Taraxacum bionic self-suspension self-repair pressure differential activated plugging agent and preparation method thereof

Abstract

The application discloses a dandelion biomimetic self-suspension self-repair pressure differential activated plugging agent and a preparation method, and belongs to the technical field of oil and gas well sealing. The dandelion biomimetic self-suspension self-repair pressure differential activated plugging agent comprises the following components: a high-molecular non-crosslinking polymer, deionized water, an activator, a defoaming agent, a terminator, a self-repair fiber forming agent and a self-suspension bridging fiber core. The application is based on the principle that dandelions can efficiently float in fluid, and the surface of the high-molecular non-crosslinking polymer attached to the high-strength fiber matrix core is dynamically crosslinked by metal cations to generate a fiber filament structure with a self-repair surface, thereby significantly improving the self-suspension capability of the pressure differential activated plugging agent. Meanwhile, the ion crosslinking bonds on the surface constructed by the self-repair fiber forming agent further improve the plugging strength and self-repair capability, and the plugging agent can be applied to plugging conditions with higher pressure differentials of leakage points.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well sealing technology, specifically to a dandelion-inspired self-suspending and self-healing differential pressure activation and plugging agent and its preparation method. Background Technology

[0002] Approximately 10% of operating wells in my country's offshore oil and gas fields suffer from wellbore integrity issues, primarily due to dynamic / static seal failure and cement sheath damage. Of these, 42% of wellbore integrity problems manifest as annular pressure caused by seal damage, and 20% of these pressured wells are high-risk, posing serious safety hazards and significant threats to production safety. Currently, repair technologies for annular pressure issues mainly include traditional mechanical repair and injection repair. However, these technologies generally suffer from complex construction, long operation cycles, high costs, high risks, low migration success rates, and difficulty in completely eliminating subsequent impacts, failing to meet the need for rapid and safe elimination of annular pressure in offshore oil and gas wells. With the increasing prominence of annular pressure issues in offshore oil and gas production wells, there is an urgent need to develop differential pressure plugging agents suitable for rapid plugging of downhole tubing, based on the characteristics of seal damage in production wells, and to establish a technical system suitable for rapid seal repair in my country's offshore oil and gas wells. The establishment of this technical system can provide technical support for well workover operations, safe production, and wellbore integrity management. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a dandelion-inspired, self-sustaining, self-healing differential pressure-activated plugging agent and its preparation method, thereby improving the plugging strength and airtightness of the plugging agent.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a dandelion biomimetic self-suspending self-healing pressure difference activation and sealing agent is provided, comprising the following components in parts by weight: 30-60 parts of high molecular weight non-crosslinked polymer, 100-200 parts of deionized water, 10-20 parts of activator, 10-15 parts of defoamer, 80-100 parts of terminator, 10-30 parts of self-healing fiber forming agent and 10-20 parts of self-suspending bridging fiber core;

[0005] The self-healing fiber forming agent is a metal cation solution; the self-suspended bridging fiber core is polyarylene ether nitrile; and the high-molecular non-crosslinked polymer is at least one of carboxyl-functionalized polysiloxane, polyacrylic acid and its copolymers, carboxylic acid polyurethane ionomer, styrene-acrylic acid copolymer and acrylic acid-acrylamide copolymer.

[0006] Furthermore, the dandelion biomimetic self-suspending self-healing pressure difference activation and sealing agent comprises the following components in parts by weight: 60 parts of high molecular weight non-crosslinked polymer, 200 parts of deionized water, 20 parts of activator, 15 parts of defoamer, 100 parts of terminator, 30 parts of self-healing fiber forming agent and 20 parts of self-suspending bridging fiber core.

[0007] Furthermore, the activator is an inorganic salt solution; the inorganic salt solution is sodium chloride, magnesium chloride, or copper chloride.

[0008] Furthermore, the defoamer is an organosilicone defoamer.

[0009] Furthermore, the terminator is a surfactant; the surfactant can be anionic, cationic, or nonionic.

[0010] Furthermore, the metal cation solution is an AlCl3 solution or a CrCl3 solution.

[0011] This invention provides a method for preparing the above-mentioned dandelion-inspired self-suspending self-healing differential pressure activation and sealing agent, comprising the following steps:

[0012] (1) Mix the non-crosslinked polymer, the self-suspended bridging fiber core and deionized water evenly to make a diluent;

[0013] (2) At 50-90℃, the activator is added dropwise to the diluted solution in step (1) while stirring, then the defoamer is added, stirring is stopped, and the reaction is carried out for 20 minutes to obtain an emulsion with micron-sized to millimeter-sized particles.

[0014] (3) While stirring, add the terminator to the emulsion obtained in step (2), then add the self-healing fiber forming agent, mix well, and obtain the product.

[0015] The present invention has the following beneficial effects:

[0016] (1) The differential pressure activation plugging agent provided by this invention only plugs leaks at points where there is a pressure difference in the tubing. During normal flow and storage, it maintains normal flow by mimicking dandelion seeds. After sealing, excess differential pressure plugging agent colloid can be returned to the surface. While achieving the plugging effect, it avoids clogging or damaging precision components downhole.

[0017] (2) The differential pressure activated plugging agent provided by this invention has the advantages of fast plugging speed, convenient construction, low cost, and high plugging strength. The metal cations cause dynamic cross-linking on the surface of the plugging particles, further enhancing the plugging strength of the entire system.

[0018] (3) The self-suspended bridging fiber core in the plugging agent of this invention serves as the core component of dandelion biomimetic, improving self-suspension performance and transportability. In addition, the high-strength fiber plays a bridging role, which can enhance the plugging strength and the friction and bridging effect between the plugging agent and itself. The non-crosslinked polymer emulsion serves as the main component of the outer surface of the plugging agent, achieving the effect of pressure difference activation sealing. The activator can cause the non-crosslinked polymer to demulsify and agglomerate on the fiber, forming an appropriate morphology and size. The defoamer is used to stabilize the system and prevent foaming during activation. The terminator is used to stop the growth of the non-crosslinked polymer particles and terminate the entire reaction. The self-healing fiber forming agent is used to form a self-healing metal crosslinking bond on the surface of the non-crosslinked polymer, enabling the plugging particles to self-heal under pressure.

[0019] (4) Synergistic effect among components: The self-suspended bridging fiber core provides the plugging particles with a high-strength fiber core, enabling them to have high underwater transport capability. In addition, the self-suspended bridging fiber core, with its ultra-high friction resistance and tensile strength of polyarylene ether nitrile, plays a bridging role to enhance the plugging strength and the friction and bridging effect between the plugging agent and itself. The non-crosslinked polymer begins to grow and enlarge under the action of the activator, adsorbing onto the self-suspended bridging fiber core. When the size reaches the required size, a terminator is added to stop the growth of the non-crosslinked polymer particles. Afterward, the non-crosslinked polymer plugging particles undergo metal ion crosslinking through the self-healing fiber forming agent to create a dandelion-inspired villous surface, transforming the non-crosslinked polymer particles from the molecular level into a three-dimensional network elastic structure, enhancing the mechanical properties and elasticity of the non-crosslinked polymer particles. In addition, the metal ion crosslinking network provided by the self-healing fiber forming agent brings self-healing properties to the plugging agent particles, enabling the plugging particles to self-heal after contact with each other under pressure, further enhancing the plugging strength and airtightness. Attached Figure Description

[0020] Figure 1 The dandelion-inspired self-suspending and self-healing differential pressure activation and sealing agent prepared in Example 1;

[0021] Figure 2 This is a scanning electron microscope image of the dandelion biomimetic self-suspending self-healing pressure difference activated plugging agent prepared in Example 1;

[0022] Figure 3 This is an optical microscope image of the dandelion biomimetic self-suspended self-healing pressure difference activated sealing agent fluid prepared in Example 1;

[0023] Figure 4 The test curves of the dandelion biomimetic self-suspending self-healing pressure difference activated plugging agent prepared in Example 1 are shown for plugging strength at 0.5 mm and 1 mm.

[0024] Figure 5The pressure differential activated plugging agent prepared in Comparative Example 1 is shown in the plugging strength test curves for 0.5 mm and 1 mm.

[0025] Figure 6 The pressure differential activated plugging agent prepared in Comparative Example 2 is shown in the plugging strength test curves for 0.5 mm and 1 mm.

[0026] Figure 7 The diagram shows the self-healing effect of the sealing agents prepared in Example 1 and Comparative Examples 1-2. Detailed Implementation

[0027] The examples given below are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified, conditions in the examples are performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0028] Example 1:

[0029] A dandelion-inspired, self-sustaining, self-healing pressure differential activation and sealing agent comprises the following components in parts by weight: 60 parts styrene-acrylic acid copolymer (Beijing Bailingwei Technology Co., Ltd., catalog number: P5917-SAA), 200 parts deionized water, 20 parts 20 wt% magnesium chloride activator, 15 parts organosilicon defoamer (Beijing Boning Biotechnology Co., Ltd.), 100 parts 20 wt% sodium dodecylbenzenesulfonate emulsifier, 30 parts 20 wt% chromium chloride solution, and 20 parts polyarylene ether nitrile (Beijing Inokai Technology Co., Ltd., catalog number: 3300281B).

[0030] The preparation method includes the following steps: 60 parts of styrene-acrylic acid copolymer, 20 parts of polyarylene ether nitrile, and 90 parts of deionized water are stirred evenly to form a diluent; at 80°C, the stirrer speed is controlled at 800 r / min, and 20 parts of 20wt% magnesium chloride activator are added dropwise to the diluent, followed by 15 parts of organosilicon defoamer. The stirring is then stopped for 20 min to obtain an emulsion with micron-sized particles; while stirring, 100 parts of 20wt% sodium dodecylbenzenesulfonate emulsifier are added, and after stirring for 15 min, 30 parts of 20wt% chromium chloride solution are added to obtain the dandelion biomimetic self-suspending self-healing differential pressure activation and sealing agent (see...). Figure 1 ).

[0031] Example 2:

[0032] A dandelion-inspired, self-sustaining, self-healing pressure differential activation and sealing agent comprises the following components in parts by weight: 30 parts of carboxyl-functionalized polysiloxane (carboxyl-functionalized polysiloxane, Hubei Xinyuhong Biomedical Technology Co., Ltd., catalog number: 68554-71-2), 100 parts of deionized water, 15 parts of 20wt% sodium chloride activator, 15 parts of organosilicon defoamer (Beijing Boning Biotechnology Co., Ltd.), 80 parts of 20wt% sodium dodecylbenzenesulfonate emulsifier, 20 parts of 20wt% AlCl3 solution, and 15 parts of polyarylene ether nitrile (Beijing Inokai Technology Co., Ltd., catalog number: 3300281B).

[0033] The preparation method includes the following steps: 30 parts of carboxyl-functionalized polysiloxane, 15 parts of polyarylene ether nitrile, and 100 parts of deionized water are stirred evenly to prepare a diluent; at 80°C, the stirrer speed is controlled at 800 r / min, and 15 parts of 20wt% sodium chloride activator are added dropwise to the diluent, followed by 15 parts of organosilicon defoamer. The stirring reaction is then stopped for 20 min to obtain an emulsion with micron-sized particles; while stirring, 80 parts of 20wt% sodium dodecylbenzenesulfonate emulsifier are added, and after stirring for 15 min, 20 parts of 20wt% AlCl3 solution are added to prepare the dandelion biomimetic self-suspended self-healing differential pressure activation and sealing agent.

[0034] Example 3:

[0035] A dandelion-inspired, self-sustaining, self-healing differential pressure activation and sealing agent comprises the following components in parts by weight: 60 parts of carboxylic acid polyurethane ionomer (aqueous polyurethane, Maclean, W741922-500g), 200 parts of deionized water, 20 parts of 20wt% copper chloride activator, 15 parts of organosilicon defoamer (Beijing Boning Biotechnology Co., Ltd.), 100 parts of 20wt% sodium dodecylbenzenesulfonate emulsifier, 30 parts of 20wt% CrCl3 solution, and 20 parts of polyarylene ether nitrile (Beijing Inokai Technology Co., Ltd., catalog number: 3300281B).

[0036] The preparation method includes the following steps: 60 parts of carboxylic acid type polyurethane ionomer, 20 parts of polyarylene ether nitrile and 200 parts of deionized water are stirred evenly to prepare a diluent; at 80°C, the stirrer speed is controlled at 800 r / min, 20 parts of 20wt% copper chloride activator are added dropwise to the diluent, and then 15 parts of organosilicon defoamer are added. The stirring reaction is then stopped for 20 min to obtain an emulsion with micron-sized particles; while stirring, 100 parts of 20wt% sodium dodecylbenzenesulfonate emulsifier are added, and after stirring for 15 min, 30 parts of 20wt% CrCl3 solution are added to prepare the dandelion biomimetic self-suspended self-healing differential pressure activation and sealing agent.

[0037] Example 4:

[0038] A dandelion-inspired, self-sustaining, self-healing pressure differential activation and sealing agent comprises the following components in parts by weight: 60 parts acrylic acid-acrylamide copolymer (polyacrylic acid-acrylamide, Beijing Innocare Technology Co., Ltd.), 200 parts deionized water, 20 parts 20 wt% copper chloride activator, 15 parts organosilicon defoamer (Beijing Boning Biotechnology Co., Ltd.), 100 parts 20 wt% sodium dodecylbenzenesulfonate emulsifier, 30 parts 20 wt% CrCl3 solution, and 20 parts polyarylene ether nitrile (Beijing Innocare Technology Co., Ltd., product number: 3300281B).

[0039] The preparation method includes the following steps: 60 parts of acrylic acid-acrylamide copolymer, 20 parts of polyarylene ether nitrile and 200 parts of deionized water are stirred evenly to prepare a diluent; at 80°C, the stirrer speed is controlled at 800 r / min, 20 parts of 20wt% copper chloride activator are added dropwise to the diluent, and then 15 parts of organosilicon defoamer are added. The stirring reaction is then stopped for 20 min to obtain an emulsion with micron-sized particles; while stirring, 100 parts of 20wt% sodium dodecylbenzenesulfonate emulsifier are added, and after stirring for 15 min, 30 parts of 20wt% CrCl3 solution are added to prepare the dandelion biomimetic self-suspended self-healing differential pressure activation and sealing agent.

[0040] Comparative Example 1:

[0041] A self-suspending differential pressure activated plugging agent comprises the following components in parts by weight: 60 parts styrene-acrylic acid copolymer (Beijing Bailingwei Technology Co., Ltd., catalog number: P5917-SAA), 200 parts deionized water, 20 parts 20 wt% magnesium chloride activator, 15 parts silicone defoamer (Beijing Boning Biotechnology Co., Ltd.), 100 parts 20 wt% sodium dodecylbenzenesulfonate emulsifier, and 20 parts polyarylene ether nitrile (Beijing Inokai Technology Co., Ltd., catalog number: 3300281B).

[0042] The preparation method includes the following steps: 60 parts of styrene-acrylic acid copolymer, 20 parts of polyarylene ether nitrile and 90 parts of deionized water are stirred evenly to form a diluent; at 80°C, the stirrer speed is controlled at 800 r / min, 20 parts of 20wt% magnesium chloride activator are added dropwise to the diluent, and then 15 parts of organosilicon defoamer are added. The stirring reaction is then stopped for 20 min to obtain an emulsion with micron-sized particles; while stirring, 100 parts of 20wt% sodium dodecylbenzenesulfonate emulsifier are added to prepare a common differential pressure activated plugging agent.

[0043] Comparative Example 2:

[0044] A self-healing differential pressure activation plugging agent comprises the following components in parts by weight: 60 parts styrene-acrylic acid copolymer (Beijing Bailingwei Technology Co., Ltd., item number: P5917-SAA), 200 parts deionized water, 20 parts 20 wt% magnesium chloride activator, 15 parts silicone defoamer (Beijing Boning Biotechnology Co., Ltd.), 100 parts 20 wt% sodium dodecylbenzenesulfonate emulsifier, and 30 parts 20 wt% chromium chloride solution.

[0045] The preparation method includes the following steps: 60 parts of styrene-acrylic acid copolymer and 200 parts of deionized water are stirred evenly to prepare a diluent; at 80°C, the stirrer speed is controlled at 800 r / min, 20 parts of 20wt% magnesium chloride activator are added dropwise to the diluent, and then 15 parts of organosilicon defoamer are added. The stirring reaction is then stopped for 20 min to obtain an emulsion with micron-sized particles; while stirring, 100 parts of 20wt% sodium dodecylbenzenesulfonate emulsifier are added, and after stirring for 15 min, 30 parts of 20wt% chromium chloride solution are added to prepare a self-healing differential pressure activation and sealing agent.

[0046] Experimental example:

[0047] (1) The plugging agent prepared in Example 1 was characterized by systematic evaluation using scanning electron microscopy (SEM) and optical microscopy.

[0048] Depend on Figure 2 As can be seen, the plugging agent prepared in Example 1 exhibits a dense three-dimensional network structure with a large number of fibrous cross-links. This structural feature is directly related to the dynamic cross-linking bonds formed between the self-suspended bridging fiber core and the surface-adsorbed carboxyl polymer and the self-healing fiber forming agent. The coarser and denser polymer network significantly improves the mechanical properties of the material, and the fibrous structure gives the plugging agent particles extremely strong transport capabilities. Figure 3 The principle of the suspending ability of the dandelion-inspired self-suspending and self-healing pressure difference activated plugging agent was revealed. Its internal plugging unit has a large number of fibrous surface structures, which provide additional steric hindrance to assist particle dispersion during dispersion. Moreover, the dandelion-like structure enables it to have fluid-level transport effect during transport.

[0049] (2) The sealing of microfractures in the downhole tubing was simulated in the laboratory. Using a syringe-type simulation device and an electronic universal testing instrument, the sealing strength of the pressure differential activated sealing agents prepared in Comparative Example 1, Comparative Example 2, and Example 1 was tested at room temperature for pores with a diameter of 1 mm. A hydraulic press drove the push rod downwards at a rate of 10 mm / min, pushing the sealing agent colloid to seal the bottom 0.5 mm or 1 mm pores. Under continuously increasing pressure, it eventually exceeded its ultimate pressure-bearing limit. The area at the point where the push rod connects to the liquid surface was approximately 0.785 cm². 2 .

[0050] The sealing strength was calculated using the pressure-displacement curve obtained from an electronic universal testing instrument, and the results are as follows: Figure 4-6 As shown; where the horizontal axis represents the stroke of the hydraulic press, and the vertical axis represents the pressure applied to the sealing fluid. Figure 4-6 The sealing curves for a 0.5mm orifice show that the dandelion-inspired, self-sustaining, self-healing pressure differential activated sealing agent prepared in Example 1 has a maximum pressure resistance of 22.30 MPa when sealing a 0.5mm diameter orifice, while the maximum pressure resistance of Comparative Example 1 is 16.3 MPa and that of Comparative Example 2 is 13.07 MPa. The overall sealing strength of the sealing agent prepared in Example 1 increased by 37% compared to Comparative Example 1 and by 71% compared to Comparative Example 2. Figure 4-6 The sealing curves for a 1mm orifice show that the dandelion-inspired, self-sustaining, self-healing pressure differential activated sealing agent prepared in Example 1 has a maximum pressure resistance of 8.03 MPa when sealing a 1mm diameter orifice, while the maximum pressure resistance of Comparative Example 1 is 7.6 MPa and that of Comparative Example 2 is 3.14 MPa. The overall sealing strength of the sealing agent prepared in Example 1 increased by 6% compared to Comparative Example 1 and by 156% compared to Comparative Example 2. Furthermore, the hydraulic press travel speed is 0.16 mm / s, which means that this pressure differential activated sealing agent can achieve sealing under relatively small pressure differentials.

[0051] (3) To investigate the self-healing properties of the dandelion-inspired self-suspending self-healing pressure difference activated plugging agents prepared in Example 1, Comparative Example 1, and Comparative Example 2, the morphology of the plugging adhesive nails after plugging was tested at 80°C. Using a syringe-type simulation device and an electronic universal testing instrument, for a pore with a diameter of 0.5 mm, the hydraulic press drove the push rod to press down at a rate of 10 mm / min, pushing the plugging agent colloid to seal the bottom 0.5 mm pore. When the load rose to 1000 N, the pressing was stopped, the leaking component was removed, and the morphology of the plugging adhesive nails was observed.

[0052] Depend on Figure 7 It can be seen that the sample prepared in Example 1 exhibited self-healing at the leak point under a high temperature of 80℃ and a load of 1000N. Compared with other dispersed sealing particles around it, the sealing particles at the leak point agglomerated into a sealed sphere under high temperature and pressure, blocking the leak point. Comparative Example 1 lacked the crucial self-healing fiber molding agent, and therefore could only rely on its own mechanical properties to seal the leak point under high temperature and pressure, unable to self-heal and form a high-quality adhesive nail under high temperature and pressure differential. Although Comparative Example 2 lacked core fibers, it still possessed self-healing properties; therefore, it was observed that the sealing particles agglomerated into a sealed sphere at the leak point under high temperature and pressure.

[0053] (4) This experimental example comprehensively evaluates the fluid properties of the plugging agents prepared in Example 1 and the comparative example, including the density of the plugging unit, fluid density, dispersion stability, and other properties. The plugging agents were sonicated at room temperature for 30 minutes and then subjected to the following tests:

[0054] 1. The density of the plugging unit and the fluid density were determined using a 50mL density bottle. The density of the plugging agent fluid was determined using a 50mL density bottle. The specific steps are as follows: First, weigh the dried density bottle and record the mass. m 1. Next, fill the density bottle with kerosene and record the mass. m 2. Then pour out the kerosene and rinse the dried density bottle. Add the sealing agent fluid into the separatory funnel, align the lower end of the funnel with the dried density bottle, and open the funnel valve to allow the sealing agent fluid to fall freely into the density bottle. During this process, ensure that the density bottle is not shaken. After the density bottle is full of sealing agent, weigh the total weight and record it as follows. m 3. The formula for calculating bulk density is: ρ b =[( m 3- m 1) / ( m 2- m 1)]× ρ 0; where: ρ b To test the bulk density of the plugging agent, g / cm³ 3 ; m 1 represents the mass of the drying density bottle, in grams; m 2 represents the mass of the density bottle after it is filled with kerosene, in grams; m 3 represents the total mass of the density bottle and the sealing agent, in grams; ρ 0 represents the density of kerosene, in g / cm³. 3 .

[0055] The density of the plugging unit particles is determined by filling the voids between the plugging agent with kerosene to obtain the volume of the plugging unit particles. Then, the apparent density of the plugging agent is calculated by dividing the known mass of the plugging unit particles by the volume. The specific steps are as follows: First, weigh out 10 grams of plugging unit particles and record the mass as... m p Next, weigh the dried density bottle and record its mass. m 4. Then pour the kerosene into a 50 ml density bottle (ensuring no air bubbles remain in the bottle during this process), and weigh the total mass of the density bottle and kerosene, recording it as follows: m 5. Next, pour out at least half of the kerosene from the density bottle. Then, align the lower end of the separatory funnel with the mouth of the density bottle and add the spare sealing unit particles. Fill the remaining space in the bottle with kerosene. If air bubbles appear, remove them and fill the bottle with kerosene to the mark. Weigh the total mass. m 6.

[0056] The formula for calculating kerosene density is: ρ 0=( m 5- m 4) / V 密度瓶 ;in, m 4 represents the mass of the dry, empty density bottle, in grams; m 5 represents the mass (in grams) of a density bottle containing kerosene at room temperature. V 密度瓶 The volume of the density bottle is in cm³. 3 .

[0057] The formula for calculating the particle density of the sealing unit is: ρ p =( m p ×ρ 0) / ( m p - m 4- m 6); among which, ρ p The density of the sealing unit particles, in g / cm³ 3 ; m p The dry weight of the sealing unit particles, in grams; m 6 represents the total mass of the sealing unit particles, kerosene, and density bottle, in grams;

[0058] The fluid density and plugging unit particle density of Example 1, Comparative Example 1, and Comparative Example 2 were tested and are shown in Table 1. The fluid density was 1.08 g / cm³. 3 1.05g / cm 3 and 1.07 g / cm 3 The particle density of the plugging unit is 1.04 g / cm³. 3 1.02 g / cm 3 and 1.06 g / cm 3 It can be seen that the particle density of the plugging unit in Example 1 is greater than that in Comparative Example 1 but less than that in Comparative Example 2. This is because the cross-linking of metal cations leads to an increase in the particle density of the plugging unit, and compared to Comparative Example 2, the addition of fibers is not homogeneous, resulting in a larger range for density measurement. The fluid density, however, has little relation to the plugging unit.

[0059] 2. The dispersion stability test only tests the loading and unloading performance of the millimeter-scale large plugging unit, because the dispersion performance of the micron-scale non-crosslinked polymer plugging unit of the plugging capsule is far superior to that of the millimeter-scale non-crosslinked polymer plugging unit. After ultrasonic dispersion, it is added to a 50mL graduated cylinder with a height of 10cm, and the time is recorded after the plugging unit at the highest point has completely settled.

[0060] Table 1. Evaluation of the fluid physicochemical properties of the plugging agents in Example 1 and Comparative Examples 1-2

[0061]

[0062] As shown in Table 1, the density of the plugging agent in Example 1 is greater than that in the comparative example, but its dispersion stability (sedimentation time) is 13 min, which is much higher than that of Comparative Example 1 (1 min) and Comparative Example 2 (6 min). The higher density than Comparative Example 1 is due to the ionic cross-linking bonds increasing the Young's modulus of the dandelion-like structure, enhancing the steric hindrance between particles, and greatly improving its dispersion performance in the fluid. Furthermore, the metal cation solution increases the zeta potential between particles, enhancing the electrostatic repulsion between the plugging particles, further improving the dispersion performance of the dandelion-inspired self-suspending and self-healing pressure difference activated plugging agent. The higher density than Comparative Example 2 is due to the increased specific surface area of ​​the plugging particles caused by the increased fiber core, resulting in greater resistance during sedimentation and thus a longer sedimentation time.

[0063] (5) In order to investigate the long-term pressure-resistant sealing performance of the differential pressure plugging agent, the leakage of the plugging agent after sealing the fluid was tested under a water pressure of 10 MPa using a displacement device.

[0064] The testing apparatus used included a fluid displacement device, a pressure monitoring component, a temperature monitoring component, a leakage simulation component, and a flow rate monitoring component. The device used a horizontal flow pump to displace water into the leakage simulation component, and then inserted a pressure monitoring component to monitor the displacement pressure in real time. The leakage component consisted of a core holder cavity and an outlet leak. The core holder cavity was filled with a sealing agent, and an analytical balance was connected to the leak as a flow rate monitoring component. During operation, the sealing agent was first added to the sealed vessel, the control valve was closed, and the horizontal flow pump was turned on. At this time, the horizontal flow pump displaced water into the core holder cavity, pushing the sealing agent through the leak. The discharged liquid fell onto the analytical balance, and the pressure was provided by the displacement pump, continuously displacing at a constant pressure of 10 MPa. Displacement Examples 1, 1 Comparative Example 1, and 2 simulated micro-fractures using cylinders with a diameter of 0.5 mm and a length of 10 mm, and the cumulative flow rate was recorded after 24 hours. The test results are shown in Table 2.

[0065] Table 2. Cumulative water output of the sealing agent in Example 1 and Comparative Examples 1-2 over 24 hours

[0066]

[0067] As shown in Table 2, Example 1, due to its self-healing and metal adsorption repair properties, showed no leakage within 24 hours. However, Comparative Example 1 lacked the crucial self-healing fiber forming agent, resulting in lower sealing efficiency and an inability to prevent water leakage through self-healing. Comparative Example 2, while improving sealing efficiency due to the addition of a self-healing fiber forming agent and its self-healing function, lacked a self-suspended bridging fiber core, leading to reduced bridging capacity and lower sealing strength. Consequently, more liquid leaked when small sealing particles at weak bridging points were ejected under high pressure.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dandelion-inspired, self-sustaining, self-healing pressure differential activation and sealing agent, characterized in that, It includes the following components in parts by weight: 30-60 parts of non-crosslinked polymer, 100-200 parts of deionized water, 10-20 parts of activator, 10-15 parts of defoamer, 80-100 parts of terminator, 10-30 parts of self-healing fiber forming agent and 10-20 parts of self-suspending bridging fiber core. Wherein, the self-healing fiber forming agent is a metal cation solution; the self-suspended bridging fiber core is polyarylene ether nitrile; and the high molecular non-crosslinked polymer is at least one of carboxyl functionalized polysiloxane, polyacrylic acid and acrylic acid copolymer, and carboxylic acid polyurethane ionomer. The activator is an inorganic salt solution; the inorganic salt solution is sodium chloride, magnesium chloride, or copper chloride. The terminator is a surfactant; the surfactant is an anionic surfactant, a cationic surfactant, or a nonionic surfactant. The metal cation solution is an AlCl3 solution or a CrCl3 solution.

2. The dandelion-inspired self-suspending self-healing pressure difference activation and sealing agent according to claim 1, characterized in that, It comprises the following components in parts by weight: 60 parts non-crosslinked polymer, 200 parts deionized water, 20 parts activator, 15 parts defoamer, 100 parts terminator, 30 parts self-healing fiber forming agent, and 20 parts self-suspending bridging fiber core.

3. The dandelion-inspired biomimetic self-suspending self-healing pressure difference activating and sealing agent according to claim 1 or 2, characterized in that, The polyacrylic acid and acrylic acid copolymer are at least one of styrene-acrylic acid copolymer and acrylic acid-acrylamide copolymer.

4. The dandelion-inspired biomimetic self-suspending self-healing pressure difference activating and sealing agent according to claim 1 or 2, characterized in that, The defoamer is an organosilicone defoamer.

5. The preparation method of the dandelion biomimetic self-suspending self-healing pressure difference activated sealing agent according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Mix the non-crosslinked polymer, the self-suspended bridging fiber core and deionized water evenly to make a diluent; (2) At 50-90℃, the activator is added dropwise to the diluted solution in step (1) while stirring, then the defoamer is added, stirring is stopped, and the reaction is carried out for 20 minutes to obtain an emulsion with micron-sized to millimeter-sized particles. (3) While stirring, add the terminator to the emulsion obtained in step (2), then add the self-healing fiber forming agent, mix well, and obtain the product.

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