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CN-121991665-A - Gel breaking temporary plugging agent and preparation method thereof

CN121991665ACN 121991665 ACN121991665 ACN 121991665ACN-121991665-A

Abstract

The invention relates to the technical field of oil gas development materials, and particularly discloses a gel breaking temporary plugging agent and a preparation method thereof. The raw material components of the gel breaking temporary plugging agent comprise beta-mannase, calcium salt solution, ammonium persulfate microcapsules, oxidation modified bacterial powder, silicon dioxide microspheres, beta-mannase based gel and water. The temporary plugging agent for breaking the gel effectively solves the problems that the traditional temporary plugging agent for breaking the gel is incomplete, secondary plugging is easy to occur and the controllability of the gel breaking time is poor.

Inventors

  • LI QINGXIA
  • WU HAIXIA
  • ZHANG FENGBIN
  • LI YUTONG
  • MA KAILE
  • YANG ZIYI

Assignees

  • 河北科技大学

Dates

Publication Date
20260508
Application Date
20260401

Claims (10)

  1. 1. The temporary plugging agent for breaking the gel is characterized by comprising, by mass, 6-9 parts of beta-mannase, 75-85 parts of a calcium salt solution, 140-160 parts of ammonium persulfate microcapsules, 70-90 parts of oxidation modified bacterial powder, 380-420 parts of silica microspheres, 7400-8200 parts of beta-mannase gel and 1400-1600 parts of water, wherein the ammonium persulfate microcapsules contain ethylenediamine tetraacetic acid chelated iron.
  2. 2. The temporary plugging agent for breaking gel according to claim 1, wherein the preparation method of the ammonium persulfate microcapsule comprises the following steps: S1, mixing ammonium persulfate, ethylenediamine tetraacetic acid chelated iron and water, and stirring for 20-30min at 50-70 ℃ to obtain a water phase; s2, mixing poly-N-isopropyl acrylamide, methylene dichloride and span 80 to obtain an oil phase; And S3, mixing the water phase with the oil phase, emulsifying to obtain emulsion, and polymerizing and curing the emulsion at the temperature of 30-40 ℃ to obtain the ammonium persulfate microcapsule.
  3. 3. The temporary plugging agent for breaking gel according to claim 2, wherein in S1, the mass volume ratio of the ammonium persulfate to the ethylenediamine tetraacetic acid chelated iron to the water is (4-5) g (0.03-0.035) g (90-110) mL; in S2, the mass volume ratio of the poly N-isopropyl acrylamide to the methylene dichloride to the span 80 is (1.4-1.6) g (55-65) mL (80-85) g; in S3, the volume ratio of the water phase to the oil phase is 1 (5-7).
  4. 4. The temporary plugging agent for breaking gel according to claim 2, wherein in S3, the rotational speed of the emulsification is 12000-15000 rpm for 5-15 min; And S3, the reaction time of polymerization and curing is 2-3 hours.
  5. 5. The temporary plugging agent for breaking gel according to claim 1, wherein the preparation method of the beta-mannans-based gel comprises the following steps: Step a, adding beta-mannans into water, stirring for 30-35 min at 55-65 ℃, heating to 80-90 ℃ and stirring for 35-45 min again to obtain a first solution; Step b, dispersing nano silicon dioxide in water to obtain nano silicon dioxide dispersion liquid; And c, adding the nano silicon dioxide dispersion liquid into the first solution, adding a calcium chloride solution, stirring for 20-30 min, and cooling to obtain the beta-mannans-based gel.
  6. 6. The temporary plugging agent for breaking gel according to claim 1, wherein in the step a, the mass-volume ratio of the beta-mannans to the water is 1g (50-60) mL; In the step b, the mass percentage of the nano silicon dioxide in the nano silicon dioxide dispersion liquid is 0.05% -0.1%; In the step c, the concentration of the calcium chloride solution is 0.1-0.2 mol/L; In the step c, the adding amount of the calcium chloride solution is 5% -10% of the volume of the first solution; In the step c, the volume ratio of the nano silicon dioxide dispersion liquid to the first solution is 1 (4-6).
  7. 7. The temporary plugging agent for breaking gel according to claim 1, wherein the preparation method of the oxidative modification bacterial powder comprises the following steps: Inoculating the bacterial powder on a culture medium, culturing for 36-42h at 45-60 ℃ and pH7-8 to obtain bacterial liquid, heating the bacterial liquid to 80-90 ℃, adding ammonium persulfate aqueous solution for oxidation treatment, and freeze-drying to obtain the oxidation modified bacterial powder.
  8. 8. The temporary plugging agent for breaking gel according to claim 7, wherein the bacterial powder is geobacillus thermophilus bacterial powder with the number BNCC136223; the number of viable bacteria in the bacterial liquid is 1 multiplied by 10 8 ~1×10 9 CFU/mL; The concentration of the ammonium persulfate aqueous solution is 0.05 mol/L-0.1 mol/L; The mass ratio of the ammonium persulfate aqueous solution to the bacterial liquid is (0.1-0.5) 100; The time of the oxidation treatment is 60-80 min.
  9. 9. The method for preparing the temporary plugging agent for breaking gel according to any one of claims 1 to 8, which is characterized by comprising the following steps: Step one, mixing beta-mannase, a calcium salt solution and beta-mannase gel to obtain an enzyme gel mixture; Dispersing the oxidation modified bacterial powder in a buffer solution to obtain bacterial suspension; dispersing the silicon dioxide microspheres in the bacterial suspension for vacuum adsorption to obtain flora microspheres; And thirdly, uniformly mixing the enzyme gel mixture, the flora microspheres and the rest raw materials at 50-70 ℃ to obtain the gel breaking temporary plugging agent.
  10. 10. The method for preparing a temporary plugging agent for breaking gel according to claim 9, wherein in the first step, the concentration of the calcium salt solution is 0.5-1 mol/L; in the second step, the concentration of thalli in the bacterial suspension is 1 multiplied by 10 8 ~1×10 9 CFU/mL; In the second step, the buffer solution is phosphate buffer solution with pH of 7.0-7.2; In the second step, the mass volume ratio of the silicon dioxide microspheres to the bacterial suspension is 1g (2-3) mL; In the second step, the vacuum adsorption pressure is-0.07 to-0.09 MPa, and the vacuum adsorption time is 20-30min.

Description

Gel breaking temporary plugging agent and preparation method thereof Technical Field The invention relates to the technical field of oil gas development materials, and particularly discloses a gel breaking temporary plugging agent and a preparation method thereof. Background In the field of oil and gas development, the fracturing yield is used as a core means for coping with the domestic oil field dead production period, and has important significance for prolonging the service life of an oil well, improving the utilization efficiency of stratum crude oil and relieving the dependence of petroleum import. At present, the oil gas development situation in China is severe, mature oil fields in China generally enter a dead production period, 65% -75% of crude oil remains in a stratum even through water injection development, and the fracturing yield increasing effect directly depends on the plugging-unplugging effect of temporary plugging agents. However, the temporary plugging agent in the prior art is mainly subjected to oxidative gel breaking through ammonium persulfate, so that the problems of incomplete gel breaking and secondary blocking risks exist, the gel breaking time of the temporary plugging agent in the prior art is poor in controllability, the gel breaking process is delayed or the temporary plugging agent is enabled to be in premature failure due to the fluctuation of the external temperature, the fracturing effect is seriously affected, the problems not only restrict the application efficiency of the fracturing yield increasing technology, but also can cause reservoir damage, and the crude oil exploitation difficulty is further increased. Therefore, how to provide a high-efficiency temporary plugging agent with thorough gel breaking, no secondary blocking risk and controllable gel breaking time becomes a technical problem to be solved in the field of oil gas development. Disclosure of Invention Aiming at the problems that the temporary plugging agent depends on ammonium persulfate to oxidize and break rubber in the prior art, the rubber breaking is incomplete, secondary plugging risks are easy to occur, the rubber breaking time controllability is poor, and the influence of external temperature fluctuation is large, the invention provides a rubber breaking temporary plugging agent and a preparation method thereof. The gel breaking temporary plugging agent provided by the invention realizes thorough gel breaking through the synergistic effect of the raw material components, has no secondary blocking risk, and meets the requirements of fracturing yield increase on the temporary plugging agent in the oil gas development field. In order to achieve the above purpose, the present invention provides the following technical solutions: The invention provides a temporary plugging agent for breaking gel, which comprises, by mass, 6-9 parts of beta-mannase, 75-85 parts of a calcium salt solution, 140-160 parts of ammonium persulfate microcapsules, 70-90 parts of oxidation modified bacterial powder, 380-420 parts of silica microspheres, 7400-8200 parts of beta-mannase gel and 1400-1600 parts of water, wherein the ammonium persulfate microcapsules contain ethylenediamine tetraacetic acid chelated iron. Compared with the prior art, the temporary plugging agent for breaking the gel provided by the invention realizes stable plugging and controllable breaking of the gel through multi-component cooperation. The beta-mannase preferentially acts on the beta-mannase to break a high molecular chain into a low molecular fragment, the gel structure is changed from compact to loose, more active sites are provided for subsequent reactions, then, the ammonium persulfate microcapsule triggers and releases an oxidant under the catalysis of ethylenediamine tetraacetic acid chelated iron to generate sulfate radicals, and the sulfate radicals are further oxidized and broken on an organic framework which is degraded by enzyme, thereby realizing thorough gel breaking. The oxidation modified bacterial powder mainly plays roles of adsorption and catalysis in a system, has a porous structure and is rich in polar functional groups on the surface, small molecular residues generated by gel breaking can be adsorbed, further oxidative degradation is promoted, residues are prevented from being deposited in pores, and the risk of secondary blockage is reduced. In addition, because ammonium persulfate exists in a microcapsule form, the release of the ammonium persulfate is controlled by temperature, the system is kept stable under the low-temperature condition, and the gel breaking reaction is triggered under the high-temperature condition, so that the effective regulation and control of the gel breaking time are realized. In conclusion, the gel breaking temporary plugging agent provided by the invention realizes thorough gel breaking through the synergistic effect of the raw material components, has no secondary blocking risk, and effectivel