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CN-122011435-A - Preparation method and application of PVA reinforced chitosan-based semi-interpenetrating network hydrogel

CN122011435ACN 122011435 ACN122011435 ACN 122011435ACN-122011435-A

Abstract

The invention discloses a preparation method and application of PVA reinforced chitosan-based semi-interpenetrating network hydrogel, and belongs to the technical field of gel temporary plugging agents. The preparation method comprises the steps of mixing a polyvinyl alcohol aqueous solution and an acidic chitosan aqueous solution, adding a cross-linking agent and a pH regulator for pre-crosslinking to obtain primary gel, and placing the primary gel in a reinforcing medium for soaking treatment and then carrying out a crosslinking reaction to obtain the PVA reinforcing chitosan-based semi-interpenetrating network hydrogel with a compact crosslinked network. The gel system can automatically degrade gel breaking without adding gel breaker, is low-viscosity liquid after gel breaking, is easy to flow back, has little damage to the well, and has the characteristics of reservoir protection, environmental protection and the like.

Inventors

  • DU GUANGYAN
  • HUANG JUNTING
  • WANG SHUOSHUO
  • ZHANG YIFEN
  • JIN WENJIE

Assignees

  • 浙江工业大学

Dates

Publication Date
20260512
Application Date
20260409

Claims (9)

  1. 1. The preparation method of the PVA reinforced chitosan-based semi-interpenetrating network hydrogel is characterized by comprising the following steps of: (a) Mixing a polyvinyl alcohol aqueous solution and an acidic chitosan aqueous solution, adding a cross-linking agent and a pH regulator for pre-crosslinking to obtain primary gel; (b) And (3) placing the nascent gel in a reinforcing medium for soaking treatment, and then carrying out crosslinking reaction to obtain the PVA reinforcing chitosan-based semi-interpenetrating network hydrogel with a compact crosslinked network.
  2. 2. The preparation method of the PVA-reinforced chitosan-based semi-interpenetrating network hydrogel according to claim 1, wherein the mass ratio of the polyvinyl alcohol to the chitosan to the cross-linking agent is (1-15): 1-3): 1-4, and the polyvinyl alcohol accounts for 1-2% of the total mass of the polyvinyl alcohol aqueous solution and the acidic chitosan aqueous solution.
  3. 3. The method for preparing the PVA-reinforced chitosan-based semi-interpenetrating network hydrogel according to claim 1, wherein the cross-linking agent is at least one of citric acid, propylene oxide and epichlorohydrin.
  4. 4. The method for preparing the PVA-reinforced chitosan-based semi-interpenetrating network hydrogel according to claim 1, wherein the pH regulator is used for regulating the pH value of a system to 6-7, and the pH regulator is at least one of sodium bicarbonate and sodium acetate.
  5. 5. The method for preparing the PVA-reinforced chitosan-based semi-interpenetrating network hydrogel according to claim 1, wherein the pre-crosslinking reaction temperature is 40-100 ℃, and the reaction time is 10-180min.
  6. 6. The method for preparing the PVA-reinforced chitosan-based semi-interpenetrating network hydrogel according to claim 1, wherein the reinforcing medium is an aqueous solution of at least one of sodium citrate, sodium sulfate, disodium hydrogen phosphate and borax, and the concentration is 0.1mol/L to saturated concentration.
  7. 7. The method for preparing the PVA-reinforced chitosan-based semi-interpenetrating network hydrogel according to claim 1, wherein the soaking temperature is 5 ℃ and the soaking time is 12-24 hours.
  8. 8. The method for preparing a PVA-reinforced chitosan-based semi-interpenetrating network hydrogel according to claim 1, wherein the crosslinking reaction temperature in the step (b) is 40-100 ℃ and the reaction time is 120min.
  9. 9. Use of a PVA-reinforced chitosan-based semi-interpenetrating network hydrogel prepared according to the method of any of claims 1-8 as a temporary plugging agent in well leakage plugging, oil and gas well plugging, temporary plugging diverting fracturing, water injection well pressurized workover operations.

Description

Preparation method and application of PVA reinforced chitosan-based semi-interpenetrating network hydrogel Technical Field The invention relates to the technical field of gel temporary plugging agents, in particular to a preparation method and application of PVA reinforced chitosan-based semi-interpenetrating network hydrogel. Background The temporary plugging agent is a functional material capable of temporarily forming a plugging barrier in a stratum, is injected into a shaft by compounding with a water-soluble polymer, and rapidly builds a compact temporary plugging layer under the action of pressure difference, so that the production of reservoir fluid or the leakage of working fluid is effectively controlled, and the temporary plugging layer can be relieved in a preset time in an automatic or external intervention mode to recover the original permeability of the stratum. The existing temporary plugging system mainly comprises types such as particles, fibers, gels and the like, however, the existing temporary plugging system has certain application limitations. For example, if the particle size of the particle temporary plugging agent is mismatched with pore throats, the particle temporary plugging agent is easy to cause false plugging or difficult to degrade, thereby causing reservoir damage, the fiber material generally faces the problems of insufficient plugging strength and poor degradation performance, and the gel temporary plugging agent has lower controllability in the process of gelling and plugging removal and relatively complex construction process. At present, the gel research focuses on improving the mechanical strength of materials, and the systematic regulation and control attention on the degradation behavior of the materials is insufficient. The existing blocking removing means mainly depend on physical methods such as mechanical drilling and grinding or chemical treatment by a strong oxidant, but the methods have obvious limitations in application, and particularly for a gel system with higher strength and applicable to a pressurized operation condition, the crosslinked structure of the gel system is difficult to break by a conventional method. Under the common medium-low temperature shaft environment (60-80 ℃), the decomposition efficiency of the oxidant is low, and the gel breaking difficulty is further increased. Therefore, the exploration of a gel self-degradation mechanism based on controllable breaking of chemical bonds becomes an important way for improving the blocking removal performance of the temporary blocking agent. Disclosure of Invention The invention aims to overcome the defects of the prior art and provide a preparation method and application of PVA reinforced chitosan-based semi-interpenetrating network hydrogel, wherein the gel temporary plugging agent is automatically degraded in a certain time and becomes low-viscosity liquid after degradation and is automatically discharged. In order to achieve the above purpose, the present invention adopts the following technical scheme: a preparation method of PVA reinforced chitosan-based semi-interpenetrating network hydrogel comprises the following steps: (a) Mixing a polyvinyl alcohol aqueous solution and an acidic chitosan aqueous solution, adding a cross-linking agent and a pH regulator for pre-crosslinking to obtain primary gel; (b) And (3) placing the nascent gel in a reinforcing medium for soaking treatment, and then carrying out crosslinking reaction to obtain the PVA reinforcing chitosan-based semi-interpenetrating network hydrogel with a compact crosslinked network. The invention is further arranged that the mass ratio of the polyvinyl alcohol to the chitosan to the cross-linking agent is (1-15): 1-3): 1-4, and the polyvinyl alcohol accounts for 1-2% of the total mass of the polyvinyl alcohol aqueous solution and the acidic chitosan aqueous solution. The invention further provides that the cross-linking agent is at least one of citric acid, propylene oxide and epichlorohydrin. The invention further provides that the pH regulator is used for regulating the pH value of the system to 6-7, and the pH regulator is at least one of sodium bicarbonate and sodium acetate. The invention is further provided that the pre-crosslinking reaction temperature is 40-100 ℃ and the reaction time is 10-180min. The invention is further arranged that the reinforcing medium is at least one aqueous solution of sodium citrate, sodium sulfate, disodium hydrogen phosphate and borax, and the concentration is 0.1mol/L to saturated concentration. The treatment temperature of the primary gel is 5 ℃ and the treatment time is 12-24h when the primary gel is treated in the reinforcing medium. The invention is further provided that the soaking temperature is 5 ℃ and the soaking time is 12-24 hours. The invention further provides that in step (b) the crosslinking reaction temperature is 40-100 ℃ and the reaction time is 120min. The PVA reinforced chitosa