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CN-122012051-A - Preparation method of bio-based degradable nano composite temporary plugging agent and application of temporary plugging agent in acidizing and fracturing process

CN122012051ACN 122012051 ACN122012051 ACN 122012051ACN-122012051-A

Abstract

The invention relates to the technical field of temporary plugging agents for fracturing, in particular to a preparation method of a bio-based degradable nano composite temporary plugging agent and application of the temporary plugging agent in an acidizing fracturing process. The preparation method of the bio-based degradable nano composite temporary plugging agent comprises the following steps of 1, mixing nano cellulose, a surfactant and a solvent, forming a uniform dispersion liquid through ultrasonic treatment, 2, adding vinyl monomers, a cross-linking agent and a nano reinforcing body into the dispersion liquid obtained in the step 1,3, reacting at 20-30 ℃ in the presence of an initiator to form composite hydrogel, and 4, soaking the composite hydrogel obtained in the step 3 in a solution containing the nano reinforcing body Forming coordination cross-linking in the metal salt solution, then loading a gel breaker, and drying to obtain solid nano composite temporary plugging agent particles. The invention adopts nanocellulose as a bio-based framework, MMT as an inorganic reinforcing agent and metal ions as dynamic crosslinking points to jointly construct the intelligent temporary plugging agent with high strength, stimulus response and degradability.

Inventors

  • WU JUAN
  • YUAN HAIBIN
  • ZHAO QIANG
  • WU LEI

Assignees

  • 兰州凯宏中原石油科技有限公司

Dates

Publication Date
20260512
Application Date
20260205

Claims (10)

  1. 1. The preparation method of the bio-based degradable nano-composite temporary plugging agent is characterized by comprising the following steps of: step 1, preparing nano cellulose dispersion liquid, namely mixing nano cellulose, a surfactant and a solvent, and forming uniform dispersion liquid through ultrasonic treatment; Step 2, constructing an in-situ polymerization reaction system, namely adding at least one vinyl monomer, a cross-linking agent and a nano reinforcing agent into the dispersion liquid obtained in the step 1, and regulating the pH of the system to 6.0-7.5; Step 3, performing free radical polymerization reaction, namely reacting at 20-30 ℃ in the presence of inert gas protection and an initiator to form composite hydrogel; Step 4, performing functionalization treatment, namely cutting the composite hydrogel obtained in the step 3 into particles, washing and soaking in a solution containing Forming coordination cross-linking in the metal salt solution, then loading a gel breaker, and drying to obtain solid nano composite temporary plugging agent particles.
  2. 2. The preparation method of the bio-based degradable nano composite temporary plugging agent according to claim 1, wherein the concentration of the nano cellulose in the step 1 is 0.5-1.0 wt%, the surfactant is sodium dodecyl sulfate, and the dosage of the sodium dodecyl sulfate is 1-5% of the mass of the nano cellulose.
  3. 3. The method for preparing the bio-based degradable nano-composite temporary plugging agent according to claim 1, wherein the ultrasonic treatment in the step 1 is performed under the ice water bath condition, the ultrasonic power is 400-600W, the frequency is 30-50 kHz, and the treatment time is 60-80 minutes.
  4. 4. The preparation method of the bio-based degradable nano composite temporary plugging agent according to claim 1, wherein in the step 2, the at least one vinyl monomer comprises N-isopropyl acrylamide and acrylic acid, the mass ratio of the N-isopropyl acrylamide to the acrylic acid is 1:1 to 2:1, the cross-linking agent is N, N' -methylene bisacrylamide, and the amount of the cross-linking agent is 0.5-1.5% of the total mass of the vinyl monomers.
  5. 5. The method for preparing the bio-based degradable nano composite temporary plugging agent according to claim 1, wherein the nano reinforcing body in the step 2 is nano montmorillonite, and the dosage of the nano montmorillonite is 5-10% of the total mass of vinyl monomers.
  6. 6. The method for preparing the bio-based degradable nano composite temporary plugging agent according to claim 1, wherein the initiator in the step 3 comprises ammonium persulfate and tetramethyl ethylenediamine, the ammonium persulfate is used in an amount of 0.5-1.5% of the total mass of the vinyl monomers, and the tetramethyl ethylenediamine is used in an amount of 0.5-1.0% of the total mass of the vinyl monomers.
  7. 7. The method for preparing the bio-based degradable nano-composite temporary plugging agent according to claim 1, wherein the reaction in the step 3 is performed at 25-30 ℃ for 6-8 hours.
  8. 8. The method for preparing the bio-based degradable nano-composite temporary plugging agent according to claim 1, wherein the step 4 comprises the following steps of Metal salts of (2) are And (2) and The concentration of the solution is 0.05-0.1M, the pH is 4.0-5.0, and the soaking time is 2-4 hours.
  9. 9. The preparation method of the bio-based degradable nano composite temporary plugging agent according to claim 1, wherein the gel breaker in the step 4 is an ammonium persulfate capsule, the dosage of the gel breaker is 2-5% of the mass of gel particles, the loading time is 1-3 hours, and the drying is carried out at 30-50 ℃.
  10. 10. The use of the bio-based degradable nano-composite temporary plugging agent prepared by the preparation method of any one of claims 1-9 in a fracturing process.

Description

Preparation method of bio-based degradable nano composite temporary plugging agent and application of temporary plugging agent in acidizing and fracturing process Technical field: the invention belongs to the technical field of temporary plugging agents for fracturing, and particularly relates to a preparation method of a bio-based degradable nano composite temporary plugging agent and application of the temporary plugging agent in an acidizing fracturing process. The background technology is as follows: The foreign temporary plugging agent technology has been developed for ninety years since the first time that haloburton in the 30 th century utilized fatty acid salt to react with calcium chloride to produce a precipitate and introduced the temporary plugging agent into the cement plugging process. In the domestic aspect, the Yumen oil field firstly carries out oil well water shutoff operation in 1957, and then the Daqing oil field carries out water injection well profile control test, which marks that the research and application of temporary plugging agents in China have gone through the history of over sixty years. The temporary plugging agent is widely applied in oilfield operation, and covers a plurality of links such as drilling, well cementation, well repair, well flushing and the like. However, its role in the fracturing process is particularly critical. In the middle and later stages of oil field development, as the water content rises, conventional repeated fracturing has a limited yield increasing effect due to the fact that fracturing fluid tends to enter along the original hypertonic layer or fracture. To improve this situation, a steering fracturing technique has been developed, and the core of the steering fracturing technique is to block a high permeability layer or an opened fracture by a temporary plugging agent, so as to drive the fracturing fluid to steer to an underutilized hypotonic region, thereby forming a new fracture network. Particularly, in the early water injection development and repeated fracturing process, injected water is easy to rush into along a hypertonic zone, so that the problems of low sweep efficiency, premature flooding of an oil well and the like are caused. At this time, temporary plugging is carried out on the high-permeability layer by adopting temporary plugging agent, so that the flow direction can be effectively changed, the swept volume of the fracturing fluid is enlarged, the integral seepage capacity of the reservoir is improved, and the effective yield increase is realized. Therefore, temporary plugging steering has become one of key technologies in reservoir volume transformation, and plays an irreplaceable role in improving the fracturing process effect. Early rigid particle plugging removers such as quartz sand and ceramsite, which have high compressive strength but are not degradable, are permanently left in the stratum once used and cause irreversible damage to the reservoir. The temporary plugging agents such as polymer balls, plastic sheets and the like which are used at present can stay in the cracks and pores of the reservoir for a long time in a solid form after the steering task is completed, and the temporary plugging agents block the oil gas seepage channels, so that the permeability of the reservoir is greatly reduced, and the long-term recovery rate is influenced. In particular to a plastic temporary plugging agent, the degradation period of which is hundreds of years, and the risk of micro plastic pollution is contrary to the increasingly strict environmental protection regulations. The conventional temporary plugging agents also have the defects of easy deformation or premature degradation under high pressure and high temperature, uncontrollable degradation rate due to physical dissolution or slow hydrolysis of many temporary plugging agents, lack of intelligent response (such as pH, temperature and the like) and difficulty in adapting to complex underground environment. Aiming at the defects existing in the prior art, the invention provides a preparation method of a bio-based degradable nano-composite temporary plugging agent and application thereof in an acidizing and fracturing process. The invention uses nano cellulose as a degradable biological supporting matrix, can replace the traditional petroleum-based polymer, has biocompatibility and degradability, thereby effectively reducing environmental pollution, has a high specific surface area and a rigid rod-shaped structure, can be used as a physical crosslinking point to improve the strength and toughness of the gel temporary plugging agent, and further, the hydroxyl groups of the nano cellulose and the carboxyl groups of AA form hydrogen bonds to enhance the interaction of polymer chains. The second aspect employs Acrylic Acid (AA) as a pH responsive monomer and N-isopropylacrylamide (NIPAM) as a temperature responsive monomer, capable of forming a dual temperature and pH response m