Plugging agent and preparation method thereof

Abstract

The invention provides a plugging agent and a preparation method thereof. The invention provides a plugging agent. The plugging agent comprises modified resin and a composite film wrapping the modified resin, the composite membrane is prepared from poly (diallyldimethylammonium chloride), polyacrylic acid and graphene oxide. The invention provides a preparation method of a blocking agent. The preparation method comprises the following steps: (1) sequentially immersing modified resin into a PDDA solution and a PAA solution; and (2) taking out, sequentially immersing into a PDDA solution, a GO particle dispersion liquid, a PAA solution and a GO particle dispersion liquid, repeating for 30-200 times to obtain modified resin coated with a composite membrane material, and curing, drying and crushing the modified resin coated with the composite membrane material to obtain the plugging agent. The plugging agent prepared by wrapping the modified resin with the composite film material deforms in a temperature window, so that the interior of the crack is plugged, and the plugging effect is improved.

Description

Technical Field

[0001] This invention relates to the field of oil drilling technology, specifically to a plugging agent and its preparation method. Background Technology

[0002] Currently, fractured formations exhibit large leakage channels and rapid leakage rates, making it difficult to form a structurally stable, dense, and pressure-bearing sealing layer within the fractures. This results in significant challenges for on-site drilling fluid plugging operations, often leading to substantial economic losses. With the increasing prominence of drilling fluid leakage problems in complex formations, highly efficient leakage prevention and plugging materials have become crucial for the rapid and efficient treatment of well leakage. Domestic and international experts have conducted extensive research on leak prevention and plugging materials. Existing plugging materials can be classified into bridging plugging materials, high-water-loss plugging materials, temporary plugging materials, chemical plugging materials, inorganic cementitious plugging materials, and soft (hard) plugging materials according to different mechanisms and functions. However, the above-mentioned traditional plugging materials do not have intelligent characteristics and cannot deform according to formation temperature. When dealing with well leakage in large-aperture fractured wells, the use of conventional large-particle-size, high-density plugging materials has poor suspension stability, which leads to settling in the mud tank or in the wellbore when dealing with long open-hole sections. On the other hand, it may cause drill string blockage. In addition, traditional bridging plugging materials are highly sensitive to fractures and cannot effectively seal fractures adaptively. They do not have the rigidity, high strength, and expansion "one agent, multiple functions" function.

[0003] With increasing understanding of new materials, more and more resin materials are being applied to wellbore plugging. Epoxy resin materials, by adding curing agents, can form a three-dimensional network structure, exhibiting excellent high-temperature resistance. In recent years, domestic and foreign scholars have conducted extensive research on the challenge of crack plugging during drilling. Intelligent plugging products made primarily from shape memory resin materials can achieve automatic bridging and plugging, protecting the reservoir, with adjustable plugging time and start-up temperature. Thermoplastic resins possess phase change characteristics and shape memory functions, allowing them to better penetrate fractures. Some resins with deformation functions can adaptively and effectively plug fractures. For example, Tian Lufei et al. successfully prepared a cement-based intelligent plugging material. This plugging material mainly includes shape memory alloys (Ni-Ti), cement-based coatings, and fillers. After entering the formation, it is affected by temperature, causing the SMAs (shape memory resins) inside the material to deform, leading to cracking and detachment of the outer coating until it finally returns to a straight state. Multiple linear SMAs interconnect to form a bridging plug, and the internal sodium carbonate causes the plugging fluid to solidify rapidly, promoting the plugging process. People have gradually realized that using variable phase change resin to coat plugging particles for leak sealing will effectively improve the sealing effect, especially for crack-related leaks.

[0004] However, currently used shape memory resin materials suffer from poor thermal conductivity, weak temperature sensing ability, and delayed phase transitions in complex drilling fluid environments. This leads to problems such as inaccurate sealing of lost circulation zones and inability to match safe drilling and completion windows. Furthermore, most resin materials also exhibit low compressive strength and are easily worn away by solid phases in the drilling fluid. These issues require further resolution.

[0005] Therefore, there is an urgent need for a high-performance sealing agent in the existing technology. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention proposes a plugging agent and its preparation method. The invention provides a plugging agent comprising a modified resin and a composite film encapsulating the modified resin. After being run into the wellbore, the plugging agent reaches its glass transition temperature, undergoing a phase change from a solid to a viscous liquid. It then coats the wellbore wall, forming a plugging layer. Simultaneously, the resin has a retention effect on large pores, preventing the plugging material from being diluted or washed away, thus losing its plugging ability.

[0007] In a first aspect, the present invention provides a sealing agent comprising a modified resin and a composite membrane encapsulated on the outside of the modified resin; the composite membrane is prepared from polydiallyl dimethyl ammonium chloride (PDDA), polyacrylic acid (PAA), and graphene oxide (GO), and the glass transition temperature of the modified resin is 100℃~150℃.

[0008] Specifically, the sealing agent is made by curing a modified resin and a composite film wrapped around the modified resin.

[0009] As a specific embodiment of the present invention, the mass ratio of the composite film to the modified resin is (1:450-320).

[0010] As a specific embodiment of the present invention, the particle size of the modified resin is 10μm to 150μm.

[0011] As a specific embodiment of the present invention, the modified resin is obtained by heating and stirring a mixture containing resin, silane coupling agent and film-forming agent; the heating temperature is 60℃~90℃.

[0012] Preferably, the mass ratio of resin, silane coupling agent and film-forming agent in the mixture containing resin, silane coupling agent and film-forming agent is (75-90):(5-12):(5-13).

[0013] As a specific embodiment of the present invention, the resin is selected from at least one of epoxy resin, polypropylene resin, and polystyrene resin.

[0014] Specifically, the epoxy resin used in this invention is a bisphenol A type epoxy resin.

[0015] As a specific embodiment of the present invention, the silane coupling agent is selected from at least one of KH550, KH560, and KH580.

[0016] As a specific embodiment of the present invention, the film-forming agent is selected from at least one of polyethylene emulsion (PE), polyacrylamide emulsion (PAM), and ethylene acrylic acid copolymer emulsion (EAA).

[0017] Preferably, the concentration of the polyethylene emulsion is 18wt% to 20wt%, the concentration of the polyacrylamide emulsion is 0.05wt% to 1wt%, and the concentration of the ethylene-acrylic acid copolymer emulsion is 20wt% to 30wt%.

[0018] Specifically, the solvent in polyethylene emulsion, polyacrylamide emulsion, and ethylene-acrylic acid copolymer emulsion is water.

[0019] As a specific embodiment of the present invention, the plugging agent is a particulate material with a particle size of 30μm to 200μm, and the mass retention rate of the plugging agent under a pressure of 15MPa is 98% to 99%.

[0020] In a second aspect, the present invention provides a method for preparing the plugging agent provided in the first aspect of the present invention, comprising the following steps:

[0021] (1) The modified resin was sequentially immersed in a polydiallyldimethylammonium chloride solution and a polyacrylic acid solution;

[0022] (2) After being removed, the resin is sequentially immersed in polydiallyldimethylammonium chloride solution, graphene oxide dispersion, polyacrylic acid solution, and graphene oxide dispersion, and repeated 30 to 200 times to obtain the modified resin coated with composite membrane material. The modified resin coated with composite membrane material is cured, dried, and pulverized to obtain the sealing agent.

[0023] The repetition of 30 to 200 times in this invention refers to repeating one complete immersion process of step (2) 30 to 200 times.

[0024] As a specific embodiment of the present invention, the solubility of the polydiallyldimethylammonium chloride solution is 0.1-0.5 wt%, the pH value of the polydiallyldimethylammonium chloride solution is 3.5-4.5, and the solvent of the polydiallyldimethylammonium chloride solution is water.

[0025] As a specific embodiment of the present invention, the concentration of the polyacrylic acid solution is 0.1 to 0.5 wt%, the pH value of the polyacrylic acid solution is 7.5 to 8.5, and the solvent of the polyacrylic acid solution is water.

[0026] As a specific embodiment of the present invention, the graphene oxide content in the graphene oxide dispersion is 0.1-0.5 wt%, the pH value of the graphene oxide dispersion is 7.5-8.5, and the dispersant of the graphene oxide dispersion is water.

[0027] In a specific embodiment of the present invention, in step (1), the time for each intrusion is 5 to 10 minutes.

[0028] In a specific embodiment of the present invention, in step (2), the immersion time is 5 to 10 minutes each time.

[0029] As a specific embodiment of the present invention, the curing temperature is 110℃~150℃ and the time is 4~5h.

[0030] As a specific embodiment of the present invention, the process includes preheating and stirring steps before curing.

[0031] As a specific embodiment of the present invention, the preheating temperature is 70℃~90℃ and the time is 1~2h.

[0032] As a specific embodiment of the present invention, the stirring conditions are a rotation speed of 100-500 r / min and a stirring time of 10-60 min.

[0033] In this invention, the modified resin coated with the composite membrane material is preheated at 70℃~90℃ for 1~2h, melted and stirred, and then heated to 110℃~150℃ and cured for 4~5h.

[0034] Thirdly, the present invention provides a drilling fluid comprising the plugging agent provided in the first aspect of the present invention or the plugging agent prepared by the preparation method provided in the second aspect of the present invention, wherein the content of the plugging agent in the drilling fluid is 3-8 wt%.

[0035] Preferably, when the shape recovery rate of the plugging agent in the drilling fluid reaches 100% under the condition of glass transition temperature Tg, the expansion delay time is 10-18 min, and the mass retention rate of the plugging agent in the drilling fluid after high-temperature hot rolling for 72 h is 95%-96.5%.

[0036] Compared with the prior art, the present invention has the following beneficial effects.

[0037] (1) The sealing agent provided by the present invention includes a modified resin and a composite film wrapped around the modified resin. The sealing agent provided by the present invention has good thermal conductivity, is sensitive to temperature, and is easy to precisely control the phase change deformation caused by temperature. The sealing agent prepared by wrapping the modified resin with the composite film material deforms in the temperature window (the temperature window is from the response temperature at which deformation begins to the glass transition temperature), thereby sealing the inside of the crack and improving the sealing effect.

[0038] (2) The plugging agent provided by this invention includes materials such as GO, polymers (PDDA, PAA, film-forming agents), etc. This significantly improves the mechanical properties, compressive strength, and toughness of the plugging agent. Simultaneously, it makes the plugging agent wear-resistant, thereby protecting it and preventing a reduction in plugging effect due to wear.

[0039] (3) The plugging agent provided by the present invention includes polymer materials such as PDDA, PAA, and film-forming agents, which can effectively improve the adhesion and shearing of the plugging agent in drilling fluid and improve its retention capacity in fractures, thereby further improving the plugging effect of larger fractures. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0041] All raw materials used in this invention are commercially available, among which,

[0042] PDDA, PAA, GO, epoxy resin, polypropylene resin, and polystyrene resin were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0043] Silane coupling agents KH550, KH560, and KH580 were purchased from Shandong Huachen New Materials Co., Ltd.

[0044] PE emulsion (18% by mass, water as solvent) was purchased from Shanghai Xinnuo Chemical Co., Ltd.

[0045] PAM emulsion (1% by mass, water as solvent) was purchased from Wuxi Tianxin Chemical Co., Ltd.

[0046] EAA emulsion (25% by mass, water as solvent), purchased from Shandong Zero Degree New Materials Co., Ltd.

[0047] Example 1

[0048] (1) Modification of resin materials: Epoxy resin, silane coupling agent KH550 and film-forming agent PE emulsion are mixed in a mass ratio of 80:10:10, then heated to 80℃, stirred, cooled and dried to obtain a modified resin with an average particle size of 60μm.

[0049] (2) Composite membrane material coating modified resin: PDDA solution (0.1% wt, pH=4) and PAA solution (0.1% wt, pH=8) and GO particle dispersion (0.1% wt, pH=8) were prepared with deionized water, and the pH value of the solution was adjusted with hydrochloric acid or sodium hydroxide.

[0050] At room temperature, the modified resin was sequentially and completely immersed in PDDA solution and PAA solution for 5 minutes. During the interval, the excess solution that had not been adsorbed on the modified resin was washed with deionized water and dried with nitrogen.

[0051] The modified resin was sequentially and completely immersed in PDDA solution, GO particle dispersion, PAA solution, and GO particle dispersion, with each immersion time being 5 minutes. During the intervals, excess solution that had not been adsorbed onto the modified resin was rinsed with deionized water and dried with nitrogen gas. This step was repeated 60 times to complete the coating of the modified resin with the composite membrane material.

[0052] (3) The modified resin coated with the composite membrane material is preheated at 80°C for 1 hour, stirred at 200 r / min for 20 minutes, and then heated to 120°C for 4 hours to cure.

[0053] (4) The modified resin coated with the cured composite membrane material is crushed and granulated to obtain particles with a particle size of 120μm, thus obtaining the sealing agent.

[0054] Example 2

[0055] (1) Modification of resin materials: Polypropylene resin, silane coupling agent KH560 and film-forming agent PAM emulsion were mixed in a mass ratio of 75:12:13, then heated to 60℃, stirred, cooled and dried to obtain a modified resin with an average particle size of 80μm.

[0056] (2) Coating modified resin with composite membrane material: Prepare PDDA solution (0.5% wt, pH=3.5) and PAA solution (0.5% wt, pH=7.5) and GO particle dispersion (0.5% wt, pH=7.5) with deionized water, and adjust the pH value of the solution with hydrochloric acid or sodium hydroxide;

[0057] At room temperature, the modified resin was sequentially and completely immersed in PDDA solution and PAA solution for 10 minutes. During the interval, the excess solution that was not adsorbed on the modified resin was washed with deionized water and dried with nitrogen.

[0058] The modified resin was sequentially and completely immersed in PDDA solution, GO particle dispersion, PAA solution, and GO particle dispersion, with each immersion time being 10 minutes. During the intervals, excess solution that had not been adsorbed onto the modified resin was rinsed with deionized water and dried with nitrogen gas. This step was repeated 200 times to complete the coating of the modified resin with the composite membrane material.

[0059] (3) The modified resin coated with the composite membrane material is preheated at 70°C for 2 hours, stirred at 100 r / min for 10 minutes, and then heated to 110°C for 5 hours to cure.

[0060] (4) The modified resin that has been cured and coated with the composite membrane material is crushed and granulated to obtain particles with a particle size of 200 μm, thus obtaining the sealing agent.

[0061] Example 3

[0062] (1) Modification of resin materials: Polystyrene resin, silane coupling agent KH580 and film-forming agent EAA emulsion were mixed in a mass ratio of 90:5:5, then heated to 90℃ and stirred; cooled and dried to obtain a modified resin with an average particle size of 10μm.

[0063] (2) Composite membrane material coating modified resin: PDDA solution (0.2% wt, pH=4.5) and PAA solution (0.2% wt, pH=8.5) and GO particle dispersion (0.2% wt, pH=8.5) were prepared with deionized water, and the pH value of the solution was adjusted with hydrochloric acid or sodium hydroxide;

[0064] At room temperature, the modified resin was sequentially and completely immersed in PDDA solution and PAA solution for 8 minutes. During the interval, the excess solution that was not adsorbed on the modified resin was washed with deionized water and dried with nitrogen gas.

[0065] The modified resin was sequentially and completely immersed in PDDA solution, GO particle dispersion, PAA solution, and GO particle dispersion, with each immersion time being 8 minutes. During the intervals, excess solution that had not been adsorbed onto the modified resin was rinsed with deionized water and dried with nitrogen gas. This step was repeated 30 times to complete the coating of the modified resin with the composite membrane material.

[0066] (3) The modified resin coated with the composite membrane material is preheated at 90°C for 1.5 hours, stirred at 500 r / min for 60 minutes, and then heated to 150°C for 4.5 hours to cure.

[0067] (4) The modified resin coated with the cured composite membrane material is crushed and granulated to obtain particles with a particle size of 30μm, thus obtaining the sealing agent.

[0068] Example 4

[0069] (1) Modification of resin materials: Epoxy resin, silane coupling agent KH550 and film-forming agent PE emulsion are mixed in a mass ratio of 80:10:10, then heated to 80℃, stirred, cooled and dried to obtain a modified resin with an average particle size of 60μm.

[0070] (2) Composite membrane material coating modified resin: PDDA solution (0.1% wt, pH=4) and PAA solution (0.1% wt, pH=8) and GO particle dispersion (0.1% wt, pH=8) were prepared with deionized water, and the pH value of the solution was adjusted with hydrochloric acid or sodium hydroxide;

[0071] At room temperature, the modified resin was sequentially and completely immersed in PDDA solution and PAA solution for 5 minutes. During the interval, the excess solution that had not been adsorbed on the modified resin was washed with deionized water and dried with nitrogen.

[0072] The modified resin was sequentially and completely immersed in PDDA solution, GO particle dispersion, PAA solution, and GO particle dispersion, with each immersion time being 5 minutes. During the intervals, excess solution that had not been adsorbed onto the modified resin was rinsed with deionized water and dried with nitrogen gas. This step was repeated 30 times to complete the coating of the modified resin with the composite membrane material.

[0073] (3) The modified resin coated with the composite membrane material is preheated at 80°C for 1 hour, stirred at 200 r / min for 20 minutes, and then heated to 120°C for 4 hours to cure.

[0074] (4) The modified resin that has been cured and coated with the composite membrane material is crushed and granulated to obtain particles with a particle size of 120μm, thus obtaining the sealing agent.

[0075] Comparative Example 1

[0076] This comparative example provides a sealing agent. It is basically the same as Example 1, except that it does not include the step of modifying the resin material, and directly coats the epoxy resin with the composite film material.

[0077] The preparation steps are as follows:

[0078] (1) Composite membrane material coating resin: PDDA solution (0.1% wt, pH=4) and PAA solution (0.1% wt, pH=8) and GO particle dispersion (0.1% wt, pH=8) were prepared with deionized water, and the pH value of the solution was adjusted with hydrochloric acid or sodium hydroxide.

[0079] At room temperature, epoxy resin with an average particle size of 60 μm was sequentially and completely immersed in PDDA solution and PAA solution for 5 min. During the interval, excess solution that had not been adsorbed on the resin was washed with deionized water and dried with nitrogen.

[0080] The epoxy resin was sequentially and completely immersed in PDDA solution, GO particle dispersion, PAA solution, and GO particle dispersion, with each immersion time being 5 minutes. During the intervals, excess solution that had not been adsorbed onto the resin was rinsed off with deionized water, and the resin was dried with nitrogen gas. This step was repeated 60 times to complete the coating of the epoxy resin with the composite membrane material.

[0081] (2) The epoxy resin coated with the composite film material is preheated at 80°C for 1 hour, stirred at 200 r / min for 20 minutes, and then heated to 120°C for 4 hours to cure.

[0082] (3) The epoxy resin coated with the cured composite membrane material is crushed and granulated to obtain particles with a particle size of 120μm, thus obtaining the sealing agent.

[0083] Comparative Example 2

[0084] This comparative example provides a sealing agent. It is essentially the same as Example 1, except that it does not include the step of coating the composite membrane material with a modified resin.

[0085] The preparation steps are as follows:

[0086] (1) Modification of resin materials: Epoxy resin, silane coupling agent KH550 and film-forming agent PE emulsion are mixed in a mass ratio of 80:10:10, then heated to 80℃ and stirred; cooled and dried to obtain a modified resin with an average particle size of 60μm.

[0087] (2) Preheat the modified resin at 80°C for 1 hour, stir at 200 r / min for 20 minutes, and then heat it to 120°C for 4 hours to cure.

[0088] (3) The cured modified resin is crushed and granulated to obtain particles with a particle size of 120μm, thus obtaining the sealing agent.

[0089] Comparative Example 3

[0090] This comparative example provides a coating sealing agent and its preparation method. It is basically the same as Example 1, except that it does not include the steps of preheating and curing the modified resin.

[0091] The preparation method is as follows:

[0092] (1) Modification of resin materials: Epoxy resin, silane coupling agent KH550 and film-forming agent PE emulsion are mixed in a mass ratio of 80:10:10, then heated to 80℃ and stirred; cooled and dried to obtain a modified resin with an average particle size of 60μm.

[0093] (2) Composite membrane material coating modified resin: PDDA solution (0.1% wt, pH=4) and PAA solution (0.1% wt, pH=8) and GO particle dispersion (0.1% wt, pH=8) were prepared with deionized water, and the pH value of the solution was adjusted with hydrochloric acid or sodium hydroxide.

[0094] At room temperature, the modified resin was sequentially and completely immersed in PDDA solution and PAA solution for 5 minutes. During the interval, the excess solution that had not been adsorbed on the modified resin was washed with deionized water and dried with nitrogen.

[0095] The modified resin was sequentially and completely immersed in PDDA solution, GO particle dispersion, PAA solution, and GO particle dispersion, with each immersion time being 5 minutes. During the intervals, excess solution that had not been adsorbed onto the modified resin was rinsed with deionized water and dried with nitrogen gas. This step was repeated 60 times to complete the coating of the modified resin with the composite membrane material.

[0096] (3) The modified resin coated with the composite membrane material is crushed and granulated to prepare particles with a particle size of 120 μm, thus obtaining the sealing agent.

[0097] Performance testing

[0098] The drilling fluid formulation used in the performance test of this invention consists of bentonite slurry, potassium polyacrylate (KPAM), sodium carboxymethyl cellulose (CMC), suspending agent, NaOH, and barite. Based on the weight of the bentonite slurry, the addition amount of KPAM is 0.8 wt%, CMC is 1.5 wt%, the suspending agent is 2 wt%, and NaOH is 0.5 wt%. The amount of barite added is considered to achieve a drilling fluid density of 1.5 g / cm³. 3 Actual usage at the time.

[0099] Experimental Example 1 - Thermal Conductivity Test:

[0100] The plugging agent sample was bent at 160℃ to prepare a "U"-shaped specimen and then cooled to complete the secondary shaping. Then, 40g of plugging agent was placed in 500mL of drilling fluid and heated in an oil bath. The expansion delay time required for the shape recovery rate of the plugging agent to reach 100% under the condition of glass transition temperature Tg was tested. The test results are shown in Table 1.

[0101] Table 1

[0102]

[0103]

[0104] The results in Table 1 show that the sealing agents prepared in the embodiments of the present invention have a shorter expansion delay time after reaching the glass transition temperature, indicating that the sealing agents prepared in the embodiments of the present invention have higher thermal conductivity and are more sensitive to ambient temperature. The expansion delay time of the sealing agents prepared in Examples 1-4 of the present invention is shorter than that of Comparative Example 1, indicating that the resin modification has a very good effect on improving the thermal conductivity of the sealing agents and improving their sensitivity to ambient temperature. At the same time, the expansion delay time of the sealing agents prepared in Examples 1-4 of the present invention is shorter than that of Comparative Example 2, indicating that the resin coating composite film has an effect on improving the thermal conductivity of the sealing agents and improving their sensitivity to ambient temperature. The comparison between Examples 1-4 and Comparative Example 3 shows that the preheating and curing process of the modified resin coated by the composite film material in the preparation of the sealing agents can shorten the expansion delay time of the sealing agents.

[0105] Experiment Example 2 - Compressive Strength Test:

[0106] A certain amount of the sealing agent sample before crushing and granulation was weighed and placed in a core barrel. It was processed under a pressure of 15 MPa for 10 minutes. After depressurization, it was sieved and the residue in the sieve (passing through a 16-30 mesh sieve) was accurately weighed. Its mass retention rate was calculated, and the test results are shown in Table 2.

[0107] Table 2

[0108] Serial Number sealing agent Quality retention rate (%) 1 Example 1 98.9 2 Example 2 98.1 3 Example 3 98.3 4 Example 4 98.1 5 Comparative Example 1 97.4 6 Comparative Example 2 96.5 7 Comparative Example 3 97.6

[0109] The results in Table 2 show that the plugging agents prepared in the embodiments of the present invention exhibit a high mass retention rate after being pressed at 15 MPa, indicating that the plugging agents prepared in the embodiments of the present invention have good compressive strength. The mass retention rates of the plugging agents prepared in Examples 1-4 of the present invention are greater than those in Comparative Example 1, indicating that resin modification has a very good effect on improving the compressive strength of the plugging agents. Simultaneously, the mass retention rates of the plugging agents prepared in Examples 1-4 of the present invention are greater than those in Comparative Example 2, indicating that the coating with the composite membrane material is beneficial to improving the compressive strength of the plugging agents. A comparison between Examples 1-4 and Comparative Example 3 shows that the preheating and curing process of the modified resin coated with the composite membrane material during the preparation of the plugging agent also helps to improve the mass retention rate of the plugging agent.

[0110] Experiment Example 3 - Wear Resistance Test:

[0111] Fold 50g of sealing agent into a container with a density of 1.5g / cm³. 3The test sample was placed in 500 mL of drilling fluid and rolled and heated using a high-temperature roller heating furnace (purchased from Qingdao Haitong Yuanda Instrument Co., Ltd., model XGRL-4) to conduct wear resistance evaluation experiments; the rolling heating temperature was 120℃ and the rolling heating time was 72 h.

[0112]

[0113] In the above formula, α is the mass retention rate (%); M1 is the mass of the material before hot rolling (g); and M2 is the mass of the material after hot rolling (g). The wear resistance test results are shown in Table 3.

[0114] Table 3

[0115] Serial Number sealing agent Quality retention rate (%) 1 Example 1 96.2 2 Example 2 95.6 3 Example 3 95.8 4 Example 4 95.7 5 Comparative Example 1 93.0 6 Comparative Example 2 92.7 7 Comparative Example 3 93.5

[0116] The results in Table 3 show that the plugging agents prepared in the embodiments of the present invention have a high mass retention rate after high-temperature hot rolling for 72 hours, indicating that the plugging agents prepared in the embodiments of the present invention have good wear resistance. The mass retention rates of the plugging agents prepared in Examples 1-4 of the present invention are greater than those of the plugging agent prepared in Comparative Example 1, indicating that the resin modification has a very good effect on improving the wear resistance of the plugging agent. At the same time, the mass retention rates of the plugging agents prepared in Examples 1-4 of the present invention are greater than those of the plugging agent prepared in Comparative Example 2, indicating that the coating of the composite membrane material has an effect on the wear resistance of the plugging agent. The comparison between Examples 1-4 and Comparative Example 3 shows that the preheating and curing process of the modified resin coated by the composite membrane material in the preparation of the plugging agent also helps to improve the wear resistance of the plugging agent.

[0117] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A sealing agent, characterized in that, The sealing agent includes a modified resin and a composite film wrapped around the modified resin; the composite film is prepared from polydiallyldimethylammonium chloride, polyacrylic acid and graphene oxide; the glass transition temperature of the modified resin is 100℃~150℃.

2. The sealing agent according to claim 1, characterized in that, The mass ratio of the composite membrane to the modified resin is (1:450-320); And / or, the particle size of the modified resin is 10 μm to 150 μm.

3. The sealing agent according to claim 1 or 2, characterized in that, The modified resin is obtained by heating and stirring a mixture containing resin, silane coupling agent and film-forming agent. Preferably, the heating temperature is 60℃~90℃; Preferably, the mass ratio of resin, silane coupling agent, and film-forming agent in the mixture is (75-90):(5-12):(5-13).

4. The sealing agent according to claim 3, characterized in that, The resin is selected from at least one of epoxy resin, polypropylene resin, and polystyrene resin; And / or, the silane coupling agent is selected from at least one of KH550, KH560, and KH580; And / or, the film-forming agent is selected from at least one of polyethylene emulsion, polyacrylamide emulsion, and ethylene-acrylic acid copolymer emulsion; Preferably, the concentration of the polyethylene emulsion is 18wt% to 20wt%, the concentration of the polyacrylamide emulsion is 0.05wt% to 1wt%, and the concentration of the ethylene-acrylic acid copolymer emulsion is 20wt% to 30wt%.

5. The sealing agent according to any one of claims 1 to 4, characterized in that, The plugging agent is a particulate material with a particle size of 30μm to 200μm, and the mass retention rate of the plugging agent at a pressure of 15MPa is 98% to 99%.

6. A method for preparing the plugging agent according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) The modified resin was sequentially immersed in a polydiallyldimethylammonium chloride solution and a polyacrylic acid solution; (2) After being taken out, it is immersed in polydiallyldimethylammonium chloride solution, graphene oxide dispersion, polyacrylic acid solution and graphene oxide dispersion in sequence, and repeated 30 to 200 times to obtain the modified resin coated with composite membrane material. The modified resin coated with composite membrane material is cured, dried and pulverized to obtain the sealing agent.

7. The preparation method according to claim 6, characterized in that, The polydiallyl dimethyl ammonium chloride solution has a solubility of 0.1–0.5 wt%, a pH value of 3.5–4.5, and is water as the solvent. And / or, the concentration of the polyacrylic acid solution is 0.1 to 0.5 wt%, the pH value of the polyacrylic acid solution is 7.5 to 8.5, and the solvent of the polyacrylic acid solution is water; And / or, the graphene oxide content in the graphene oxide dispersion is 0.1 to 0.5 wt%, the pH value of the graphene oxide dispersion is 7.5 to 8.5, and the dispersant of the graphene oxide dispersion is water.

8. The preparation method according to claim 6 or 7, characterized in that, In step (1), the time for each intrusion is 5 to 10 minutes; And / or, in step (2), the time for each intrusion is 5 to 10 minutes; And / or, the curing temperature is 110℃~150℃, and the time is 4~5h.

9. The preparation method according to any one of claims 6 to 8, characterized in that, The curing process also includes preheating and stirring; Preferably, the preheating temperature is 70℃~90℃ and the time is 1~2h; the stirring conditions are 100~500r / min and the time is 10~60min.

10. A drilling fluid, characterized in that, The drilling fluid contains a plugging agent according to any one of claims 1 to 5 or a plugging agent prepared by the preparation method according to any one of claims 6 to 9, wherein the plugging agent content in the drilling fluid is 3 to 8 wt%; preferably, the expansion delay time of the plugging agent in the drilling fluid is 10 to 18 min, and the mass retention rate of the plugging agent in the drilling fluid after high-temperature hot rolling for 72 h is 95% to 96.5%.

Images