Water-based modified trimanganese tetraoxide weighting agent for drilling, and preparation method and application thereof

Abstract

The application belongs to the technical field of preparation of trimanganese tetraoxide, and particularly relates to a modified trimanganese tetraoxide weighting agent for water-based drilling, a preparation method and application thereof. The modified trimanganese tetraoxide weighting agent for water-based drilling comprises a core-shell structure; the inner core comprises trimanganese tetraoxide; and the shell comprises an interface anchoring inner layer, a hydrophobic cross-linking middle layer and a temperature-resistant capping outer layer. The modified trimanganese tetraoxide weighting agent for water-based drilling has a three-layer shell structure hydrophobic film on the surface of the trimanganese tetraoxide particles, the film comprising an interface anchoring inner layer, a hydrophobic cross-linking middle layer and a temperature-resistant capping outer layer, so that the binding force, hydrophobicity, flexibility and temperature resistance of the film are improved.

Description

Technical Field

[0001] This invention belongs to the field of manganese tetroxide preparation technology, specifically relating to a modified manganese tetroxide weighting agent for water-based drilling, its preparation method, and its application. Background Technology

[0002] As oil exploration progresses to deeper formations, the demand for high-density drilling fluids increases, while the density of conventional barite weighting agents is generally 4.2 g / cm³. 3 ~4.3g / cm 3 Its disadvantages include poor rheological properties and severe sedimentation; the density of iron ore powder is 4.7 g / cm³. 3 ~5.1g / cm 3 While it has a relatively lower solids content in drilling fluid, its high hardness causes severe wear and settling on drill bits and drilling fluid pumps, making it difficult to meet the requirements of current deep and ultra-deep wells.

[0003] Manganese tetroxide is a stable oxide with a density typically of 4.7 g / cm³. 3 ~4.9g / cm 3 To meet the density requirements of weighting agents, according to Stokes' sedimentation law, the smaller the particle size of a solid, the slower its settling velocity in solution. When the particle size of the solid is in the micro-nano range, its suspension stability in solution is further improved. At the same time, improving the sphericity of the solid particles can effectively improve the lubrication coefficient of the drilling fluid and reduce wear. Therefore, micro-nano spherical manganese tetroxide is very suitable for application in drilling scenarios.

[0004] However, existing methods for preparing manganese tetroxide mainly include hydrothermal methods, sol-gel methods, and solid-state sintering methods. Hydrothermal methods generally use high-purity manganese salts as raw materials, resulting in high production costs and difficulty in controlling the particle size of the product at the ultra-micro scale. Sol-gel methods are complex and difficult to industrialize. Traditional solid-state sintering methods mostly use high-purity oxides as raw materials, which suffer from problems such as incomplete reaction, severe agglomeration of product particles, and poor sphericity. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a modified manganese tetroxide weighting agent for water-based drilling, its preparation method, and its application. This addresses at least one aspect of solving the above-mentioned technical problems.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a modified manganese tetroxide weighting agent for water-based drilling, comprising a core-shell structure; The core contains manganese tetroxide; The outer shell consists of an interface anchoring inner layer, a hydrophobic cross-linking middle layer, and a heat-resistant end capping outer layer.

[0007] Secondly, the present invention provides a method for preparing the above-mentioned modified manganese tetroxide weighting agent for water-based drilling, comprising the following steps: The first coating treatment was carried out with manganese tetroxide and a compound modifier to obtain the first coated product; The first coating product and the capping agent are subjected to a second coating treatment.

[0008] Thirdly, the present invention provides an application in the field of oil drilling, which uses the above-mentioned modified manganese tetroxide weighting agent for water-based drilling.

[0009] The modified manganese tetroxide weighting agent for water-based drilling provided by this invention has at least the following beneficial technical effects compared with the prior art: The modified manganese tetroxide weighting agent for water-based drilling provided by this invention has a three-layer structured hydrophobic film on the surface of manganese tetroxide particles, consisting of an interface anchoring inner layer, a hydrophobic crosslinking middle layer, and a temperature-resistant end-capping outer layer, which improves the film's adhesion, hydrophobicity, flexibility, and temperature resistance.

[0010] The preparation method of the modified manganese tetroxide weighting agent for water-based drilling provided by the present invention has at least the following beneficial technical effects compared with the prior art: The present invention provides a method for preparing a modified manganese tetroxide weighting agent for water-based drilling. The method involves mixing manganese tetroxide and a compound modifier for a first coating treatment, forming an interface anchoring inner layer and a hydrophobic crosslinking middle layer on the surface of the manganese tetroxide. Then, it is mixed with a sealing agent for a second coating treatment, forming a temperature-resistant sealing outer layer. This three-layer structured hydrophobic membrane, consisting of an interface anchoring inner layer, a hydrophobic crosslinking middle layer, and a temperature-resistant sealing outer layer, improves the membrane's adhesion, hydrophobicity, flexibility, and temperature resistance. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0012] Figure 1 This is a SEM image of a modified manganese tetroxide weighting agent for water-based drilling provided in Embodiment 1 of the present invention; Figure 2 This is a particle size distribution diagram of a modified manganese tetroxide weighting agent for water-based drilling provided in Embodiment 1 of the present invention; Figure 3 The particle size distribution diagram of a modified manganese tetroxide weighting agent for water-based drilling provided in Comparative Example 1 of this invention.

[0013] The purpose, features, and advantages of this accompanying drawing will be further explained in conjunction with the embodiments and with reference to the accompanying drawing. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described and illustrated below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments provided by this invention without inventive effort are within the scope of protection of this invention.

[0015] Obviously, the following description is merely some examples or embodiments of the present invention. Those skilled in the art can apply the present invention to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this invention, modifications to design, manufacturing, or production based on the technical content disclosed in this invention are merely conventional technical means and should not be construed as insufficient disclosure of the present invention.

[0016] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to enable those skilled in the art to fully understand the invention and is not intended to limit the subject matter of the claims.

[0017] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions, and all technical features and optional technical features of the present invention can be combined with each other to form new technical solutions.

[0018] The first aspect of this invention provides a modified manganese tetroxide weighting agent for water-based drilling, comprising a core-shell structure; The core contains manganese tetroxide; The outer shell consists of an interface anchoring inner layer, a hydrophobic cross-linking middle layer, and a heat-resistant end capping outer layer.

[0019] The modified manganese tetroxide weighting agent for water-based drilling provided in this invention has a three-layer structured hydrophobic film on the surface of manganese tetroxide particles, consisting of an interface anchoring inner layer, a hydrophobic crosslinking middle layer, and a temperature-resistant end-capping outer layer, which improves the film's adhesion, hydrophobicity, flexibility, and temperature resistance.

[0020] In some embodiments, the raw materials for preparing the modified manganese tetroxide weighting agent for water-based drilling include: Manganese tetroxide, compound modifier and end-capping agent; The mass of the compound modifier is 0.5% to 2% of the mass of manganese tetroxide.

[0021] In this case, the compound modifier is used to prepare the interface anchoring inner layer and the hydrophobic crosslinking middle layer, and the end-capping agent is used to prepare the heat-resistant end-capping outer layer.

[0022] In some embodiments, the raw materials for preparing manganese tetroxide include: a mixture and a dispersant.

[0023] In some embodiments, the mass ratio of the mixture to the dispersant is 100:(1~3).

[0024] In some embodiments, the mixture comprises manganese ore and calcium oxide. In this case, the role of calcium oxide is to remove impurities such as SiO2 and Al2O3 contained in the manganese ore.

[0025] In some embodiments, the mass ratio of manganese ore to calcium oxide is (28~95):5. It should be noted that the mass ratio of manganese ore to calcium oxide in this embodiment is merely an example. In actual preparation, the proportion of calcium oxide, atmosphere, and temperature can be adjusted according to the impurity content in the manganese ore to maximize its conversion into calcium silicate and calcium aluminate. (The density of aluminum silicate and calcium silicate is approximately 2.6 g / cm³.) 3 The density of manganese tetroxide is 5.0 g / cm³. 3 Separation can be achieved by utilizing density difference and gravity sedimentation.

[0026] In some embodiments, the mass fraction of manganese in the manganese ore is 10% to 35%.

[0027] In some embodiments, the mass fraction of iron oxide in the manganese ore is 1% to 10%.

[0028] In some embodiments, the mass fraction of impurities in the manganese ore is <3%.

[0029] In some embodiments, impurities in manganese ore include SiO2 and Al2O3.

[0030] In some embodiments, the particle size D50 of the manganese ore is 50 μm to 100 μm.

[0031] In some embodiments, the dispersant includes PEG6000.

[0032] In some embodiments, the particle size D50 of manganese tetroxide is 0.5 μm to 3 μm.

[0033] In some embodiments, the iron content in manganese tetroxide is 0.5wt% to 3wt%.

[0034] In some embodiments, the compound modifier comprises a mixture of fluorosilane coupling agents and long-chain alkylsilanes.

[0035] In some embodiments, the mass ratio of fluorosilane coupling agent to long-chain alkylsilane is (11~30):5.

[0036] In some embodiments, the fluorosilane coupling agent includes perfluorodecyltriethoxysilane (FAS-17).

[0037] In some embodiments, the CAS number of perfluorodecyltriethoxysilane (FAS-17) is 101947-16-4.

[0038] In some embodiments, the long-chain alkylsilane includes at least one of hexadecyltrimethoxysilane and dodecyltrimethoxysilane.

[0039] In some embodiments, the CAS number of hexadecyltrimethoxysilane is 16415-12-6.

[0040] In some embodiments, the CAS number of dodecyltrimethoxysilane is 3069-21-4.

[0041] In some embodiments, the compound modifier may further include a synergist.

[0042] In some embodiments, the synergist is present at a mass of 0.1% to 0.3% of the mass of manganese tetroxide.

[0043] In some embodiments, the synergist includes at least one of KH550, KH492, and KH602.

[0044] In some embodiments, the compound modifier further includes a mineralization resistance modifier. In this case, the addition of the mineralization resistance modifier enables the modified manganese tetroxide weighting agent for water-based drilling to achieve a three-in-one effect of hydrophobicity and anti-agglomeration, mineralization resistance, and anti-settling.

[0045] In some embodiments, the mass of the anti-mineralization modifier is 0.2% to 0.5% of the mass of manganese tetroxide.

[0046] In some embodiments, the anti-mineralization modifier includes at least one of EDTA-2Na, EDTA-4Na, and sodium citrate.

[0047] In some embodiments, the capping agent includes at least one of hexamethyldisilazane, trimethylchlorosilane, and triethoxysilane.

[0048] In some embodiments, the CAS number of hexamethyldisilazane is 999-97-3.

[0049] In some embodiments, the CAS number of trimethylchlorosilane is 75-77-4.

[0050] In some embodiments, the CAS number of triethoxysilane is 998-30-1.

[0051] In some embodiments, the mass of the capping agent is 0.1% to 0.13% of the mass of manganese tetroxide.

[0052] A second aspect of this invention provides a method for preparing a modified manganese tetroxide weighting agent for water-based drilling, comprising the following steps: S10. Manganese tetroxide and a compound modifier are subjected to a first coating treatment to obtain a first coated product; S20. The first coating product and the capping agent undergo a second coating treatment.

[0053] The present invention provides a method for preparing a modified manganese tetroxide weighting agent for water-based drilling. The method involves mixing manganese tetroxide and a compound modifier for a first coating treatment, forming a first coating product on the surface of the manganese tetroxide with an interface-anchored inner layer and a hydrophobic cross-linked middle layer. This is then mixed with a capping agent for a second coating treatment, forming a temperature-resistant capping outer layer. This three-layered structured hydrophobic membrane, consisting of an interface-anchored inner layer, a hydrophobic cross-linked middle layer, and a temperature-resistant capping outer layer, improves the membrane's adhesion, hydrophobicity, flexibility, and temperature resistance.

[0054] In some embodiments, the preparation of manganese tetroxide in step S10 above includes the following steps: S101. After ball milling the ball-milled slurry, an oxidation treatment is performed; Ball milling slurry includes mixtures and dispersants.

[0055] In some embodiments, in step S101 above, the solid-liquid ratio of the ball mill slurry is 1:(2~4).

[0056] In some embodiments, the preparation of the ball milling slurry in step S101 above includes the following steps: S1011. Manganese ore and calcium oxide are mixed to obtain a mixture.

[0057] S1012. After mixing the mixture and dispersant, water is added to adjust the solid-liquid ratio of the slurry to obtain the ball milled slurry.

[0058] In some embodiments, in step S101 above, the ball milling media is zirconia balls.

[0059] In some embodiments, in step S101 above, the ball-to-material ratio in the ball milling process is (9~11):1.

[0060] In some embodiments, in step S101 above, the ball milling speed is 300 rpm to 400 rpm.

[0061] In some embodiments, in step S101 above, the ball milling time is 6h to 18h.

[0062] In some embodiments, in step S101 above, the particle size D90 of the slurry obtained after ball milling is less than 100 μm.

[0063] In some embodiments, the oxidation treatment in step S101 above includes the following steps: S1013. Obtain the composite particles after ball milling, and heat the composite particles to 800℃~1200℃ under an oxidizing atmosphere and then keep them at that temperature.

[0064] In some embodiments, in step S1013 above, obtaining the composite particles after ball milling includes the following steps: S10131. Spray dry the slurry obtained after ball milling.

[0065] In some embodiments, in step S10131 above, the inlet air temperature for spray drying is 130°C to 160°C.

[0066] In some embodiments, in step S10131 above, the outlet air temperature of the spray dryer is 85°C to 95°C.

[0067] In some embodiments, in step S1013 above, the volume fraction of oxygen in the oxidizing atmosphere is 30% to 40%.

[0068] In some embodiments, the oxidizing atmosphere is a mixture of air and oxygen, or a mixture of nitrogen and oxygen.

[0069] In some embodiments, in step S1013 above, the heating rate is 4°C / min to 6°C / min.

[0070] In some embodiments, the heat preservation time in step S1013 is 3h to 6h.

[0071] In some embodiments, the preparation of manganese tetroxide in step S10 above further includes the following steps: S102. After mixing the product obtained from the oxidation treatment with cation exchange resin for ion exchange, post-treatment is performed.

[0072] In this process, the product obtained from the oxidation treatment is subjected to ion exchange to remove excess calcium oxide and other soluble impurities, resulting in deep purification and the production of manganese tetroxide with higher purity. The resulting manganese tetroxide has a pH value of <11 and an iron content of 0.5wt%~3wt%.

[0073] In some embodiments, in step S102 above, the cation exchange resin includes at least one of D113 (macroporous weak acid acrylic cation exchange resin), D402 (macroporous styrene chelating resin), and D001 (macroporous strong acid styrene cation exchange resin).

[0074] In some embodiments, the post-processing in step S102 above includes washing and drying. It should be noted that washing and drying are both conventional post-processing techniques in the art. For example, washing involves mixing the ion-exchange product with water and centrifuging to wash it 2 to 4 times, while drying removes water and other solvents. Therefore, washing and drying are not particularly limited in the embodiments of this invention.

[0075] In some embodiments, in step S10 above, the first coating process includes the following steps: S103. Manganese tetroxide is activated to obtain hydroxy manganese tetroxide.

[0076] S104. Hydroxymanganese tetroxide was mixed with a compound modifier dispersion and stirred to obtain a precursor. Then, it was cured to obtain manganese tetroxide coated with an interface anchoring inner layer and a hydrophobic crosslinking middle layer.

[0077] In some embodiments, the activation process in step S103 above includes the following steps: S1031. Activate manganese tetroxide under vacuum.

[0078] In some embodiments, in step S1031 above, the vacuum degree is -0.05MPa to -0.1MPa.

[0079] In some embodiments, in step S1031 above, the activation temperature is 90°C to 110°C.

[0080] In some embodiments, the activation time in step S1031 is 1 h to 2.5 h.

[0081] In some specific embodiments, the activation time in step S1031 above is 1.3h to 2.5h.

[0082] In some specific embodiments, the activation time in step S1031 is 2.3h to 2.5h.

[0083] In some embodiments, in step S103 above, the surface hydroxyl content in manganese tetroxide is 1.1 mmol / g to 1.8 mmol / g.

[0084] In some embodiments, in step S104 above, the viscosity of the compound modifier dispersion is 5 mPa·s to 10 mPa·s.

[0085] In some embodiments, in step S104 above, the preparation of the compound modifier dispersion includes the following steps: S1041. Disperse the compound modifier in alcohol.

[0086] In some embodiments, in step S1041 above, the alcohol includes at least one of ethanol, methanol, and propanol.

[0087] In some embodiments, in step S104 above, the temperature of the stirring treatment is 60°C to 80°C.

[0088] In some embodiments, the stirring time in step S104 is 30 min to 60 min.

[0089] In some embodiments, in step S104 above, the stirring speed of the stirring process is 250 rpm to 350 rpm.

[0090] In some embodiments, in step S104 above, the curing process includes the following steps: S1042. After obtaining the solid precursor, perform gradient curing under an inert atmosphere.

[0091] In this configuration, an inert atmosphere-gradient curing coupling is used. Under the premise of preventing oxidation, the fluorosilane coupling agent in the compound modifier is grafted with the hydroxyl groups of manganese tetroxide to form an interfacial anchoring inner layer. Further curing then forms a hydrophobic cross-linked middle layer. The formation mechanism is as follows: the highly reactive siloxane groups preferentially and rapidly condense with the activated hydroxyl groups of manganese tetroxide to form Si-O-Mn covalent bonds, thus acting as an anchor. Alkylsilanes, on the other hand, react slowly and do not compete for bottom-layer sites. They mainly undergo intermolecular cross-linking with the exposed residual active groups of fluorosilanes, combining the advantages of tight bonding and good hydrophobicity.

[0092] In some specific embodiments, in step S1042 above, centrifugation or filtration is used to obtain the solid precursor.

[0093] In some embodiments, in step S1042 above, the inert atmosphere is at least one of argon, helium, and neon.

[0094] In some embodiments, in step S1042 above, gradient curing includes the following steps: S10421. Low temperature stage: The solid precursor is heated to 100℃~110℃ and then kept at that temperature.

[0095] S10422. Medium temperature stage: Continue to heat to 140℃~160℃ and then maintain the temperature.

[0096] S10423. High temperature stage: Continue to heat up to 180℃~200℃ and then keep warm.

[0097] S10424. Cooling stage: Cool down to below 60℃.

[0098] In this process, the low-temperature stage completely removes residual moisture, solvents, and low-molecular-weight impurities from the precursor surface, eliminating pinholes and blistering in the film layer and gently reinforcing the Si-O-Mn covalent bonds in the interfacial anchoring layer. This stabilizes the underlying structure in advance and prevents bond breakage and film detachment caused by sudden high-temperature heating. The medium-temperature stage activates silane active groups, promoting full cross-linking of the compound modifier molecules and rapidly constructing a dense and continuous hydrophobic three-dimensional network structure in the middle layer. At the same time, it repairs the microscopic defects in the underlying layer, achieving seamless bonding between the anchoring layer and the cross-linking layer. The high-temperature stage bonds and shapes the surface end-capping agent, constructing a complete temperature-resistant end-capping layer. It also releases the internal stress of film curing, eliminating problems such as film cracking and peeling, and significantly improving the film's high-temperature resistance, hydrolysis resistance, and high-mineralization resistance.

[0099] In some embodiments, during step S10421 above, the flow rate of the inert atmosphere in the low-temperature stage is 0.5 m³ / s. 3 / h~1m 3 / h.

[0100] In some embodiments, during the low-temperature stage in step S10421 above, the holding time is 20 min to 30 min.

[0101] In some embodiments, during step S10422 above, the flow rate of the inert atmosphere in the intermediate temperature stage is 1.5 m³ / s. 3 / h~2m 3 / h.

[0102] In some embodiments, during the intermediate temperature stage in step S10422, the holding time is 20 min to 30 min.

[0103] In some embodiments, during step S10423 above, the flow rate of the inert atmosphere in the high-temperature stage is 1.5 m³ / s. 3 / h~2m 3 / h.

[0104] In some embodiments, during the high-temperature stage in step S10423 described above, the heat preservation time is 60 min to 120 min.

[0105] In some embodiments, during step S10424 above, the flow rate of the inert atmosphere in the cooling stage is 0.3 m³ / s. 3 / h~0.5m 3 / h.

[0106] In some embodiments, in step S20 above, the second coating process includes the following steps: S201. Mix and stir the first coating product and the capping agent.

[0107] In some embodiments, in step S201 above, the stirring speed for mixing is 250 rpm to 300 rpm.

[0108] In some embodiments, in step S201 above, the mixing and stirring time is 20 min to 30 min.

[0109] In some embodiments, the second coating process in step S20 above further includes the following steps: S202. The product after mixing and stirring is dried under vacuum.

[0110] In some embodiments, in step S202 above, the temperature of vacuum drying is 90°C to 100°C.

[0111] In some embodiments, in step S202 above, the vacuum degree of vacuum drying is 0.1 MPa to 0.09 MPa. In some embodiments, in step S106 above, the vacuum drying time is 1.5 h to 2 h. It should be noted that the vacuum degree and drying time range are only examples of this application. In actual drying process, the vacuum degree and drying time can be adjusted according to the actual situation, which is a conventional technique in the art.

[0112] The following description, in conjunction with specific embodiments, provides further details.

[0113] Example 1 Example 1 provides a modified manganese tetroxide weighting agent for water-based drilling, which has a core-shell structure; The core is manganese tetroxide; The outer shell consists of an interface anchoring inner layer, a hydrophobic cross-linking middle layer, and a heat-resistant end capping outer layer.

[0114] The raw materials for preparing the modified manganese tetroxide weighting agent for water-based drilling are: manganese tetroxide, compound modifier and hexamethyldisilazane (end-capping agent).

[0115] Among them, (1) manganese tetroxide: The particle size D50 of manganese tetroxide is 1.2 μm.

[0116] The raw materials for preparing manganese tetroxide are a mixture of raw materials and PEG6000, with a mass ratio of 100:1.85.

[0117] The mixture is a mixture of manganese ore and calcium oxide in a mass ratio of 62.5:5.

[0118] The manganese ore contains 33% manganese, 1.6% iron oxide, 1.1% SiO2, and 0.7% Al2O3 by mass, with a particle size D50 of 80 μm.

[0119] (2) In compound modifiers: The compound modifier is a mixture of perfluorodecyltriethoxysilane (FAS-17) and hexadecyltrimethoxysilane in a mass ratio of 82:18 (approximately 22.78:5).

[0120] The mass of the compound modifier is 1% of the mass of manganese tetroxide.

[0121] (3) Hexamethyldisilazane (capping agent) is 0.1% of the mass of manganese tetroxide.

[0122] This embodiment also provides a method for preparing the above-mentioned modified manganese tetroxide weighting agent for water-based drilling, the steps of which are as follows: E10. Preparation of manganese tetroxide E101. Preparation of ball milling slurry: E1011. Manganese ore and calcium oxide are mixed to obtain a mixture.

[0123] E1012. After mixing the mixture with PEG6000, water is added to adjust the solid-liquid ratio of the slurry to 1:2.7 to obtain the ball milling slurry.

[0124] E102. Ball milling treatment: The ball mill slurry is ball-milled.

[0125] The ball milling media were zirconia balls with a ball-to-material ratio of 10:1; the ball milling speed was 350 rpm; the ball milling time was 8 h; and the particle size D90 of the slurry obtained after ball milling was 1.9 μm.

[0126] E103. Oxidation treatment: E1031. The slurry obtained after ball milling is spray-dried to obtain composite particles.

[0127] The inlet air temperature of the spray dryer is 140℃ and the outlet air temperature is 90℃.

[0128] E1032. In a mixed atmosphere of air and oxygen (oxygen volume fraction of 35%), the composite particles are heated to 1100℃ at a heating rate of 5℃ / min and then held at that temperature for 4h.

[0129] E104. Crushing Classification: The dried material was crushed and classified to obtain a coarse product with a particle size D50 of 1.2 μm.

[0130] E105. The product obtained from the oxidation treatment was mixed with cation exchange resin for ion exchange, centrifuged and washed for 30 min, washed once, and dehydrated for 20 min after washing. Finally, the material was dried at 90℃ for 8 h to obtain manganese tetroxide.

[0131] The cation exchange resin is D113 (macroporous weakly acidic acrylic cation exchange resin).

[0132] E20. First Coating Process E201. Activation treatment: Manganese tetroxide was activated under vacuum to obtain hydroxyl manganese tetroxide with a surface hydroxyl content of 1.5 mmol / g.

[0133] The vacuum level was -0.09 MPa, the activation temperature was 95℃, and the activation time was 1.5 h.

[0134] E202. Stirring treatment: Hydroxymanganese tetroxide was mixed with a dispersion of compound modifier and stirred to obtain a precursor.

[0135] Among them, the compound modifier dispersion is made by dispersing the compound modifier in alcohol, and its viscosity is 8 mPa·s.

[0136] The stirring process was carried out at a temperature of 70℃ for 45 minutes and a stirring speed of 300 rpm.

[0137] E203. Curing treatment: E2031. Centrifugation is used to obtain the solid precursor.

[0138] E2032. Gradient curing: (1) Low temperature stage: with an argon atmosphere flow rate of 0.8 m³ / s. 3 At a temperature of / h, the solid precursor is heated to 100℃ and held for 30 min.

[0139] (2) Intermediate temperature stage: with an argon atmosphere flow rate of 1.8 m³ / s. 3 Continue heating to 150℃ at / h and hold for 30 minutes.

[0140] (3) High temperature stage: with an argon atmosphere flow rate of 1.8 m³ / s. 3 Continue heating to 180℃ at / h and hold for 90min.

[0141] (4) Cooling stage: with an argon atmosphere flow rate of 0.4 m³ / s. 3 At a temperature of / h, the temperature was lowered to below 60℃ to obtain manganese tetroxide coated with an interface anchoring inner layer and a hydrophobic cross-linked middle layer.

[0142] E30. Second Coating Treatment E301. Mixing and stirring: The product after the first coating treatment was mixed and stirred with hexamethyldisilazane.

[0143] The mixing speed was 280 rpm and the time was 20 min.

[0144] E302. Post-processing: The product after mixing and stirring was vacuum dried to obtain a modified manganese tetroxide weighting agent for water-based drilling.

[0145] The vacuum drying temperature was 100℃, the vacuum degree was 0.09MPa, and the vacuum drying time was 1.5h.

[0146] Example 2 Example 2 provides a modified manganese tetroxide weighting agent for water-based drilling, which has a core-shell structure; The core is manganese tetroxide; The outer shell consists of an interface anchoring inner layer, a hydrophobic cross-linking middle layer, and a heat-resistant end capping outer layer.

[0147] The raw materials for preparing the modified manganese tetroxide weighting agent for water-based drilling are: manganese tetroxide, compound modifier and trimethylchlorosilane (end-capping agent).

[0148] Among them, (1) manganese tetroxide: The particle size D50 of manganese tetroxide is 1.5 μm.

[0149] The raw materials for preparing manganese tetroxide are a mixture of raw materials and PEG6000, with a mass ratio of 100:1.82.

[0150] The mixture is a mixture of manganese ore and calcium oxide in a mass ratio of 50:5.

[0151] The manganese ore contains 29.6% manganese, 1.77% iron oxide, 1.5% SiO2, and 0.9% Al2O3 by mass, with a particle size D50 of 75 μm.

[0152] (2) In compound modifiers: The compound modifier is a mixture of perfluorodecyltriethoxysilane (FAS-17) and hexadecyltrimethoxysilane in a mass ratio of 73:27 (approximately 13.52:5).

[0153] The mass of the compound modifier is 1.2% of the mass of manganese tetroxide.

[0154] (3) Trimethylchlorosilane (capping agent) is 0.1% of the mass of manganese tetroxide.

[0155] This embodiment also provides a method for preparing the above-mentioned modified manganese tetroxide weighting agent for water-based drilling, the steps of which are as follows: E11. Preparation of manganese tetroxide E111. Preparation of ball milling slurry: E1111. Manganese ore and calcium oxide are mixed to obtain a mixture.

[0156] E1112. After mixing the mixture with PEG6000, water is added to adjust the solid-liquid ratio of the slurry to 1:3, thus obtaining the ball milling slurry.

[0157] E112. Ball milling treatment: The ball mill slurry is ball-milled.

[0158] The ball milling media were zirconia balls with a ball-to-material ratio of 10:1; the ball milling speed was 350 rpm; the ball milling time was 10 h; and the particle size D90 of the slurry obtained after ball milling was 1.7 μm.

[0159] E113. Oxidation treatment: S1131. Spray dry the slurry obtained after ball milling to obtain composite particles.

[0160] The inlet air temperature of the spray dryer is 145℃ and the outlet air temperature is 92℃.

[0161] S1132. In a mixed atmosphere of air and oxygen (oxygen volume fraction of 37%), the composite particles are heated to 1150℃ at a heating rate of 5℃ / min and then held at that temperature for 4.5h.

[0162] E114. Crushing and Grading: The dried material was crushed and classified to obtain a coarse product with a particle size D50 of 1.5 μm.

[0163] E115. The product obtained from the oxidation treatment was mixed with cation exchange resin for ion exchange, centrifuged and washed for 30 min, washed twice, and dehydrated for 20 min after washing. Finally, the material was dried at 90℃ for 8 h to obtain manganese tetroxide.

[0164] The cation exchange resin is D113 (macroporous weakly acidic acrylic cation exchange resin).

[0165] E21. First Coating Treatment E211. Activation treatment: Manganese tetroxide was activated under vacuum to obtain hydroxyl manganese tetroxide with a surface hydroxyl content of 1.6 mmol / g.

[0166] The vacuum level was -0.095 MPa, the activation temperature was 100℃, and the activation time was 1.8 h.

[0167] E212. Stirring treatment: Hydroxymanganese tetroxide was mixed with a dispersion of compound modifier and stirred to obtain a precursor.

[0168] Among them, the compound modifier dispersion is made by dispersing the compound modifier in alcohol, and its viscosity is 7 mPa·s.

[0169] The stirring process was carried out at a temperature of 70℃ for 50 minutes and a stirring speed of 300 rpm.

[0170] E213. Curing treatment: E2131. Centrifugation is used to obtain the solid precursor.

[0171] E2132. Gradient curing: (1) Low temperature stage: with an argon atmosphere flow rate of 0.7 m³ / s. 3 At a temperature of / h, the solid precursor is heated to 100℃ and held for 25 min.

[0172] (2) Intermediate temperature stage: with an argon atmosphere flow rate of 1.7 m³ / s. 3 Continue heating to 150℃ at / h and hold for 25 minutes.

[0173] (3) High temperature stage: with an argon atmosphere flow rate of 1.7 m³ / h 3 Continue heating to 190℃ at / h and hold for 80 minutes.

[0174] (4) Cooling stage: with an argon atmosphere flow rate of 0.4 m³ / s. 3 At a temperature of / h, the temperature was lowered to below 60℃ to obtain manganese tetroxide coated with an interface anchoring inner layer and a hydrophobic cross-linked middle layer.

[0175] E31. Second Coating Treatment E311. Mixing and stirring: The product after the first coating treatment was mixed and stirred with hexamethyldisilazane.

[0176] The mixing speed was 280 rpm and the time was 20 min.

[0177] E312. Post-processing: The product after mixing and stirring was vacuum dried to obtain a modified manganese tetroxide weighting agent for water-based drilling.

[0178] The vacuum drying temperature was 100℃, the vacuum degree was 0.09MPa, and the vacuum drying time was 1.5h.

[0179] Example 3 Example 3 provides a modified manganese tetroxide weighting agent for water-based drilling, which has a core-shell structure; The core is manganese tetroxide; The outer shell consists of an interface anchoring inner layer, a hydrophobic cross-linking middle layer, and a heat-resistant end capping outer layer.

[0180] The raw materials for preparing modified manganese tetroxide weighting agent for water-based drilling are: manganese tetroxide, compound modifier and triethoxysilane (end-capping agent).

[0181] Among them, (1) manganese tetroxide: The particle size D50 of manganese tetroxide is 0.5 μm.

[0182] The raw materials for preparing manganese tetroxide are a mixture of raw materials and PEG6000, with a mass ratio of 100:2.61.

[0183] The mixture is a mixture of manganese ore and calcium oxide in a mass ratio of 33.4:5.

[0184] The manganese ore contains 27.5% manganese, 1.9% iron oxide, 1.8% SiO2, and 1.1% Al2O3 by mass, with a particle size D50 of 70 μm.

[0185] (2) In compound modifiers: The compound modifier is a mixture of perfluorodecyltriethoxysilane (FAS-17) and hexadecyltrimethoxysilane in a mass ratio of 78:22 (approximately 17.73:5).

[0186] The mass of the compound modifier is 1.5% of the mass of manganese tetroxide.

[0187] (3) Trimethylchlorosilane (capping agent) is 0.13% of the mass of manganese tetroxide.

[0188] This embodiment also provides a method for preparing the above-mentioned modified manganese tetroxide weighting agent for water-based drilling, the steps of which are as follows: E12. Preparation of manganese tetroxide E121. Preparation of ball milling slurry: E1211. Manganese ore and calcium oxide are mixed to obtain a mixture.

[0189] E1212. After mixing the mixture with PEG6000, water is added to adjust the solid-liquid ratio of the slurry to 1:3.5 to obtain the ball milling slurry.

[0190] E122. Ball milling treatment: The ball mill slurry is ball-milled.

[0191] The ball milling media were zirconia balls with a ball-to-material ratio of 10:1; the ball milling speed was 380 rpm; the ball milling time was 12 h; and the particle size D90 of the slurry obtained after ball milling was 1.6 μm.

[0192] E123. Oxidation treatment: S1231. Spray dry the slurry obtained after ball milling to obtain composite particles.

[0193] The inlet air temperature of the spray dryer is 150℃ and the outlet air temperature is 95℃.

[0194] S1232. In a mixed atmosphere of air and oxygen (oxygen volume fraction of 40%), the composite particles are heated to 1200℃ at a heating rate of 5℃ / min and then held at that temperature for 5.5h.

[0195] E124. Crushing and Grading: The dried material was crushed and classified to obtain a coarse product with a particle size D50 of 0.5 μm.

[0196] E125. The product obtained from the oxidation treatment was mixed with cation exchange resin for ion exchange, centrifuged and washed for 30 min, washed 3 times, dehydrated for 20 min after washing, and finally dried at 90℃ for 8 h to obtain manganese tetroxide.

[0197] The cation exchange resin is D113 (macroporous weakly acidic acrylic cation exchange resin).

[0198] E22. First Coating Treatment E221. Activation treatment: Manganese tetroxide was activated under vacuum to obtain hydroxyl manganese tetroxide with a surface hydroxyl content of 1.7 mmol / g.

[0199] The vacuum level was -0.095 MPa, the activation temperature was 105℃, and the activation time was 2 hours.

[0200] E222. Stirring treatment: Hydroxymanganese tetroxide was mixed with a dispersion of compound modifier and stirred to obtain a precursor.

[0201] Among them, the compound modifier dispersion is made by dispersing the compound modifier in alcohol, and its viscosity is 9 mPa·s.

[0202] The stirring process was carried out at a temperature of 75℃ for 50 minutes and a stirring speed of 320 rpm.

[0203] E223. Curing treatment: E2231. Centrifugation is used to obtain the solid precursor.

[0204] E2232. Gradient curing: (1) Low temperature stage: with an argon atmosphere flow rate of 0.9 m³ / s. 3 At a temperature of / h, the solid precursor is heated to 100℃ and held for 28 min.

[0205] (2) Intermediate temperature stage: with an argon atmosphere flow rate of 1.8 m³ / s. 3 Continue heating to 150℃ at / h and hold for 28 minutes.

[0206] (3) High temperature stage: with an argon atmosphere flow rate of 1.8 m³ / s. 3 Continue heating to 195℃ at / h and hold for 90 minutes.

[0207] (4) Cooling stage: with an argon atmosphere flow rate of 0.45m³ / h 3 At a temperature of / h, the temperature was lowered to below 60℃ to obtain manganese tetroxide coated with an interface anchoring inner layer and a hydrophobic cross-linked middle layer.

[0208] E32. Second Coating Treatment E321. Mixing and stirring: The product after the first coating treatment was mixed and stirred with hexamethyldisilazane.

[0209] The mixing speed was 280 rpm and the time was 20 min.

[0210] E322. Post-processing: The product after mixing and stirring was vacuum dried to obtain a modified manganese tetroxide weighting agent for water-based drilling.

[0211] The vacuum drying temperature was 100℃, the vacuum degree was 0.095MPa, and the vacuum drying time was 1.8h.

[0212] Comparative Example 1 Comparative Example 1 provides a modified manganese tetroxide weighting agent for water-based drilling, with a core-shell structure; The core is manganese tetroxide; The raw material for preparing the outer shell is hexamethyldisilazane, which is 0.1% of the mass of manganese tetroxide.

[0213] In manganese tetroxide: The particle size D50 of manganese tetroxide is 4 μm.

[0214] The raw materials for preparing manganese tetroxide are a mixture of raw materials and PEG6000, with a mass ratio of 100:1.85.

[0215] The mixture is a mixture of manganese ore and calcium oxide in a mass ratio of 62.5:5.

[0216] The manganese ore contains 33% manganese, 1.6% iron oxide, 1.1% SiO2, and 0.7% Al2O3 by mass, with a particle size D50 of 80 μm.

[0217] This comparative example also provides a method for preparing the above-mentioned modified manganese tetroxide weighting agent for water-based drilling, the steps of which are as follows: D10. Preparation of manganese tetroxide D101. Preparation of ball milling slurry: D1011. Manganese ore and calcium oxide are mixed to obtain a mixture.

[0218] D1012. After mixing the mixture with PEG6000, water is added to adjust the solid-liquid ratio of the slurry to 1:2.7 to obtain the ball milling slurry.

[0219] D102. Ball milling treatment: The ball mill slurry is ball-milled.

[0220] The ball milling media were zirconia balls with a ball-to-material ratio of 10:1; the ball milling speed was 350 rpm; the ball milling time was 4 h; and the particle size D90 of the slurry obtained after ball milling was 6 μm.

[0221] D103. Oxidation treatment: D1031. The slurry obtained after ball milling is spray-dried to obtain composite particles.

[0222] The inlet air temperature of the spray dryer is 140℃ and the outlet air temperature is 90℃.

[0223] D1032. In a mixed atmosphere of air and oxygen (oxygen volume fraction of 35%), the composite particles were heated to 1100℃ at a heating rate of 5℃ / min and then held at that temperature for 4h.

[0224] D104. Crushing and Classification: The dried material was crushed and classified to obtain a coarse product with a particle size D50 of 4μm.

[0225] D105. The product obtained from the oxidation treatment was mixed with cation exchange resin for ion exchange, centrifuged and washed for 30 min, washed once, and dehydrated for 20 min after washing. Finally, the material was dried at 90℃ for 8 h to obtain manganese tetroxide.

[0226] The cation exchange resin is D113 (macroporous weakly acidic acrylic cation exchange resin).

[0227] D20. Coating treatment D201. Activation treatment: Manganese tetroxide was activated under vacuum to obtain hydroxyl manganese tetroxide with a surface hydroxyl content of 1.5 mmol / g.

[0228] The vacuum level was -0.09 MPa, the activation temperature was 95℃, and the activation time was 1.5 h.

[0229] D202. Mixing and stirring: Mix and stir hydroxymanganese tetroxide and hexamethyldisilazane.

[0230] The mixing speed was 280 rpm and the time was 20 min.

[0231] D203. Post-processing: The product after mixing and stirring was vacuum dried to obtain a modified manganese tetroxide weighting agent for water-based drilling.

[0232] The vacuum drying temperature was 100℃, the vacuum degree was -0.09MPa, and the vacuum drying time was 1.5h.

[0233] Comparative Example 2 Comparative Example 2 provides a modified manganese tetroxide weighting agent for water-based drilling, with a core-shell structure; The core is manganese tetroxide; The raw material for preparing the shell is a compound modifier, which is 1% of the mass of manganese tetroxide; the compound modifier is a mixture of perfluorodecyltriethoxysilane (FAS-17) and hexadecyltrimethoxysilane, with a mass ratio of 82:18 (approximately 22.78:5).

[0234] This comparative example also provides a method for preparing the above-mentioned modified manganese tetroxide weighting agent for water-based drilling, the steps of which are as follows: D11. Preparation of manganese tetroxide D111. Preparation of ball milling slurry: D1111. Manganese ore and calcium oxide are mixed to obtain a mixture.

[0235] D1112. After mixing the mixture with PEG6000, water is added to adjust the solid-liquid ratio of the slurry to 1:2.7 to obtain the ball milling slurry.

[0236] D112. Ball milling treatment: The ball mill slurry is ball-milled.

[0237] The ball milling media were zirconia balls with a ball-to-material ratio of 10:1; the ball milling speed was 350 rpm; the ball milling time was 8 h; and the particle size D90 of the slurry obtained after ball milling was 1.9 μm.

[0238] D113. Oxidation treatment: D1131. The slurry obtained after ball milling is spray-dried to obtain composite particles.

[0239] The inlet air temperature of the spray dryer is 140℃ and the outlet air temperature is 90℃.

[0240] D1132. In a mixed atmosphere of air and oxygen (oxygen volume fraction of 35%), the composite particles were heated to 1100℃ at a heating rate of 5℃ / min and then held at that temperature for 4h.

[0241] D114. Crushing and Classification: The dried material was crushed and classified to obtain a coarse product with a particle size D50 of 1.2 μm.

[0242] D115. Iron doping treatment: The product obtained from the oxidation treatment was mixed with cation exchange resin for ion exchange, centrifuged and washed for 30 min, washed once, and then dehydrated for 20 min after washing. Finally, the material was dried at 90℃ for 8 h to obtain manganese tetroxide.

[0243] The cation exchange resin is D113 (macroporous weakly acidic acrylic cation exchange resin).

[0244] D21. Coating treatment D211. Activation treatment: Manganese tetroxide was activated under vacuum to obtain hydroxyl manganese tetroxide with a surface hydroxyl content of 1.5 mmol / g.

[0245] The vacuum level was -0.09 MPa, the activation temperature was 95℃, and the activation time was 1.5 h.

[0246] D212. Stirring treatment: Hydroxymanganese tetroxide was mixed with a dispersion of compound modifier and stirred to obtain a precursor.

[0247] Among them, the compound modifier dispersion is made by dispersing the compound modifier in alcohol, and its viscosity is 8 mPa·s.

[0248] The stirring process was carried out at a temperature of 70℃ for 45 minutes and a stirring speed of 300 rpm.

[0249] D213. Curing treatment: D2131. Centrifugation is used to obtain the solid precursor.

[0250] D2132. Gradient curing: (1) Low temperature stage: with an argon atmosphere flow rate of 0.8 m³ / s. 3 At a temperature of / h, the solid precursor is heated to 100℃ and held for 30 min.

[0251] (2) Intermediate temperature stage: with an argon atmosphere flow rate of 1.8 m³ / s. 3 Continue heating to 150℃ at / h and hold for 30 minutes.

[0252] (3) High temperature stage: with an argon atmosphere flow rate of 1.8 m³ / s. 3 Continue heating to 180℃ at / h and hold for 90min.

[0253] (4) Cooling stage: with an argon atmosphere flow rate of 0.4 m³ / s. 3 At a temperature of / h, the temperature was lowered to below 60℃ to obtain a modified manganese tetroxide weighting agent.

[0254] Comparative Example 3 Comparative Example 3 provides a method for preparing a modified manganese tetroxide weighting agent for water-based drilling. The steps are basically the same as in Example 1, except that: The curing steps in step E2032 are as follows: With an argon atmosphere flow rate of 1m³ 3 At a temperature of / h, the solid precursor is heated to 180℃ and held at that temperature for 90 minutes, then allowed to cool naturally to below 60℃.

[0255] To verify the advancement of the modified manganese tetroxide weighting agent for water-based drilling and its preparation method provided in this invention, the true density, particle size D50, iron content, membrane grafting rate (interface anchoring inner layer and hydrophobic crosslinked middle layer), and settling velocity of the modified manganese tetroxide weighting agents for water-based drilling prepared in this invention and comparative examples were tested. The results are shown in Table 1 below. Taking Example 1 and Comparative Example 1 as examples, SEM images of the modified manganese tetroxide weighting agent for water-based drilling in Example 1 are provided, along with particle size distribution diagrams of the modified manganese tetroxide weighting agents for water-based drilling in Example 1 and Comparative Example 1, as shown below. Figures 1-3 As shown.

[0256] Among them, (1) the true density was tested using the Lee's density bottle method of the standard SY / T 5504.7-2024.

[0257] (2) The iron content was tested using the ICP-OES method of GB / T 21836-2024.

[0258] (3) The membrane grafting rate was tested using thermogravimetric analysis (TGA) in T / SDAMA 006-2024.

[0259] (4) The settling velocity was measured using the graduated cylinder static settling method of T / CSTM 01200-2025.

[0260] Table 1

[0261] From Table 1 above, at least the following conclusions can be drawn: Comparative Example 1 only had a capping agent without constructing an interface anchoring inner layer and a hydrophobic crosslinking middle layer. It only exhibited simple physical adsorption, resulting in an extremely low membrane grafting rate. In the water-based system, it was prone to detachment and had a relatively fast settling rate. Comparative Example 2 constructed an anchoring layer and a hydrophobic crosslinking layer without adding a capping agent. Although the membrane grafting rate was improved, a large number of hydrophilic hydroxyl groups remained on the surface, resulting in poor water resistance and mineralization resistance, insufficient long-term stability, and a settling rate higher than the acceptable value. Comparative Example 3 did not employ a gradient curing method, leading to insufficient membrane grafting, high internal stress, structural defects, a low grafting rate, a relatively fast settling rate, and insufficient overall performance. Therefore, the modified manganese tetroxide weighting agent provided in this invention, with its three-layer structured hydrophobic membrane consisting of an interface anchoring inner layer, a hydrophobic crosslinking middle layer, and a temperature-resistant capping outer layer on the surface of the manganese tetroxide particles, improves the membrane's adhesion, hydrophobicity, flexibility, and temperature resistance, achieving a true density of 4.85 g / cm³. 3 ~5.08g / cm 3 The membrane grafting rate is ≥91.4%, and the settling velocity is 0.018mm / s~0.24mm / s.

[0262] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A modified manganese tetroxide weighting agent for water-based drilling, characterized in that, Including core-shell structure; The core contains manganese tetroxide; The outer shell consists of an interface anchoring inner layer, a hydrophobic cross-linking middle layer, and a heat-resistant end capping outer layer.

2. The modified manganese tetroxide weighting agent for water-based drilling according to claim 1, characterized in that, The raw materials for preparing the modified manganese tetroxide weighting agent for water-based drilling include: Manganese tetroxide, compound modifier and end-capping agent; The mass of the compound modifier is 0.5% to 2% of the mass of manganese tetroxide.

3. The modified manganese tetroxide weighting agent for water-based drilling according to claim 2, characterized in that, It satisfies at least one of the following characteristics (1) to (5): (1) The raw materials for preparing manganese tetroxide include: a mixture of raw materials and a dispersant; (2) The mass ratio of the mixture to the dispersant is 100:(1~3); (3) The mixture includes manganese ore and calcium oxide; (4) The mass ratio of manganese ore to calcium oxide is (28~95):5; (5) The particle size D50 of manganese ore is 50μm~100μm.

4. The modified manganese tetroxide weighting agent for water-based drilling according to any one of claims 2 to 3, characterized in that, The compound modifier comprises a mixture of fluorosilane coupling agents and long-chain alkylsilanes.

5. The modified manganese tetroxide weighting agent for water-based drilling according to claim 4, characterized in that, It satisfies at least one of the following characteristics (1) to (7): (1) The mass ratio of the fluorosilane coupling agent to the long-chain alkylsilane is (11~30):5; (2) The compound modifier also includes a synergist; (3) The mass of the synergist is 0.1% to 0.3% of the mass of manganese tetroxide; (4) The compound modifier also includes a mineralization resistance modifier; (5) The mass of the anti-mineralization modifier is 0.2%~0.5% of the mass of manganese tetroxide; (6) The end-capping agent includes at least one of hexamethyldisilazane, trimethylchlorosilane, and triethoxysilane; (7) The mass of the capping agent is 0.1% to 0.13% of the mass of manganese tetroxide.

6. A method for preparing a modified manganese tetroxide weighting agent for water-based drilling, characterized in that, The preparation of the modified manganese tetroxide weighting agent for water-based drilling as described in any one of claims 1 to 5 comprises the following steps: The first coating treatment was carried out with manganese tetroxide and a compound modifier to obtain the first coated product; The first coating product and the capping agent are subjected to a second coating treatment.

7. The preparation method of the modified manganese tetroxide weighting agent for water-based drilling according to claim 6, characterized in that, It satisfies at least one of the following characteristics (1) to (3): (1) The preparation of the manganese tetroxide includes the following steps: After ball milling, the ball-milled slurry is subjected to oxidation treatment. The ball milling slurry includes a mixture of materials and a dispersant; (2) The first coating process includes the following steps: Manganese tetroxide was activated to obtain hydroxy manganese tetroxide; The hydroxyl manganese tetroxide is mixed with the compound modifier dispersion and stirred to obtain a precursor. Then, it is solidified to obtain the first coated product. (3) The second coating process includes the following steps: The product after the first coating treatment and the capping agent are mixed and stirred.

8. The preparation method of the modified manganese tetroxide weighting agent for water-based drilling according to claim 7, characterized in that, In the first coating process, at least one of the following features (1) to (7) is satisfied: (1) The activation process includes the following steps: Manganese tetroxide was activated under vacuum. (2) In the first coating treatment, the surface hydroxyl content of manganese tetroxide is 1.1 mmol / g to 1.8 mmol / g; (3) In the first coating treatment, the viscosity of the compound modifier dispersion is 5 mPa·s to 10 mPa·s; (4) In the first coating process, the stirring temperature is 60℃~80℃; (5) In the first coating treatment, the stirring time is 30 min to 60 min; (6) In the first coating process, the stirring speed of the stirring process is 250 rpm to 350 rpm; (7) In the first coating process, the curing process includes the following steps: After obtaining the solid precursor, it is subjected to gradient curing under an inert atmosphere.

9. The preparation method of the modified manganese tetroxide weighting agent for water-based drilling according to claim 7, characterized in that, In the preparation of manganese tetroxide, at least one of the following characteristics (1) to (9) is satisfied: (1) The solid-liquid ratio of the ball mill slurry is 1:(2~4); (2) The preparation of ball mill slurry includes the following steps: Manganese ore and calcium oxide are mixed to obtain a mixture. After mixing the materials and dispersant, water is added to adjust the solid-liquid ratio of the slurry, thus obtaining a ball-milled slurry; (3) In the ball milling process, the milling media is zirconia balls; (4) In the ball milling process, the ball-to-material ratio is (9~11):1; (5) During ball milling, the rotation speed of the ball mill is 300 rpm to 400 rpm; (6) In the ball milling process, the ball milling time is 6h~18h; (7) The particle size D90 of the slurry obtained after ball milling is less than 100 μm; (8) The oxidation treatment includes the following steps: The composite particles after ball milling were obtained, and then heated to 800℃~1200℃ and kept at that temperature under an oxidizing atmosphere. (9) The preparation of manganese tetroxide also includes the following steps: The product obtained from the oxidation treatment is mixed with cation exchange resin for ion exchange, followed by post-treatment.

10. An application in the field of oil drilling, characterized in that, The modified manganese tetroxide weighting agent for water-based drilling as described in any one of claims 1 to 5, or the modified manganese tetroxide weighting agent for water-based drilling prepared by any one of claims 6 to 9, is used.

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