A high-temperature resistant cement slurry system for 10,000-meter deep wells

Abstract

The present invention discloses a high-temperature resistant cementing slurry system for 10,000-meter deep wells, relating to the technical field of cementing materials for oil and gas well engineering. The cementing slurry system of the present invention comprises the following components, measured by weight: 100 parts of low-heat Portland cement, 10-20 parts of an anti-abnormal gelling material, 35-55 parts of an enhanced anti-fading material, 10-20 parts of a suspended fluid loss reducer, 6-8 parts of a high-temperature fluid loss reducer, and 2-5 parts of a high-temperature retarder; wherein the anti-abnormal gelling material comprises, by weight, ulexite: colemanite: ulexite: chollastone = (40-60): (20-40): (10-20): (5-15). The present invention reduces the hydration rate of the slurry under high-temperature conditions by limiting the dicalcium silicate content in the cement components and reducing the specific surface area of ​​the cement, thereby suppressing the rapid abnormal gelling of the cement slurry. The anti-abnormal gelling material, based on the perspective of cement hydration products, addresses the abnormal gelling effect of cement mineral component fluctuations in different batches on the cement slurry, while also ensuring stable control of other properties of the slurry.

Description

Technical Field

[0001] The present invention relates to the technical field of cementing materials for oil and gas well engineering, and more particularly to a high-temperature resistant cementing slurry system for 10,000-meter deep wells. Background Art

[0002] Deep and ultra-deep oil and gas resources have become a key area for increasing reserves and production in my country's oil and gas reservoirs. During oil and gas well development, cementing is a key engineering technology for ensuring safe production throughout the wellbore's lifecycle and achieving profitable development. However, cementing deep wells, even ultra-deep wells exceeding 10,000 meters, faces ultra-high temperatures and high pressures, which can easily lead to abnormal gelation of the cement slurry, poor slurry suspension stability, and a rapid decline in cement stone strength. This, in turn, affects cementing construction safety and the quality of long-term wellbore isolation. Therefore, it is urgent to address these issues in order to achieve stable control of the working performance of ultra-high-temperature cement slurry systems.

[0003] Existing technical approaches primarily adjust cement slurry performance through aspects such as strength decay resistance and admixture synthesis optimization. For example, the invention patent application, entitled "A High-Temperature Resistant Cementing Slurry System," published on April 28, 2020, with application publication number CN111072350A, specifically discloses that the system consists of 60-75% Portland cement; 15-25% strength decay agent; 2-8% crystal stabilizer; 0.5-6% high-temperature retarder; and 3-8% high-temperature fluid loss additive. Crystal stabilizers are primarily added to the slurry to participate in the hydration reaction during hydration. Metal ions enter the structure of the hydrated calcium silicate, preventing the conversion of tobermorite to xonotlite in the hydration product, thereby maintaining a dense structure and imparting excellent high-temperature stability.

[0004] For example, the invention patent application, entitled "A High-Temperature Strength-Degradation Resistant Oil Well Cement Slurry System," published on November 8, 2022, with application publication number CN115304317A, specifically discloses that the system consists of 47.5-72.5 wt% of cementitious material; 15-25 wt% of silica sand; 10-25 wt% of high-temperature strength-degradation resistant material; 2 wt% of high-temperature stabilizer; and 0.5 wt% of dispersant. This system exhibits the advantages of high-temperature strength-degradation resistance and stable high-temperature performance, effectively alleviating the strength degradation problem of cement paste under high-temperature conditions and meeting the requirements of oil and gas well cementing.

[0005] For example, the invention patent application, entitled "A suspension stabilizer for high-temperature cement slurry and high-temperature-resistant cement slurry prepared therefrom," published on October 26, 2018, with application publication number CN108706927A, specifically discloses that the suspension stabilizer comprises 0.5 to 4 parts of a fiber material, 1 to 5 parts of a surfactant powder material, and 0.5 to 2 parts of a flocculant powder material. The high-temperature-resistant cement slurry prepared using the suspension stabilizer exhibits a low initial consistency and good sedimentation stability.

[0006] For example, the invention patent application, entitled "High-temperature-resistant polymer suspension stabilizer slurry for oil well cement and preparation method thereof," published on December 3, 2021, with application publication number CN113736016A, specifically discloses that the system consists of Portland cement, silica fume, a fluid loss additive, a retarder SD210, a defoamer, slurry preparation water, and a high-temperature-resistant polymer suspension stabilizer. The disclosed high-temperature-resistant suspension stabilizer can withstand temperatures up to 200°C, preventing a significant decrease in polymer viscosity due to thermal degradation at high temperatures, thereby enhancing its high-temperature suspension capacity.

[0007] In general, the above-mentioned technical means mainly optimize a specific problem faced by high-temperature cement slurry, and rarely consider the overall performance of the cement slurry system. At the same time, there is also a lack of ideas for dealing with the abnormal gelation phenomenon caused by high-temperature cement slurry. Therefore, it is difficult to ensure the stable performance control of cement slurry throughout the life cycle of the wellbore. Summary of the Invention

[0008] In order to overcome the defects and shortcomings of the above-mentioned prior art, the present invention provides a high-temperature resistant cement cementing slurry system for 10,000-meter deep wells. The purpose of the present invention is to solve the problem of abnormal gelation of high-temperature cement slurry, while at the same time achieving stable control of other properties of the slurry.

[0009] In order to solve the above problems in the prior art, the present invention is implemented through the following technical solutions.

[0010] The present invention provides a high-temperature resistant cement slurry system for a 10,000-meter deep well. The cement slurry system comprises the following components in parts by weight:

[0011] 100 parts of low-heat Portland cement;

[0012] 10~20 parts of anti-abnormal gelling material;

[0013] 35~55 parts of enhanced anti-recession material;

[0014] 10-20 parts of suspended fluid loss material;

[0015] 6-8 parts of high temperature fluid loss additive;

[0016] 2~5 parts of high temperature retarder;

[0017] The C2S content of the low-heat Portland cement is ≥45 wt.%, and the specific surface area is controlled between 260 and 300 m 2 / kg, 7d hydration heat ≤ 250kJ / kg;

[0018] The anti-abnormal gelling material comprises the following components in parts by weight: 40-60 parts of ulexite, 20-40 parts of colemanite, 10-20 parts of sillimanite, and 5-15 parts of chondrite; the chemical composition requirements of the anti-abnormal gelling material for cementing slurry are: 37wt.%<B2O3≤55wt.%, 11wt.%<CaO≤21wt.%, 5wt.%<SiO2≤13wt.%, 6wt.%<Na2O≤12wt.%, 1wt.%<SO3≤6wt.%, 1wt.%<CuO≤6wt.%, and the sum of the mass percentages of each chemical component is 100wt.%; the particle fineness requirements of the anti-abnormal gelling material for cementing slurry are Dx(10)≤5μm, Dx(50)≤14μm, and Dx(90)≤30μm.

[0019] Further preferably, the purity of ulexite in the abnormality-preventing gelling material is required to be ≥90wt.%, and the chemical composition requirements thereof are: Na2O>6wt.%, CaO>12wt.%, and B2O3>38wt.%.

[0020] Further preferably, the purity of colemanite in the abnormality-preventing gelling material is required to be ≥90wt.%, and the chemical composition requirements are: CaO>18wt.%, B2O3>33wt.%.

[0021] Further preferably, the purity of leucite in the abnormality-preventing gelling material is required to be ≥90wt.%, and the chemical composition requirements are: Na2O>22wt.%, SiO2>42wt.%, and B2O3>24wt.%.

[0022] Further preferably, the purity of the gallstone in the abnormality-preventing gelling material is required to be ≥90wt.%, and the chemical composition requirements are: CuO>28wt.%, SO3>28wt.%.

[0023] More preferably, the abnormality-preventing gelling material is obtained by processing through the following steps:

[0024] S1. Evenly mix 40-60 parts of ulexite, 20-40 parts of colemanite, and 10-20 parts of leucite, and crush the mixture after even mixing, with a crushing ratio controlled at 40-70; grind the crushed mixture into a mixed fine material, with a crushing ratio controlled at 400-900; send the crushed mixed fine material to a high-temperature calcining furnace for calcination, with the calcination temperature controlled at 800° C.-1500° C.; after calcination, quickly cool the mixture to room temperature, with a cooling time controlled at 10-20 min; and obtain a Class A mixture after cooling;

[0025] S2. Mix the Class A mixture prepared in step S1 with 5 to 15 parts of gallstones, grind the mixture evenly, and obtain Class B mixture after grinding. The particle fineness requirements of the Class B mixture are Dx(10)≤5μm, Dx(50)≤14μm, and Dx(90)≤30μm.

[0026] S3, subjecting the Class B mixture to a coating treatment, specifically, adding the Class B mixture to a coating solution, mixing evenly, reacting for a set time, and vacuum drying to obtain the abnormality-preventing gelling material.

[0027] More preferably, the coating solution in step S3 comprises the following components by mass ratio:

[0028] Anhydrous ethanol: phenolic resin: polymethyl methacrylate: dimethyl phthalate: diethyl phthalate = (55~70): (15~25): (5~10): (5~10): (5~10).

[0029] More preferably, the concentration of the plating solution in step S3 is 55 wt.% to 85 wt.%.

[0030] More preferably, in step S3, the ratio of the type B mixture to the plating solution is 1:(5-20).

[0031] More preferably, in step S3, the reaction time is set to 5-35 min; and the vacuum drying temperature is 35° C.-55° C.

[0032] Further preferably, the reinforcing anti-recession material is a mixture of quartz sand and metakaolin, wherein the mass ratio is quartz sand:metakaolin = (80-90): (10-20).

[0033] More preferably, the quartz sand has a composition of SiO2 ≥ 98 wt.%, and a powder fineness ≥ 325 mesh; the metakaolin has a composition of Al2O3 ≥ 45 wt.%, and SiO2 ≥ 45 wt.%, and a powder fineness ≥ 800 mesh.

[0034] Further preferably, the suspended fluid loss material is a mixture of ultrafine calcium carbonate and dolomite fine powder, wherein the mass ratio of ultrafine calcium carbonate: dolomite fine powder is (30-70): (30-70).

[0035] More preferably, the ultrafine calcium carbonate has a purity of ≥90wt.%, and a powder fineness of ≥800 mesh; the dolomite fine powder has a purity of ≥90wt.%, and a powder fineness of ≥1000 mesh.

[0036] Further preferably, the high-temperature fluid loss additive is an AMPS anionic polymer.

[0037] More preferably, the high-temperature retarder is an AMPS copolymer system.

[0038] Compared with the prior art, the beneficial technical effects brought about by the present invention are as follows:

[0039] 1. The present invention adopts low-heat Portland cement as the cement base material. By limiting the content of dicalcium silicate in the cement component and reducing the specific surface area of ​​the cement, the hydration rate of the slurry in a high-temperature environment is alleviated, which can inhibit the rapid abnormal gelation of the cement slurry to a certain extent, and is conducive to the adjustment of the slurry construction performance.

[0040] 2. The suspended fluid loss reducing material used in the present invention, on the one hand, utilizes the characteristics of the material such as small particle size, large specific surface area, and high surface activity to reduce the distance between solid phase particles in the cement slurry, thereby increasing viscosity and thickening; on the other hand, it utilizes the principle of particle grading to improve the pore structure of the cement filter cake through "bridging" and blocking, forming a thin and dense filter cake to achieve the purpose of reducing water loss.

[0041] 3. The anti-abnormal gelling material used in the present invention can solve the abnormal gelling effect on cement slurry caused by fluctuations in cement mineral components in different batches from the perspective of cement hydration products.

[0042] The solution is as follows: different batches of cement have different tricalcium aluminate contents in their mineral components, and thus different aluminum ion contents in the cement slurry. Tricalcium aluminate hydrates very quickly, quickly forming hydrated calcium aluminate gel products in the cement slurry, causing abnormal gelling phenomena such as thickening of the cement slurry. In addition, when the aluminum ion concentration in the cement slurry reaches a certain level, it will combine and cross-link with the calcium ions and the high molecular chains in the polymer admixture to form a mutually doped cross-linked network structure, resulting in abnormal gelling of the cement slurry (the thickening curve shows "bulging" and "core-encapsulation" phenomena). The anti-abnormal gelling material used in the present invention releases sulfate ions through a hydrolysis reaction, which react with aluminum ions and calcium ions under medium-high temperature hydrothermal conditions to form monosulfurized calcium sulfoaluminate. On the one hand, the aluminum ion content in the cement slurry is reduced, preventing the aluminum ions from forming a mutually doped cross-linked network structure with other ions and the high molecular chains in the polymer admixture; on the other hand, the monosulfurized calcium sulfoaluminate is wrapped around the surface of tricalcium aluminate to prevent its rapid hydration, thereby preventing the rapid formation of hydrated calcium aluminate in the cement slurry, thereby preventing abnormal gelling of the cement slurry.

[0043] Therefore, no matter how the cement batches and their mineral components change, the main difference is the difference in the aluminum phase content in the cement components. This technical means solves the abnormal gelling effect of aluminum ions on cement slurry from the root, so that the anti-abnormal gelling material of the present invention can adapt to different batches of cement.

[0044] 4. The anti-abnormal gelling material used in this invention effectively suppresses abnormal gelling caused by complexation between admixtures and cement components. The mechanism of action is as follows: the polymer molecules in the polymer admixture compete for calcium ions in the cement slurry. Typically, multiple polymer molecules chelate one calcium ion, resulting in a bridged network of long-chain polymers and abnormal gelling of the cement slurry. The anti-abnormal gelling material used in the present invention releases borate ions and copper ions through a hydrolysis reaction. On the one hand, the copper ions deprive the polymer molecules of chelated calcium ions. Since the relative atomic mass of copper ions is larger than that of calcium ions, the copper ions in the cement slurry will carry the chelated polymer molecules downward, thereby separating multiple polymer molecules. On the other hand, the borate ions also snatch the chelated calcium ions from the polymer molecules, preferentially forming calcium borate. The calcium borate quickly wraps around the surfaces of tricalcium silicate and dicalcium silicate, preventing them from undergoing hydration reactions and thereby prolonging the thickening time of the cement slurry. At this time, the deprived polymer molecules are evenly dispersed in the cement slurry in a flowing state, thereby inhibiting the formation of a bridging network of high-molecular-weight long-chain polymers and preventing abnormal gelling of the cement slurry.

[0045] 5. In the preparation of the abnormal-proof cementitious material of the present invention, the Class B mixture is subjected to a coating treatment. The purpose is that the sulfate component in the Class B mixture undergoes a hydrolysis reaction during the cement slurry preparation process, and the released sulfate ions react with the aluminum ions and calcium ions in the cement slurry to form ettringite. Under low temperature conditions (generally below 70°C), ettringite is relatively stable. The formation of ettringite consumes a large amount of water. At the same time, the needle-shaped ettringite intersperses and intertwines, which can easily cause the cement slurry to thicken rapidly in a short period of time (mainly manifested in the "bulge" phenomenon on the cementing cement slurry thickening curve), seriously affecting the safety of cementing construction. Therefore, a coating method is adopted to form a plastic resin protective film on the surface of the Class B mixture particles. Under low temperature conditions, it can effectively prevent the sulfate component in the Class B mixture from reacting with water, reducing the concentration of sulfate ions in the cement slurry, thereby preventing the formation of ettringite. At this time, the Class B mixture is evenly dispersed in the cement slurry as a filling material. As the temperature rises during the grouting process, the resin protective film begins to decompose (generally above 70°C), and the Class B mixture begins to hydrolyze. Although the sulfate ion concentration in the cement slurry will increase at this time, the generated ettringite is extremely unstable in medium and high temperature environments and will decompose rapidly, which will not cause the cementing cement slurry to thicken rapidly, thereby ensuring the smooth progress of cementing construction.

[0046] 6. The coating solution used in preparing the abnormal gelling material of the present invention can be any conventional coating solution, as long as it can form a plastic resin protective film on the surface of the Class B mixed material particles and the resin protective film can be decomposed above 70°C. As a preferred embodiment of the present invention, the coating solution used in the present invention comprises anhydrous ethanol, phenolic resin, polymethyl methacrylate, dimethyl phthalate, and diethyl phthalate, compounded in a predetermined ratio. The constituent monomers and the ratio are optimized.

[0047] 7. 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 various performances of the cementing slurry system obtained after the materials are compounded meet the expected requirements. On the other hand, it can improve the compounding success rate of the cement slurry system and bring out the best performance of each material. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a graph showing the thickening curve test results of the cement slurry system provided in Example 1 of the present invention;

[0049] Figure 2 This is a graph showing the thickening curve test results of the cement slurry system provided in Comparative Example 1 of the present invention;

[0050] Figure 3 This is a graph showing the thickening curve test results of a cement slurry system provided in Example 2 of the present invention;

[0051] Figure 4 This is a graph showing the thickening curve test results of a cement slurry system provided in Example 3 of the present invention;

[0052] Figure 5 This is a graph showing the thickening curve test results of a cement slurry system provided in Example 4 of the present invention;

[0053] Figure 6 This is a graph showing the thickening curve test results of the cement slurry system provided in Example 5 of the present invention. DETAILED DESCRIPTION

[0054] The following will clearly and completely describe the technical solutions of the present invention in conjunction with specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] The following examples all prepared cement slurries according to GB / T 19139-2012. In the cement slurry systems listed in the examples, low-heat Portland cement was provided by Jiahua Special Cement Co., Ltd. The raw materials used in the anti-fading reinforcement and suspended fluid loss control materials were all commercially available. The high-temperature fluid loss additive and high-temperature retarder were both provided by Puyang Zhenghe Petroleum Engineering Technology Co., Ltd. The liquid-to-solid ratio of the cement slurry system is 0.44 .

[0056] Example 1

[0057] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant cementing slurry system for 10,000-meter deep wells, including the following components by weight: 100 parts of low-heat silicate cement, 10 parts of anti-abnormal gelling material, 35 parts of enhanced anti-recession material, 10 parts of suspended fluid loss reducing material, 6 parts of high-temperature fluid loss reducing agent, 2 parts of high-temperature retarder, and 60 parts of water.

[0058] The C2S content of the low-heat Portland cement is ≥45 wt.%, and the specific surface area is controlled between 260 and 300 m 2 / kg, 7d hydration heat ≤250kJ / kg; the enhanced anti-recession material is a mixture of quartz sand and metakaolin, wherein the mass ratio is quartz sand: metakaolin = 80:20; the quartz sand has SiO2 ≥ 98 wt.%, and the powder fineness ≥ 325 mesh; the metakaolin has Al2O3 ≥ 45 wt.%, SiO2 ≥ 45 wt.%, and the powder fineness ≥ 800 mesh; the suspended fluid loss reducing material is a mixture of ultrafine calcium carbonate and dolomite fine powder, wherein the mass ratio is ultrafine calcium carbonate: dolomite fine powder = 30:70; the ultrafine calcium carbonate has a purity of ≥90 wt.%, and the powder fineness ≥800 mesh; the dolomite fine powder has a purity of ≥90 wt.%, and the powder fineness ≥1000 mesh; the high-temperature fluid loss reducer is an AMPS anionic polymer; and the high-temperature retarder is an AMPS copolymer system;

[0059] The abnormal gelling material includes the following components in parts by weight: 60 parts of ulexite, 25 parts of colemanite, 10 parts of leonite and 5 parts of chalcanthite.

[0060] In this embodiment, the anti-abnormal gelling material is prepared by the following preparation method:

[0061] S1. 60 parts by weight of ulexite, 25 parts by weight of colemanite and 10 parts by weight of leucite are mixed uniformly, and then crushed by a grinding mill with a crushing ratio controlled at 60; the crushed mixture is sent to a ball mill and ground into a mixed fine material with a crushing ratio controlled at 700; the crushed mixed fine material is then sent to a high-temperature calcining furnace for calcination with a calcination temperature controlled at 1350° C. After calcination, the mixture is rapidly cooled to room temperature by a cooler with a cooling time controlled at 20 min to obtain a Class A mixture.

[0062] S2. The Class A mixture prepared in step S1 is mixed evenly with 5 parts by weight of gallstones, and then sent to a ball mill for grinding to obtain a Class B mixture after fine grinding; the particle fineness requirements of the Class B mixture are Dx(10)≤5μm, Dx(50)≤14μm, and Dx(90)≤30μm.

[0063] S3. The Class B mixture is subjected to a coating treatment, specifically, 100 parts by weight of the Class B mixture is added to 500 parts by weight of a coating solution having a concentration of 80 wt.%, mixed evenly and reacted for 5 minutes, and then placed in a vacuum drying oven at 35° C. and dried to obtain the abnormality-proof gelling material.

[0064] The chemical composition requirements of the above-mentioned anti-abnormal gelling material are: 37wt.%<B2O3≤55wt.%, 11wt.%<CaO≤21wt.%, 5wt.%<SiO2≤13wt.%, 6wt.%<Na2O≤12wt.%, 1wt.%<SO3≤6wt.%, 1wt.%<CuO≤6wt.%.

[0065] As an example, in order to meet the chemical composition requirements of the above-mentioned anti-abnormal cementitious material, the purity and chemical composition of ulexite, colemanite, leucite, and chalcanthite can be limited, that is, the selection of ulexite, colemanite, leucite, and chalcanthite materials. Specifically, the ulexite purity requirement is ≥90wt.%, and its chemical composition requirements are: Na2O>6wt.%, CaO>12wt.%, B2O3>38wt.%; the colemanite purity requirement is ≥90wt.%, and its chemical composition requirements are: CaO>18wt.%, B2O3>33wt.%; the leucite purity requirement is ≥90wt.%, and its chemical composition requirements are: Na2O>22wt.%, SiO2>42wt.%, B2O3>24wt.%; the chalcanthite purity requirement is ≥90wt.%, and its chemical composition requirements are: CuO>28wt.%, SO3>28wt.%.

[0066] In this embodiment, when preparing the anti-abnormal gelling material, the coating solution used is composed of anhydrous ethanol, phenolic resin, polymethyl methacrylate, dimethyl phthalate and diethyl phthalate, and the mass ratio is anhydrous ethanol:phenolic resin:polymethyl methacrylate:dimethyl phthalate:diethyl phthalate=65:15:10:5:5.

[0067] Example 2

[0068] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant cementing slurry system for 10,000-meter deep wells, including the following components by weight: 100 parts of low-heat silicate cement, 13 parts of anti-abnormal gelling material, 40 parts of enhanced anti-recession material, 13 parts of suspended fluid loss reducing material, 6.5 parts of high-temperature fluid loss reducing agent, 2.5 parts of high-temperature retarder, and 64 parts of water.

[0069] The C2S content of the low-heat Portland cement is ≥45 wt.%, and the specific surface area is controlled between 260 and 300 m 2 / kg, 7d hydration heat ≤250kJ / kg; the enhanced anti-recession material is a mixture of quartz sand and metakaolin, wherein the mass ratio is quartz sand:metakaolin = 83:17; the quartz sand has SiO2 ≥ 98 wt.%, and the powder fineness ≥ 325 mesh; the metakaolin has Al2O3 ≥ 45 wt.%, SiO2 ≥ 45 wt.%, and the powder fineness ≥ 800 mesh; the suspended fluid loss material is a mixture of ultrafine calcium carbonate and dolomite fine powder, wherein the mass ratio is ultrafine calcium carbonate: dolomite fine powder = 40:60; the ultrafine calcium carbonate has a purity of ≥90 wt.%, and the powder fineness ≥800 mesh; the dolomite fine powder has a purity of ≥90 wt.%, and the powder fineness ≥1000 mesh; the high-temperature fluid loss additive is an AMPS anionic polymer; and the high-temperature retarder is an AMPS copolymer system;

[0070] The abnormal gelling material includes the following components in parts by weight: 40 parts of ulexite, 35 parts of colemanite, 20 parts of leonite and 5 parts of chalcanthite.

[0071] In this embodiment, the anti-abnormal gelling material is prepared by the following preparation method:

[0072] S1. 40 parts by weight of ulexite, 35 parts by weight of colemanite and 20 parts by weight of leucite are mixed uniformly, and then crushed by a grinding mill with a crushing ratio controlled at 65; the crushed mixture is sent to a ball mill and ground into a mixed fine material with a crushing ratio controlled at 750; the crushed mixed fine material is then sent to a high-temperature calcining furnace for calcination at a calcination temperature of 1200° C. After calcination, the mixture is rapidly cooled to room temperature by a cooler with a cooling time controlled at 15 min to obtain a Class A mixture.

[0073] S2. The Class A mixture prepared in step S1 is mixed evenly with 5 parts by weight of gallstones, and then sent to a ball mill for grinding to obtain a Class B mixture after fine grinding; the particle fineness requirements of the Class B mixture are Dx(10)≤5μm, Dx(50)≤14μm, and Dx(90)≤30μm.

[0074] S3. The Class B mixture is subjected to a coating treatment, specifically, 100 parts by weight of the Class B mixture is added to 1000 parts by weight of a 75 wt.% coating solution, mixed evenly and reacted for 10 minutes, and then placed in a vacuum drying oven at 40° C. and dried to obtain the abnormality-proof gelling material.

[0075] The chemical composition requirements of the above-mentioned anti-abnormal gelling material are: 37wt.%<B2O3≤55wt.%, 11wt.%<CaO≤21wt.%, 5wt.%<SiO2≤13wt.%, 6wt.%<Na2O≤12wt.%, 1wt.%<SO3≤6wt.%, 1wt.%<CuO≤6wt.%.

[0076] As an example, in order to meet the chemical composition requirements of the above-mentioned anti-abnormal cementitious material, the purity and chemical composition of ulexite, colemanite, leucite, and chalcanthite can be limited, that is, the selection of ulexite, colemanite, leucite, and chalcanthite materials. Specifically, the ulexite purity requirement is ≥90wt.%, and its chemical composition requirements are: Na2O>6wt.%, CaO>12wt.%, B2O3>38wt.%; the colemanite purity requirement is ≥90wt.%, and its chemical composition requirements are: CaO>18wt.%, B2O3>33wt.%; the leucite purity requirement is ≥90wt.%, and its chemical composition requirements are: Na2O>22wt.%, SiO2>42wt.%, B2O3>24wt.%; the chalcanthite purity requirement is ≥90wt.%, and its chemical composition requirements are: CuO>28wt.%, SO3>28wt.%.

[0077] In this embodiment, when preparing the anti-abnormal gelling material, the coating solution used is composed of anhydrous ethanol, phenolic resin, polymethyl methacrylate, dimethyl phthalate and diethyl phthalate, and the mass ratio is anhydrous ethanol:phenolic resin:polymethyl methacrylate:dimethyl phthalate:diethyl phthalate=55:20:8:10:7.

[0078] Example 3

[0079] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant cementing slurry system for 10,000-meter deep wells, including the following components by weight: 100 parts of low-heat silicate cement, 15 parts of anti-abnormal gelling material, 45 parts of enhanced anti-recession material, 15 parts of suspended fluid loss reducing material, 7 parts of high-temperature fluid loss reducing agent, 3 parts of high-temperature retarder, and 67 parts of water.

[0080] The C2S content of the low-heat Portland cement is ≥45 wt.%, and the specific surface area is controlled between 260 and 300 m 2 / kg, 7d hydration heat ≤250kJ / kg; the enhanced anti-recession material is a mixture of quartz sand and metakaolin, wherein the mass ratio is quartz sand: metakaolin = 85:15; the quartz sand has SiO2 ≥ 98 wt.%, and the powder fineness ≥ 325 mesh; the metakaolin has Al2O3 ≥ 45 wt.%, SiO2 ≥ 45 wt.%, and the powder fineness ≥ 800 mesh; the suspended fluid loss material is a mixture of ultrafine calcium carbonate and dolomite fine powder, wherein the mass ratio is ultrafine calcium carbonate: dolomite fine powder = 50:50; the ultrafine calcium carbonate has a purity of ≥90 wt.%, and the powder fineness ≥ 800 mesh; the dolomite fine powder has a purity of ≥90 wt.%, and the powder fineness ≥ 1000 mesh; the high-temperature fluid loss additive is an AMPS anionic polymer; and the high-temperature retarder is an AMPS copolymer system;

[0081] The abnormal gelling material includes the following components in parts by weight: 40 parts of ulexite, 35 parts of colemanite, 10 parts of leonite and 15 parts of chalcanthite.

[0082] In this embodiment, the anti-abnormal gelling material is prepared by the following preparation method:

[0083] S1. 40 parts by weight of ulexite, 35 parts by weight of colemanite and 10 parts by weight of leonidite are mixed uniformly, and then crushed by a grinding mill with a crushing ratio controlled at 70; the crushed mixture is sent to a ball mill and ground into a mixed fine material with a crushing ratio controlled at 800; the crushed mixed fine material is then sent to a high-temperature calcining furnace for calcination at a calcination temperature of 1000° C. After calcination, the mixture is rapidly cooled to room temperature by a cooler with a cooling time controlled at 10 min to obtain a Class A mixture.

[0084] S2. The Class A mixture prepared in step S1 is mixed evenly with 15 parts by weight of gallstones, and then sent to a ball mill for grinding to obtain a Class B mixture after fine grinding; the particle fineness requirements of the Class B mixture are Dx(10)≤5μm, Dx(50)≤14μm, and Dx(90)≤30μm.

[0085] S3. The Class B mixture is subjected to a coating treatment, specifically, 100 parts by weight of the Class B mixture is added to 1500 parts by weight of a 70 wt.% coating solution, mixed evenly and reacted for 15 minutes, and then placed in a 45° C. vacuum drying oven to obtain the abnormality-proof gelling material.

[0086] The chemical composition requirements of the above-mentioned anti-abnormal gelling material are: 37wt.%<B2O3≤55wt.%, 11wt.%<CaO≤21wt.%, 5wt.%<SiO2≤13wt.%, 6wt.%<Na2O≤12wt.%, 1wt.%<SO3≤6wt.%, 1wt.%<CuO≤6wt.%.

[0087] As an example, in order to meet the chemical composition requirements of the above-mentioned anti-abnormal cementitious material, the purity and chemical composition of ulexite, colemanite, leucite, and chalcanthite can be limited, that is, the selection of ulexite, colemanite, leucite, and chalcanthite materials. Specifically, the ulexite purity requirement is ≥90wt.%, and its chemical composition requirements are: Na2O>6wt.%, CaO>12wt.%, B2O3>38wt.%; the colemanite purity requirement is ≥90wt.%, and its chemical composition requirements are: CaO>18wt.%, B2O3>33wt.%; the leucite purity requirement is ≥90wt.%, and its chemical composition requirements are: Na2O>22wt.%, SiO2>42wt.%, B2O3>24wt.%; the chalcanthite purity requirement is ≥90wt.%, and its chemical composition requirements are: CuO>28wt.%, SO3>28wt.%.

[0088] In this embodiment, when preparing the anti-abnormal gelling material, the coating solution used is composed of anhydrous ethanol, phenolic resin, polymethyl methacrylate, dimethyl phthalate and diethyl phthalate, and the mass ratio is anhydrous ethanol: phenolic resin: polymethyl methacrylate: dimethyl phthalate: diethyl phthalate = 55:25:10:5:5.

[0089] Example 4

[0090] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant cementing slurry system for 10,000-meter deep wells, including the following components in parts by weight: 100 parts of low-heat silicate cement, 17 parts of anti-abnormal gelling material, 50 parts of enhanced anti-recession material, 17 parts of suspended fluid loss reducing material, 7.5 parts of high-temperature fluid loss reducing agent, 4 parts of high-temperature retarder, and 69 parts of water.

[0091] The C2S content of the low-heat Portland cement is ≥45 wt.%, and the specific surface area is controlled between 260 and 300 m 2 / kg, 7d hydration heat ≤250kJ / kg; the enhanced anti-recession material is a mixture of quartz sand and metakaolin, wherein the mass ratio is quartz sand:metakaolin = 88:12; the quartz sand has SiO2 ≥ 98 wt.%, and the powder fineness ≥ 325 mesh; the metakaolin has Al2O3 ≥ 45 wt.%, SiO2 ≥ 45 wt.%, and the powder fineness ≥ 800 mesh; the suspended fluid loss material is a mixture of ultrafine calcium carbonate and dolomite fine powder, wherein the mass ratio is ultrafine calcium carbonate: dolomite fine powder = 60:40; the ultrafine calcium carbonate has a purity of ≥90 wt.%, and the powder fineness ≥ 800 mesh; the dolomite fine powder has a purity of ≥90 wt.%, and the powder fineness ≥ 1000 mesh; the high-temperature fluid loss additive is an AMPS anionic polymer; and the high-temperature retarder is an AMPS copolymer system;

[0092] The abnormal gelling material includes the following components in parts by weight: 50 parts of ulexite, 20 parts of colemanite, 15 parts of leonite and 15 parts of chalcanthite.

[0093] In this embodiment, the anti-abnormal gelling material is prepared by the following preparation method:

[0094] S1. 50 parts by weight of ulexite, 20 parts by weight of colemanite and 15 parts by weight of leonidite are mixed uniformly, and then crushed by a grinding mill with a crushing ratio controlled at 40; the crushed mixture is sent to a ball mill and ground into a mixed fine material with a crushing ratio controlled at 400; the crushed mixed fine material is then sent to a high-temperature calcining furnace for calcination at a calcination temperature of 800°C. After calcination, the mixture is rapidly cooled to room temperature by a cooler with a cooling time controlled at 10 min to obtain a Class A mixture.

[0095] S2. The Class A mixture prepared in step S1 is mixed evenly with 15 parts by weight of gallstones, and then sent to a ball mill for grinding to obtain a Class B mixture after fine grinding; the particle fineness requirements of the Class B mixture are Dx(10)≤5μm, Dx(50)≤14μm, and Dx(90)≤30μm.

[0096] S3. The Class B mixture is subjected to a coating treatment, specifically, 100 parts by weight of the Class B mixture is added to 2000 parts by weight of a 55 wt.% coating solution, mixed evenly and reacted for 25 minutes, and then placed in a 50° C. vacuum drying oven to obtain the abnormality-proof gelling material.

[0097] The chemical composition requirements of the above-mentioned anti-abnormal gelling material are: 37wt.%<B2O3≤55wt.%, 11wt.%<CaO≤21wt.%, 5wt.%<SiO2≤13wt.%, 6wt.%<Na2O≤12wt.%, 1wt.%<SO3≤6wt.%, 1wt.%<CuO≤6wt.%.

[0098] As an example, in order to meet the chemical composition requirements of the above-mentioned anti-abnormal cementitious material, the purity and chemical composition of ulexite, colemanite, leucite, and chalcanthite can be limited, that is, the selection of ulexite, colemanite, leucite, and chalcanthite materials. Specifically, the ulexite purity requirement is ≥90wt.%, and its chemical composition requirements are: Na2O>6wt.%, CaO>12wt.%, B2O3>38wt.%; the colemanite purity requirement is ≥90wt.%, and its chemical composition requirements are: CaO>18wt.%, B2O3>33wt.%; the leucite purity requirement is ≥90wt.%, and its chemical composition requirements are: Na2O>22wt.%, SiO2>42wt.%, B2O3>24wt.%; the chalcanthite purity requirement is ≥90wt.%, and its chemical composition requirements are: CuO>28wt.%, SO3>28wt.%.

[0099] In this embodiment, when preparing the anti-abnormal gelling material, the coating solution used is composed of anhydrous ethanol, phenolic resin, polymethyl methacrylate, dimethyl phthalate and diethyl phthalate, and the mass ratio is anhydrous ethanol: phenolic resin: polymethyl methacrylate: dimethyl phthalate: diethyl phthalate = 70:15:5:5:5.

[0100] Example 5

[0101] As a preferred embodiment of the present invention, this embodiment discloses a high-temperature resistant cementing slurry system for 10,000-meter deep wells, including the following components by weight: 100 parts of low-heat silicate cement, 20 parts of anti-abnormal gelling material, 55 parts of enhanced anti-recession material, 20 parts of suspended fluid loss reducing material, 8 parts of high-temperature fluid loss reducing agent, 5 parts of high-temperature retarder, and 73 parts of water.

[0102] The C2S content of the low-heat Portland cement is ≥45 wt.%, and the specific surface area is controlled between 260 and 300 m 2 / kg, 7d hydration heat ≤250kJ / kg; the enhanced anti-recession material is a mixture of quartz sand and metakaolin, wherein the mass ratio is quartz sand: metakaolin = 90:10; the quartz sand has SiO2 ≥ 98 wt.%, and the powder fineness ≥ 325 mesh; the metakaolin has Al2O3 ≥ 45 wt.%, SiO2 ≥ 45 wt.%, and the powder fineness ≥ 800 mesh; the suspended fluid loss material is a mixture of ultrafine calcium carbonate and dolomite fine powder, wherein the mass ratio is ultrafine calcium carbonate: dolomite fine powder = 70:30; the ultrafine calcium carbonate has a purity of ≥90 wt.%, and the powder fineness ≥800 mesh; the dolomite fine powder has a purity of ≥90 wt.%, and the powder fineness ≥1000 mesh; the high-temperature fluid loss additive is an AMPS anionic polymer; and the high-temperature retarder is an AMPS copolymer system;

[0103] The abnormal gelling material includes the following components in parts by weight: 40 parts of ulexite, 40 parts of colemanite, 10 parts of leonite and 10 parts of chalcanthite.

[0104] In this embodiment, the anti-abnormal gelling material is prepared by the following preparation method:

[0105] S1. 40 parts by weight of ulexite, 40 parts by weight of colemanite and 10 parts by weight of leonidite are mixed uniformly, and then crushed by a grinding mill with a crushing ratio controlled at 50; the crushed mixture is sent to a ball mill and ground into a mixed fine material with a crushing ratio controlled at 900; the crushed mixed fine material is then sent to a high-temperature calcining furnace for calcination at a calcination temperature of 1500°C. After calcination, the mixture is rapidly cooled to room temperature by a cooler with a cooling time controlled at 20 min to obtain a Class A mixture.

[0106] S2. The Class A mixture prepared in step S1 is mixed evenly with 10 parts by weight of gallstones, and then sent to a ball mill for grinding to obtain a Class B mixture after fine grinding; the particle fineness requirements of the Class B mixture are Dx(10)≤5μm, Dx(50)≤14μm, and Dx(90)≤30μm.

[0107] S3. The Class B mixture is subjected to a coating treatment, specifically, 100 parts by weight of the Class B mixture is added to 1500 parts by weight of a coating solution having a concentration of 85 wt.%, mixed evenly and reacted for 35 minutes, and then placed in a vacuum drying oven at 55° C. and dried to obtain the abnormality-proof gelling material.

[0108] The chemical composition requirements of the above-mentioned anti-abnormal gelling material are: 37wt.%<B2O3≤55wt.%, 11wt.%<CaO≤21wt.%, 5wt.%<SiO2≤13wt.%, 6wt.%<Na2O≤12wt.%, 1wt.%<SO3≤6wt.%, 1wt.%<CuO≤6wt.%.

[0109] As an example, in order to meet the chemical composition requirements of the above-mentioned anti-abnormal cementitious material, the purity and chemical composition of ulexite, colemanite, leucite, and chalcanthite can be limited, that is, the selection of ulexite, colemanite, leucite, and chalcanthite materials. Specifically, the ulexite purity requirement is ≥90wt.%, and its chemical composition requirements are: Na2O>6wt.%, CaO>12wt.%, B2O3>38wt.%; the colemanite purity requirement is ≥90wt.%, and its chemical composition requirements are: CaO>18wt.%, B2O3>33wt.%; the leucite purity requirement is ≥90wt.%, and its chemical composition requirements are: Na2O>22wt.%, SiO2>42wt.%, B2O3>24wt.%; the chalcanthite purity requirement is ≥90wt.%, and its chemical composition requirements are: CuO>28wt.%, SO3>28wt.%.

[0110] In this embodiment, when preparing the anti-abnormal gelling material, the coating solution used is composed of anhydrous ethanol, phenolic resin, polymethyl methacrylate, dimethyl phthalate and diethyl phthalate, and the mass ratio is anhydrous ethanol: phenolic resin: polymethyl methacrylate: dimethyl phthalate: diethyl phthalate = 60:15:8:7:10.

[0111] Comparative Example 1

[0112] Compared with Example 1, the cement slurry system in this comparative example does not add an anti-abnormal gelling material, and the formula is: 100 parts by weight of low-heat Portland cement + 35 parts by weight of reinforcing anti-recession material + 10 parts by weight of suspended fluid loss material + 6 parts by weight of high-temperature fluid loss additive + 2 parts by weight of high-temperature retarder + 56 parts by weight of water.

[0113] According to GB / T 19139-2012 standard, the engineering properties and mechanical properties of the cement slurry systems obtained in Examples 1 to 5 and Comparative Example 1 were tested. The test results are shown in Table 1.

[0114] Table 1 Test results of engineering properties and mechanical properties of high-temperature cementing slurry system

[0115]

[0116] Note: The curing conditions for the upper and lower density difference experiment are: 260℃×20.7MPa×48h, the free liquid content test conditions are: 90℃×0.1MPa×2h, the API water loss test conditions are: 215℃×6.9MPa×30min, the cement paste compressive strength curing conditions are: 260℃×20.7MPa, and the thickening test conditions are: 215℃×125MPa×120min.

[0117] The engineering performance test results in Table 1 indicate that the cementing slurry systems prepared in Examples 1 to 5 of the present invention have the advantages of good fluidity, zero free liquid content, low API water loss, good suspension stability, linearly adjustable thickening time, and no abnormal gelling during the thickening process, all of which meet the industry standard requirements for high-temperature cement cement.

[0118] From the mechanical property test results in Table 1, it can be seen that the cement stone formed by curing the cement slurry system prepared in Examples 1 to 5 of the present invention has the advantages of high compressive strength at high temperatures and no decay, and meets the long-term sealing requirements of high-temperature deep wells.

[0119] Refer to the instruction manual Figure 1 and attached Figure 2 As shown in the figures, compared with Example 1, the cementing cement slurry system prepared in Comparative Example 1 exhibited severe abnormal gelation during the thickening process, specifically manifested as: a linear mutation value of the consistency exceeding 10Bc (obvious bulging appeared on the curve), and severe fluctuations in the temperature curve (obvious core coating appeared on the thickening blades). This indicates that the cement slurry system without the addition of the anti-abnormal gelling material of the present invention is difficult to ensure stable thickening performance of the high-temperature cement slurry, thereby affecting the safety of cementing construction.

[0120] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention and are intended to illustrate the technical solutions of the present invention, rather than limiting them, and certainly not limiting the patent scope of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features therein may be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention. In other words, any changes or refinements made to the main design concept and spirit of the present invention that have no substantive significance, provided that the technical problems they solve are still consistent with those of the present invention, should be included in 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 should also be included in the patent protection scope of the present invention.

Claims

1. A high-temperature resistant cement slurry system for 10,000-meter deep wells, characterized by: The cementing slurry system includes the following components in parts by weight: 100 parts of low-heat Portland cement; 10~20 parts of anti-abnormal gelling material; 35~55 parts of enhanced anti-recession material; 10-20 parts of suspended fluid loss material; 6-8 parts of high temperature fluid loss additive; 2~5 parts of high temperature retarder; The C2S content of the low-heat Portland cement is ≥45 wt.%, and the specific surface area is controlled between 260 and 300 m 2 / kg, 7d hydration heat ≤ 250kJ / kg; The anti-abnormal gelling material comprises the following components in parts by weight: 40-60 parts of ulexite, 20-40 parts of colemanite, 10-20 parts of sillimanite, and 5-15 parts of chondrite; the chemical composition requirements of the anti-abnormal gelling material are: 37wt.%<B2O3≤55wt.%, 11wt.%<CaO≤21wt.%, 5wt.%<SiO2≤13wt.%, 6wt.%<Na2O≤12wt.%, 1wt.%<SO3≤6wt.%, 1wt.%<CuO≤6wt.%, and the sum of the mass percentages of each chemical component is 100wt.%; the particle fineness requirements of the anti-abnormal gelling material are Dx(10)≤5μm, Dx(50)≤14μm, and Dx(90)≤30μm; The anti-abnormal gelling material is obtained by processing the following steps: S1. Evenly mix 40-60 parts of ulexite, 20-40 parts of colemanite, and 10-20 parts of leucite, and crush the mixture after even mixing, with a crushing ratio controlled at 40-70; grind the crushed mixture into a mixed fine material, with a crushing ratio controlled at 400-900; send the crushed mixed fine material to a high-temperature calcining furnace for calcination, with the calcination temperature controlled at 800° C.-1500° C.; after calcination, quickly cool the mixture to room temperature, with a cooling time controlled at 10-20 min; and obtain a Class A mixture after cooling; S2. Mix the Class A mixture prepared in step S1 with 5 to 15 parts of gallstones, grind the mixture evenly, and obtain Class B mixture after grinding. The particle fineness requirements of the Class B mixture are Dx(10)≤5μm, Dx(50)≤14μm, and Dx(90)≤30μm. S3, subjecting the Class B mixture to a coating treatment, specifically, adding the Class B mixture to a coating solution, mixing evenly, reacting for a set time, and vacuum drying to obtain the abnormality-preventing gelling material.

2. The high-temperature resistant cement slurry system for 10,000-meter deep wells according to claim 1, characterized in that: The purity of ulexite in the anti-abnormal gelling material is required to be ≥90wt.%, and the chemical composition requirements are: Na2O>6wt.%, CaO>12wt.%, and B2O3>38wt.%.

3. The high-temperature resistant cement slurry system for 10,000-meter deep wells according to claim 1, characterized in that: The purity of the colemanite in the anti-abnormal gelling material is required to be ≥90wt.%, and the chemical composition requirements are: CaO>18wt.%, B2O3>33wt.%.

4. The high-temperature resistant cement slurry system for 10,000-meter deep wells according to claim 1, characterized in that: The purity of the gallic acid sulfate in the anti-abnormal gelling material is required to be ≥90wt.%, and the chemical composition requirements are: CuO>28wt.%, SO3>28wt.%.

5. The high-temperature resistant cement slurry system for 10,000-meter deep wells according to claim 1, characterized in that: The coating solution described in step S3 includes the following components by mass ratio: Anhydrous ethanol: phenolic resin: polymethyl methacrylate: dimethyl phthalate: diethyl phthalate = (55~70): (15~25): (5~10): (5~10): (5~10).

6. The high-temperature resistant cement slurry system for 10,000-meter deep wells according to claim 1, characterized in that: The concentration of the plating solution in step S3 is 55 wt.% to 85 wt.%.

7. The high-temperature resistant cement slurry system for 10,000-meter deep wells according to claim 1, characterized in that: In step S3, the ratio of the type B mixture to the coating solution is 1:(5~20).

8. The high-temperature resistant cement slurry system for 10,000-meter deep wells according to claim 1, characterized in that: In step S3, the reaction time is set to 5-35 min; the vacuum drying temperature is 35°C-55°C.

9. A high temperature resistant cement slurry system for 10,000-meter deep wells according to any one of claims 1 to 5, characterized in that: The reinforcing anti-decay material is a mixture of quartz sand and metakaolin, wherein the mass ratio is quartz sand: metakaolin = (80-90): (10-20).

10. The high-temperature resistant cement slurry system for 10,000-meter deep wells according to claim 9, characterized in that: The composition of the quartz sand is SiO2≥98 wt.%, and the powder fineness is ≥325 mesh; the composition of the metakaolin is Al2O3≥45 wt.%, SiO2≥45 wt.%, and the powder fineness is ≥800 mesh.

11. A high temperature resistant cement slurry system for 10,000-meter deep wells according to any one of claims 1 to 5, characterized in that: The suspended fluid loss reducing material is a mixture of ultrafine calcium carbonate and dolomite fine powder, wherein the mass ratio of ultrafine calcium carbonate: dolomite fine powder is (30-70): (30-70).

12. The high temperature resistant cement slurry system for 10,000-meter deep wells according to claim 11, characterized in that: The ultrafine calcium carbonate has a purity of ≥90wt.%, and a powder fineness of ≥800 mesh; the dolomite fine powder has a purity of ≥90wt.%, and a powder fineness of ≥1000 mesh.

13. A high temperature resistant cement slurry system for 10,000-meter deep wells according to any one of claims 1 to 5, characterized in that: The high-temperature fluid loss additive is an AMPS anionic polymer.

14. A high temperature resistant cement slurry system for 10,000-meter deep wells according to any one of claims 1 to 5, characterized in that: The high temperature retarder is an AMPS copolymer system.

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