1. The water-soluble polymer degradation agent is characterized by being prepared from the following components in percentage by mass based on 100% of the total mass of the prepared water-soluble polymer degradation agent: 1 to 2 percent of nano ferrous sulfide, 6 to 8 percent of organic ferrous, 0.01 to 0.03 percent of polyphenol compound, 0.01 to 0.0125 percent of organic acid with the molecular weight less than 300, 0.5 to 0.8 percent of polyhydric alcohol type nonionic surfactant, 0.01 to 0.03 percent of peroxide, 1 to 2 percent of inorganic salt and the balance of water; the water-soluble polymer degrading agent is prepared by a method comprising the following steps: dissolving organic acid with the molecular weight of less than 300 in water until the organic acid is completely dissolved, then adding organic ferrous iron, nano ferrous sulfide, polyphenol compounds, polyol type nonionic surfactant, peroxide and inorganic salt, completely dissolving, and stirring for at least 0.5h to obtain the water-soluble polymer degradation agent.

2. The water-soluble polymer degrading agent according to claim 1, wherein the water-soluble polymer degrading agent is prepared mainly from the following components: 2% of nano ferrous sulfide, 8% of organic ferrous, 0.01% of polyphenol compound, 0.01% of organic acid with the molecular weight less than 300, 0.5% of polyhydric alcohol type nonionic surfactant, 0.01% of peroxide, 2% of inorganic salt and the balance of water.

3. The water-soluble polymer degrading agent according to claim 1, wherein the water-soluble polymer degrading agent comprises the following components in percentage by mass: 2% of nano ferrous sulfide, 8% of organic ferrous, 0.02% of polyphenol compound, 0.0125% of organic acid with the molecular weight less than 300, 0.5% of polyhydric alcohol type nonionic surfactant, 0.01% of peroxide, 2% of inorganic salt and the balance of water.

4. The water-soluble polymer degrading agent according to any one of claims 1 to 3, wherein the organic ferrous iron is ferrous lactate and/or ferrous gluconate; the polyphenol compound is pyrogallol and/or phloroglucinol; the organic acid with the molecular weight less than 300 is citric acid and/or acrylic acid; the polyhydric alcohol type nonionic surfactant is a Tween series surfactant; the peroxide is persulfate; the inorganic salt is one or more of ammonium chloride, potassium chloride and sodium chloride.

5. The water-soluble polymer degrading agent as claimed in any one of claims 1 to 3, wherein the particle size of the nano ferrous sulfide is 100-500 nm.

6. The method for preparing the water-soluble polymer degrading agent of any one of claims 1 to 5, wherein the method comprises the following steps: dissolving organic acid with the molecular weight of less than 300 in water until the organic acid is completely dissolved, then adding organic ferrous iron, nano ferrous sulfide, polyphenol compounds, polyol type nonionic surfactant, peroxide and inorganic salt, completely dissolving, and stirring for at least 0.5h to obtain the water-soluble polymer degradation agent.

7. Use of a water-soluble polymer degrader as claimed in any one of claims 1 to 5 in polymer degradation.

8. Use according to claim 7, wherein the water-soluble polymer degrading agent is the degradation of a polymer used in an oil well.

9. A method for degrading an oil well polymer, which comprises injecting the water-soluble polymer degrading agent according to any one of claims 1 to 5 into an oil well.

10. The method according to claim 9, characterized in that it comprises the steps of:

under the condition of reservoir temperature, connecting an injection unit and a ground pipeline by an oil pipe, and testing the pressure of the pipeline without puncture and leakage to be qualified;

and injecting the water-soluble polymer degradation agent into the underground stratum of the water injection well to degrade the water-soluble polymer.

Background

With the development of oil field exploration, the water-soluble polymer is widely applied to profile control, oil displacement, fracturing modification and the like to improve the recovery ratio of oil and gas in the oil field. After the polymer is injected into the oil field, although the viscosity of the degradation liquid is very low after the degradation agent is added, because the soft agglomerate plug and the hard agglomerate plug exist at the same time after the gel breaking, the soft agglomerate plug and the hard agglomerate plug are combined to form a plug with considerable strength and certain deformability, the whole stratum pore can be filled, a tight plugging layer is formed, the stratum permeability is greatly reduced, and the exploitation of reservoir oil gas is greatly influenced. How to completely degrade cross-linked polymers and reduce the damage to a reservoir so as to recover the crude oil recovery ratio is a problem to be solved urgently at present.

The invention patent CN103666424B 'a polymer degradation agent' provides a polymer degradation agent, which comprises the following components by mass percent: 70% of ammonium sulfate, 5% to 10% of ammonium persulfate, 1% to 3% of amino trimethylene phosphonic acid, 1% to 2% of ethylene diamine tetraacetic acid, 3% of OP, 2% of dodecyl dimethyl benzyl ammonium chloride and the balance of water. The polymer degradation agent can generate free radicals at a lower temperature, can rapidly degrade polymer solution with very high viscosity into solution with viscosity close to water, can effectively remove pollution and damage of the polymer solution to the stratum, and recover the seepage capability of the polluted stratum, and has the advantages of good field application effect, simple process, low requirements on conditions and equipment, and easy popularization and use.

The invention patent CN110498500A Polymer degrading agent, a preparation method and an application thereof discloses a polymer degrading agent, a preparation method and an application thereof, and belongs to the technical field of oilfield sewage treatment. The polymer degradation agent comprises the following components in parts by weight: 10-15 parts of a phenolic compound; 50-80 parts of sodium hypochlorite; 25-40 parts of thiourea; 5-8 parts of an alkaline pH regulator; 200-300 parts of water. The polymer degradation agent provided by the invention can rapidly break and degrade a polymer chain into small molecular compounds, is suitable for various polymers, and has the advantages of wide application range, high degradation speed, wide application temperature range, strong degradation capability and small pollution to the environment and a water injection well.

The invention patent CN108359992A discloses a method for reducing corrosion of oil well pipe string by strong oxidative polymer degradation agent, comprising: (1) dissolving a strong oxidizing polymer degradation agent into water to obtain a strong oxidizing polymer degradation agent solution, wherein the mass percent of the degradation agent is 1%; (2) dissolving sodium silicate and sodium tripolyphosphate in water according to the mass ratio of 1-4.6: 0.5-2.3, and stirring for ten minutes at normal temperature to obtain (Si-P) composite corrosion inhibitor aqueous solutions with different proportions; (3) the (Si-P) composite corrosion inhibitor aqueous solution is used for reducing corrosion of steel in the strong oxidizing polymer degradation agent solution, and the total mass percentage of the sodium silicate and the sodium tripolyphosphate in the strong oxidizing polymer degradation agent solution is 0.15-0.69%. The invention utilizes the binding force and the adsorption effect between the inorganic corrosion inhibitor and steel interface atoms to form a protective film on the surface of the oil well pipe column, effectively isolates the metal surface from contacting with strong oxidant molecules, reduces the corrosion of the strong oxidative polymer degradation agent to the oil well pipe column, and has wide market application prospect.

The invention patent CN102977237B relates to a method for degrading acrylamide polymer. The method comprises the following steps: adjusting the pH value of the acrylamide polymer solution to 4-10, adding pyrogallol into the acrylamide polymer solution, stirring to dissolve the pyrogallol, and degrading at the constant temperature of 50-95 ℃. Different from the conventional viscosity reducer with strict requirements on pH, the pyrogallol can be suitable for a larger pH range during degradation and can play a good degradation effect, and the concentration gradient of the pyrogallol can be ignored during use. The pyrogallol degradation effect is less influenced by external ions, so that the pyrogallol degradation agent has a good application effect in the treatment of the saline polyacrylamide sewage.

The utility model patent CN207600908U provides an experimental apparatus for evaluating polymer degradation in temperature-resistant and pressure-resistant drilling fluid, which comprises a columnar pressure-bearing container 2 and an anticorrosive inner container 3, wherein the bottom of the columnar pressure-bearing container 2 is provided with a bottom cover 1, the upper part of the columnar pressure-bearing container is provided with a container cover 6 connected with the columnar pressure-bearing container 2, the container cover 6 is axially provided with a plunger 8 in threaded fit, and the bottom of the plunger 8 and a gland 5 arranged at the upper opening of the columnar pressure-bearing container form extrusion fit; the anti-corrosion liner 3 is arranged between the bottom cover 1 and the gland 5 of the columnar pressure-bearing container 2, the anti-corrosion liner 3 is a columnar cylinder body with an upper cover 4 in sealing fit, and the outer diameter is smaller than the inner diameter of the columnar pressure-bearing container 2. The utility model discloses an experimental apparatus have that the appearance is pleasing to the eye, and simple structure is reasonable, uses portably, and corrosion resistance is good, the temperature resistant is high, resistance to pressure characteristics such as big.

The inventor finds that the prior art has at least the following technical problems:

in the prior art, most polymer degradation agents are efficiently degraded for a certain polymer, but in the field practical application process, the polymer degradation agents not only have low-viscosity polymers, but also have high-viscosity polymers, and also have crosslinked polymer systems formed after crosslinking, and no degradation agent report that the polymer degradation agents can degrade both the degradable polymers and the crosslinked polymer systems is found.

Disclosure of Invention

An object of the present invention is to provide a water-soluble polymer degrading agent; the degradation agent provided by the invention is safer and can degrade different polymers more thoroughly.

The invention also aims to provide a preparation method of the water-soluble polymer degradation agent;

still another object of the present invention is the use of said water-soluble polymer degrader for polymer degradation.

In order to achieve the above object, in one aspect, the present invention provides a water-soluble polymer degradation agent, wherein the water-soluble polymer degradation agent is mainly prepared from the following components, based on 100% of the total mass of the prepared water-soluble polymer degradation agent: 1 to 2 percent of nano ferrous sulfide, 6 to 8 percent of organic ferrous, 0.01 to 0.03 percent of polyphenol compound, 0.01 to 0.0125 percent of organic acid with the molecular weight less than 300, 0.5 to 0.8 percent of polyhydric alcohol type nonionic surfactant, 0.01 to 0.03 percent of peroxide, 1 to 2 percent of inorganic salt and the balance of water.

According to some embodiments of the invention, the degradation agent is prepared from the following components: 2% of nano ferrous sulfide, 8% of organic ferrous, 0.01% of polyphenol compound, 0.01% of organic acid with the molecular weight less than 300, 0.5% of polyhydric alcohol type nonionic surfactant, 0.01% of peroxide, 2% of inorganic salt and the balance of water.

According to some embodiments of the invention, the water-soluble polymer degradation agent comprises the following components in percentage by mass: 2% of nano ferrous sulfide, 8% of organic ferrous, 0.02% of polyphenol compound, 0.0125% of organic acid with the molecular weight less than 300, 0.5% of polyhydric alcohol type nonionic surfactant, 0.01% of peroxide, 2% of inorganic salt and the balance of water.

The organic ferrous iron is used for providing ferrous ions which are catalysts for chemical degradation of the polymer, and the three-dimensional network structure of the cross-linked polymer is destroyed, so that the polymer is degraded; the particle size of the nano ferrous sulfide is nano-scale, so that the nano ferrous sulfide can more easily enter low-permeability or small pores, thereby catalyzing the degradation of polymers at the inner side;

the micromolecular organic acid is weak acid and can slowly release hydrogen ions in the aqueous solution, so that the pH value of the solution is reduced, and a large number of experiments prove that the lower the pH value of the solution is, the higher the degradation speed of the polymer is, so that the micromolecular organic acid can further promote the degradation speed of the polymer;

the polyphenol compound is a reducing agent, can generate a negatively charged free radical, has strong repulsion on a negatively charged part in the polymer, thereby relieving the winding state of the polymer, inhibiting the free extension of molecules, compressing the polymer from the free extension state to an agglomeration state, and reducing the viscosity;

the polyhydric alcohol type nonionic surfactant is a solubilizer and can increase the solubility of each component of the polymer degradation agent in an aqueous solution;

the peroxide is an oxidant, and can break unsaturated bonds in the cross-linked polymer through oxidation, so that a three-dimensional net structure of the cross-linked polymer is damaged, long chains of the polymer are further broken into short chains, and the effect of reducing the viscosity of the polymer is achieved.

The inorganic salt is an anti-swelling agent, so that the phenomenon that the hydration expansion of the clay minerals of the stratum is caused by the fact that a large amount of polymer degrading agents enter the stratum to influence the permeability of the reservoir is prevented, and the effect of protecting the reservoir is achieved.

According to some embodiments of the invention, the organic ferrous iron is ferrous lactate and/or ferrous gluconate.

According to some embodiments of the invention, wherein the polyphenol compound is pyrogallol and/or phloroglucinol.

According to some embodiments of the invention, the organic acid having a molecular weight of less than 300 is citric acid and/or acrylic acid.

According to some embodiments of the invention, the polyol-type nonionic surfactant is a tween series surfactant.

According to some specific embodiments of the present invention, wherein the polyhydric alcohol type nonionic surfactant is tween 20 and/or tween 80.

According to some embodiments of the invention, the peroxide is a persulfate.

According to some embodiments of the invention, wherein the inorganic salt is a chloride salt; such as ammonium chloride or a chloride salt of an alkali metal.

According to some embodiments of the invention, the inorganic salt is a combination of one or more of ammonium chloride, potassium chloride and sodium chloride.

According to some specific embodiments of the present invention, the nano ferrous sulfide particle size is 100-500 nm.

According to some specific embodiments of the present invention, the nano ferrous sulfide particle size is 300-500 nm.

According to some specific embodiments of the present invention, the nano ferrous sulfide particle size is 100-200 nm.

According to some embodiments of the invention, the water-soluble polymer degradation agent comprises the following components in percentage by mass: 2% of nano ferrous sulfide, 8% of organic ferrous, 0.01% of polyphenol compound, 0.01% of organic acid with the molecular weight less than 300, 0.5% of polyhydric alcohol type nonionic surfactant, 0.01% of peroxide, 2% of inorganic salt and the balance of water; the particle size of the nano ferrous sulfide is 300-500 nm.

According to some embodiments of the invention, the water-soluble polymer degradation agent comprises the following components in percentage by mass: 2% of nano ferrous sulfide, 8% of organic ferrous, 0.02% of polyphenol compound, 0.0125% of organic acid with the molecular weight less than 300, 0.5% of polyalcohol type nonionic surfactant, 0.01% of peroxide, 2% of inorganic salt and the balance of water; the particle size of the nano ferrous sulfide is 100-200 nm.

According to some embodiments of the invention, the water-soluble polymer degradation agent is prepared by a method comprising the following steps: dissolving organic acid with the molecular weight of less than 300 in water until the organic acid is completely dissolved, adding organic ferrous iron, nano ferrous sulfide, polyphenol compounds, polyol type nonionic surfactant, peroxide and inorganic salt, completely dissolving, and stirring for at least 0.5h to obtain the water-soluble polymer degradation agent.

According to some embodiments of the present invention, the water-soluble polymer degradation agent is obtained by adding organic ferrous iron, nano ferrous sulfide, polyphenol compound, polyol type nonionic surfactant, peroxide and inorganic salt, completely dissolving, and then stirring for 0.5-1 h.

In another aspect, the present invention also provides a preparation method of the water-soluble polymer degradation agent, wherein the method comprises the following steps: dissolving organic acid with the molecular weight of less than 300 in water until the organic acid is completely dissolved, adding organic ferrous iron, nano ferrous sulfide, polyphenol compounds, polyol type nonionic surfactant, peroxide and inorganic salt, completely dissolving, and stirring for at least 0.5h to obtain the water-soluble polymer degradation agent.

According to some embodiments of the present invention, the water-soluble polymer degradation agent is obtained by adding organic ferrous iron, nano ferrous sulfide, polyphenol compound, polyol type nonionic surfactant, peroxide and inorganic salt, completely dissolving, and then stirring for 0.5-1 h.

In still another aspect, the invention also provides the application of the water-soluble polymer degradation agent in polymer degradation.

According to some embodiments of the invention, wherein the water soluble polymer degrading agent is a polymer for oil well degradation.

According to some embodiments of the present invention, the water-soluble polymer degradation agent is used for degradation of polymers for oil well polymer injection flooding, oil-water well profile control and water shutoff, fracturing sand carrying and the like.

According to some embodiments of the invention, the polymer comprises one or more of aluminum crosslinked polyacrylamide, chromium crosslinked guar gum, or zirconium crosslinked guar gum.

According to some embodiments of the invention, wherein the polymer comprises polyacrylamide having a molecular weight of 400-2500 ten thousand.

According to some specific embodiments of the present invention, the raw materials for preparing the chromium or zirconium cross-linked guar gum comprise 0.2-0.5wt% of hydroxypropyl or carboxymethyl guar gum, 0.12-0.15wt% of sodium carbonate, 0.8-1.0wt% of potassium chloride, 0.1-0.5wt% of tetramethylammonium chloride, 0.005-0.5wt% of OP-10, 0.1-0.5wt% of glutaraldehyde, 0.4-0.5wt% of sodium hydroxide, 0.4-0.6wt% of dichromium trioxide or zirconium oxychloride and the balance of water, wherein the total weight of the chromium or zirconium cross-linked guar gum is 100%.

According to some embodiments of the present invention, the raw material for preparing the aluminum crosslinked polyacrylamide comprises 0.1-0.2wt% of polyacrylamide, 0.3-0.4wt% of aluminum citrate, and the balance of water, wherein the total weight of the aluminum crosslinked polyacrylamide is 100%.

According to some embodiments of the present invention, the polyacrylamide raw material composition comprises 0.1-0.2wt% polyacrylamide and the balance water, based on 100% by weight of the finally prepared polymer solution.

In yet another aspect, the invention also provides a method of degrading an oil well polymer, the method comprising injecting into an oil well a water-soluble polymer degrading agent according to the invention.

According to some embodiments of the invention, the method comprises the steps of:

under the condition of reservoir temperature, connecting an injection unit and a ground pipeline by an oil pipe, and testing the pressure of the pipeline without puncture and leakage to be qualified;

injecting a water soluble polymer degrading agent into the downhole formation of the water injection well to degrade the water soluble polymer.

According to some embodiments of the invention, wherein the reservoir temperature is between 25 ℃ and 150 ℃.

According to some embodiments of the invention, the pressure at which the pipeline is tested is in the range of 20 to 30 MPa.

According to some embodiments of the invention, the pressure at which the pipeline is pressure tested is 25 MPa.

According to some embodiments of the invention, the method is connecting the injection unit and the surface pipeline by tubing positive injection.

According to some embodiments of the present invention, the method further comprises the step of installing an oil pressure gauge and a casing pressure pipe after connecting the injection unit and the surface pipeline by the oil pipe, and then performing pressure testing on the pipeline.

It is to be understood that the various embodiments of the invention may be combined in any combination without departing from the scope of the invention.

In conclusion, the invention provides a water-soluble polymer degradation agent, and preparation and application thereof. The degradation agent of the invention has the following advantages:

(1) the degradation agent provided by the invention is simple in component, and each component is relatively safe and environment-friendly;

(2) the degradation agent provided by the invention can completely degrade different polymers, and has a good degradation effect on one or more polymers selected from 400-2500 ten thousand HPAM, aluminum cross-linked polyacrylamide, chromium cross-linked hydroxypropyl guar gum, chromium cross-linked carboxymethyl guar gum, zirconium cross-linked hydroxypropyl guar gum and zirconium cross-linked carboxymethyl guar gum.

Detailed Description

The following detailed description is provided for the purpose of illustrating the embodiments and the advantageous effects thereof, and is not intended to limit the scope of the present disclosure.

Example 1

1) Preparation of water-soluble polymer degradation agent: dissolving 0.0125 g of acrylic acid in 10 g of water until the acrylic acid is completely dissolved, then adding 6g of ferrous lactate, 2g of nano ferrous sulfide (100-200 nm), 0.02 g of pyrogallol, 0.5g of Tween 80, 0.01 g of ammonium persulfate and 2g of ammonium chloride, adding water until the weight of the solution is 100 g, and stirring for 0.5-1h to obtain a water-soluble polymer degradation agent solution (degradation agent 1);

2) preparation of water-soluble polymer degradation agent: firstly, 6g of ferrous lactate, 2g of nano ferrous sulfide (100-200 nm), 0.02 g of pyrogallol, 0.5g of Tween 80, 0.01 g of ammonium persulfate and 2g of ammonium chloride are dissolved in 10 g of water, then 0.0125 g of acrylic acid is added, then water is added until the weight of the solution is 100 g, and the solution is stirred for 0.5 to 1 hour to obtain a water-soluble polymer degradation agent solution (degradation agent 2);

the degradation capability of the water-soluble polymer degradation agent on 1900 ten thousand HPAM is determined: stirring at normal temperature by using a MYP11-2A constant-temperature magnetic stirrer at the rotating speed of 1000r/min, adding 0.2g1900 ten thousand HPAM into 98 g of tap water while stirring, and stirring and dissolving for 4 hours for later use; according to the water-soluble polymer degradation agent: 1900 ten thousand HPAM solution is added in the ratio of 1g to 1g, the two solutions are mixed evenly and put into a blue screw thread bottle to react for 4 hours in a baking oven at 25 ℃; the specific experimental results are shown in table 1.

Example 2

1) Preparation of water-soluble polymer degradation agent: completely dissolving 0.01 g of acrylic acid in 20 g of water, then adding 6g of ferrous lactate, 1g of nano ferrous sulfide (300- & gt 500 nm), 0.03 g of pyrogallol, 0.8 g of Tween 80, 0.03 g of potassium persulfate and 2g of ammonium chloride, adding water until the mixture is 100 g, and stirring for 0.5-1h to obtain a water-soluble polymer degradation agent solution (degradation agent 3);

2) preparation of water-soluble polymer degradation agent: firstly, 6g of ferrous lactate, 1g of nano ferrous sulfide (300-;

the degradation capability of the water-soluble polymer degradation agent on a zirconium cross-linked hydroxypropyl guar gum system is determined: 1) 484.65g of tap water is added into a liquid preparation container at normal temperature, then 2.25g of hydroxypropyl guar gum, 0.6g of sodium carbonate, 4g of potassium chloride, 2.5g of tetramethylammonium chloride, 2.5g of OP-10 and 0.5g of glutaraldehyde are added into the water liquid by using a MYP11-2A constant-temperature magnetic stirrer at the speed of 1000r/min while stirring, and after the addition, the mechanical stirring is carried out for 1 to 2 hours to form base liquid; 2) after the base liquid is prepared, 2g of sodium hydroxide is added to adjust the pH value of the base liquid to 9-13; 3) adding 3g of zirconium oxychloride in the total weight of the base solution, and stirring for 1-2 minutes by glass fat to obtain a zirconium cross-linked hydroxypropyl guar cross-linked polymer; according to the water-soluble polymer degradation agent: uniformly mixing zirconium cross-linked hydroxypropyl guar gum with the ratio of =1g:1g, placing the mixture in a blue screw thread bottle, and reacting in an oven at 150 ℃ for 0.5 h; the specific experimental results are shown in table 2.

Example 3

1) Preparation of water-soluble polymer degradation agent: completely dissolving 0.01 g of acrylic acid in 20 g of water, then adding 6.5 g of ferrous lactate, 1g of nano ferrous sulfide (100-200 nm), 0.02 g of phloroglucinol, 0.6g of Tween 80, 0.02 g of potassium persulfate and 2g of ammonium chloride, adding water until the mixture reaches 100 g, and heating at the temperature of 60-70 ℃ for 2-3h to obtain a water-soluble polymer degradation agent solution (degradation agent 5);

2) preparation of water-soluble polymer degradation agent: firstly adding 6.5 g of ferrous lactate, 1g of nano ferrous sulfide (100-200 nm), 0.02 g of phloroglucinol, 0.6g of Tween 80, 0.02 g of potassium persulfate and 2g of ammonium chloride into 20 g of water, then adding 0.01 g of acrylic acid, then adding water until the weight is 100 g, and stirring for 0.5-1h to obtain a water-soluble polymer degradation agent solution (degradation agent 6);

and (3) determining the degradation capability of the water-soluble polymer degradation agent on an aluminum cross-linked polyacrylamide system: stirring at normal temperature by using a MYP11-2A constant-temperature magnetic stirrer at the rotating speed of 1000r/min, adding 1900 ten thousand HPAM (sodium hydrogen phosphate) 0.2g into tap water 99.4 g while stirring, stirring for dissolving for 4h, adding aluminum citrate 0.4 g, and stirring for 30min for later use; according to the water-soluble polymer degradation agent: uniformly mixing aluminum crosslinked polyacrylamide with the weight ratio of =1g:1g, placing the mixture in a blue screw thread bottle, and reacting in a 65 ℃ oven for 2 hours; the specific experimental results are shown in table 3.

Example 4

1) Preparation of water-soluble polymer degradation agent: dissolving 0.01 g of acrylic acid in 10 g of water until the acrylic acid is completely dissolved, then adding 6g of ferrous lactate, 2g of nano ferrous sulfide (100-500 nm), 0.02 g of pyrogallol, 0.5g of Tween 80, 0.01 g of ammonium persulfate and 2g of ammonium chloride, adding water until the weight of the solution is 100 g, and heating at 60-70 ℃ for 2-3h to obtain a water-soluble polymer degradation agent solution (degradation agent 7);

2) preparation of water-soluble polymer degradation agent: firstly, 6g of ferrous lactate, 2g of nano ferrous sulfide (100-500 nm), 0.02 g of pyrogallol, 0.5g of Tween 80, 0.01 g of ammonium persulfate and 2g of ammonium chloride are dissolved in 10 g of water, then 0.01 g of acrylic acid is added, then water is added until the weight of the solution is 100 g, and the solution is stirred for 0.5 to 1 hour to obtain a water-soluble polymer degradation agent solution (degradation agent 8);

the degradation capability of the water-soluble polymer degradation agent on 1900 ten thousand HPAM is determined: stirring at normal temperature by using a MYP11-2A constant-temperature magnetic stirrer at the rotating speed of 1000r/min, adding 0.2g1900 ten thousand HPAM into 98 g of tap water while stirring, and stirring and dissolving for 4 hours for later use; according to the water-soluble polymer degradation agent: 1900 ten thousand HPAM solution is added in the ratio of 1g to 1g, the two solutions are mixed evenly and put into a blue screw thread bottle to react for 4 hours in a baking oven at 25 ℃; the results of the experiments are shown in Table 4.

Example 5

1) Preparation of water-soluble polymer degradation agent: completely dissolving 0.0125 g of acrylic acid in 20 g of water, then adding 6g of ferrous lactate, 1g of nano ferrous sulfide (300- & lt 500 & gtnm), 0.03 g of pyrogallol, 0.8 g of Tween 80, 0.03 g of ammonium persulfate and 2g of ammonium chloride, adding water until the weight is 100 g, and stirring for 0.5-1h to obtain a water-soluble polymer degradation agent solution (degradation agent 9);

2) preparation of water-soluble polymer degradation agent: firstly, 6g of ferrous lactate, 1g of nano ferrous sulfide (300-;

the degradation capability of the water-soluble polymer degradation agent on a zirconium cross-linked hydroxypropyl guar gum system is determined: 1) 484.65g of tap water is added into a liquid preparation container at normal temperature, then 2.25g of hydroxypropyl guar gum, 0.6g of sodium carbonate, 4g of potassium chloride, 2.5g of tetramethylammonium chloride, 2.5g of OP-10 and 0.5g of glutaraldehyde are added into the water liquid by using a MYP11-2A constant-temperature magnetic stirrer at the speed of 1000r/min while stirring, and after the addition, the mechanical stirring is carried out for 1 to 2 hours to form base liquid; 2) after the base liquid is prepared, 2g of sodium hydroxide is added to adjust the pH value of the base liquid to 9-13; 3) adding 3g of zirconium oxychloride in the total weight of the base solution, and stirring for 1-2 minutes by glass fat to obtain a zirconium cross-linked hydroxypropyl guar cross-linked polymer; according to the water-soluble polymer degradation agent: uniformly mixing zirconium cross-linked hydroxypropyl guar gum with the ratio of =1g:1g, placing the mixture in a blue screw thread bottle, and reacting in an oven at 150 ℃ for 0.5 h; the results of the experiments are shown in Table 5.

Example 6

1) Preparation of water-soluble polymer degradation agent: completely dissolving 0.013 g of acrylic acid in 20 g of water, then adding 6.5 g of ferrous lactate, 1g of nano ferrous sulfide (100-;

2) preparation of water-soluble polymer degradation agent: firstly, 6.5 g of ferrous lactate, 1g of nano ferrous sulfide (300-;

and (3) determining the degradation capability of the water-soluble polymer degradation agent on an aluminum cross-linked polyacrylamide system: stirring at normal temperature by using a MYP11-2A constant-temperature magnetic stirrer at the rotating speed of 1000r/min, adding 1900 ten thousand HPAM (sodium hydrogen phosphate) 0.2g into tap water 99.4 g while stirring, stirring for dissolving for 4h, adding aluminum citrate 0.4 g, and stirring for 30min for later use; according to the water-soluble polymer degradation agent: uniformly mixing aluminum crosslinked polyacrylamide with the weight ratio of =1g:1g, placing the mixture in a blue screw thread bottle, and reacting in a 65 ℃ oven for 2 hours; the results of the experiments are shown in Table 6.

Example 7

1) Preparation of water-soluble polymer degradation agent: completely dissolving 0.013 g of citric acid in 20 g of water, then adding 6.5 g of ferrous gluconate, 1g of nano ferrous sulfide (100-200 nm), 0.02 g of phloroglucinol, 0.6g of Tween 20, 0.02 g of ammonium persulfate and 2g of potassium chloride, adding water until the weight is 100 g, and stirring for 0.5-1h to obtain a water-soluble polymer degradation agent solution (degradation agent 13);

2) preparation of water-soluble polymer degradation agent: firstly, 6.5 g of ferrous gluconate, 1g of nano ferrous sulfide (100-200 nm), 0.02 g of phloroglucinol, 0.6g of Tween 20, 0.02 g of ammonium persulfate and 2g of potassium chloride are dissolved in 20 g of water, then 0.013 g of citric acid is added, finally water is added until the weight is 100 g, and the mixture is stirred for 0.5 to 1 hour to obtain a water-soluble polymer degradation agent solution (degradation agent 14);

and (3) determining the degradation capability of the water-soluble polymer degradation agent on an aluminum cross-linked polyacrylamide system: stirring at normal temperature by using a MYP11-2A constant-temperature magnetic stirrer at the rotating speed of 1000r/min, adding 1900 ten thousand HPAM (sodium hydrogen phosphate) 0.2g into tap water 99.4 g while stirring, stirring for dissolving for 4h, adding aluminum citrate 0.4 g, and stirring for 30min for later use; according to the water-soluble polymer degradation agent: uniformly mixing aluminum crosslinked polyacrylamide with the weight ratio of =1g:1g, placing the mixture in a blue screw thread bottle, and reacting in a 65 ℃ oven for 2 hours; the results of the experiments are shown in Table 7.

Example 8

1) Preparation of water-soluble polymer degradation agent: dissolving 0.01 g of citric acid in 10 g of water until the citric acid is completely dissolved, then adding 6g of ferrous gluconate, 2g of nano ferrous sulfide (100-200 nm), 0.02 g of pyrogallol, 0.5g of Tween 80, 0.01 g of ammonium persulfate and 2g of ammonium chloride, adding water until the weight of the solution is 100 g, and stirring for 0.5-1h to obtain a water-soluble polymer degradation agent solution (degradation agent 15);

2) preparation of water-soluble polymer degradation agent: firstly, 6g of ferrous gluconate, 2g of nano ferrous sulfide (100-200 nm), 0.02 g of pyrogallol, 0.5g of Tween 80, 0.01 g of ammonium persulfate and 2g of ammonium chloride are dissolved in 10 g of water, then 0.01 g of citric acid is added, then water is added until the weight of the solution is 100 g, and the solution is stirred for 0.5 to 1 hour to obtain a water-soluble polymer degradation agent solution (degradation agent 16);

the degradation capability of the water-soluble polymer degradation agent on 1900 ten thousand HPAM is determined: stirring at normal temperature by using a MYP11-2A constant-temperature magnetic stirrer at the rotating speed of 1000r/min, adding 0.2g1900 ten thousand HPAM into 98 g of tap water while stirring, and stirring and dissolving for 4 hours for later use; according to the water-soluble polymer degradation agent: 1900 ten thousand HPAM solution is added in the ratio of 1g to 1g, the two solutions are mixed evenly and put into a blue screw thread bottle to react for 4 hours in a baking oven at 25 ℃; the results of the experiments are shown in Table 8.