is as follows: 100 parts of low-heat silicate cement, 15 parts of type I reinforcing anti-fading material, 10 parts of type II reinforcing anti-fading material, 25 parts of type III reinforcing anti-fading material, 15 parts of suspension filtration loss reducing material, 8 parts of high-temperature water loss reducing agent, 4 parts of high-temperature retarder, and 61 parts of water.

[0203] According to GB / T 19139-2012 and GB / T33293-2016 standards, the engineering properties, mechanical properties and expansion properties of each cement slurry system obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were tested. The expansion properties were tested with the addition of high temperature pressure curing test based on the above standards. The results are shown in Table 1.

[0204] Table 1. Test results of physical properties of high-temperature cementing cement

[0205]

[0206] In Table 1, the curing conditions for the density difference test are: 210℃×20.7MPa×48h; the free liquid content test conditions are: 90℃×0.1MPa×2h; the API water loss test conditions are: 175℃×6.9MPa×30min; the cement stone compressive strength curing conditions are: 210℃×20.7MPa; the thickening test conditions are: 175℃×95MPa×95min; and the cement expansion rate test curing conditions are: 210℃×20.7MPa.

[0207] According to the physical performance test results in Table 1, the high-temperature cement slurry systems prepared in Examples 1 to 5 of this invention have excellent comprehensive performance and all meet the requirements of industry standards. Specifically, they have good fluidity, zero free liquid content, low API water loss, high settling stability, and the resulting cement stone has high compressive strength without degradation and excellent expansion performance.

[0208] Figure 1 This is a microscopic morphology diagram of the cement stone formed by the cement slurry system of Example 1 under high-temperature curing environment. As can be seen from the figure, the cement stone formed by the cement slurry system prepared in this invention under high-temperature curing environment has a dense internal structure, a high degree of crystallization of high-temperature hydration products and less grain coarsening, and thus exhibits high compressive strength and thermal stability in macroscopic properties.

[0209] Based on the comparative analysis of the cement stone compressive strength test data in Table 1, compared with Example 1, the initial strength of the cement stone formed after the cementing slurry system prepared in Comparative Example 1 after setting and hardening is lower, and significant strength degradation occurs with the extension of the curing period. This result clearly shows that conventional reinforcing materials (quartz sand) cannot replace the reinforcing and anti-degradation material of the present invention to meet the requirements for long-term stable strength of cement stone in high-temperature cementing.

[0210] Based on the comparative analysis of the cement stone compressive strength test data in Table 1, compared with Example 2, the cement stone strength formed after the cementing slurry system prepared in Comparative Example 2 has relatively low strength after setting and hardening; and it shows a degradation trend with the extension of the curing period. This result fully demonstrates that using conventional reinforcing materials such as commercially available quartz sand to replace the reinforcing and anti-degradation Type I material of this invention cannot solve the problem of cement stone strength degradation under high temperature conditions. Therefore, the reinforcing and anti-degradation Type I material of this invention plays an irreplaceable key role in solving the problem of cement stone strength degradation at high temperatures.

[0211] Based on the comparative analysis of the cement stone compressive strength test data in Table 1, compared to Example 3, the cement stone strength formed after the cementing slurry system prepared in Comparative Example 3 has relatively low strength after setting and hardening; and it shows a declining trend with the extension of the curing period. This result fully demonstrates that replacing the reinforced anti-decay type II material of this invention with conventional reinforcing materials such as commercially available quartz sand cannot solve the problem of high-temperature cement stone strength decline. Therefore, the role of the reinforced anti-decay type II material in this invention is irreplaceable.

[0212] Table 1 shows the compressive strength data of the cement stone: Compared with Example 4, the cement stone strength formed after hardening of the cement slurry system prepared in Comparative Example 4 (using commercially available quartz sand) is relatively low; and it shows a decreasing trend with the extension of the curing age. This result clearly shows that replacing the reinforced and anti-fading Type III material of this invention with conventional materials such as commercially available quartz sand cannot solve the problem of high-temperature strength degradation. This fully demonstrates the irreplaceability of Type III material.

[0213] As shown in Table 1, the expansion rate test data indicates that, compared to Example 5, the cement slurry system prepared in Comparative Example 5 exhibited almost no significant expansion during the setting and hardening process. Even with extended curing periods, the cement stone showed virtually no expansion. This lack of expansion performance is particularly important for high-temperature cementing, as it severely weakens the sealing integrity of the cement sheath, leading to a significant increase in the risk of annular pressure and interlayer flow, which not only jeopardizes cementing safety but also affects subsequent oil and gas extraction operations.

[0214] 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 high-temperature enhanced micro-expansion cement slurry system, characterized in that, The product comprises the following components by weight: 100 parts low-heat silicate cement; 10-15 parts type I reinforcing and anti-fading material; 10-20 parts type II reinforcing and anti-fading material; 15-25 parts type III reinforcing and anti-fading material; 2-8 parts high-temperature expansion material; 5-15 parts suspension filtration reduction material; 6-8 parts high-temperature water loss reduction agent; and 2-4 parts high-temperature retarder. Among them, the enhanced anti-decay type I material is a mixture of quartz sand and metakaolin in a mass ratio of (60-80):(20-40); The enhanced anti-fading type II material comprises the following components in parts by weight: 60-80 parts of low-heat silicate cement, 15-30 parts of quartz sand, and 5-10 parts of meta-high terephthalic acid; its preparation method includes: mixing the components in proportion, making slurry, molding and curing, drying, and grinding to obtain the final product. The enhanced anti-fading type III material comprises the following components in parts by weight: 60-80 parts of low-heat silicate cement and 20-40 parts of quartz sand; its preparation method includes: mixing the components in proportion, making slurry, molding and curing, drying, and grinding to obtain the final product; The high-temperature expansion material comprises the following components by weight: 30-40 parts dolomite, 10-20 parts serpentine, 5-10 parts calcium iron pyroxene, 5-10 parts calcium zeolite, 25-35 parts quicklime powder, and 5-10 parts quartz powder. Its preparation method includes: mixing dolomite, serpentine, calcium iron pyroxene, and calcium zeolite, then crushing, grinding, and calcining them; then mixing and grinding them with the remaining raw materials, pressing them into tablets, and drying them; followed by calcination and grinding to obtain the final product.

2. The high-temperature enhanced micro-expansion cement slurry system according to claim 1, characterized in that, The low-heat silicate cement has a C2S content ≥ 47 wt.% and a specific surface area of ​​280–310 m². 2 / kg, 7d heat of hydration ≤245kJ / kg.

3. The high-temperature enhanced micro-expansion cement slurry system according to claim 1, characterized in that, The quartz sand in the enhanced anti-aging type I material and the enhanced anti-aging type II material has a SiO2 content of ≥99wt.% and a powder fineness of ≥200 mesh; The metakaolin in the enhanced anti-aging type I material and enhanced anti-aging type II material has an Al2O3 content ≥45wt.%, a SiO2 content ≥45wt.%, and a powder fineness ≥800 mesh.

4. The high-temperature enhanced micro-expansion cement slurry system according to claim 1, characterized in that, The particle size requirements for the enhanced anti-aging type II material are Dx(10)≤4μm, Dx(50)≤17μm, and Dx(90)≤35μm; Preferably, in the preparation method of the enhanced anti-aging type II material, after mixing the components in proportion, 40-50 parts of water are added to make a slurry, more preferably 44 parts of water; More preferably, the curing conditions are 55~65℃ and normal pressure for 26~30 days; more preferably, 60℃ and normal pressure for 28 days. Preferably, the cured cement stone is placed in a vacuum drying oven at 55~65℃ and dried for 24~60 h; more preferably, it is placed in a vacuum drying oven at 60℃ and dried for 48 h.

5. The high-temperature enhanced micro-expansion cement slurry system according to claim 1, characterized in that, The particle size requirements for the enhanced anti-aging type III material are Dx(10)≤3μm, Dx(50)≤9μm, and Dx(90)≤18μm; Preferably, the quartz sand in the enhanced anti-aging type III material has a SiO2 content ≥99 wt.% and a powder fineness ≥325 mesh; Preferably, in the preparation method of the enhanced anti-aging type III material, after mixing the components in proportion, 40-50 parts of water are added to make a slurry, more preferably 44 parts of water; More preferably, the curing conditions are curing in a pressurized curing vessel at 145~155℃ for 6~8 days; more preferably, curing at 150℃ and normal pressure for 7 days. Preferably, the cured cement stone is placed in a vacuum drying oven at 55~65℃ and dried for 24~60 h; more preferably, it is placed in a vacuum drying oven at 60℃ and dried for 48 h.

6. The high-temperature enhanced micro-expansion cement slurry system according to claim 1, characterized in that, The particle size requirements for high-temperature expansion materials are Dx(10)≤4μm, Dx(50)≤10μm, and Dx(90)≤20μm; Preferably, the composition of the high-temperature expansion material is as follows: 13 wt.% < MgO < 23 wt.%, 38 wt.% < CaO < 55 wt.%, 18 wt.% < SiO2 < 32 wt.%, Al2O3 < 3.5 wt.%, Fe2O3 < 1 wt.%; Preferably, in the preparation method of the high-temperature expansion material, dolomite, serpentine, calcium iron pyroxene and calcium zeolite are mixed and then crushed, and the crushing ratio is controlled to be 60~75. Preferably, the crushed mixture is ground into fine powder, and the grinding ratio is controlled at 700~850; Preferably, the pulverized mixed fines are fed into a high-temperature calcining furnace for calcination at a temperature of 950°C to 1000°C, with a heating time of 25 to 35 minutes and a holding time of 100 to 140 minutes; more preferably, the heating time is controlled at 30 minutes and the holding time is controlled at 120 minutes. Preferably, the tableting conditions are: peak pressure controlled at 120~150kN, loading speed at 4~6kN / s, more preferably 5 kN / s; Preferably, the sample tablets after compression and drying are placed in a high-temperature calcination furnace for calcination. The calcination process is carried out in two stages: the first stage calcination temperature is 850~950℃, the heating time is 25~35min, and the holding time is 8~12min; the second stage calcination temperature is 1300~1350℃, the heating time is 35~45min, and the holding time is 100~140min; more preferably, the first stage calcination temperature is 900℃, the heating time is 30min, and the holding time is 10min; the second stage calcination temperature is 1300~1350℃, the heating time is 40min, and the holding time is 120min.

7. The high-temperature enhanced micro-expansion cement slurry system according to claim 1, characterized in that, The high-temperature expansion material contains dolomite with a purity ≥95%, and its chemical composition is: MgO > 20 wt.%, CaO > 28 wt.%. Serpentine purity ≥ 95%, its chemical composition is: MgO > 40 wt.%, SiO2 > 40 wt.%; The purity of calcium iron pyroxene is ≥90%, and its chemical composition is: CaO > 20 wt.%, SiO2 > 43 wt.%, FeO > 26 wt.%; The purity of calcium zeolite is ≥90%, and its chemical composition is: CaO > 12 wt.%, Al2O3 > 23 wt.%, SiO2 > 41 wt.%; The fineness of the slaked lime powder is ≥325 mesh, and its chemical composition content is: CaO > 74 wt.%; Quartz powder with a fineness ≥325 mesh and a chemical composition content of SiO2 >98wt.%.

8. A high-temperature enhanced micro-expansion cement slurry system according to any one of claims 1 to 7, characterized in that, The suspended filtration loss reduction material is a mixture of palygorskite powder, sepiolite powder and ultrafine calcium carbonate in a mass ratio of (15-25):(15-25):(50-70); Preferably, the purity of palygorskite powder is ≥90 wt.%, and the fineness of the powder is ≥500 mesh; Preferably, the purity of sepiolite powder is ≥90wt.%, and the fineness of the powder is ≥600 mesh; Preferably, the purity of the ultrafine calcium carbonate is ≥95wt.%, and the fineness of the powder is ≥800 mesh.

9. A high-temperature enhanced micro-expansion cement slurry system according to any one of claims 1 to 6, characterized in that, The high-temperature water loss reducing agent is an AMPS anionic polymer; Preferably, the high-temperature retarder is an AMPS copolymer system.

10. A method for preparing a high-temperature enhanced micro-expansion cement slurry system according to any one of claims 1-9, characterized in that, The process includes the following steps: preparing low-heat silicate cement, type I reinforcing anti-fading material, type II reinforcing anti-fading material, type III reinforcing anti-fading material, high-temperature expansion material, suspension filtration loss reducing material, high-temperature water loss reducing agent and high-temperature retarder in proportion, mixing them evenly, adding water to make slurry, and thus obtaining the final product.

11. The method for preparing a high-temperature enhanced micro-expansion cement slurry system according to claim 10, characterized in that, The amount of water added during pulping is 59-64 parts.

12. The application of a high-temperature enhanced micro-expansion cement slurry system according to any one of claims 1-9, characterized in that, Its application as a cementing material in oil and gas well engineering is preferably as a sealing material for deep wells and / or ultra-deep wells.

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