Plugging agent as well as preparation method and application thereof

Abstract

The invention discloses a plugging agent as well as a preparation method and application thereof, and belongs to the technical field of petroleum drilling. The plugging agent is prepared from a composition containing an oligomer monomer, a curing agent, an initiator, silicon dioxide and a foaming agent, and is used for improving the plugging effect of drilling well wall cracks and / or pores, the preparation method of the plugging agent comprises the steps that the oligomer monomer is copolymerized and cured to form a polymer plugging agent, the foaming agent is added into a copolymer, and the plugging agent is prepared. When the polymer particles are foamed, the polymer particles act in drilling well wall cracks, after foaming, the plugging agent expands at high temperature, the bridging effect of the polymer particles is strengthened, and a more compact and higher-strength plugging layer is formed, so that the well wall cracks and / or pores are further filled and plugged, and the plugging effect is improved.

Description

Technical Field

[0001] The invention relates to the technical field of oil drilling, and in particular to a plugging agent and a preparation method and application thereof. Background Art

[0002] Well leakage is the phenomenon that various working fluids leak into the formation under the action of pressure difference during various downhole operations such as drilling, cementing completion, testing or well repair. Once well leakage occurs, it will not only delay drilling time, lose drilling fluid, damage oil and gas layers, interfere with geological logging work, increase drilling costs, but also easily cause a series of complex situations such as drill sticking, blowout, well collapse, and even lead to the scrapping of the wellbore, causing huge economic losses.

[0003] With the further understanding of the causes of different well leakage, the research and development of plugging materials is also constantly improving. When a well leak occurs, the compound ratio of granular, flaky and fibrous plugging materials is generally adjusted according to the different pore sizes and positions of the leakage layer, and appropriate inert materials are added to complement them to enhance the plugging effect. Commonly used granular plugging materials include walnut shells, rubber particles, diatomaceous earth, asphalt, etc.; fibrous materials include sawdust, cotton fiber, flax fiber, etc.; sheet materials include mica flakes, rice husks, etc. During the drilling process, artificial cracks caused by fast drilling speed or fast drilling can be plugged by using the non-solidified characteristics of soft and hard plugging materials to form non-flowing viscous substances. Such materials mainly include diesel bentonite slurry, shear thickening liquid, barite plug and lime milk. The above types of plugging materials can solve partial leakage and loss-return leakage caused by pores and cracks, but some complex leakage cannot be solved well. Therefore, various new plugging agents such as chemical plugging agents, high water loss plugging agents, mixed plugging slurries, etc. have emerged, providing effective means to deal with various types of well leakage and improve the success rate of well leakage treatment.

[0004] Intelligent plugging and sealing materials are currently the hotspots and frontiers of research in the world, providing new ideas for plugging technology. "Intelligent materials" is a concept that was first proposed abroad in the mid-1980s. Intelligent materials can sense changes in the external environment by themselves, thereby obtaining external information, making corresponding judgments and processing, and then issuing instructions to adjust their own state and adapt to changes in the external environment, thereby realizing the self-detection, self-diagnosis, self-regulation, self-adaptation, self-repair, etc. of the materials themselves, which are similar to the functions of biological systems. Intelligent materials are the fourth generation of materials after natural materials, synthetic polymer materials, and artificially designed materials. They are one of the important directions for the development of modern high-tech new materials and will support the development of high technology in the future. Intelligent materials gradually eliminate the boundaries between functional materials and structural materials in the traditional sense, realize structural functionalization and functional diversification, and are mainly used in aerospace, electronics, and smart life. So far, international research on intelligent materials has mainly focused on the intelligentization of key engineering structural component materials and the intelligentization of bionic materials. As oil drilling continues to develop towards the stage of informatization, intelligence, and automation, intelligent new materials will continue to be used in drilling.

[0005] Shape memory materials are a type of smart materials that give traditional materials the intelligent property of shape memory. They refer to polymer materials that can restore their original shape after the initial conditions of a product are changed and fixed under certain conditions, and then stimulated by external conditions (such as heat, electricity, light, chemical induction, etc.).

[0006] Shape memory polymer (SMP) gives traditional polymer materials the intelligent property of shape memory. It refers to a polymer material that can return to its original shape through external conditions (such as heat, electricity, light, chemical induction, etc.) after the initial shape of the product is changed and fixed under certain conditions. Shape memory polymer has the following characteristics: large deformation, which can reach more than 400%, small stress required for deformation, and easy to use; easy to shape, good processing performance, and easy to make complex structured special-shaped products; low relative density, generally 1.0-1.3g / cm 3 ; Adequate raw materials; Corrosion resistance; Cheaper than shape memory alloys; Adjustable activation temperature. So far, it has been found that cross-linked polyethylene, polyurethane, trans-polyisoprene, and epoxy resins based on polymers all have shape memory effects.

[0007] However, at present, the deformation activation temperature of smart plugging and sealing materials such as shape memory polymers is relatively low, usually around 100°C. Therefore, in drilling, especially in deep wells, the effect of high temperature is not ideal, and other methods are needed to provide plugging effect; moreover, the strength of shape memory polymers also decreases during the deformation process. Therefore, it is necessary to strengthen the shape memory polymer to form a denser and higher-strength plugging layer to improve the plugging effect. Summary of the invention

[0008] In view of the deficiencies in the prior art, the present invention provides a plugging agent and a preparation method and application thereof, which are used to improve the plugging effect of wellbore wall cracks and / or pores. The preparation method of the plugging agent comprises the following steps: copolymerizing oligomer monomers to form a polymer plugging agent after solidification, adding a foaming agent into the copolymer, and causing the plugging agent to act in the wellbore wall cracks. After foaming, the plugging agent expands at high temperature, thereby strengthening the bridging effect of the polymer particles and forming a denser and stronger plugging layer, thereby further filling and plugging the wellbore wall cracks and / or pores and improving the plugging effect.

[0009] In order to solve the above technical problems, the first aspect of the present invention provides a plugging agent, which is prepared from a composition comprising an oligomer monomer, a curing agent, an initiator, silicon dioxide and a foaming agent.

[0010] According to some embodiments of the present invention, the oligomer monomer is selected from at least one of epoxy resin and polyurethane. Preferably, the epoxy resin is selected from bisphenol A epoxy resin, and the polyurethane is selected from polyester polyurethane.

[0011] According to some embodiments of the present invention, the curing agent is selected from at least one of methylhexahydrophthalic anhydride (MHHPA), diethylenetriamine, and polyamide; preferably, the polyamide is selected from polyamide curing agent 651.

[0012] According to some embodiments of the present invention, the initiator is selected from at least one of N,N-benzyldimethylamine (BDMA) and polyetheramine; preferably, the polyetheramine is selected from polyetheramine D230.

[0013] According to some embodiments of the present invention, the foaming agent is selected from microsphere expansion agent WS606.

[0014] According to some embodiments of the present invention, the particle size of the silicon dioxide is 50 μm to 200 μm, for example, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, or 70 μm.

[0015] According to some embodiments of the present invention, the mass ratio of the oligomer monomer, the curing agent and the initiator is (1-2): (2-6): (0.2-0.6), for example 1:2:0.2, 1:3:0.3, 2:5:0.5, 1:2:0.2, 1:3:0.4, 1:2:0.3, 1:4:0.4; preferably, based on the total mass of the oligomer monomer, the curing agent and the initiator, the amount of silicon dioxide added is 0.5wt% to 5wt%, for example 0.5wt%, 1.0wt%, 2.0wt%, 3.0wt%, 4.0wt%, 5.0wt%, and the amount of the foaming agent added is 0.1wt% to 3wt%, for example 0.1wt%, 1wt%, 2wt%, 3wt%.

[0016] According to some embodiments of the present invention, the silica is selected from modified silica modified by a silane coupling agent or a hydroxy silicone oil; preferably, the silane coupling agent is selected from any one of KH550, KH570, and KH151; the hydroxy silicone oil is selected from any one of 203 hydroxy silicone oil and 209 hydroxy silicone oil.

[0017] The modification method of silicon dioxide described in the present invention is a conventional technical means in the art. For the modification method of silicon dioxide, refer to, for example, "Preparation and Characterization of Ultrafine SiO2 Modified by Silane Coupling Agent" (Organic Silicone Materials, 2023.1) and "Research on Nano-kaolin Modified by Silane Coupling Agent" (Non-metallic Minerals, 2008.5).

[0018] Preferably, the silicon dioxide in the present invention is modified using a silane coupling agent, and the specific method is as follows:

[0019] Step 1, add 1g of silica and 300g of toluene into a 500ml beaker, perform ultrasonic treatment for 0.5h until the silica is evenly dispersed, and then continue ultrasonic treatment for 1h to prepare a silica suspension;

[0020] Step 2: Take 0.4 g of silane coupling agent (KH570), add 0.3 g of deionized water and mix well, then adjust the pH to 4 with acetic acid, pre-hydrolyze for 143 min, and obtain a KH570 pre-hydrolyzed solution;

[0021] Step 3: Pour the silica suspension prepared in step 1 into a 500 ml three-necked flask, shear at a rate of 1200 rpm for 0.5 h, heat to 75°C, then add the KH570 pre-hydrolysis solution prepared in step 2, and stir evenly; then maintain the temperature at 75°C for reflux reaction for 7 h, centrifuge, wash, dry, and finally grind the dried silica with a mortar to obtain modified silica.

[0022] In the present invention, more active groups such as hydroxyl groups are formed on the surface of silica after modification, which is beneficial to the surface bonding of silica particles with oligomers; the purpose of adding silica to the plugging agent is to improve the mechanical properties of the plugging agent, especially the toughness and strength, which is beneficial to utilize the friction and extrusion effect to play the role of skeleton bridging, thereby forming a denser plugging layer of the plugging agent.

[0023] The second aspect of the present invention provides a method for preparing the above-mentioned plugging agent, comprising the following steps:

[0024] 1) Mixing oligomer monomers, curing agent, initiator, silicon dioxide and foaming agent to obtain a premix;

[0025] 2) Solidifying the premix to obtain the plugging agent.

[0026] According to some embodiments of the present invention, in step 1), during the mixing, the oligomer monomer, the curing agent and the initiator are first mixed to obtain a mixed solution; preferably, the conditions of the first mixing include: a temperature of 60°C to 80°C, such as 60°C, 70°C, 80°C, and a time of 10min to 30min, such as 10min, 20min, 30min;

[0027] The mixed liquid is then mixed with silicon dioxide and a foaming agent for a second time to obtain a premix; preferably, the conditions for the second mixing include: a temperature of 30°C to 60°C, such as 30°C, 40°C, 50°C, and a time of 10min to 30min, such as 10min, 20min, 30min; further preferably, the mixed liquid is clear and transparent.

[0028] According to some embodiments of the present invention, in step 1), before the oligomer monomer, curing agent and initiator are first mixed, the oligomer monomer is vacuum dehydrated at a temperature of 110°C to 120°C for 1h to 3h, for example, the oligomer monomer is vacuum dehydrated at a temperature of 110°C for 1h, and the oligomer monomer is vacuum dehydrated at a temperature of 120°C for 3h; preferably, the vacuum degree of vacuum dehydration is 60Pa to 100Pa, for example 100Pa; further preferably, the vacuum dehydration is cooled to room temperature, for example 25°C.

[0029] According to some embodiments of the present invention, in step 2), the curing conditions include: a temperature of 120°C to 140°C, for example, 120°C, 130°C, 140°C, and a time of 0.5h to 5h, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h; preferably, after curing, naturally cool to room temperature, for example, 25°C.

[0030] According to some embodiments of the present invention, in step 2), the solidification further includes crushing and granulation; and / or the particle size of the plugging agent is 10 mesh to 40 mesh, for example, 10 mesh, 20 mesh, 30 mesh, 40 mesh.

[0031] In the present invention, the curing temperature does not reach the foaming temperature of the foaming agent, and the foaming agent does not work; during the application process, the plugging agent enters the cracks and / or pores of the wellbore wall. As the well depth increases, the drilling fluid temperature increases. After reaching the foaming temperature of the foaming agent, the foaming agent expands, causing the plugging agent that has been softened at high temperature to expand, thereby further filling and plugging the cracks and pores in the wellbore wall, making the plugging layer denser and improving the plugging effect.

[0032] A third aspect of the present invention provides a plugging agent or use of the plugging agent prepared by the above preparation method in plugging cracks and / or pores in a wellbore wall.

[0033] Beneficial effects:

[0034] The plugging agent prepared by the present invention has a shape memory function, which mainly utilizes the shape memory function of the epoxy resin after curing. After being added into the wellbore, as the wellbore temperature increases, the phase change temperature of the epoxy resin is reached, a certain expansion occurs, causing the epoxy resin to soften, creating conditions for the internal expansion agent to expand. After entering the crack, the expansion agent expands, causing the prepared plugging agent to deform, thereby exceeding the crack width, forming an effective plugging layer for the crack.

[0035] The plugging agent of the present invention can utilize the shape memory function of epoxy resin. During the demolding and crushing process, the plugging agent can be prepared into a plugging agent of a specific shape, such as an ellipsoid or a cone, so that the plugging agent is conducive to entering the wellbore formation cracks. After entering the cracks, the plugging agent is deformed and expanded at temperature. After expansion, the toughness and strength of the plugging agent are improved due to the addition of silica and polyurethane, thereby forming a dense, tough, and high-strength plugging layer, thereby preventing the plugging layer from being weak, decomposing and collapsing under a higher drilling fluid column pressure, or being squeezed into a deeper formation, thereby causing a decrease in the plugging effect.

[0036] The plugging agent prepared by the preparation method of the present invention has the strength of the plugging agent increased by adding silicon dioxide.

[0037] The plugging agent of the present invention utilizes the increase in the temperature of the drilling fluid to expand after reaching the foaming temperature of the foaming agent, causing the plugging agent that has been softened at high temperature to expand accordingly, thereby further filling and plugging the cracks and / or pores in the well wall, making the plugging layer denser and improving the plugging effect. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the embodiments, but the present invention is not limited by these embodiments.

[0039] The curing molding mold in the present invention is used for curing molding of epoxy resin and is purchased from Shanghai Chunxu Mold Industry Co., Ltd.

[0040] The universal testing machine in the present invention was purchased from Jiangsu Tianyuan Testing Equipment Co., Ltd., and the model number is TY8000-A.

[0041] The crack plugging simulation experimental device in the present invention was purchased from Qingdao Haitong Yuanda Instrument Co., Ltd., and the model number is HTD18984.

[0042] The flask, beaker, oven and air drying oven in the present invention can be any commercially available ones unless otherwise specified.

[0043] The epoxy resin monomer in the present invention is purchased from Wuxi Resin Factory of Bluestar New Materials Co., Ltd., and the model is E51.

[0044] The polyurethane in the present invention is purchased from Sigma-Aldrich (Shanghai) Co., Ltd., model number 81367.

[0045] In the present invention, N,N-benzyldimethylamine was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0046] The diethylenetriamine in the present invention is purchased from Sigma-Aldrich (Shanghai) Co., Ltd.

[0047] In the present invention, the microsphere expansion agent WS606 was purchased from Jining Tangyi Chemical Co., Ltd.

[0048] The methyl hexahydrophthalic anhydride in the present invention is purchased from Puyang Huicheng Chemical Co., Ltd.

[0049] The silicon dioxide in the present invention was purchased from Jinan Yinfeng Silicon Products Co., Ltd. and modified by KH570.

[0050] Boric acid in the present invention is purchased from Sigma-Aldrich (Shanghai) Co., Ltd.

[0051] The polyetheramine in the present invention is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and the model is D230.

[0052] The particle foaming agent SM-1 in the present invention was purchased from Zhejiang Shuntai Rubber & Plastic Technology Co., Ltd.

[0053] Example 1

[0054] This embodiment provides a plugging agent and a preparation method thereof.

[0055] Preparation of premix: accurately weigh epoxy resin monomer (E51) in a flask, vacuum dehydrate for 1 hour at a temperature of 110°C and a vacuum degree of 100 Pa, and wait for cooling to 25°C; then add diethylenetriamine and N,N-benzyldimethylamine in a ratio of 1:2:0.2 to the epoxy resin monomer in a beaker to obtain a mixed solution, and then stir the mixed solution at a temperature of 60°C and a speed of 200 rpm for 30 minutes to remove bubbles; after the mixed solution becomes clear, add silica and microsphere expansion agent WS606 (the amount of silica added is 0.5wt%, and the amount of microsphere expansion agent WS606 added is 0.1wt%) to the beaker and continue stirring at a speed of 200 rpm for 30 minutes at a temperature of 40°C to obtain a premix, wherein the particle size of silica is 20μm, and the silica is modified silica modified by KH570.

[0056] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0057] High temperature curing: The premix is ​​injected into the preheated curing molding mold, and cured in a forced air drying oven at 120°C for 5 hours, and then naturally cooled to 25°C.

[0058] Demolding: After taking out the sample and demolding it, crush and granulate it to obtain plugging agent particles with a particle size of 40 mesh.

[0059] Example 2

[0060] This embodiment provides a plugging agent and a preparation method thereof.

[0061] Preparation of premix: accurately weigh epoxy resin monomer (E51) in a flask, vacuum dehydrate for 1 hour at a temperature of 110° C. and a vacuum degree of 100 Pa, and wait for cooling to 25° C.; add methyl hexahydrophthalic anhydride and N, N-benzyldimethylamine in a beaker in a ratio of 1:3:0.3 to the epoxy resin monomer to obtain a mixed solution, and then stir the mixed solution at a temperature of 60° C. and a speed of 300 rpm for 30 minutes to remove bubbles; after the mixed solution becomes clear, add silica particles and microsphere expansion agent WS606 (the amount of silica added is 3wt%, and the amount of microsphere expansion agent WS606 added is 1wt%) to the beaker and continue stirring at a speed of 300 rpm for 30 minutes at a temperature of 50° C. to obtain a premix, wherein the particle size of silica is 30 μm, and the silica is modified silica after KH570 modification.

[0062] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0063] High temperature curing: The premix is ​​injected into the preheated curing molding mold and cured in a forced air drying oven at 120°C for 5 hours, and then naturally cooled to 25°C.

[0064] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 40 mesh plugging agent particles.

[0065] Example 3

[0066] This embodiment provides a plugging agent and a preparation method thereof.

[0067] Preparation of premix: accurately weigh epoxy resin monomer (E51) in a flask, vacuum dehydrate for 1 hour at a temperature of 110°C and a vacuum degree of 100 Pa, and wait for cooling to 25°C; add methyl hexahydrophthalic anhydride and polyetheramine (D230) in a beaker in a ratio of 2:5:0.5 to the epoxy resin monomer to obtain a mixed solution, and then stir the mixed solution at a temperature of 60°C and a speed of 300 rpm for 30 minutes to remove bubbles; after the mixed solution becomes clear, add silica particles and microsphere expansion agent WS606 (the amount of silica added is 5wt%, and the amount of microsphere expansion agent WS606 added is 3wt%) to the beaker and continue stirring at a speed of 300 rpm for 30 minutes at a temperature of 50°C to obtain a premix, wherein the particle size of the modified silica is 70μm, and the silica is modified silica modified with 203 hydroxy silicone oil.

[0068] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0069] High temperature curing: The premix is ​​injected into the preheated curing molding mold and cured in a forced air drying oven at 140°C for 0.5h, and then naturally cooled to 25°C.

[0070] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 10-mesh plugging agent particles.

[0071] Example 4

[0072] This embodiment provides a plugging agent and a preparation method thereof.

[0073] Preparation of premix: accurately weigh epoxy resin monomer (E51) and polyurethane monomer (81367) in a flask (mass ratio of epoxy resin monomer to polyurethane monomer is 8:1), dehydrate under vacuum at 120°C and 100 Pa for 3 h, and cool to 25°C; add polyamide and N, N-benzyldimethylamine in a ratio of 1:2:0.2 to the oligomer monomer in a beaker to obtain a mixed solution, and then place the mixed solution at 80°C and rotate at 300 rpm. The mixture was stirred at a rate of 100 rpm for 10 min to remove bubbles; after the mixed solution became clear and transparent, silica particles and microsphere expansion agent WS606 (the amount of silica added was 2 wt%, and the amount of microsphere expansion agent WS606 added was 2 wt%) were added into a beaker and stirred at a rate of 300 rpm for 10 min at a temperature of 50°C to obtain a premix, wherein the particle size of the silica was 70 μm and the silica was modified silica after being modified with KH570.

[0074] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0075] High temperature curing: Inject the premix into the preheated curing molding mold, and wash and cure it in a blast drying oven at 130°C for 2 hours, and cool it naturally to 25°C.

[0076] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 20-mesh plugging agent particles.

[0077] Example 5

[0078] This embodiment provides a plugging agent and a preparation method thereof.

[0079] Preparation of premix: accurately weigh epoxy resin monomer (E51) and polyurethane monomer (81367) in a flask (mass ratio of epoxy resin monomer to polyurethane monomer is 8:1), dehydrate under vacuum at 120°C and 100Pa for 3h, and cool to 25°C; add polyamide and N,N-benzyldimethylamine in a ratio of 1:3:0.4 to the oligomer monomer in a beaker to obtain a mixed solution, and then place the mixed solution at 80°C and rotate at 300 rpm. The mixture was stirred at a rate of 100 rpm for 10 min to remove bubbles; after the mixed solution became clear and transparent, silica particles and microsphere expansion agent WS606 (the amount of silica added was 5 wt%, and the amount of microsphere expansion agent WS606 added was 2 wt%) were added into a beaker and stirred at a rate of 300 rpm for 10 min at a temperature of 50°C to obtain a premix, wherein the particle size of the silica was 70 μm and the silica was modified silica after being modified with KH570.

[0080] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0081] High temperature curing: Inject the premix into the preheated curing molding mold, and wash and cure it in a blast drying oven at 130°C for 2 hours, and cool it naturally to 25°C.

[0082] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 20-mesh plugging agent particles.

[0083] Example 6

[0084] This embodiment provides a plugging agent and a preparation method thereof.

[0085] Preparation of premix: accurately weigh epoxy resin monomer (E51) and polyurethane monomer (81367) in a flask (mass ratio of epoxy resin monomer to polyurethane monomer is 6:1), dehydrate under vacuum at 120°C and 100 Pa for 3 h, and cool to 25°C; add polyamide and N, N-benzyldimethylamine in a ratio of 1:2:0.3 to the oligomer monomer in a beaker to obtain a mixed solution, and then place the mixed solution at 80°C and rotate at 300 rpm. The mixture was stirred at a rate of 100 rpm for 10 min to remove bubbles; after the mixed solution became clear and transparent, silica particles and microsphere expansion agent WS606 (the amount of silica added was 5 wt%, and the amount of microsphere expansion agent WS606 added was 3 wt%) were added into a beaker and stirred at a rate of 300 rpm for 10 min at a temperature of 50°C to obtain a premix, wherein the particle size of the silica was 70 μm and the silica was modified silica after being modified with KH570.

[0086] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0087] High temperature curing: Inject the premix into the preheated curing molding mold, and wash and cure it in a blast drying oven at 140°C for 2 hours, and cool it naturally to 25°C.

[0088] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 20-mesh plugging agent particles.

[0089] Example 7

[0090] This embodiment provides a plugging agent and a preparation method thereof.

[0091] Preparation of premix: accurately weigh epoxy resin monomer (E51) and polyurethane monomer (81367) in a flask (mass ratio of epoxy resin monomer to polyurethane monomer is 6:1), dehydrate under vacuum at 120°C and 100 Pa for 3 h, and cool to 25°C; add polyamide and N, N-benzyldimethylamine in a ratio of 1:4:0.4 to the oligomer monomer in a beaker to obtain a mixed solution, and then place the mixed solution at 80°C and rotate at 300 rpm. The mixture was stirred at a rate of 300 rpm for 10 min to remove bubbles; after the mixed solution became clear and transparent, silica particles and microsphere expansion agent WS606 (the amount of silica added was 3 wt%, and the amount of microsphere expansion agent WS606 added was 3 wt%) were added into a beaker and stirred at a rate of 300 rpm for 10 min at a temperature of 50°C to obtain a premix, wherein the particle size of the silica was 70 μm and the silica was modified silica after being modified with KH570.

[0092] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0093] High temperature curing: Inject the premix into the preheated curing molding mold, and wash and cure it in a blast drying oven at 130°C for 2 hours, and cool it naturally to 25°C.

[0094] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 20-mesh plugging agent particles.

[0095] Example 8

[0096] This embodiment provides a plugging agent and a preparation method thereof.

[0097] Preparation of premix: accurately weigh epoxy resin monomer (E51) and polyurethane monomer (81367) in a flask (mass ratio of epoxy resin monomer to polyurethane monomer is 10:1), dehydrate under vacuum at 120°C and 100 Pa for 3 h, and cool to 25°C; add polyamide and N, N-benzyldimethylamine in a ratio of 1:3:0.3 to the oligomer monomer in a beaker to obtain a mixed solution, and then place the mixed solution at 80°C and rotate at 300 rpm. The mixture was stirred at a rate of 100 rpm for 10 min to remove bubbles; after the mixed solution became clear and transparent, silica particles and microsphere expansion agent WS606 (the amount of silica added was 4 wt%, and the amount of microsphere expansion agent WS606 added was 2 wt%) were added into a beaker and stirred at a rate of 300 rpm for 10 min at a temperature of 50°C to obtain a premix, wherein the particle size of the silica was 70 μm and the silica was modified silica after being modified with KH570.

[0098] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0099] High temperature curing: Inject the premix into the preheated curing molding mold, and wash and cure it in a blast drying oven at 140°C for 2 hours, and cool it naturally to 25°C.

[0100] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 20-mesh plugging agent particles.

[0101] The plugging agent of the present invention has a temperature-controlled deformation function and is suitable for plugging wellbore sections with a plugging temperature below 160°C. When used, the plugging agent is added to the drilling fluid at an amount of 0.5wt% to 3wt%. After the plugging agent enters the cracks in the well wall, it will expand under the action of temperature, plugging the cracks and pores, and has the effect of reinforcing the well wall and plugging leaks.

[0102] Comparative Example 1

[0103] This comparative example provides a plugging agent and a preparation method thereof.

[0104] Preparation of premix: Accurately weigh epoxy resin monomer (E51) in a flask, vacuum dehydrate for 1 hour at a temperature of 110°C and a vacuum degree of 100 Pa, and wait to cool to 25°C; add methyl hexahydrophthalic anhydride and N, N-benzyldimethylamine in a beaker at a ratio of 1:3:0.3 to the epoxy resin monomer to obtain a mixed solution, and then stir the mixed solution at a temperature of 60°C and a speed of 300 rpm for 30 minutes to remove bubbles to obtain a premix.

[0105] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0106] High temperature curing: The premix is ​​injected into the preheated curing molding mold and cured in a forced air drying oven at 120°C for 5 hours, and then naturally cooled to 25°C.

[0107] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 40 mesh plugging agent particles.

[0108] Comparative Example 2

[0109] This comparative example provides a plugging agent and a preparation method thereof.

[0110] Preparation of premix: accurately weigh epoxy resin monomer (E51) in a flask, vacuum dehydrate for 1 hour at a temperature of 110°C and a vacuum degree of 100 Pa, and wait for cooling to 25°C; add methyl hexahydrophthalic anhydride and N, N-benzyldimethylamine in a beaker in a ratio of 1:3:0.3 to the epoxy resin monomer to obtain a mixed solution, and then stir the mixed solution at a temperature of 60°C and a speed of 300 rpm for 30 minutes to remove bubbles; after the mixed solution becomes clear, add silica particles (the amount of silica added is 3wt%) to the beaker and continue stirring at a temperature of 50°C and a speed of 300 rpm for 30 minutes to obtain a premix, wherein the particle size of the silica is 30μm, and the silica is modified silica after KH570 modification.

[0111] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0112] High temperature curing: The premix is ​​injected into the preheated curing molding mold and cured in a forced air drying oven at 120°C for 5 hours, and then naturally cooled to 25°C.

[0113] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 40 mesh plugging agent particles.

[0114] Comparative Example 3

[0115] This comparative example provides a plugging agent and a preparation method thereof.

[0116] Preparation of premix: accurately weigh epoxy resin monomer (E51) in a flask, vacuum dehydrate for 1 hour at a temperature of 110°C and a vacuum degree of 100 Pa, and wait for cooling to 25°C; add methyl hexahydrophthalic anhydride and N, N-benzyldimethylamine in a beaker at a ratio of 1:3:0.3 to the epoxy resin monomer to obtain a mixed solution, and then stir the mixed solution at a temperature of 60°C and a speed of 300 rpm for 30 minutes to remove bubbles; after the mixed solution becomes clear, add microsphere expansion agent WS606 (the amount of microsphere expansion agent WS606 added is 1wt%) to the beaker and continue stirring at a temperature of 50°C and a speed of 300 rpm for 30 minutes to obtain a premix.

[0117] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0118] High temperature curing: The premix is ​​injected into the preheated curing molding mold and cured in a forced air drying oven at 120°C for 5 hours, and then naturally cooled to 25°C.

[0119] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 40 mesh plugging agent particles.

[0120] Comparative Example 4

[0121] This comparative example provides a plugging agent and a preparation method thereof.

[0122] Preparation of premix: accurately weigh epoxy resin monomer (E51) in a flask, vacuum dehydrate for 1 hour at a temperature of 110°C and a vacuum degree of 100 Pa, and wait for cooling to 25°C; add methyl hexahydrophthalic anhydride and N, N-benzyldimethylamine in a beaker at a ratio of 1:3:0.3 to the epoxy resin monomer to obtain a mixed solution, and then stir the mixed solution at a temperature of 60°C and a speed of 300 rpm for 30 minutes to remove bubbles; after the mixed solution becomes clear, add silica particles (the amount of silica added is 3wt%) to the beaker and continue stirring at a temperature of 50°C and a speed of 300 rpm for 30 minutes to obtain a premix, wherein the particle size of the silica is 30μm.

[0123] Pretreatment of the curing molding mold: After evenly applying silicone grease on the surface of the curing molding mold, put it in an oven at 80°C and preheat it for 0.5h for use.

[0124] High temperature curing: The premix is ​​injected into the preheated curing molding mold and cured in a forced air drying oven at 120°C for 5 hours, and then naturally cooled to 25°C.

[0125] Demolding: Take out the sample, demould it, crush it and granulate it to obtain 40 mesh plugging agent particles.

[0126] Comparative Example 5

[0127] This comparative example provides a plugging agent and a preparation method thereof.

[0128] The preparation method of Example 2 was adopted, except that calcium carbonate particles were used instead of silicon dioxide particles.

[0129] Comparative Example 6

[0130] This comparative example provides a plugging agent and a preparation method thereof.

[0131] The preparation method of Example 2 was adopted, except that the particle foaming agent SM-1 was used instead of the microsphere expansion agent WS606.

[0132] Performance evaluation and testing

[0133] 1. Compressive strength test:

[0134] With reference to the national standard GB / T2567-2008 "Test Method for Properties of Resin Castings", a universal testing machine was used to test the compressive properties of the plugging agent of the present invention at a temperature of 25°C. The compressive strength calculation formula is shown in formula (1).

[0135]

[0136] In formula (1): c is the compressive strength, in megapascals (MPa); P is the breaking load (or maximum load), in Newtons (N); F is the cross-sectional area of ​​the specimen, in square millimeters (mm 2 );d is the diameter of the sample, in millimeters (mm).

[0137] Table 1

[0138] Serial number Plugging agents prepared in different embodiments Compressive strength(MPa) 1 Example 1 105.6 2 Example 2 108.7 3 Example 3 107.6 4 Example 4 108.5 5 Example 5 107.1 6 Example 6 108.2 7 Example 7 106.3 8 Example 8 107.9 9 Comparative Example 1 78.6 10 Comparative Example 2 95.1 11 Comparative Example 3 86.5 12 Comparative Example 4 105.3 13 Comparative Example 5 100.1 14 Comparative Example 6 95.8

[0139] The results in Table 1 show that the plugging agents prepared in Examples 1-8 of the present invention can improve their compressive resistance by adding silica (silicon dioxide modified by KH550) and microsphere expansion agent WS606; in Comparative Examples 2 and 3, adding foaming agent (microsphere expansion agent WS606) and silica (silicon dioxide modified by KH550) alone can improve the compressive resistance of the plugging agents, but both are significantly lower than those in Examples 1-8; in Comparative Examples 5 and 6, calcium carbonate is used to replace silica (silicon dioxide modified by KH550) and other foaming agents (granular expansion agent WS606) are used to replace silica (silicon dioxide modified by KH550). In comparative example 4, although the addition of silica (unmodified) alone can significantly improve the compressive strength of the plugging agent, it cannot improve the expansion performance. It can be seen that the silica and microsphere expansion agent WS606 added in the present invention have a synergistic effect, which can improve the compressive performance of the plugging agent, and the addition of microsphere expansion agent WS606 has a higher retention rate. Therefore, the plugging agents prepared in Examples 1-8 have both high compressive strength and expansion effect.

[0140] 2. Expansion rate test:

[0141] The plugging agent is heated and pressurized using a fracture plugging simulation experimental device, and then the diameter change of the plugging agent of the present invention is measured using a vernier caliper. The linear expansion rate of the present invention is calculated using the following formula (2):

[0142] LER = δD / D × 100% (2)

[0143] In formula (2), LER is the linear expansion rate, %; δD / D is the diameter change rate.

[0144] The specific test procedure is as follows: the diameter of the plugging agent of the present invention is measured at a temperature of 25°C, and a drilling fluid is prepared: 4% bentonite slurry + 0.4% CMC-HV. The drilling fluid and the plugging agent of the present invention are loaded into the kettle of the experimental device, heated to 150°C, pressurized to 7MPa, maintained for 10 minutes, and then the kettle is taken out and cooled to 25°C. The pressure is released to end the experiment, and the plugging agent of the present invention is taken out and naturally air-dried, and then the diameter is measured.

[0145] Table 2

[0146]

[0147]

[0148] The results in Table 2 show that the expansion rates of the plugging agents prepared in Examples 1-8 of the present invention are significantly increased after adding silica (silicon dioxide modified by KH550) and microsphere expansion agent WS606 at the same time; the expansion rates of the plugging agents prepared in Comparative Example 1 without adding silica (silicon dioxide modified by KH550) and microsphere expansion agent WS606, Comparative Example 2 without adding microsphere expansion agent WS606, and Comparative Example 4 without adding microsphere expansion agent WS606 are significantly lower. It can be seen that the addition of silica alone in the plugging agent Adding cannot improve the expansion performance of the plugging agent; while in Comparative Examples 3, 5 and 6, silica (KH550 modified silica) and a foaming agent are added in combination. Compared with Examples 1-8, it is found that the expansion rates of the plugging agents prepared in Comparative Examples 3, 4 and 5 are all smaller than those in Examples 1-8; it can be seen that the silica and microsphere expansion agent WS606 added in Examples 1-8 of the present invention have a synergistic effect, which can improve the compressive resistance of the plugging agent, and the microsphere expansion agent WS606.

[0149] 3. Plugging pressure bearing capacity test:

[0150] The high-temperature plugging pressure bearing capacity test was carried out using a crack plugging simulation experimental device. The test temperature was 160°C, a 1mm crack plate was used, and a plugging slurry was prepared: 4% bentonite slurry + 0.4% CMC-HV + 1% of the plugging agent described in the present invention. The breakthrough pressure of the test was the pressure bearing capacity.

[0151] Table 3

[0152]

[0153]

[0154] The results in Table 3 show that the plugging agents prepared in Examples 1-8 of the present invention have better pressure bearing capacity at high temperature (160° C.) than the plugging agents prepared in Comparative Examples 1-6, and are suitable for plugging well wall cracks and plugging leaks.

[0155] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to 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 words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A plugging agent, characterized in that: The plugging agent is prepared from a composition comprising an oligomer monomer, a curing agent, an initiator, silicon dioxide and a foaming agent.

2. The plugging agent according to claim 1, characterized in that: The oligomer monomer is selected from at least one of epoxy resin and polyurethane; preferably, the epoxy resin is selected from bisphenol A epoxy resin, and the polyurethane is selected from polyester polyurethane; And / or, the curing agent is selected from at least one of methyl hexahydrophthalic anhydride, diethylenetriamine, and polyamide; preferably, the polyamide is selected from polyamide curing agent 651; And / or, the initiator is selected from at least one of N,N-benzyldimethylamine and polyetheramine; preferably, the polyetheramine is selected from polyetheramine D230; And / or, the foaming agent is selected from microsphere expansion agent WS606.

3. The plugging agent according to claim 1 or 2, characterized in that: The mass ratio of the oligomer monomer, the curing agent and the initiator is (1-2): (2-6): (0.2-0.6); preferably, based on the total mass of the oligomer monomer, the curing agent and the initiator, the added amount of silicon dioxide is 0.5wt%-5wt%, and the added amount of the foaming agent is 0.1wt%-3wt%.

4. The plugging agent according to any one of claims 1 to 3, characterized in that: The silica is selected from modified silica modified by a silane coupling agent or a hydroxy silicone oil; preferably, the silane coupling agent is selected from any one of KH550, KH570, and KH151; the hydroxy silicone oil is selected from any one of 203 hydroxy silicone oil and 209 hydroxy silicone oil; And / or, the particle size of the silicon dioxide is 50 μm to 200 μm.

5. The method for preparing the plugging agent according to any one of claims 1 to 4, characterized in that: The steps include: 1) Mixing oligomer monomers, curing agent, initiator, silicon dioxide and foaming agent to obtain a premix; 2) Solidifying the premix to obtain the plugging agent.

6. The preparation method according to claim 5, characterized in that: In step 1), during the mixing, the oligomer monomer, curing agent and initiator are first mixed to obtain a mixed solution; preferably, the conditions of the first mixing include: a temperature of 60° C. to 80° C. and a time of 10 min to 30 min; Then the mixed liquid is mixed with silicon dioxide and a foaming agent for a second time to obtain a premix; preferably, the conditions of the second mixing include: a temperature of 30° C. to 60° C. and a time of 10 min to 30 min.

7. The preparation method according to claim 5 or 6, characterized in that: In step 1), before the oligomer monomer, curing agent and initiator are first mixed, the oligomer monomer is vacuum dehydrated at a temperature of 110° C. to 120° C. for 1 h to 3 h; preferably, the vacuum degree of the vacuum dehydration is 60 Pa to 100 Pa.

8. The preparation method according to any one of claims 5 to 7, characterized in that: In step 2), the curing conditions include: temperature of 120° C. to 140° C. and time of 0.5 h to 5 h.

9. The preparation method according to any one of claims 5 to 8, characterized in that: In step 2), the solidification further includes granulation; And / or, the particle size of the plugging agent is 10 mesh to 40 mesh.

10. Use of the plugging agent according to any one of claims 1 to 4 or the plugging agent prepared by the preparation method according to any one of claims 5 to 9 in plugging cracks and / or pores in a wellbore wall.

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