Comb-type polymer modified barite powder as well as preparation method and application thereof

Abstract

The invention relates to the technical field of oil field drilling fluid, in particular to comb-shaped polymer modified barite powder as well as a preparation method and application thereof.The comb-shaped polymer modified barite powder is prepared by immersing barite powder into an aqueous solution containing a comb-shaped polymer and enabling the comb-shaped polymer to be adsorbed to the surface of the barite powder; wherein the mass ratio of the barite powder to the comb-type polymer water solution is (2-10): 1, and the comb-type polymer is prepared by polymerizing at least one carboxylic acid-containing monomer, at least one sulfonic acid group-containing monomer and at least one unsaturated polyether macromonomer. The prepared comb-type polymer modified barite powder can effectively solve the problem that the rheological property of high-density water-based drilling fluid is difficult to regulate and control. The comb-type polymer modified barite powder is added into the water-based drilling fluid, so that the barite powder can be effectively dispersed and kept stable by utilizing the characteristics of hydrophilicity and strong steric hindrance effect of the comb-type polymer.

Description

Technical Field

[0001] This invention relates to the field of oilfield drilling fluid technology, specifically to a comb-type polymer-modified barite powder, its preparation method, and its application. Background Technology

[0002] During deep and ultra-deep well drilling, the bottom hole temperature and pressure increase significantly, and complex formations such as salt-gypsum layers are often encountered. Saltwater drilling fluids are widely used in complex deep well drilling due to their excellent shale inhibition and stability in such formations. However, high-density drilling fluids struggle to disperse barite in high-temperature, high-solids, and saltwater environments, easily leading to high-temperature thickening or even solidification. This deteriorates the rheological properties of the drilling fluid, severely hindering the safe and efficient operation of drilling projects.

[0003] Extensive research has been conducted for a long time to regulate the rheological properties of high-density water-based drilling fluids, resulting in the development of various types of viscosity reducers and dispersants, such as sulfonated tannin and sulfonated lignin. However, their application is limited due to issues with temperature resistance, salt resistance, viscosity-reducing effect, and cost. Therefore, there is an urgent need in the field for a treatment agent that is resistant to high temperatures and salt, effectively disperses barite powder, and reduces the viscosity of high-density brine drilling fluid systems.

[0004] In recent years, polymer viscosity reducers have developed rapidly. Commonly used copolymers include carboxyl monomers, sulfonic acid monomers, and cationic monomers. For example, patent CN114853937A uses a viscosity reducer obtained by copolymerizing carboxyl monomers, amino monomers, and sulfonic acid monomers, while patent CN118496407A uses a viscosity reducer obtained by copolymerizing carboxyl monomers, sulfonic acid monomers, and cationic monomers. However, these viscosity reducers lack special molecular structures and salt-resistant monomers, making them unsuitable for high-density brine drilling fluids. Therefore, it is necessary to design special molecular structures and optimize monomers for polymer viscosity reducers. Summary of the Invention

[0005] Based on this, the present invention proposes a comb-type polymer-modified barite powder, its preparation method and application, which can effectively solve the problem of difficult control of the rheological properties of high-density water-based drilling fluid.

[0006] According to a first aspect of the present invention, a comb-type polymer modified barite powder is provided, comprising modified barite powder obtained by immersing barite powder in an aqueous solution containing a comb-type polymer, thereby causing the comb-type polymer to adsorb onto the surface of the barite powder.

[0007] The mass ratio of barite powder to comb-type polymer aqueous solution is (2-10):1;

[0008] The comb-shaped polymer is obtained by polymerizing at least one carboxylic acid monomer, at least one sulfonic acid group monomer and at least one unsaturated polyether macromonomer.

[0009] According to a second aspect of the present invention, a method for preparing the comb-type polymer-modified barite powder of claim 1 is provided, comprising the following steps:

[0010] Solution A is obtained by thoroughly mixing a carboxylic acid monomer, a sulfonic acid group monomer, and deionized water.

[0011] Solution B is obtained by thoroughly mixing the initiator, NaOH, and deionized water.

[0012] Unsaturated polyether macromonomers and deionized water are added to the reactor, stirred thoroughly to dissolve, and nitrogen gas is introduced.

[0013] Solution A and solution B are added dropwise to the reaction vessel in sequence, and the mixture is heated and stirred thoroughly under a nitrogen atmosphere to obtain an aqueous solution of comb-type polymer;

[0014] Barite powder was added to the aqueous solution of the comb-type polymer, stirred, and allowed to stand for a certain period of time to allow the comb-type polymer to be fully adsorbed on the surface of the barite powder, thus obtaining modified barite powder.

[0015] The modified barite powder was washed, dried, and ground to obtain comb-type polymer-modified barite powder.

[0016] According to an embodiment of the present invention, the carboxylic acid-containing monomer is one or more selected from acrylic acid, methacrylic acid, maleic anhydride, and fumaric acid;

[0017] And / or, the sulfonic acid-containing monomer includes one or more of 2-acrylamido-2-methylpropanesulfonic acid, sodium vinyl sulfonate, sodium propenyl sulfonate, and sodium methacryl sulfonate;

[0018] And / or, the initiator includes one or more of potassium persulfate, sodium persulfate, ammonium persulfate, and azobisisobutyronitrile.

[0019] According to embodiments of the present invention, the unsaturated polyether macromonomer includes one or more of polyethylene glycol monomethyl ether acrylate, polyethylene glycol propylene glycol monomethyl ether acrylate, polyethylene glycol acrylate, polyethylene glycol propylene glycol acrylate, polyethylene glycol monomethyl ether methacrylate, polyethylene glycol propylene glycol monomethyl ether methacrylate, polyethylene glycol methacrylate, and polyethylene glycol propylene glycol methacrylate.

[0020] The molecular weight of the unsaturated polyether macromonomer is 200-10000.

[0021] According to an embodiment of the present invention, solution A and solution B are sequentially added dropwise to the reaction vessel, and the mixture is heated and stirred thoroughly under a nitrogen atmosphere to obtain an aqueous solution of the comb-type polymer:

[0022] When the unsaturated polyether macromonomer is polyethylene glycol monomethyl ether acrylate, the reaction temperature is 25℃-40℃.

[0023] When the unsaturated polyether macromonomer is polyethylene glycol propylene glycol acrylate, the reaction temperature is 35℃-60℃.

[0024] When the unsaturated polyether macromonomer is polyethylene glycol propylene glycol methacrylate, the reaction temperature is 60℃-85℃.

[0025] According to an embodiment of the present invention, the mass ratio of the carboxylic acid monomer, the sulfonic acid group monomer, and the deionized water is (1-3):(1-2):4;

[0026] And / or, the mass ratio of the initiator, the NaOH, and the deionized water is (1-8):(5-20):200.

[0027] And / or, the mass ratio of the unsaturated polyether macromonomer to deionized water is 1:(1.5-2.5).

[0028] According to an embodiment of the present invention, the unsaturated polyether macromonomer and deionized water are added to the reactor, stirred thoroughly to dissolve, and nitrogen gas is introduced. The stirring speed is 300-1000 r / min, and the stirring time is 15-50 min.

[0029] According to an embodiment of the present invention, the solution A and the solution B are added dropwise to the reaction vessel in sequence, and the mixture is heated and stirred thoroughly under a nitrogen atmosphere to obtain a comb-type polymer aqueous solution. The time taken for adding solution A dropwise is 30-60 minutes.

[0030] The time required to add solution B is 30-60 minutes;

[0031] The stirring speed is 300-1000 r / min, and the stirring time is 1.5-6 h;

[0032] According to an embodiment of the present invention, barite powder is added to the aqueous solution of the comb-type polymer, stirred, and then allowed to stand for a certain period of time to allow the comb-type polymer to be fully adsorbed on the surface of the barite powder, thereby obtaining modified barite powder. The stirring speed is 1000-3000 r / min, the stirring time is 30-120 min, and the standing time should be no less than 24 h.

[0033] According to a third aspect of the present invention, an application of comb-type polymer-modified barite powder in oilfield drilling fluid is provided; the comb-type polymer-modified barite powder is used at temperatures below 260°C and with a density of 1.8 g / cm³. 3 -2.6g / cm 3 Water-based drilling fluid.

[0034] As can be seen from the above technical solutions, the comb-type polymer-modified barite powder, its preparation method, and its application provided by the present invention have the following beneficial effects:

[0035] The comb-shaped polymer-modified barite powder prepared in this invention can effectively solve the problem of difficult control of the rheological properties of high-density water-based drilling fluids. Adding the comb-shaped polymer-modified barite powder to water-based drilling fluids utilizes the hydrophilicity and strong steric hindrance of the comb-shaped polymer to effectively disperse and stabilize the barite powder. Furthermore, the use of non-ionic monomers as side chains in the comb-shaped polymer enhances its salt resistance, significantly reducing the impact of salt on the polymer molecular chain. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0037] According to a first aspect of the present invention, a comb-type polymer modified barite powder is provided, comprising modified barite powder obtained by immersing barite powder in an aqueous solution containing a comb-type polymer, thereby causing the comb-type polymer to adsorb onto the surface of the barite powder.

[0038] The mass ratio of barite powder to comb-type polymer aqueous solution is (2-10):1;

[0039] Comb polymers are obtained by polymerizing at least one carboxylic acid monomer, at least one sulfonic acid monomer, and at least one unsaturated polyether macromonomer.

[0040] Comb-shaped polymers are a type of polymer material with a special structure. Their molecular chains have numerous side chains, giving them a shape resembling a comb. Compared to traditional polymer viscosity reducers, this unique structure endows comb-shaped polymers with strong steric hindrance, enabling them to disperse solid particles in liquids, ensuring uniform distribution and stability. The side chains of comb-shaped polymers are typically non-ionic monomers with strong hydrophilicity, significantly reducing the influence of salts on the polymer, enhancing hydration, and forming a hydration film on the surface of solid particles. This reduces inter-particle contact, further improving particle dispersion and achieving the viscosity-reducing effect. Furthermore, the main chain of comb-shaped polymers contains multiple carboxylic acid and sulfonic acid groups, allowing for multi-site adsorption on the surface of barite powder, making it less prone to detachment.

[0041] According to a second aspect of the present invention, a method for preparing the comb-type polymer-modified barite powder of claim 1 is provided, comprising the following steps:

[0042] Solution A is obtained by thoroughly mixing a carboxylic acid monomer, a sulfonic acid group monomer, and deionized water.

[0043] Solution B is obtained by thoroughly mixing the initiator, NaOH, and deionized water.

[0044] Unsaturated polyether macromonomers and deionized water are added to the reactor, stirred thoroughly to dissolve, and nitrogen gas is introduced.

[0045] Solution A and solution B were added dropwise to the reaction vessel in sequence, and the mixture was heated and stirred thoroughly under a nitrogen atmosphere to obtain an aqueous solution of comb-shaped polymer.

[0046] Barite powder was added to the aqueous solution of the comb-type polymer, stirred, and allowed to stand for a certain period of time to allow the comb-type polymer to be fully adsorbed on the surface of the barite powder, thus obtaining modified barite powder.

[0047] The modified barite powder was washed, dried, and ground to obtain comb-type polymer-modified barite powder.

[0048] According to embodiments of the present invention, the carboxylic acid monomer is one or more selected from acrylic acid, methacrylic acid, maleic anhydride, and fumaric acid;

[0049] And / or, monomers containing sulfonic acid groups include one or more of 2-acrylamido-2-methylpropanesulfonic acid, sodium vinyl sulfonate, sodium propenyl sulfonate, and sodium methacryl sulfonate;

[0050] And / or, the initiator includes one or more of potassium persulfate, sodium persulfate, ammonium persulfate, and azobisisobutyronitrile.

[0051] According to embodiments of the present invention, the unsaturated polyether macromonomer includes one or more of polyethylene glycol monomethyl ether acrylate, polyethylene glycol propylene glycol monomethyl ether acrylate, polyethylene glycol acrylate, polyethylene glycol propylene glycol acrylate, polyethylene glycol monomethyl ether methacrylate, polyethylene glycol propylene glycol monomethyl ether methacrylate, polyethylene glycol methacrylate, and polyethylene glycol propylene glycol methacrylate.

[0052] The molecular weight of unsaturated polyether macromonomers ranges from 200 to 10,000.

[0053] According to an embodiment of the present invention, solution A and solution B are added dropwise to a reaction vessel in sequence, and the mixture is heated and stirred thoroughly under a nitrogen atmosphere to obtain an aqueous solution of the comb-type polymer:

[0054] When the unsaturated polyether macromonomer is polyethylene glycol monomethyl ether acrylate, the reaction temperature is 25℃-40℃.

[0055] When the unsaturated polyether macromonomer is polyethylene glycol propylene glycol acrylate, the reaction temperature is 35℃-60℃.

[0056] When the unsaturated polyether macromonomer is polyethylene glycol propylene glycol methacrylate, the reaction temperature is 60℃-85℃.

[0057] According to an embodiment of the present invention, the mass ratio of the carboxylic acid monomer, the sulfonic acid monomer, and deionized water is (1-3):(1-2):4;

[0058] And / or, the mass ratio of initiator, NaOH and deionized water is (1-8):(5-20):200.

[0059] And / or, the mass ratio of unsaturated polyether macromonomer to deionized water is 1:(1.5-2.5).

[0060] According to an embodiment of the present invention, unsaturated polyether macromonomer and deionized water are added to a reaction vessel, stirred thoroughly to dissolve, and nitrogen gas is introduced. The stirring speed is 300-1000 r / min, and the stirring time is 15-50 min.

[0061] According to an embodiment of the present invention, solution A and solution B are added dropwise to a reaction vessel in sequence, and the mixture is heated and stirred thoroughly under a nitrogen atmosphere to obtain a comb-type polymer aqueous solution. The time taken for adding solution A dropwise is 30-60 minutes.

[0062] The time required to add solution B is 30-60 minutes;

[0063] The stirring speed is 300-1000 r / min, and the stirring time is 1.5-6 h;

[0064] According to an embodiment of the present invention, barite powder is added to an aqueous solution of a comb-type polymer, stirred, and allowed to stand for a certain period of time to allow the comb-type polymer to be fully adsorbed on the surface of the barite powder, thereby obtaining modified barite powder. The stirring speed is 1000-3000 r / min, the stirring time is 30-120 min, and the standing time should be no less than 24 h.

[0065] According to a third aspect of the present invention, an application of comb-type polymer-modified barite powder in oilfield drilling fluid is provided, wherein the comb-type polymer-modified barite powder is used at temperatures below 260°C and with a density of 1.8 g / cm³. 3 -2.6g / cm 3 Water-based drilling fluid.

[0066] The technical solution of the present invention will be described in detail below through preferred embodiments. It should be noted that the specific embodiments in the following text are for illustrative purposes only and are not intended to limit the present invention.

[0067] The reagents used in the following examples are as follows:

[0068] Acrylic acid is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., with CAS number 79-10-7.

[0069] Maleic anhydride is a commercially available product from Sinopharm Chemical Reagent Co., Ltd. with CAS number 708-31-6;

[0070] Methacrylic acid is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., with CAS number 79-41-4.

[0071] 2-Acrylamido-2-methylpropanesulfonic acid (AMPS) is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., with CAS number 15214-89-8.

[0072] Sodium methylpropene sulfonate is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., with CAS number 2495-39-8.

[0073] NaOH is a commercially available product from Sinopharm Chemical Reagent Co., Ltd. with CAS number 1310-73-2;

[0074] Potassium persulfate is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., with CAS number 7727-21-1.

[0075] Sodium persulfate is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., with CAS number 7775-27-1.

[0076] Azobisisobutyronitrile is a commercially available product from Sinopharm Chemical Reagent Co., Ltd. with CAS number 78-67-1.

[0077] Polyethylene glycol monomethyl ether acrylate is a commercially available product of Wuhan Jixin Yibang Biotechnology Co., Ltd.

[0078] Polyethylene glycol propylene glycol monomethyl ether methacrylate is a commercially available product of KELON Fine Chemicals Co., Ltd.

[0079] The barite powder is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., with CAS number 7727-43-7.

[0080] Sulfonated tannin is a commercially available product of Chengdu Chuanfeng Chemical Engineering Co., Ltd.

[0081] Bentonite is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., with CAS number 1302-78-9.

[0082] Sodium carbonate is a commercially available product from Sinopharm Chemical Reagent Co., Ltd., with CAS number 497-19-8.

[0083] DSP-1 is a commercially available product of Shandong Deshunyuan Petroleum Technology Co., Ltd.

[0084] SMP-Ⅱ is a commercially available product of Zhengzhou Jingyuan Slurry Materials Co., Ltd.

[0085] SPNH is a commercially available product of Chengdu Chuanfeng Chemical Engineering Co., Ltd.

[0086] FF-1 is a commercially available product of Shandong Deshunyuan Petroleum Technology Co., Ltd.

[0087] Super Calcium (2000 mesh), a commercially available product from Shandong Deshunyuan Petroleum Technology Co., Ltd.

[0088] The contact angle measuring instrument is the OCA15EC video optical contact angle measuring instrument from the German company Dataphysics.

[0089] Example 1

[0090] (1) Dissolve 35g of acrylic acid and 30g of AMPS in 100g of deionized water to obtain solution A; dissolve 5g of NaOH and 2g of potassium persulfate in 100g of deionized water to obtain solution B;

[0091] (2) Add 100g of polyethylene glycol monomethyl ether acrylate with a molecular weight of 2000 and 200g of deionized water to a three-necked flask in sequence, stir at 450r / min for 30min, and introduce nitrogen gas.

[0092] (3) Under a nitrogen atmosphere, solution A was added dropwise at a uniform rate to a three-necked flask and the addition was completed in 30 min; solution B was added dropwise at a uniform rate to a three-necked flask and the addition was completed in 45 min; after adding solutions A and B, the mixture was stirred for 4 h under a nitrogen atmosphere, at 40 °C and 500 r / min to obtain comb-type polymer aqueous solution C1.

[0093] (4) Add 800g of barite powder (6000 mesh) to 200g of comb-type polymer aqueous solution C1, stir at 2000r / min for 1h, and then let stand for 24h.

[0094] (5) The product was thoroughly washed and dried at 45°C for 24 hours, and then pulverized through a 6000-mesh sieve to obtain modified barite powder B1.

[0095] Example 2

[0096] (1) Dissolve 35g of acrylic acid and 30g of AMPS in 100g of deionized water to obtain solution A; dissolve 5g of NaOH and 2g of potassium persulfate in 100g of deionized water to obtain solution B;

[0097] (2) Add 100g of polyethylene glycol propylene glycol monomethyl ether methacrylate with a molecular weight of 3500 and 200g of deionized water to a three-necked flask, stir at 450r / min for 30min, and purge with nitrogen.

[0098] (3) Under a nitrogen atmosphere, solution A was added dropwise at a uniform rate to a three-necked flask and the addition was completed in 30 min; solution B was added dropwise at a uniform rate to a three-necked flask and the addition was completed in 45 min; after adding solutions A and B, the mixture was stirred at 75℃ and 500 r / min for 4 h to obtain comb-type polymer aqueous solution C2.

[0099] (4) Add 800g of barite powder (6000 mesh) to 200g of comb-type polymer aqueous solution C2, stir at 2000r / min for 1h, and then let stand for 24h;

[0100] (5) The product was thoroughly washed and dried at 45°C for 24 hours, and then pulverized through a 6000-mesh sieve to obtain modified barite powder B2.

[0101] Example 3

[0102] (1) Dissolve 50g of acrylic acid and 35g of AMPS in 100g of deionized water to obtain solution A; dissolve 7g of NaOH and 2g of azobisisobutyronitrile in 100g of deionized water to obtain solution B;

[0103] (2) Add 100g of polyethylene glycol monomethyl ether acrylate with a molecular weight of 2000 and 200g of deionized water to a three-necked flask in sequence, stir at 450r / min for 30min, and introduce nitrogen gas.

[0104] (3) Under a nitrogen atmosphere, solution A was added dropwise at a uniform rate to a three-necked flask and the addition was completed in 30 min; solution B was added dropwise at a uniform rate to a three-necked flask and the addition was completed in 45 min; after adding solutions A and B, the mixture was stirred at 30℃ and 500 r / min for 4 h to obtain comb-type polymer aqueous solution C3.

[0105] (4) Add 800g of barite powder (6000 mesh) to 200g of comb-type polymer aqueous solution C3, stir at 2000r / min for 1h, and then let stand for 24h;

[0106] (5) The product was thoroughly washed and dried at 45°C for 24 hours, and then pulverized through a 6000-mesh sieve to obtain modified barite powder B3.

[0107] Example 4

[0108] (1) Dissolve 35g of maleic anhydride and 30g of sodium methylpropene sulfonate in 100g of deionized water to obtain solution A; dissolve 5g of NaOH and 2g of potassium persulfate in 100g of deionized water to obtain solution B;

[0109] (2) Add 100g of polyethylene glycol monomethyl ether acrylate with a molecular weight of 2000 and 200g of deionized water to a three-necked flask in sequence, stir at 450r / min for 30min, and introduce nitrogen gas.

[0110] (3) Under a nitrogen atmosphere, solution A was added dropwise at a uniform rate to a three-necked flask and the addition was completed in 45 min; solution B was added dropwise at a uniform rate to a three-necked flask and the addition was completed in 55 min; after adding solutions A and B, the mixture was stirred at 40℃ and 500 r / min for 4 h to obtain comb-type polymer aqueous solution C4.

[0111] (4) Add 800g of barite powder (6000 mesh) to 100g of comb-type polymer aqueous solution C4, stir at 3000r / min for 1h, and then let stand for 24h.

[0112] (5) The product was thoroughly washed and dried at 45°C for 24 hours, and then pulverized through a 6000-mesh sieve to obtain modified barite powder B4.

[0113] Example 5

[0114] (1) Dissolve 35g of methacrylic acid and 30g of sodium methacrylate in 100g of deionized water to obtain solution A; dissolve 5g of NaOH, 1g of potassium persulfate and 1g of sodium persulfate in 100g of deionized water to obtain solution B;

[0115] (2) Add 100g of polyethylene glycol propylene glycol monomethyl ether methacrylate with a molecular weight of 4000 and 200g of deionized water to a three-necked flask, stir at 450r / min for 30min, and purge with nitrogen.

[0116] (3) Under a nitrogen atmosphere, solution A was added dropwise at a uniform rate to a three-necked flask and the addition was completed in 30 min; solution B was added dropwise at a uniform rate to a three-necked flask and the addition was completed in 45 min; after adding solutions A and B, the mixture was stirred for 5 h under a nitrogen atmosphere, at 85 °C and 500 r / min to obtain comb-type polymer aqueous solution C5.

[0117] (4) Add 800g of barite powder (6000 mesh) to 100g of comb-type polymer aqueous solution C5, stir at 2000r / min for 1h, and then let stand for 24h.

[0118] (5) The product was thoroughly washed and dried at 45°C for 24 hours, and then pulverized through a 6000-mesh sieve to obtain modified barite powder B5.

[0119] Comparative Example 1

[0120] Barite powder that has not undergone any modification is designated as D1.

[0121] Comparative Example 2

[0122] The difference from Example 1 is that this comparative example uses sodium lignosulfonate to modify barite powder to obtain barite powder D2.

[0123] Comparative Example 3

[0124] The difference from Example 1 is that this comparative example uses sulfonated tannin to modify barite powder to obtain barite powder D3.

[0125] Experimental Example 1:

[0126] The contact angle of barite powder with water was measured using a contact angle meter to observe the hydrophilicity of barite powder. The experimental steps are as follows:

[0127] Weigh 15g of the modified barite B1-B5 prepared in Examples 1-5 and the barite powder D1-D3 prepared in Comparative Examples 1-3, pour them into a cylindrical mold, and press them at 20MPa for 5min to form a cylindrical solid sheet with a smooth surface. Place the solid sheet on the sample stage, control the contact between the droplet and the surface of the solid sheet, and measure the contact angle of the barite powder surface with water after the droplet stabilizes.

[0128] The results are shown in Table 1.

[0129] Table 1. Contact angle of barite powder surface to water

[0130] Test solution Contact angle (°) Example 1 26.12 Example 2 25.24 Example 3 26.27 Example 4 26.25 Example 5 28.36 Comparative Example 1 33.56 Comparative Example 2 32.73 Comparative Example 3 32.47

[0131] As can be seen from Table 1, compared with unmodified or other viscosity-reducing barite powder, the contact angle of comb-type polymer-modified barite powder is significantly reduced, indicating that its hydrophilicity is enhanced, making it easier to form a hydration film in drilling fluid, reducing the contact between particles, and thus improving the dispersion of barite in drilling fluid.

[0132] Experiment Example 2

[0133] Modified barite B1-B5 prepared in Examples 1-5 and barite powder D1-D3 prepared in Comparative Examples 1-3 were added to the basic experimental slurry to adjust the drilling fluid density to 2.0 g / cm³. 3 The mixture was stirred at 12000 r / min for 30 min, then placed in an aging tank and hot-rolled at 200℃ for 16 h. Its rheological properties and sedimentation stability were then tested at room temperature. The results are shown in Table 2.

[0134] Basic experimental slurry formulation: 1.5% bentonite-based slurry (300mL) + 0.2% Na2CO3 + 0.3% NaOH + 2% DSP-1 + 1% SMP-2 + 4% SPNH + 3% FF-1 + 3% supercalcium (2000 mesh).

[0135] Table 2. Rheological properties and sedimentation stability of Examples 1-5

[0136]

[0137] As shown in Table 2, the drilling fluid weighted with comb-type polymer-modified barite powder exhibits significantly reduced apparent viscosity and plastic viscosity, effectively mitigating the problem of deteriorating rheological properties in high-density drilling fluids. Furthermore, the density difference between the upper and lower layers of the drilling fluid decreased significantly after aging and standing for 24 hours, indicating good settling stability and stable dispersion of barite within the fluid.

[0138] In summary, the comb-type polymer-modified barite powder prepared in the embodiments of this invention can effectively solve the problem of difficult control of the rheological properties of high-density water-based drilling fluids. Adding the comb-type polymer-modified barite powder to water-based drilling fluids utilizes the hydrophilicity and strong steric hindrance of the comb-type polymer to effectively disperse and stabilize the barite powder. Furthermore, the use of non-ionic monomers as side chains in the comb-type polymer enhances its salt resistance, significantly reducing the impact of salt on the polymer molecular chain.

[0139] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A comb-type polymer-modified barite powder, characterized in that, This includes modified barite powder obtained by immersing barite powder in an aqueous solution containing a comb-shaped polymer, thereby allowing the comb-shaped polymer to adsorb onto the surface of the barite powder. The mass ratio of barite powder to comb-type polymer aqueous solution is (2-10):1; The comb-shaped polymer is obtained by polymerizing at least one carboxylic acid monomer, at least one sulfonic acid group monomer and at least one unsaturated polyether macromonomer.

2. A method for preparing the comb-type polymer-modified barite powder according to claim 1, characterized in that, Includes the following steps: Solution A is obtained by thoroughly mixing a carboxylic acid monomer, a sulfonic acid group monomer, and deionized water. Solution B is obtained by thoroughly mixing the initiator, NaOH, and deionized water. Unsaturated polyether macromonomers and deionized water are added to the reactor, stirred thoroughly to dissolve, and nitrogen gas is introduced. Solution A and solution B are added dropwise to the reaction vessel in sequence, and the mixture is heated and stirred thoroughly under a nitrogen atmosphere to obtain an aqueous solution of comb-type polymer; Barite powder was added to the aqueous solution of the comb-type polymer, stirred, and allowed to stand for a certain period of time to allow the comb-type polymer to be fully adsorbed on the surface of the barite powder, thus obtaining modified barite powder. The modified barite powder was washed, dried, and ground to obtain comb-type polymer-modified barite powder.

3. The preparation method according to claim 2, characterized in that, The carboxylic acid monomer is one or more of acrylic acid, methacrylic acid, maleic anhydride, and fumaric acid. And / or, the sulfonic acid-containing monomer includes one or more of 2-acrylamido-2-methylpropanesulfonic acid, sodium vinyl sulfonate, sodium propenyl sulfonate, and sodium methacryl sulfonate; And / or, the initiator includes one or more of potassium persulfate, sodium persulfate, ammonium persulfate, and azobisisobutyronitrile.

4. The preparation method according to claim 2, characterized in that, The unsaturated polyether macromonomer includes one or more of polyethylene glycol monomethyl ether acrylate, polyethylene glycol propylene glycol monomethyl ether acrylate, polyethylene glycol acrylate, polyethylene glycol propylene glycol acrylate, polyethylene glycol monomethyl ether methacrylate, polyethylene glycol propylene glycol monomethyl ether methacrylate, polyethylene glycol methacrylate, and polyethylene glycol propylene glycol methacrylate. The molecular weight of the unsaturated polyether macromonomer is 200-10000.

5. The preparation method according to claim 4, characterized in that, The solution A and solution B are added dropwise to the reaction vessel in sequence, and the mixture is heated and stirred thoroughly under a nitrogen atmosphere to obtain an aqueous solution of the comb-shaped polymer: When the unsaturated polyether macromonomer is polyethylene glycol monomethyl ether acrylate, the reaction temperature is 25℃-40℃. When the unsaturated polyether macromonomer is polyethylene glycol propylene glycol acrylate, the reaction temperature is 35℃-60℃. When the unsaturated polyether macromonomer is polyethylene glycol propylene glycol methacrylate, the reaction temperature is 60℃-85℃.

6. The preparation method according to claim 2, characterized in that, The mass ratio of the carboxylic acid monomer, the sulfonic acid monomer, and the deionized water is (1-3):(1-2):4; And / or, the mass ratio of the initiator, the NaOH, and the deionized water is (1-8):(5-20):

200. And / or, the mass ratio of the unsaturated polyether macromonomer to deionized water is 1:(1.5-2.5).

7. The preparation method according to claim 2, characterized in that, The unsaturated polyether macromonomer and deionized water are added to the reactor, stirred thoroughly to dissolve, and nitrogen gas is introduced. The stirring speed is 300-1000 r / min, and the stirring time is 15-50 min.

8. The preparation method according to claim 2, characterized in that, The solution A and solution B are added dropwise to the reaction vessel in sequence, and the mixture is heated and stirred thoroughly under a nitrogen atmosphere to obtain a comb-type polymer aqueous solution. The time taken for adding solution A is 30-60 minutes. The time required to add solution B is 30-60 minutes; The stirring speed is 300-1000 r / min, and the stirring time is 1.5-6 h.

9. The preparation method according to claim 2, characterized in that, The process involves adding barite powder to the comb-type polymer aqueous solution, stirring, and then allowing it to stand for a certain period of time to allow the comb-type polymer to be fully adsorbed onto the surface of the barite powder, thereby obtaining modified barite powder. The stirring speed is 1000-3000 r / min, the stirring time is 30-120 min, and the standing time should be no less than 24 h.

10. The application of the comb-type polymer-modified barite powder according to claim 1 in oilfield drilling fluid, wherein the comb-type polymer-modified barite powder is used at temperatures below 260°C and with a density of 1.8 g / cm³. 3 -2.6g / cm 3 Water-based drilling fluid.

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