High-density high-temperature-resistant zwitterionic gel temporary plugging particle and preparation method thereof
By preparing the temporary blocking particles of high-density high-temperature zwitterionic gels, the problems of poor temperature resistance and reservoir damage during perforation completion of high-temperature and high-pressure wells are solved, and efficient absorption of high-density saline and safe reflow are achieved, which improves the success rate of well completion.
Patent Information
- Application Number
- CN202510804388.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-17
- Publication Date
- 2025-08-19
AI Technical Summary
During the perforation completion process of existing high-temperature and high-pressure wells, conventional pre-crosslinked temporarily blocked particles have poor temperature resistance and are difficult to absorb high-density saline, resulting in reservoir damage and difficulty in reflux, affecting the success rate of well completion.
Using cationic monomers, anionic monomers and high-temperature resistant crosslinking agents with a specific mass ratio, high-density high-temperature resistant zwitterionic gel temporary blocking particles are prepared. By crosslinking the cationic monomer with anionic monomer, gel temporary blocking particles with a temperature resistance of 160℃ can be formed, which can quickly absorb 1.55g/cm3 potassium formate saline.
It has achieved stable existence under high temperature and high pressure wells, reduced reservoir damage, ensured safe reflow of completion fluid, and improved completion success rate.
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Figure CN120505081A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of oilfield chemistry, in particular to high-density, high-temperature-resistant zwitterionic gel temporary plugging particles. Background Art
[0002] High-density, high-temperature-resistant pre-crosslinked temporary plugging particles are a current research hotspot. They not only offer strong pressure-bearing capabilities but also enable smooth flowback, avoiding reservoir damage and flowback difficulties caused by in-situ crosslinked temporary plugging fluids, thereby increasing well completion success rates. Currently, conventional pre-crosslinked temporary plugging particles are typically crosslinked with conventional acrylic acid, acrylamide, and N,N-methylenebisacrylamide (MBA). These particles have poor temperature resistance and are unable to absorb high-density brine, making them difficult to meet the temporary plugging requirements of high-temperature, high-pressure perforation completion operations in wells. Summary of the Invention
[0003] In view of the problems existing in the prior art, the present invention provides a high-density, high-temperature resistant zwitterionic gel temporary plugging particle. By adopting a specific mass ratio of cationic monomers, anionic monomers and high-temperature resistant crosslinking agents, a high-density, high-temperature resistant zwitterionic gel temporary plugging particle with a temperature resistance of 160°C and an absorption density of 1.55g / cm 3 The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles of potassium formate brine can solve the problem of completion fluid loss during the perforation completion of high-temperature and high-pressure wells and reduce reservoir damage.
[0004] To achieve this object, the present invention adopts the following technical solutions:
[0005] In a first aspect, the present invention provides high-density, high-temperature-resistant zwitterionic gel temporary plugging particles. The raw materials constituting the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles include, by mass percentage, 5% to 10% sodium carboxymethylcellulose (CMC) (relative to the mass of acrylic acid, the same below). The particles also include 5wt% to 10wt% of a cationic monomer, wherein the cationic monomer is one or more combinations of acryloyloxyethyltrimethylammonium chloride (DAC) and dimethyldiallylammonium chloride (DADMAC). The particles also include 0.1wt% to 1wt% of a cross-linking agent, wherein the cross-linking agent is tetraallylammonium chloride (TAAC). A certain mass of acrylic acid (neutralization degree 80% to 90%), wherein the anionic monomer is provided by a neutralized acrylate, and the raw material used for neutralization is a sodium hydroxide solution or a potassium hydroxide solution. 10wt% to 30wt% of a temperature-resistant monomer, wherein the temperature-resistant monomer is 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 5wt% to 10wt% of acrylamide, and 0.5wt% to 1wt% of an initiator, wherein the initiator is one or more combinations of potassium persulfate (KPS) and ammonium persulfate (APS).
[0006] The preparation method of the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles disclosed herein comprises: adding a certain amount of sodium carboxymethylcellulose (CMC) and an appropriate amount of distilled water to a flask, heating to 60°C and stirring to dissolve the sodium carboxymethylcellulose; adding a certain amount of deionized water to a beaker, adding an initiator and stirring until dissolved, then pouring the initiator into the upper flask for activation; adding a certain amount of deionized water to a clean beaker, adding sodium hydroxide, and stirring in an ice-water bath until completely dissolved to obtain a sodium hydroxide solution; weighing a certain amount of acrylic acid and adding it dropwise to the sodium hydroxide solution using a dropper to achieve a desired degree of neutralization of the acrylic acid to obtain an anionic monomer solution; then, weighing a certain amount of a temperature-resistant monomer, acrylamide, a cationic monomer, and a crosslinker in a beaker, adding a certain amount of deionized water, and stirring until completely dissolved to obtain a composite solution; finally, adding the acrylic acid solution and the composite solution to the activation solution, heating to 70°C while stirring, and reacting for 3 hours. After the reaction is complete, the gel in the flask is removed, shredded, and rinsed with deionized water at least three times to remove unreacted monomers. The cleaned gel is placed in a constant temperature oven at 85°C for 12 hours and finally ground into 40-60 meshes to obtain the desired high-density, high-temperature resistant zwitterionic gel temporary plugging particles.
[0007] Notes: ① To increase the reaction rate and yield, use a stirrer to stir the solution thoroughly to ensure uniform concentration throughout the reaction. ② To prevent oxidation of the reactants by oxygen in the air, maintain a constant flow of nitrogen through the system. ③ To allow the reaction system to communicate with the outside world, remove nitrogen, and retain low-boiling-point reactants, install a reflux condenser on the flask.
[0008] The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles finally obtained in the present invention need to be mixed with completion brine and swelled to form solidified water particles with a certain shape and mechanical properties to play a role. The solidified water particles enter the wellbore blasthole with the completion fluid and then accumulate at the blasthole to reduce the loss of brine to the formation.
[0009] The raw materials of the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles of the present invention include 5% to 10% sodium carboxymethyl cellulose (CMC), for example, 5%, 6%, 7%, 8%, 9% or 10%, etc., but are not limited to the listed values. Other values not listed within the numerical range are also applicable.
[0010] 5 wt% to 10 wt% of the cationic monomer, for example, 5%, 6%, 7%, 8%, 9% or 10%, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable;
[0011] 0.1 wt% to 1 wt% of the crosslinking agent may be, for example, 0.1%, 0.6%, 0.7%, 0.8%, 0.9%, 0.95% or 1%, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable.
[0012] Acrylic acid with a neutralization degree of 80% to 90% may be, for example, 80%, 84%, 86%, 88% or 90%, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable.
[0013] 10 wt% to 30 wt% of the temperature-resistant monomer may be, for example, 10%, 20%, 25% or 30%, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable.
[0014] 5 wt% to 10 wt% acrylamide may be, for example, 5%, 6%, 7%, 8%, 9% or 10%, etc., but is not limited to the listed values, and other values not listed within the numerical range are also applicable.
[0015] 0.5 wt% to 1 wt% initiator, for example, can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 0.95% or 1%, etc., but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0016] In the present invention, when the mass percentage of sodium carboxymethyl cellulose is preferably between 5% and 10%, the high-density, high-temperature resistant zwitterionic gel temporary plugging particles have good temperature resistance and mechanical properties. When the mass percentage is higher than this, the network structure complexity of the gel temporary plugging particles will increase, resulting in a decrease in the salt water absorption performance. When the mass percentage is lower than this, the network structure of the gel temporary plugging particles will increase, the particle strength will decrease, and it will be difficult to use it for high-strength pressure bearing.
[0017] Preferably, the cationic monomer includes one or more combinations of acryloyloxyethyltrimethylammonium chloride (DAC) and dimethyldiallyl ammonium chloride (DADMAC). Since the two monomers have the same cationic content, different ratios of the two monomer substances will not significantly affect the positive charge density of the gel temporary plugging particle network. However, due to the different intramolecular functional groups (double bonds and lipid bonds), different ratios of the two monomers will affect the mechanical properties of the gel temporary plugging particles.
[0018] Preferably, the anionic monomer is provided by neutralized acrylic acid, and the acrylic acid is neutralized by sodium hydroxide solution or potassium hydroxide solution. The mass fraction of the anion is determined by the neutralization degree of acrylic acid. The greater the neutralization degree, the greater the anion mass fraction.
[0019] Preferably, the initiator is one or more combinations of potassium persulfate (KPS) and ammonium persulfate (APS). Different ratios of the two initiator combinations will result in different amounts of substances under the same initiator mass, which will ultimately affect the polymerization effect. When the initiator mass fraction is too high, the polymerization rate will be accelerated, resulting in an incomplete gel network structure, and ultimately reducing the water absorption and temperature resistance.
[0020] The high-density, high-temperature resistant zwitterionic gel temporary plugging particles of the present invention have high-temperature resistance and salt water absorption performance, and are applied to the completion and testing process of high-temperature wells to ensure safe, accurate and efficient operations. The water absorption performance of the pre-crosslinked particles is mainly related to the ionic strength of the salt water. After absorbing water, the ions on the gel network are hydrolyzed and enter the interior of the network to form free hydrated ions, so that a certain salt concentration difference is formed inside and outside the network, generating osmotic pressure. Driven by the osmotic pressure, external free water continuously enters the gel network to cause it to swell. According to Flory's law of water absorption, the increase in the internal fixed charge and hydrophilicity of the unexpanded gel network structure can enhance the water absorption performance. The present invention improves the internal fixed charge of the gel network and the hydrophilicity of the polymer through cross-linking polymerization of cationic monomers and anionic monomers, thereby improving the salt water absorption performance. In addition, the temperature-resistant crosslinking agent is used to increase the complexity of the cross-linked polymer network and improve the temperature resistance.
[0021] Compared with the prior art, the present invention has at least the following beneficial effects:
[0022] The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles provided by the present invention have good high-temperature stability, can quickly absorb high-density saline and form high-density gel temporary plugging particles, and are suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 Example 1: Performance diagram of high-density, high-temperature-resistant zwitterionic gel temporary plugging particles absorbing salt water
[0024] Figure 2 Example 1 High-density high-temperature resistant zwitterionic gel temporary plugging particles heat resistance performance diagram
[0025] Figure 3 Example 2 High-density high-temperature resistant zwitterionic gel temporary plugging particles absorbing salt water performance diagram
[0026] Figure 4 Example 2 High-density high-temperature resistant zwitterionic gel temporary plugging particles temperature resistance performance diagram
[0027] Figure 5 Example 3: Performance diagram of high-density, high-temperature-resistant zwitterionic gel temporary plugging particles absorbing salt water
[0028] Figure 6 Example 4: Performance of high-density, high-temperature-resistant zwitterionic gel temporary plugging particles absorbing salt water
[0029] Figure 7 Example 4 High-density high-temperature resistant zwitterionic gel temporary plugging particles heat resistance performance diagram
[0030] Figure 8 Example 5: Performance diagram of high-density, high-temperature-resistant zwitterionic gel temporary plugging particles absorbing salt water
[0031] Figure 9 Example 5 High-density high-temperature resistant zwitterionic gel temporary plugging particles temperature resistance performance diagram DETAILED DESCRIPTION
[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.
[0033] The present invention is further described in detail below. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.
[0034] In the following examples and comparative examples, all raw materials used are commercially available products, and all methods used are conventional methods in the art.
[0035] The high temperature resistance and salt water absorption rate and performance test methods of the high-density high temperature resistant zwitterionic gel temporary plugging particles in the following examples and comparative examples include:
[0036] Weigh a certain amount of product into a beaker, then add excess high-density saline into the beaker. After a period of time, the product will absorb the liquid completely.
[0037] Pour the mixture in the beaker into a 120-mesh sieve and let it sit for 30 minutes. Finally, weigh the filtered gel using an electronic balance and calculate the gel's liquid absorption performance using the following formula.
[0038] Q s =(M1-M0) / M0
[0039] Where:
[0040] Q s ———Brine solution absorption rate, g / g. The larger the rate, the better the salt solution absorption performance;
[0041] M1——The mass of solidified water temporarily blocked particles when they completely absorb the salt solution, g;
[0042] M0——dry weight of solidified water temporary blocking particles, g;
[0043] In the following examples, the temperature resistance was measured using the following method:
[0044] After saturation, solidified water particles are filtered and weighed, and the solid phase mass is recorded as m0. Then, the solidified water particles are mixed with high-density brine and poured into an aging tank. The aging tank is placed in a high-temperature constant temperature oven for aging. The aging tank is opened every other day, filtered and re-weighed, and recorded as m1, m2...m i , the curing water mass retention rate is calculated by the following formula to evaluate its temperature resistance:
[0045] F=m i / m0*100%
[0046] Among them, F represents the quality retention rate of the curing water after aging, with a maximum value of 100%. For the same aging time, the larger the F value, the better the temperature resistance of the curing water.
[0047] Example 1
[0048] This embodiment provides a raw material ratio and preparation method for high-density, high-temperature resistant zwitterionic gel temporary plugging particles. In terms of mass percentage, the raw materials of the high-density, high-temperature resistant zwitterionic gel temporary plugging particles include: 10% sodium carboxymethylcellulose (CMC) (relative to the mass of acrylic acid, the same below). It also includes 10wt% of a cationic monomer, including 5wt% of acryloyloxyethyltrimethylammonium chloride (DAC) and 5wt% of dimethyldiallylammonium chloride (DADMAC). 0.5wt% of a cross-linking agent, 10g of acrylic acid (neutralization degree 80%), and 4.44g of sodium hydroxide used for neutralization. 30wt% of a temperature-resistant monomer, 10wt% of acrylamide, and 0.5wt% of an initiator, wherein the initiator is potassium persulfate (KPS).
[0049] This embodiment also provides a method for preparing the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles, the preparation method comprising:
[0050] Add 1g of sodium carboxymethyl cellulose (CMC) and an appropriate amount of distilled water to a flask, heat to 60°C and stir to dissolve the sodium carboxymethyl cellulose to obtain a sodium carboxymethyl cellulose solution; take a certain amount of deionized water to a beaker, add 0.05g of initiator and stir until dissolved, then pour it into the sodium carboxymethyl cellulose solution to activate it; take a certain amount of deionized water to a clean beaker, add 4.44g of sodium hydroxide and stir under an ice water bath to completely dissolve it to obtain a sodium hydroxide solution, weigh 10g of acrylic acid and add it dropwise to the hydrogen using a dropper. An anionic monomer solution is prepared by adding a sodium oxide solution to the desired degree of neutralization of acrylic acid. Next, 3g of a heat-resistant monomer, 1g of acrylamide, a cationic monomer (0.5g of acryloyloxyethyltrimethylammonium chloride (DAC) and 0.5g of dimethyldiallyl ammonium chloride (DADMAC)), and 0.05g of a crosslinker are weighed sequentially into a beaker, added with a predetermined amount of deionized water, and stirred until completely dissolved to obtain a composite solution. Finally, the acrylic acid solution and composite solution are added to the activation solution and heated to 70°C while stirring for 3 hours. After the reaction, the gel in the flask is removed, shredded, and rinsed with deionized water three or more times to remove unreacted monomers. The rinsed gel is placed in an 85°C oven for 12 hours and finally ground to a 40-60 mesh size to produce the desired high-density, heat-resistant zwitterionic gel temporary plugging particles.
[0051] In this embodiment, the mass of brine absorbed by the high-density high-temperature resistant zwitterionic gel temporary plugging particles in 24 hours is 29.11 g / g. Figure 1 As shown in Figure 2, after aging at 160 °C for 10 days, the mass retention rate is 98.12%. Figure 2 As shown, the particles are complete in shape and have a certain elasticity.
[0052] Example 2
[0053] This embodiment provides high-density, high-temperature-resistant zwitterionic gel temporary plugging particles. The raw materials of the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles, measured in percentage by mass, include: 10% sodium carboxymethylcellulose (CMC) (relative to the mass of acrylic acid, the same below). It also includes 5wt% of a cationic monomer, including 5wt% of acryloyloxyethyltrimethylammonium chloride (DAC) and 0wt% of dimethyldiallylammonium chloride (DADMAC). It also includes 1wt% of a cross-linking agent, 10g of acrylic acid (neutralization degree 80%), and 4.44g of sodium hydroxide used for neutralization. It also includes 30wt% of a temperature-resistant monomer, 10wt% of acrylamide, and 0.5wt% of an initiator, wherein the initiator is potassium persulfate (KPS).
[0054] The preparation method of the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles in this embodiment is the same as that in Example 1 and will not be further described.
[0055] In this embodiment, the mass of brine absorbed by the high-density high-temperature resistant zwitterionic gel temporary plugging particles in 24 hours is 21.30 g / g. Figure 3 As shown in Figure 2, after aging at 160 °C for 10 days, the mass retention rate is 98.92%. Figure 4 As shown, the particles are complete in shape and have a certain elasticity.
[0056] Example 3
[0057] The present embodiment provides a high-density, high-temperature resistant zwitterionic gel temporary plugging particles. In terms of mass percentage, the raw materials constituting the high-density, high-temperature resistant zwitterionic gel temporary plugging particles include: 10% sodium carboxymethylcellulose (CMC) (relative to the mass of acrylic acid, the same below). It also includes 5wt% of dimethyldiallylammonium chloride (DADMAC). 0.1wt% of a cross-linking agent, 10g of acrylic acid (neutralization degree 80%), and 4.44g of sodium hydroxide used for neutralization. 30wt% of a temperature-resistant monomer, 10wt% of acrylamide, and 0.5wt% of an initiator, wherein the initiator is potassium persulfate (KPS). The preparation method of the high-density, high-temperature resistant zwitterionic gel temporary plugging particles in this embodiment is the same as that in Example 1 and will not be described further.
[0058] The preparation method of the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles in this embodiment is the same as that in Example 1 and will not be further described.
[0059] In this embodiment, the mass of brine absorbed by the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles in 24 hours is 25.30 g / g. Figure 5 As shown, however, during further swelling, the particles began to dissolve, the particle edges became irregular, and they lost a certain degree of elasticity. The temperature resistance of these particles was not further evaluated. The reason for the dissolution may be that the cross-linking agent concentration is too low, the degree of cross-linking is low, and a complete gel network structure cannot be formed, allowing the long hydrophilic polymer chains to dissolve in the saline.
[0060] Example 4
[0061] The present embodiment provides a raw material ratio and preparation method for high-density, high-temperature resistant zwitterionic gel temporary plugging particles. In terms of mass percentage, the raw materials of the high-density, high-temperature resistant zwitterionic gel temporary plugging particles include: 10% sodium carboxymethyl cellulose (CMC) (relative to the mass of acrylic acid, the same below). It also includes 10wt% of cationic monomers, including 5wt% of acryloyloxyethyltrimethylammonium chloride (DAC) and 5wt% of dimethyldiallylammonium chloride (DADMAC). 0.5wt% of cross-linking agent, 10g of acrylic acid (neutralization degree 80%), and 4.44g of sodium hydroxide used for neutralization. 10wt% of temperature-resistant monomer, 5wt% of acrylamide, and 0.5wt% of initiator, which is a composite initiator of potassium persulfate (KPS) and ammonium persulfate (APS).
[0062] The preparation method of the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles in this embodiment is the same as that in Example 1 and will not be further described.
[0063] In this embodiment, the mass of brine absorbed by the high-density high-temperature resistant zwitterionic gel temporary plugging particles in 24 hours is 26.30 g / g. Figure 6 As shown in Figure 2, after aging at 160 °C for 10 days, the mass retention rate is 90.13%. Figure 7 As shown, the particle shape is complete but has no elasticity. This may be because the temperature resistance of the temporary blocking particles decreases after the mass fraction of the temperature-resistant monomer and the acrylamide monomer in this embodiment is reduced, resulting in a decrease in mass after aging and the destruction of the network structure, resulting in a loss of elasticity.
[0064] Example 5
[0065] This embodiment provides a raw material ratio and preparation method for high-density, high-temperature resistant zwitterionic gel temporary plugging particles. In terms of mass percentage, the raw materials of the high-density, high-temperature resistant zwitterionic gel temporary plugging particles include: 10% sodium carboxymethylcellulose (CMC) (relative to the mass of acrylic acid, the same below). It also includes 10wt% of a cationic monomer, including 5wt% of acryloyloxyethyltrimethylammonium chloride (DAC) and 5wt% of dimethyldiallyl ammonium chloride (DADMAC). 0.5wt% of a cross-linking agent, 10g of acrylic acid (neutralization degree 80%), and 4.44g of sodium hydroxide used for neutralization. 30wt% of a temperature-resistant monomer, 10wt% of acrylamide, and 1wt% of an initiator, wherein the initiator is potassium persulfate (KPS).
[0066] The preparation method of the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles in this embodiment is the same as that in Example 1 and will not be further described.
[0067] In this embodiment, the mass of brine absorbed by the high-density high-temperature resistant zwitterionic gel temporary plugging particles in 24 hours is 18.30 g / g. Figure 8 As shown in Figure 2, after aging at 160 °C for 10 days, the mass retention rate is 91.56%. Figure 9 As shown, the particle shape is complete but an opaque area appears in the center. The strength is very hard and there is no elasticity. This may be because the increase in the mass fraction of the initiator in this embodiment causes the polymerization process rate to be too fast, and a regular network structure cannot be constructed, resulting in a decrease in the salt water absorption performance. The opaque area after absorbing salt water is the area that failed to absorb the salt water and expand.
[0068] In summary, the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles provided by the present invention have good salt water absorption performance and high-temperature stability, can work for a long time in high-temperature and high-pressure wells, ensure the safe completion of well completion operations, and have broad prospects for large-scale promotion and application.
[0069] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.
Claims
1. A high-density, high-temperature-resistant zwitterionic gel temporary plugging particle and a preparation method thereof, characterized in that: In terms of mass percentage, the raw materials of the high-density, high-temperature resistant zwitterionic gel temporary plugging particles include 5% to 10% sodium carboxymethyl cellulose (CMC) (relative to the mass of acrylic acid, the same below); 5wt% to 10wt% of a cationic monomer, which is one or more combinations of acryloyloxyethyltrimethylammonium chloride (DAC) and dimethyldiallyl ammonium chloride (DADMAC); 0.1wt% to 1wt% of a cross-linking agent, which is tetraallyl ammonium chloride (TAAC); a certain mass of acrylic acid (neutralization degree 80% to 90%), the anionic monomer is provided by the neutralized acrylate, and the raw material used for neutralization is sodium hydroxide solution or potassium hydroxide solution; 10wt% to 30wt% of a temperature-resistant monomer, which is 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 5wt% to 10wt% of acrylamide, and 0.5wt% to 1wt% of an initiator, which is one or more combinations of potassium persulfate (KPS) and ammonium persulfate (APS).
2. The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles according to claim 1, characterized in that: Measured in percentage by mass, the raw materials of the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles include 5% to 10% sodium carboxymethyl cellulose (CMC), 5wt% to 10wt% of a cationic monomer, 0.1wt% to 1wt% of a cross-linking agent, a certain mass of acrylic acid (neutralization degree 80% to 90%), 10wt% to 30wt% of a temperature-resistant monomer, 5wt% to 10wt% of acrylamide and 0.5wt% to 1wt% of an initiator.
3. The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles according to claim 1 or 2, characterized in that: The cationic monomer is one or more combinations of acryloyloxyethyltrimethylammonium chloride (DAC) and dimethyldiallyl ammonium chloride (DADMAC).
4. The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles according to any one of claims 1 to 3, characterized in that: The cationic monomer comprises a positively charged ammonium salt ion and one or two olefinic double bond groups.
5. The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles according to any one of claims 1 to 4, characterized in that: The anionic monomer is provided by the carboxyl group of the neutralized acrylate, and the mass fraction of the anion is determined by the neutralization degree of acrylic acid. The greater the neutralization degree, the greater the anion mass fraction.
6. The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles according to any one of claims 1 to 5, characterized in that: The cross-linking agent is tetraallyl ammonium chloride (TAAC), which is cross-linked with the monomer main chain through four double bonds, thereby increasing the temperature resistance and strength of the temporary plugging particles. At the same time, its molecule contains a positively charged ammonium salt ion, which can effectively increase the positive charge inside the gel network.
7. The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles according to any one of claims 1 to 6, characterized in that: The maximum operating temperature of the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles is 160°C.
8. The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles according to any one of claims 1 to 7, characterized in that: The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles can absorb saline and have a maximum density of 1.55 g / cm 3 Potassium formate saturated brine.
9. The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles according to any one of claims 1 to 8, characterized in that: The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles have a solid phase mass remaining of 98% after aging at 160° C. for 10 days, and have good strength and elasticity.
10. Use of the high-density, high-temperature-resistant zwitterionic gel temporary plugging particles according to any one of claims 1 to 9, characterized in that: The high-density, high-temperature-resistant zwitterionic gel temporary plugging particles are used in the temporary plugging process of perforation in high-temperature and high-pressure well completions.