Temperature-sensitive adhesive polymer applied to water-based and oil-based drilling fluids for improving formation pressure-bearing plugging and preparation method of temperature-sensitive adhesive polymer

Abstract

The invention discloses a temperature-sensitive adhesive polymer applied to water-based and oil-based drilling fluids for improving formation pressure-bearing plugging, relates to the technical field of oil field drilling, and solves the problems of return-loss leakage, repeated leakage and poor plugging efficiency of the drilling fluids caused by insufficient pressure-bearing capacity of plugging materials in the existing method. The temperature-sensitive adhesive polymer for pressure-bearing plugging comprises the following components: bridging particles, mica, polyurethane foam, a functional adhesive material, branched epoxy resin, graphite and superfine calcium carbonate in a mass ratio of (30-35): (10-15): (1-2): (1-2): (2-4): (2-4): (40-45), the preparation method comprises the following steps: weighing the bridging particles, the mica, the polyurethane foam, the branched epoxy resin, the graphite, the superfine calcium carbonate and the functional adhesive material in proportion, mixing, and adding into soil slurry / drilling fluid; and uniformly stirring and mixing to prepare the temperature-sensitive adhesive polymer. The temperature-sensitive adhesive polymer and the plugging material are high in pressure bearing capacity, and the range of plugging cracks is wider.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field drilling technology, and in particular to a temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids, and its preparation method. Background Technology

[0002] Loss of drilling fluid (WSDF) is a phenomenon where a large amount of drilling fluid leaks into the formation during drilling operations. It is one of the most common and difficult-to-handle complex accidents in drilling projects, particularly in complex formations with well-developed fractures, fractures, and complex pressure systems. WSDF can lead to drilling fluid loss, prolonged drilling cycles, and increased drilling costs. Improper handling can cause further complications such as drilling fluid loss, blowouts, intra-layer spills, and formation collapse, while also posing a significant threat to the safety of drilling personnel.

[0003] Generally, the principle of "prevention first, combined with plugging" is adopted for drilling fluid loss. Preventing well leakage involves designing a reasonable wellbore structure, reducing drilling fluid pressure surges, implementing safe mechanical drilling rates, adjusting drilling fluid properties, reducing drilling fluid density, and adding anti-leakage sealing materials to the drilling fluid in advance. After leakage occurs, the flow rate is first reduced to observe the leakage rate. Then, depending on the leakage situation, plugging methods such as drilling-while-drilling plugging, static plugging, and solidification plugging are selected to reduce the amount of drilling fluid loss until it stops. Typically, drilling-while-drilling plugging is used to handle low and moderate leakage, while static plugging and solidification plugging are used to handle moderate, severe, and reversible leakage. However, in formations that are sensitive to formation pressure, such as fractured, fractured, and complex pressure systems, the sealing effect of static plugging materials is affected by factors such as the gradation of the bridging material, the concentration of the bridging slurry, and the displacement pressure during construction. This can easily lead to problems such as "gate sealing," incomplete sealing, and repeated leakage, thus affecting the plugging efficiency. Solidification and sealing construction carries high safety risks, as it is easily contaminated or diluted by highly mineralized formation water, leading to stuck drill bits or poor retention capacity.

[0004] Currently used plugging materials can address conventional drilling fluid losses in the field. However, with the continuous expansion of drilling operations, encountering fractured formations, broken formations, formations with complex pressure systems, abnormally high-pressure wells, and wells with narrow / negative safety density windows, can lead to problems such as drilling fluid backflow, repeated losses, and poor plugging efficiency due to insufficient pressure-bearing capacity of the plugging materials during drilling operations. Therefore, developing plugging materials that improve formation pressure-bearing capacity to address these complex well leakage issues is an urgent problem to be solved. Summary of the Invention

[0005] This invention addresses the problems of drilling fluid backflow, repeated leakage, and poor plugging efficiency caused by insufficient pressure-bearing capacity of plugging materials in conventional plugging methods described in the background art when drilling into complex formations. It provides a temperature-sensitive adhesive polymer for improving formation pressure-bearing and plugging in water-based and oil-based drilling fluids. This temperature-sensitive adhesive polymer for improving formation pressure-bearing and plugging in water-based and oil-based drilling fluids incorporates functional adhesive materials with temperature-sensitive properties and synthesizes a branched epoxy resin that improves pressure-bearing capacity. The resulting plugging material has strong pressure-bearing capacity, can seal a wider range of fractures, and can better solve the problem of drilling fluid leakage.

[0006] The present invention solves its problems through the following technical solution: The temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids has the following components and mass ratios: the mass ratio of cross-linked particles, mica, polyurethane foam, functional adhesive materials, branched epoxy resin, graphite and ultrafine calcium carbonate is 30-35:10-15:1-2:1-2:2-4:2-4:40-45.

[0007] Preferably, the bridging particles are either walnut shells or vermiculite;

[0008] The mesh size of the walnut shells, vermiculite, and mica ranges from 2 to 40 mesh.

[0009] The typical particle sizes of the graphite and ultrafine calcium carbonate are 800 mesh and 1250 mesh, respectively.

[0010] Preferably, the functional adhesive material is any one of thermoplastic adhesive materials, thermosetting adhesive materials, elastomeric adhesive materials, and composite adhesive materials.

[0011] The thermosetting adhesive material is at least one of epoxy resin, urea-formaldehyde resin and phenolic resin; The elastomeric adhesive material is at least one of nitrile rubber, thermoplastic elastomer, and silicone rubber; The composite adhesive material is at least one of phenolic-nitrile rubber, epoxy-nitrile rubber, and epoxy-polyurethane rubber.

[0012] Preferably, the raw materials for synthesizing the branched epoxy resin include amino-containing phenolic substances, benzene-containing nitrile substances, epichlorohydrin, zirconium dioxide, and silane coupling agents;

[0013] The molar ratio of the amino-containing phenolic substance, the benzene-containing nitrile substance, and epichlorohydrin is 1:(0.3-2):(3-6).

[0014] Preferably, the branched epoxy resin is prepared by the following steps:

[0015] S1. Epichlorohydrin is added to a three-necked flask, heated to 30-50°C, then an amino-containing phenolic substance is added, followed by NaOH to adjust the pH to alkaline. Then, benzyltriethylammonium chloride catalyst is added, and the mixture is stirred at 40-60°C for 0.5-4 hours. The temperature is then raised to 80-100°C and reacted for 4-8 hours. The solution is cooled to 40-50°C, and sodium hydroxide aqueous solution is added dropwise. The mixture is stirred for 2-4 hours and purified to obtain an epoxy-containing substance.

[0016] S2. After adding the nitriles containing benzene rings and deionized water to a round-bottom flask, CuFe2O4 was added and stirred for 2-5 hours. Then NaBH4 was added and the mixture was refluxed and stirred for 0.5-4 hours. After cooling to room temperature, the catalyst was separated using an external magnet. Ethyl acetate was added to extract the reaction mixture. The mixture was dried on anhydrous sodium sulfate, the solvent was evaporated under reduced pressure, and the mixture was washed three times to obtain the benzene compounds containing amino groups.

[0017] S3. Place zirconium dioxide in a vacuum drying oven and dry for 8-12 hours. Accurately weigh the dried zirconium dioxide into a three-necked flask, add anhydrous ethanol and ultrasonically disperse for 30-50 minutes. Then place the flask in a water bath, equip it with a reflux condenser, slowly add HCl to adjust the pH of the solution to 3-4, and then slowly add silane coupling agent. Heat the flask to 70-90℃ and stir for 60-80 minutes. Filter the flask, wash it 3-5 times, and vacuum dry it at 60-70℃ for 24-26 hours to obtain silane coupling agent modified zirconium dioxide.

[0018] S4. Mix the epoxy-containing substance prepared in step S1 and the amino-containing benzene substance prepared in step S2, heat to 120-180℃ and react for 5-8 hours to obtain a branched epoxy resin polymer. Then mix the branched epoxy resin polymer and the silane coupling agent modified zirconium dioxide prepared in step S3 to prepare a pressure-bearing and leak-sealing branched epoxy resin.

[0019] Preferably, the silane coupling agent is any one of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and 3-(2,3-epoxypropoxy)propyltriethoxysilane.

[0020] Preferably, the amino-containing phenolic substance is at least one selected from 4-amino-1-naphthol, 1-amino-4-hydroxyanthraquinone, 1,8-diamino-4,5-dihydroxy-9,10-anthradinone, and 1,5-diamino-4,8-dihydroxy-9,10-anthradinone.

[0021] Preferably, the nitrile containing a benzene ring is at least one of triphenyl-1,3-dicarboxylon, 5-phenoxy-1,3-benzenedilon, and 5-[3-[(3,5-dicyanophenoxy)methyl]phenoxy]-1,3-benzenedilon.

[0022] This invention also provides a method for preparing a temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids, comprising the following steps:

[0023] Weigh out the crosslinking particles, mica, polyurethane foam, branched epoxy resin, graphite, ultrafine calcium carbonate and functional adhesive materials in proportion, mix them and add them to the soil slurry / drilling fluid; stir and mix evenly to prepare the temperature-sensitive adhesive polymer.

[0024] Preferably, the stirring speed is 8000 r / min and the stirring time is 20 min.

[0025] Compared with the above-mentioned background technology, the present invention has the following beneficial effects:

[0026] (1) The present invention synthesizes a branched epoxy resin with strong pressure bearing capacity, which can effectively improve the mechanical properties of the material, with a pressure bearing strength of 175MPa, and can reduce drilling fluid loss and improve the pressure bearing capacity and stability of the formation.

[0027] (2) The present invention preferably uses a functional adhesive material, which improves the retention capacity of the plugging material in the fracture by utilizing the material's temperature sensitivity and oil / water resistance, thereby improving the sealing effect and formation stability. The functional adhesive material preferred by the present invention is suitable for different bottom hole temperatures. Above the response temperature, the functional adhesive material undergoes a melting change and bonds with the bridge plug particles, fiber materials and other filler materials, so that the plugging material is retained in the leakage channel, thereby improving the plugging effect;

[0028] (3) Existing gelling plugging materials can effectively plug 3mm cracks at 150℃, with a sealing pressure of 9.8 MPa, while consolidation plugging materials have a maximum pressure resistance of 14 MPa. Compared with similar technologies, the temperature-sensitive adhesive polymer of this invention, which is used in water-based and oil-based drilling fluids to improve formation pressure sealing, can be used in water-based / oil-based drilling fluids at 60-150℃. It can effectively plug cracks within 5mm, with a maximum pressure resistance of 28 MPa. It can form a tight sealing layer for loosely cemented formations, fractured formations, and formations with complex pressure systems, thereby improving the success rate of plugging. Attached Figure Description

[0029] Figure 1 This diagram illustrates the transformation of the functional adhesive material of this invention from plastic to viscoelastic states; in order: a) the original state; b) the state after temperature-sensitive changes in water and bonding with the sealing material; c) the state after temperature-sensitive changes in water; and d) the state after temperature-sensitive changes in oil.

[0030] Figure 2 This is an example of the sealing condition in an artificially simulated wedge-shaped seam with a seam width of 3mm, according to an embodiment of the present invention.

[0031] Figure 3This illustrates the sealing condition of a wedge-shaped seam plate with a seam width of 1–3 mm in an embodiment of the present invention.

[0032] Figure 4 This illustrates the sealing condition of a wedge-shaped seam plate with a seam width of 3-5 mm in an embodiment of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0034] A temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids, comprising the following components and their mass ratios: bridging particles, mica, polyurethane foam, functional adhesive materials, branched epoxy resin, graphite, and ultrafine calcium carbonate in a mass ratio of 30–35:10–15:1–2:1–2:2–4:2–4:40–45.

[0035] The bridging particles are either walnut shells or vermiculite; the mesh size of the walnut shells, vermiculite, and mica ranges from 2 to 40 mesh; the typical particle sizes of the graphite and ultrafine calcium carbonate are 800 mesh and 1250 mesh, respectively.

[0036] The functional adhesive material is any one of thermoplastic adhesive materials, thermosetting adhesive materials, elastomeric adhesive materials, and composite adhesive materials.

[0037] The thermosetting adhesive material is at least one of epoxy resin, urea-formaldehyde resin and phenolic resin; The elastomeric adhesive material is at least one of nitrile rubber, thermoplastic elastomer, and silicone rubber; The composite adhesive material is at least one of phenolic-nitrile rubber, epoxy-nitrile rubber, and epoxy-polyurethane rubber.

[0038] This invention preferentially utilizes a functional adhesive material, which, by employing its temperature sensitivity and oil / water resistance, enhances the retention capacity of the plugging material in fractures, thereby improving the sealing effect and formation stability. The preferred functional adhesive material of this invention is suitable for different bottomhole temperatures. Above the response temperature, the functional adhesive material undergoes a melting change, bonding with bridge plug particles, fiber materials, and other filler materials, thus retaining the plugging material in the leakage channels and improving the sealing effect. The transition state of the functional adhesive material from plastic to viscoelastic is shown in the appendix. Figure 1 As shown, where: a is the original state; b is the state after temperature change in water and bonding with the sealing material; c is the state after temperature change in water; and d is the state after temperature change in oil.

[0039] The raw materials for synthesizing branched epoxy resins include amino-containing phenolic substances, benzene-containing nitrile substances, epichlorohydrin, zirconium dioxide, and silane coupling agents.

[0040] The molar ratio of the amino-containing phenolic substance, the benzene-containing nitrile substance, and epichlorohydrin is 1:(0.3-2):(3-6).

[0041] The branched epoxy resin is prepared by the following steps:

[0042] S1. Epichlorohydrin is added to a three-necked flask, heated to 30-50°C, then an amino-containing phenolic substance is added, followed by NaOH to adjust the pH to alkaline. Then, benzyltriethylammonium chloride catalyst is added, and the mixture is stirred at 40-60°C for 0.5-4 hours. The temperature is then raised to 80-100°C and reacted for 4-8 hours. The solution is cooled to 40-50°C, and sodium hydroxide aqueous solution is added dropwise. The mixture is stirred for 2-4 hours and purified to obtain an epoxy-containing substance.

[0043] S2. After adding the nitriles containing benzene rings and deionized water to a round-bottom flask, CuFe2O4 was added and stirred for 2-5 hours. Then NaBH4 was added and the mixture was refluxed and stirred for 0.5-4 hours. After cooling to room temperature, the catalyst was separated using an external magnet. Ethyl acetate was added to extract the reaction mixture. The mixture was dried on anhydrous sodium sulfate, the solvent was evaporated under reduced pressure, and the mixture was washed three times to obtain the benzene compounds containing amino groups.

[0044] S3. Place zirconium dioxide in a vacuum drying oven and dry for 8-12 hours. Accurately weigh the dried zirconium dioxide into a three-necked flask, add anhydrous ethanol and ultrasonically disperse for 30-50 minutes. Then place the flask in a water bath, equip it with a reflux condenser, slowly add HCl to adjust the pH of the solution to 3-4, and then slowly add silane coupling agent. Heat the flask to 70-90℃ and stir for 60-80 minutes. Filter the flask, wash it 3-5 times, and vacuum dry it at 60-70℃ for 24-26 hours to obtain silane coupling agent modified zirconium dioxide.

[0045] S4. Mix the epoxy-containing substance prepared in step S1 and the amino-containing benzene substance prepared in step S2, heat to 120-180℃ and react for 5-8 hours to obtain a branched epoxy resin polymer. Then mix the branched epoxy resin polymer and the silane coupling agent modified zirconium dioxide prepared in step S3 to prepare a pressure-bearing and leak-sealing branched epoxy resin.

[0046] The silane coupling agent is either 3-(2,3-epoxypropoxy)propyltrimethoxysilane or 3-(2,3-epoxypropoxy)propyltriethoxysilane.

[0047] The amino-containing phenolic substances are at least one of 4-amino-1-naphthol, 1-amino-4-hydroxyanthraquinone, 1,8-diamino-4,5-dihydroxy-9,10-anthradinone and 1,5-diamino-4,8-dihydroxy-9,10-anthradinone;

[0048] The nitrile containing a benzene ring is at least one of triphenyl-1,3-dicarboxynitrile, 5-phenoxy-1,3-benzenedionitrile, and 5-[3-[(3,5-dicyanophenoxy)methyl]phenoxy]-1,3-benzenedionitrile.

[0049] The method for preparing the temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids includes the following steps:

[0050] Weigh out the crosslinking particles, mica, polyurethane foam, branched epoxy resin, graphite, ultrafine calcium carbonate and functional adhesive materials in proportion, mix them and add them to the soil slurry / drilling fluid; the stirring speed is 8000 r / min and the stirring time is 20 min. After stirring and mixing evenly, the temperature-sensitive adhesive polymer is prepared.

[0051] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0052] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. In the present invention, unless otherwise specified, all quantities refer to parts by weight.

[0053] I. Preparation of Branched Epoxy Resins

[0054] Preparation Example 1

[0055] ① Synthesis of substances containing epoxy groups

[0056] 0.3 mol epichlorohydrin was added to a three-necked flask, and the temperature was raised to 40 °C. Then, 0.1 mol 4-amino-1-naphthol was added, and 2 mL of NaOH was added to adjust the pH to alkaline. Then, benzyltriethylammonium chloride catalyst was added, and the mixture was stirred at 55 °C for 1.5 h. The temperature was then raised to 90 °C and reacted for 6 h. After cooling the solution to 40 °C, 12 mL of sodium hydroxide aqueous solution was added dropwise, and the mixture was stirred for 3 h. After purification, a substance containing epoxy groups was obtained.

[0057] ② Synthesis of amino-containing benzene compounds

[0058] 0.08 mol of 5-phenoxy-1,3-benzenedionitrile and 160 mL of deionized water were added to a round-bottom flask, followed by the addition of 4 g of CuFe2O4 and stirring for 3 h. Then, 6 g of NaBH4 was added and the mixture was refluxed and stirred for 2 h. After cooling to room temperature, the catalyst was separated using an external magnet. The reaction mixture was extracted with ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The mixture was washed three times to obtain amino-containing benzene compounds.

[0059] ③Silane coupling agent modified zirconium dioxide

[0060] Zirconia was dried in a vacuum drying oven for 8 hours. 15 g of the dried zirconium dioxide was accurately weighed into a three-necked flask, and 150 mL of anhydrous ethanol was added and ultrasonically dispersed for 40 min. The flask was then placed in a water bath with a reflux condenser. HCl was slowly added dropwise to adjust the pH of the solution to 3-4. 0.3 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane was then slowly added. The mixture was heated to 80 °C and stirred for 60 min. After filtration and washing three times, the solution was vacuum dried at 60 °C for 25 h to obtain silane coupling agent modified zirconium dioxide.

[0061] ④ Preparation of epoxy resin pressure-bearing and leak-sealing materials

[0062] The epoxy-containing substance prepared in step ① and the amino-containing benzene substance prepared in step ② are mixed and heated to 160℃ for 5 hours to obtain a branched epoxy resin polymer. Then, the branched epoxy resin polymer and the silane coupling agent modified zirconium dioxide prepared in step ③ are mixed to prepare a pressure-bearing and leak-sealing branched epoxy resin.

[0063] Preparation Example 2

[0064] ① Synthesis of substances containing epoxy groups

[0065] 0.3 mol epichlorohydrin was added to a three-necked flask, and the temperature was raised to 40°C. Then, 0.1 mol 1-amino-4-hydroxyanthraquinone was added, and 2 mL of NaOH was added to adjust the pH to alkaline. Then, benzyltriethylammonium chloride catalyst was added, and the mixture was stirred at 45°C for 3 h. The temperature was then raised to 90°C and reacted for 6 h. After cooling the solution to 45°C, 12 mL of sodium hydroxide aqueous solution was added dropwise, and the mixture was stirred for 3 h. After purification, a substance containing epoxy groups was obtained.

[0066] ② Synthesis of amino-containing benzene compounds

[0067] 0.04 mol of 5-[3-[(3,5-dicyanophenoxy)methyl]phenoxy]-1,3-benzenedionitrile and 80 mL of deionized water were added to a round-bottom flask, followed by the addition of 2 g of CuFe2O4 and stirring for 2 h. Then, 3 g of NaBH4 was added and the mixture was refluxed and stirred for 3 h. After cooling to room temperature, the catalyst was separated using an external magnet. The reaction mixture was extracted with ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The mixture was washed three times to obtain amino-containing benzene compounds.

[0068] ③Silane coupling agent modified zirconium dioxide

[0069] Zirconia was dried in a vacuum drying oven for 8 hours. 20 g of the dried zirconium dioxide was accurately weighed into a three-necked flask, and 200 mL of anhydrous ethanol was added. The flask was then ultrasonically dispersed for 40 min and placed in a water bath with a reflux condenser. HCl was slowly added dropwise to adjust the pH of the solution to 3-4. 0.4 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane was then slowly added. The mixture was heated to 70 °C and stirred for 80 min. After filtration and washing three times, the solution was vacuum dried at 65 °C for 24 h to obtain silane coupling agent modified zirconium dioxide.

[0070] ④ Preparation of epoxy resin pressure-bearing and leak-sealing materials

[0071] The epoxy-containing substance prepared in step ① and the amino-containing benzene-based substance prepared in step ② are mixed and heated to 160℃ for 6 hours to obtain a branched epoxy resin polymer. Then, the branched epoxy resin polymer and the silane coupling agent modified zirconium dioxide prepared in step ③ are mixed to prepare a pressure-bearing and leak-sealing branched epoxy resin.

[0072] Preparation Example 3

[0073] ① Synthesis of substances containing epoxy groups

[0074] 0.3 mol epichlorohydrin was added to a three-necked flask, and the temperature was raised to 45°C. Then, 0.1 mol 1-amino-4-hydroxyanthraquinone was added, and 2 mL of NaOH was added to adjust the pH to alkaline. Then, benzyltriethylammonium chloride catalyst was added, and the mixture was stirred at 60°C for 1 h. The temperature was then raised to 90°C and reacted for 5 h. After cooling the solution to 45°C, 12 mL of sodium hydroxide aqueous solution was added dropwise, and the mixture was stirred for 2 h. After purification, a substance containing epoxy groups was obtained.

[0075] ② Synthesis of amino-containing benzene compounds

[0076] 0.08 mol of triphenyl-1,3-dicarboxynitrile and 160 mL of deionized water were added to a round-bottom flask, followed by the addition of 4 g of CuFe2O4 and stirring for 2 h. Then, 6 g of NaBH4 was added and the mixture was refluxed and stirred for 3 h. After cooling to room temperature, the catalyst was separated using an external magnet. The reaction mixture was extracted with ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The mixture was washed three times to obtain benzene compounds containing amino groups.

[0077] ③Silane coupling agent modified zirconium dioxide

[0078] Zirconia was dried in a vacuum drying oven for 10 hours. 25 g of the dried zirconium dioxide was accurately weighed into a three-necked flask, and 250 mL of anhydrous ethanol was added and ultrasonically dispersed for 40 min. The flask was then placed in a water bath with a reflux condenser. HCl was slowly added dropwise to adjust the pH of the solution to 3-4. 0.5 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane was then slowly added. The mixture was heated to 90 °C and stirred for 60 min. After filtration and washing four times, the solution was vacuum dried at 70 °C for 25 h to obtain silane coupling agent modified zirconium dioxide.

[0079] ④ Preparation of epoxy resin pressure-bearing and leak-sealing materials

[0080] The epoxy-containing substance prepared in step ① and the amino-containing benzene substance prepared in step ② are mixed and heated to 150℃ for 8 hours to obtain a branched epoxy resin polymer. Then, the branched epoxy resin polymer and the silane coupling agent modified zirconium dioxide prepared in step ③ are mixed to prepare a pressure-bearing and leak-sealing branched epoxy resin.

[0081] The local structure of the prepared branched epoxy resin polymer is as follows:

[0082]

[0083] in:

[0084]

[0085] Preparation Example 4

[0086] ① Synthesis of substances containing epoxy groups

[0087] 0.6 mol epichlorohydrin was added to a three-necked flask, and the temperature was raised to 35°C. Then, 0.1 mol 1,8-diamino-4,5-dihydroxy-9,10-anthradinone was added. After adjusting the pH to alkaline with 2 mL of NaOH, the catalyst benzyltriethylammonium chloride was added. The mixture was stirred at 60°C for 2 h, and then the temperature was raised to 95°C for 5 h. After cooling the solution to 50°C, 22 mL of sodium hydroxide aqueous solution was added dropwise, and the mixture was stirred for 4 h. After purification, a substance containing epoxy groups was obtained.

[0088] ② Synthesis of amino-containing benzene compounds

[0089] 0.15 mol of triphenyl-1,3-dicarboxynitrile and 300 mL of deionized water were added to a round-bottom flask, followed by the addition of 7.2 g of CuFe2O4 and stirring for 4 h. Then, 11.4 g of NaBH4 was added and the mixture was refluxed and stirred for 3 h. After cooling to room temperature, the catalyst was separated using an external magnet. The reaction mixture was extracted with ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The mixture was washed three times to obtain amino-containing benzene compounds.

[0090] ③Silane coupling agent modified zirconium dioxide

[0091] Zirconia was dried in a vacuum drying oven for 10 hours. 30 g of the dried zirconium dioxide was accurately weighed into a three-necked flask, and 300 mL of anhydrous ethanol was added. The flask was then ultrasonically dispersed for 50 min and placed in a water bath with a reflux condenser. HCl was slowly added dropwise to adjust the pH of the solution to 3-4. 0.6 g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane was then slowly added. The mixture was heated to 80 °C and stirred for 70 min. After filtration and washing five times, the solution was vacuum dried at 70 °C for 24 h to obtain silane coupling agent modified zirconium dioxide.

[0092] ④ Preparation of epoxy resin pressure-bearing and leak-sealing materials

[0093] The epoxy-containing substance prepared in step ① and the amino-containing benzene-based substance prepared in step ② are mixed and heated to 170℃ for 6 hours to obtain a branched epoxy resin polymer. Then, the branched epoxy resin polymer and the silane coupling agent-modified zirconium dioxide prepared in step ③ are mixed to prepare a pressure-bearing and leak-sealing branched epoxy resin.

[0094] Preparation Example 5

[0095] ① Synthesis of substances containing epoxy groups

[0096] 0.6 mol of epichlorohydrin was added to a three-necked flask, and the temperature was raised to 35°C. Then, 0.1 mol of 1,5-diamino-4,8-dihydroxy-9,10-anthradinone was added. After adjusting the pH to alkaline by adding 2 mL of NaOH, the catalyst benzyltriethylammonium chloride was added. The mixture was stirred at 60°C for 3 h, and then the temperature was raised to 95°C for 5 h. After cooling the solution to 50°C, 22 mL of sodium hydroxide aqueous solution was added dropwise, and the mixture was stirred for 4 h. After purification, a substance containing epoxy groups was obtained.

[0097] ② Synthesis of amino-containing benzene compounds

[0098] 0.15 mol of triphenyl-1,3-dicarboxynitrile and 300 mL of deionized water were added to a round-bottom flask, followed by the addition of 7.2 g of CuFe2O4 and stirring for 4 h. Then, 11.4 g of NaBH4 was added and the mixture was refluxed and stirred for 3 h. After cooling to room temperature, the catalyst was separated using an external magnet. The reaction mixture was extracted with ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The mixture was washed three times to obtain amino-containing benzene compounds.

[0099] ③Silane coupling agent modified zirconium dioxide

[0100] Zirconia was dried in a vacuum drying oven for 10 hours. 35 g of the dried zirconium dioxide was accurately weighed into a three-necked flask, and 350 mL of anhydrous ethanol was added and ultrasonically dispersed for 50 min. The flask was then placed in a water bath with a reflux condenser. HCl was slowly added dropwise to adjust the pH of the solution to 3-4. 0.7 g of 3-(2,3-epoxypropoxy)propyltriethoxysilane was then slowly added. The mixture was heated to 90 °C and stirred for 60 min. After filtration and washing five times, the solution was vacuum dried at 70 °C for 26 h to obtain silane coupling agent modified zirconium dioxide.

[0101] ④ Preparation of epoxy resin pressure-bearing and leak-sealing materials

[0102] The epoxy-containing substance prepared in step ① and the amino-containing benzene-based substance prepared in step ② are mixed and heated to 170℃ for 6 hours to obtain a branched epoxy resin polymer. Then, the branched epoxy resin polymer and the silane coupling agent-modified zirconium dioxide prepared in step ③ are mixed to prepare a pressure-bearing and leak-sealing branched epoxy resin.

[0103] II. Formulation of temperature-sensitive adhesive polymers for improving formation pressure sealing in water-based and oil-based drilling fluids

[0104] Example 1

[0105] Weigh walnut shells, mica, polyurethane foam, branched epoxy resin (Preparation Example 2), graphite, ultrafine calcium carbonate, and thermoplastic adhesive TPE to prepare a water-based and oil-based drilling fluid temperature-sensitive adhesive polymer to improve formation pressure sealing. The mass ratio is 35:10:1:1:2:2:40. Add the mixture to the soil slurry / drilling fluid and stir at 8000 r / min for 20 min. After mixing evenly, conduct a leakage plugging test with a crack width of 1-5 mm.

[0106] Example 2

[0107] Weigh vermiculite, mica, polyurethane foam, branched epoxy resin (Preparation Example 4), graphite, ultrafine calcium carbonate, and elastomeric adhesive EVA to prepare a water-based and oil-based temperature-sensitive adhesive polymer for improving formation pressure sealing. The mass ratio is 35:10:1:1:2:2:40. Add the polymer to the soil slurry / drilling fluid and stir at 8000 r / min for 20 min. After mixing evenly, conduct a plugging test on cracks with a width of 1-5 mm.

[0108] Example 3

[0109] Weigh walnut shells, mica, polyurethane foam, branched epoxy resin (Preparation Example 5), graphite, ultrafine calcium carbonate, and thermoplastic adhesive TPU to prepare a water-based and oil-based drilling fluid temperature-sensitive adhesive polymer to improve formation pressure sealing. The mass ratio is 35:10:1:1:2:2:40. Add the polymer to the oil-based drilling fluid and stir at 12000 r / min for 20 min. After mixing evenly, conduct a plugging test on cracks with a width of 1-5 mm.

[0110] III. Performance Testing of Temperature-Sensitive Adhesive Polymers Used in Water-Based and Oil-Based Drilling Fluids to Enhance Formation Pressure-Bearing Capacity and Plugging

[0111] Test Example 1: Test of the compressive strength of branched epoxy resin for pressure sealing and leak plugging

[0112] Samples of the final products from Preparation Examples 1, 2, 3, 4, and 5 were taken for compressive strength testing, with three sets of samples for each material. The compression test followed ASTM D6641, with two strain gauges (one longitudinal and one transverse) attached to each of the front and rear surfaces of the test specimen to obtain the average compressive strain and Poisson's ratio on both surfaces. An Instron 5882 testing machine (range 100 kN) was used, along with a combined loading compression fixture (CLC), to apply compressive load to the test specimens. The average value of the test data was taken. Table 1 shows the compressive strength records for Preparation Examples 1, 2, 3, 4, and 5. The results in Table 1 show that the branched epoxy resin has good compressive strength, and its compressive strength increases with the increase of rigid material particle content.

[0113] Table 1. Compressive strength test of branched epoxy resin

[0114]

[0115] Test Example 2: Experiment on sealing 1mm-5mm wedge-shaped fractures using temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids.

[0116] Take appropriate amounts of walnut shells, vermiculite, mica, polyurethane foam, functional adhesive materials, branched epoxy resin, graphite, and ultrafine calcium carbonate, and mechanically mix them evenly. Add the mixture to the soil slurry / drilling fluid and stir at 8000 r / min or 12000 r / min for 20 minutes. Then conduct plugging experiments for different crack widths. The experimental results are shown in Table 2, and some plugging effect pictures are attached. Figures 2-4 .in Figure 2 This is an example of the sealing condition in an artificially simulated wedge-shaped seam with a seam width of 3mm, according to an embodiment of the present invention. Figure 3 This illustrates the sealing condition of a wedge-shaped seam plate with a seam width of 1–3 mm in an embodiment of the present invention. Figure 4 This illustrates the sealing condition of a wedge-shaped seam plate with a seam width of 3-5 mm in an embodiment of the present invention.

[0117] Table 2. Evaluation Experiment of the Leakage Plugging Effect of Temperature-Sensitive Adhesive Polymers Applied to Water-Based and Oil-Based Drilling Fluids for Enhancing Formation Pressure-Bearing Capacity.

[0118]

[0119] Note: The room temperature leak sealing device uses an artificial wedge-shaped joint, while the high temperature and high pressure leak sealing device uses a wedge-shaped rigid joint plate. The test temperature is 60–150℃.

[0120] Table 2 shows that the temperature-sensitive adhesive polymer used in water-based and oil-based drilling fluids to improve formation pressure sealing can effectively seal fractures within 5 mm.

[0121] In the embodiments described above, the walnut shells, vermiculite, mica, polyurethane foam, graphite, and ultrafine calcium carbonate are commercially available products, and the functional adhesive materials are products sold by Dongguan Cangyuan Plastic Raw Materials Co., Ltd. and Huayu Plastic Raw Materials Co., Ltd.

[0122] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the implementation methods of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of the present invention.

Claims

1. A temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids, characterized in that: Its components and the mass ratio of each component are as follows: the mass ratio of crosslinking particles, mica, polyurethane foam, functional adhesive materials, branched epoxy resin, graphite and ultrafine calcium carbonate is 30-35:10-15:1-2:1-2:2-4:2-4:40-45.

2. The temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids according to claim 1, characterized in that: The bridging particles are either walnut shells or vermiculite. The mesh size of the walnut shells, vermiculite, and mica ranges from 2 to 40 mesh. The typical particle sizes of the graphite and ultrafine calcium carbonate are 800 mesh and 1250 mesh, respectively.

3. The temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids according to claim 1, characterized in that: The functional adhesive material is any one of thermoplastic adhesive materials, thermosetting adhesive materials, elastomeric adhesive materials, and composite adhesive materials.

4. The temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids according to claim 3, characterized in that: The thermoplastic adhesive material is at least one of ethylene vinyl acetate, polyethylene, polypropylene, polyurethane, polyamide, and polyacrylamide. The thermosetting adhesive material is at least one of epoxy resin, urea-formaldehyde resin and phenolic resin; The elastomeric adhesive material is at least one of nitrile rubber, thermoplastic elastomer, and silicone rubber; The composite adhesive material is at least one of aldehyde-nitrile rubber, epoxy-nitrile rubber, and epoxy-polyurethane rubber.

5. The temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids according to claim 1, characterized in that: The raw materials for synthesizing branched epoxy resins include amino-containing phenolic substances, benzene-containing nitrile substances, epichlorohydrin, zirconium dioxide, and silane coupling agents. The molar ratio of the amino-containing phenolic substance, the benzene-containing nitrile substance, and epichlorohydrin is 1:(0.3-2):(3-6).

6. The temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids according to claim 5, characterized in that: The branched epoxy resin is prepared by the following steps: S1. Epichlorohydrin is added to a three-necked flask, heated to 30-50°C, then an amino-containing phenolic substance is added, followed by NaOH to adjust the pH to alkaline. Then, benzyltriethylammonium chloride catalyst is added, and the mixture is stirred at 40-60°C for 0.5-4 hours. The temperature is then raised to 80-100°C and reacted for 4-8 hours. The solution is cooled to 40-50°C, and sodium hydroxide aqueous solution is added dropwise. The mixture is stirred for 2-4 hours and purified to obtain an epoxy-containing substance. S2. After adding the nitriles containing benzene rings and deionized water to a round-bottom flask, CuFe2O4 was added and stirred for 2-5 hours. Then NaBH4 was added and the mixture was refluxed and stirred for 0.5-4 hours. After cooling to room temperature, the catalyst was separated using an external magnet. Ethyl acetate was added to extract the reaction mixture. The mixture was dried on anhydrous sodium sulfate, the solvent was evaporated under reduced pressure, and the mixture was washed three times to obtain the benzene compounds containing amino groups. S3. Place zirconium dioxide in a vacuum drying oven and dry for 8-12 hours. Accurately weigh the dried zirconium dioxide into a three-necked flask, add anhydrous ethanol and ultrasonically disperse for 30-50 minutes. Then place the flask in a water bath, equip it with a reflux condenser, slowly add HCl to adjust the pH of the solution to 3-4, and then slowly add silane coupling agent. Heat the flask to 70-90℃ and stir for 60-80 minutes. Filter the flask, wash it 3-5 times, and vacuum dry it at 60-70℃ for 24-26 hours to obtain silane coupling agent modified zirconium dioxide. S4. Mix the epoxy-containing substance prepared in step S1 and the amino-containing benzene substance prepared in step S2, heat to 120-180℃ and react for 5-8 hours to obtain a branched epoxy resin polymer. Then mix the branched epoxy resin polymer and the silane coupling agent modified zirconium dioxide prepared in step S3 to prepare a pressure-bearing and leak-sealing branched epoxy resin.

7. The temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids according to claim 5, characterized in that: The silane coupling agent is either 3-(2,3-epoxypropoxy)propyltrimethoxysilane or 3-(2,3-epoxypropoxy)propyltriethoxysilane.

8. The temperature-sensitive adhesive polymer for improving formation pressure sealing in water-based and oil-based drilling fluids according to claim 5, characterized in that: The amino-containing phenolic substances are at least one of 4-amino-1-naphthol, 1-amino-4-hydroxyanthraquinone, 1,8-diamino-4,5-dihydroxy-9,10-anthradinone and 1,5-diamino-4,8-dihydroxy-9,10-anthradinone; The nitrile containing a benzene ring is at least one of triphenyl-1,3-dicarboxynitrile, 5-phenoxy-1,3-benzenedionitrile, and 5-[3-[(3,5-dicyanophenoxy)methyl]phenoxy]-1,3-benzenedionitrile.

9. A method for preparing a temperature-sensitive adhesive polymer according to any one of claims 1-8 for improving formation pressure sealing in water-based and oil-based drilling fluids, characterized in that: Includes the following steps: Weigh out the crosslinking particles, mica, polyurethane foam, branched epoxy resin, graphite, ultrafine calcium carbonate and functional adhesive materials in proportion, mix them and add them to the soil slurry / drilling fluid; stir and mix evenly to prepare the temperature-sensitive adhesive polymer.

10. The preparation method according to claim 9, characterized in that: The stirring speed is 8000 r / min and the stirring time is 20 min.

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