Environment-friendly branched hydroxylamine cross-linked jelly as well as preparation method and application thereof

Abstract

The invention discloses an environment-friendly branched hydroxylamine cross-linked jelly, which is composed of the following components: 0.3%-1.0% of a water-soluble polymer, 0.3%-0.8% of a branched hydroxylamine cross-linking agent, 0.1%-0.3% of a gelling accelerator, 0.5%-1.0% of a nanoparticle stabilizer, 0.1%-0.5% of a deoxidant, and the balance of water. The invention discloses a preparation method of environment-friendly branched hydroxylamine cross-linked jelly. The preparation method comprises the following steps: (1) dividing water into two parts according to a formula ratio; (2) adding a formula amount of water-soluble polymer into one part of water, and stirring until the water-soluble polymer is completely dissolved to obtain a water-soluble polymer solution; (3) adding a formula amount of branched hydroxylamine cross-linking agent, a formula amount of gelatinizing accelerant, a formula amount of nano-particle stabilizer and a formula amount of deoxidant into the other part of water, dissolving, and uniformly mixing to obtain a mixed solution; and (4) pouring the mixed solution into the water-soluble polymer solution, and continuously stirring to obtain the environment-friendly branched hydroxylamine cross-linked gel solution.

Description

Technical Field

[0001] The present invention belongs to the field of oilfield chemistry, and particularly relates to an environmentally friendly branched hydroxylamine crosslinked gel and its preparation method and application. Background Art

[0002] At present, polymer gels are the dominant system for profile control and water plugging at home and abroad, accounting for more than 80% of the field applications. However, polymer gels still face the following technical problems: 1. In the gel systems of domestic oilfields in China, the crosslinking agents are mainly organic chromium and phenolic aldehyde crosslinking agents, both of which have varying degrees of biological toxicity and will cause a certain degree of pollution to the environment, which does not conform to the principle of green and environmental protection in oilfield development; 2. With the continuous deepening of water injection development, the remaining oil in the near-wellbore area is getting less and less, and the profile control and water plugging idea has changed from the traditional "near plugging" to "far profile control", so higher requirements are put forward for the migration ability of gels in the formation. Chromium gels generally have a short gelation time, and trivalent chromium ions have serious adsorption problems in the formation and cannot migrate to the deep part of the formation. In contrast, phenolic aldehyde gels gel more slowly, but the controllability of phenolic aldehyde gel formation is low, and the gelation time is mainly achieved by adjusting the component concentration.

[0003] Therefore, people have turned to environmentally friendly polymer gels at present. Polyethyleneimine is a typical environmentally friendly crosslinking agent. Chinese Patent Application Publication No. CN106634907A discloses a polyethyleneimine-based water plugging and profile control agent, which is composed of the following components: partially hydrolyzed polyacrylamide 0.05%-5%, crosslinking agent polyethyleneimine 0.01%-0.5%, gelation delaying agent 0.05%-1%, stabilizer 0.1%-3%, regulator 0.01%-0.05%, and the balance is water, and the sum of each component is 100% by weight percentage. The present invention also relates to a preparation method of the polyethyleneimine-based water plugging and profile control agent. However, the plugging agent in the above technical solution has a gelation time greater than 6 days at 150°C, and the gel strength is greater than 0.075 MPa. Due to the relatively high cost of polyethyleneimine, this system has not been widely promoted and applied in China at present.

[0004] Compared with trivalent chromium ions, zirconium ions have relatively low biological toxicity and can be used as an environmentally friendly cross-linking agent. Chinese invention patent CN1003048B discloses a water plugging agent composed of a gelling agent polyacrylamide (PAM) or methylene polyacrylamide (MPAM) and a cross-linking agent inorganic zirconium compound. Inorganic zirconium compounds include zirconium oxychloride, zirconium tetrachloride, zirconium sulfate, zirconium nitrate, etc. The plugging agent can be used for oil well water plugging and water injection well profile adjustment, but the gelling time is short and a double liquid injection process is required, which cannot achieve deep plugging and adjustment. Subsequently, a gel system cross-linked with organic zirconium was gradually formed. Chinese invention patent CN102936490B discloses a method for preparing an environmentally friendly multi-scale zirconium gel dispersion plugging agent. The plugging agent is composed of a non-ionic polyacrylamide aqueous solution and industrial-grade zirconium acetate, and the gelling time is 102 minutes at 30°C. Even though acetate can complex zirconium ions to a certain extent and slow down the release rate of zirconium ions, the plugging agent still gels too quickly at low temperatures and cannot be used directly as a deep plugging agent. This type of plugging agent is generally ground with a colloid mill after gelling to make a millimeter-scale gel dispersion before being injected into the formation.

[0005] Chinese invention patent application CN103131399A discloses a method for preparing an environmentally friendly plant gum plugging agent, which is composed of konjac powder, xanthan gum powder and sodium carbonate. The gelling components are dissolved, dried and ground to obtain plant gum dry powder, which swells at 50°C-90°C for 12 hours-10 days to form a plugging agent. This type of plugging agent is gelled in the form of physical cross-linking, which avoids the introduction of toxic materials into the system, and the polymer used is extracted from natural plants, so the system is environmentally friendly and non-toxic. However, physical gels are very sensitive to temperature, hydrogen bonds are destroyed at high temperatures, and the strength of the gel is sharply reduced.

[0006] In general, the environmentally friendly cross-linking agents in the currently disclosed technologies are difficult to take into account the requirements of the gel plugging agent for slow cross-linking, thermal stability and environmental protection. Summary of the invention

[0007] Purpose of the invention: In view of the above-mentioned deficiencies in the prior art, the present invention provides an environmentally friendly branched hydroxylamine cross-linked jelly and its preparation method and application. The present invention uses conventional water-soluble polymers and a class of environmentally friendly branched hydroxylamine cross-linking agents to construct a jelly system, and by adding nanoparticle stabilizers and deoxidizers, provides a jelly system suitable for temperatures of 60°C-90°C and a mineralization degree of less than 20,000.

[0008] Technical solution: An environmentally friendly branched hydroxylamine cross-linked gel, which is composed of the following components by mass percentage:

[0009] 0.3%-1.0% water-soluble polymer, 0.3%-0.8% branched hydroxylamine crosslinking agent, 0.1%-0.3% gelling accelerator, 0.5%-1.0% nanoparticle stabilizer, 0.1%-0.5% deoxidizer, and the balance is water. Further, the water-soluble polymer is partially hydrolyzed polyacrylamide or acrylamide-(2-acrylamide-2-methylpropanesulfonic acid) copolymer.

[0010] Furthermore, the viscosity average molecular weight of the partially hydrolyzed polyacrylamide is 8 million to 20 million, preferably 12 million to 15 million.

[0011] Furthermore, the hydrolysis degree of the partially hydrolyzed polyacrylamide is 3%-20%, preferably 10-15%. Furthermore, the viscosity average molecular weight of the acrylamide-(2-acrylamide-2-methylpropanesulfonic acid) copolymer is 8 million-20 million, preferably 12 million-15 million.

[0012] Furthermore, the structural formula of the branched hydroxylamine crosslinking agent is as follows:

[0013] in:

[0014] R is one of pyrimidine, pyrazine, and s-triazine;

[0015] R' is methyl or ethyl.

[0016] Furthermore, the gelling accelerator is one of citric acid, lactic acid, acetic acid and ammonium chloride, preferably lactic acid.

[0017] Furthermore, the nanoparticle stabilizer is silica sol, preferably silica sol Sw-30.

[0018] Furthermore, the median particle size of the nanoparticle stabilizer is 10nm-20nm.

[0019] Furthermore, the deoxidizer is one of thiourea, sodium sulfite and urea, preferably thiourea.

[0020] Furthermore, the water has a mineralization degree of less than 2×10 4 mg / L of water.

[0021] The method for preparing the environmentally friendly branched hydroxylamine cross-linked jelly described in any one of the above items comprises the following steps:

[0022] (1) Divide the amount of water in the formula into two parts;

[0023] (2) adding a water-soluble polymer in a formula amount to one portion of the water, and stirring at room temperature for at least 4 hours until the water is completely dissolved to obtain a water-soluble polymer solution;

[0024] (3) adding a formulated amount of a branched hydroxylamine crosslinker, a formulated amount of a gelling accelerator, a formulated amount of a nanoparticle stabilizer, and a formulated amount of an oxygen scavenger to another portion of water, dissolving and mixing the mixture to obtain a mixed solution;

[0025] (4) Pour the mixed solution obtained in step (3) into the water-soluble polymer solution obtained in step (2), and continue stirring for at least 1 hour to obtain an environmentally friendly branched hydroxylamine cross-linked gel solution.

[0026] An environmentally friendly branched hydroxylamine cross-linked jelly is prepared by the above-mentioned preparation method.

[0027] The above-mentioned environmentally friendly branched hydroxylamine cross-linked gel is used as a water plugging and profile control agent in medium and high permeability oil reservoirs.

[0028] The effects of each component of the present invention are as follows:

[0029] After the water-soluble polymer of the present invention, partially hydrolyzed polyacrylamide or acrylamide-(2-acrylamide-2-methylpropanesulfonic acid) copolymer, is dissolved in water, the amide groups on the molecules thereof can react with an organic crosslinking agent to form a gel.

[0030] The branched hydroxylamine crosslinking agent in the present invention is a type of environmentally friendly crosslinking agent. During the synthesis process, polyamines with low biological toxicity are used as raw materials to replace phenol in conventional phenolic crosslinking agents, thereby achieving an environmentally friendly upgrade of the plugging agent; in addition, the crosslinking sites are shielded by chemical reactions, so that the crosslinking sites are slowly released under reservoir conditions, thereby extending the gelling time of the gel and achieving the purpose of deep plugging and adjustment.

[0031] The gelling accelerator in the present invention is a kind of weak acid, which adjusts the pH value of the gelling liquid system to weak acidity to promote the reaction between the amide groups on the polymer molecules and the hydroxymethyl groups on the crosslinking agent molecules, thereby increasing the crosslinking density of the jelly, thereby increasing the strength of the jelly.

[0032] The nanoparticle stabilizer described in the present invention is silica sol, preferably silica sol Sw-30, which can form hydrogen bonds with the amide groups on the polymer molecules to increase the density of the three-dimensional network structure of the jelly. At the same time, the nanoparticles in the silica sol can form a certain steric hindrance after being adsorbed on the polymer molecules, which can delay the cross-linking reaction of the jelly on the one hand, and delay the further hydrolysis and oxidative degradation of the amide groups on the other hand, thereby enhancing the stability of the jelly.

[0033] The preferred oxygen scavenger in the present invention can act as a sacrificial agent to preferentially react with dissolved oxygen in water to avoid oxidative degradation of the polymer, thereby improving the stability of the jelly.

[0034] Beneficial effects: The environmentally friendly branched hydroxylamine cross-linked jelly disclosed in the present invention and its preparation method and application have the following beneficial effects:

[0035] 1. Able to achieve environmentally friendly upgrades of existing technologies;

[0036] 2. Water plugging and profile control in medium and high permeability reservoirs can realize the diversion of subsequent injected fluid flow, expand the sweep coefficient, and improve the crude oil recovery rate.

[0037] 3. The gel plugging agent provided by the present invention has a gelling time of 112 hours to 280 hours under formation conditions of 60°C to 90°C, and can achieve deep plugging.

[0038] 4. The dehydration rate of the present invention is less than 10% after aging for 180 days, and the plugging period is long and the plugging efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flow chart of a method for preparing an environmentally friendly branched hydroxylamine cross-linked jelly. DETAILED DESCRIPTION

[0040] The specific embodiments of the present invention are described in detail below.

[0041] Unless otherwise specified, the methods are conventional methods. Unless otherwise specified, the raw materials can be obtained from public commercial channels.

[0042] Example 1

[0043] An environmentally friendly branched hydroxylamine cross-linked gel, composed of the following components by mass percentage:

[0044] 0.3% water-soluble polymer, 0.3% branched hydroxylamine crosslinking agent, 0.1% gelling accelerator, 0.5% nanoparticle stabilizer, 0.1% deoxidizer, and the balance is water.

[0045] Furthermore, the water-soluble polymer is partially hydrolyzed polyacrylamide.

[0046] Furthermore, the viscosity average molecular weight of the partially hydrolyzed polyacrylamide is 8 million. In another embodiment, the viscosity average molecular weight of the partially hydrolyzed polyacrylamide is 12 million.

[0047] Furthermore, the degree of hydrolysis of the partially hydrolyzed polyacrylamide is 3%. In another embodiment, the degree of hydrolysis of the partially hydrolyzed polyacrylamide is 10%.

[0048] Furthermore, the structural formula of the branched hydroxylamine crosslinking agent is as follows:

[0049] in:

[0050] R is pyrimidine;

[0051] R' is methyl.

[0052] Furthermore, the gelling accelerator is lactic acid.

[0053] Furthermore, the nanoparticle stabilizer is silica sol Sw-30.

[0054] Furthermore, the median particle size of the nanoparticle stabilizer is 10 nm.

[0055] Furthermore, the deoxidizer is thiourea.

[0056] Furthermore, the water has a mineralization degree of less than 2×10 4 mg / L of water.

[0057] The method for preparing the environmentally friendly branched hydroxylamine cross-linked jelly described in any one of the above items comprises the following steps:

[0058] (1) Divide the amount of water in the formula into two parts;

[0059] (2) adding a water-soluble polymer in a formula amount to one portion of the water, and stirring at room temperature for 4 hours until the water is completely dissolved to obtain a water-soluble polymer solution;

[0060] (3) adding a formulated amount of a branched hydroxylamine crosslinker, a formulated amount of a gelling accelerator, a formulated amount of a nanoparticle stabilizer, and a formulated amount of an oxygen scavenger to another portion of water, dissolving and mixing the mixture to obtain a mixed solution;

[0061] (4) Pour the mixed solution obtained in step (3) into the water-soluble polymer solution obtained in step (2), and continue stirring for 1 hour to obtain an environmentally friendly branched hydroxylamine cross-linked gel solution.

[0062] An environmentally friendly branched hydroxylamine cross-linked jelly is prepared by the above-mentioned preparation method.

[0063] The above-mentioned environmentally friendly branched hydroxylamine cross-linked gel is used as a water plugging and profile control agent in medium and high permeability oil reservoirs.

[0064] Example 2

[0065] An environmentally friendly branched hydroxylamine cross-linked gel, composed of the following components by mass percentage:

[0066] 0.6% water-soluble polymer, 0.5% branched hydroxylamine crosslinking agent, 0.2% gelling accelerator, 0.7% nanoparticle stabilizer, 0.3% deoxidizer, and the balance is water.

[0067] Furthermore, the water-soluble polymer is partially hydrolyzed polyacrylamide.

[0068] Furthermore, the viscosity average molecular weight of the partially hydrolyzed polyacrylamide is 20 million. In another embodiment, the viscosity average molecular weight of the partially hydrolyzed polyacrylamide is 15 million. In another embodiment, the viscosity average molecular weight of the partially hydrolyzed polyacrylamide is 13 million.

[0069] Furthermore, the partially hydrolyzed polyacrylamide has a degree of hydrolysis of 20%. In another embodiment, the partially hydrolyzed polyacrylamide has a degree of hydrolysis of 15%. In another embodiment, the partially hydrolyzed polyacrylamide has a degree of hydrolysis of 13%.

[0070] Furthermore, the structural formula of the branched hydroxylamine crosslinking agent is as follows:

[0071] in:

[0072] R is pyrazine;

[0073] R' is ethyl.

[0074] Furthermore, the gelling accelerator is citric acid.

[0075] Furthermore, the nanoparticle stabilizer is silica sol Sw-30.

[0076] Furthermore, the median particle size of the nanoparticle stabilizer is 15 nm.

[0077] Furthermore, the deoxidizer is sodium sulfite.

[0078] Furthermore, the water has a mineralization degree of less than 2×10 4 mg / L of water.

[0079] The method for preparing the environmentally friendly branched hydroxylamine cross-linked jelly described in any one of the above items comprises the following steps:

[0080] (1) Divide the amount of water in the formula into two parts;

[0081] (2) adding a water-soluble polymer in a formula amount to one portion of the water, and stirring at room temperature for 6 hours until the water is completely dissolved to obtain a water-soluble polymer solution;

[0082] (3) adding a formulated amount of a branched hydroxylamine crosslinker, a formulated amount of a gelling accelerator, a formulated amount of a nanoparticle stabilizer, and a formulated amount of an oxygen scavenger to another portion of water, dissolving and mixing the mixture to obtain a mixed solution;

[0083] (4) Pour the mixed solution obtained in step (3) into the water-soluble polymer solution obtained in step (2), and continue stirring for 2 hours to obtain an environmentally friendly branched hydroxylamine cross-linked gel solution.

[0084] An environmentally friendly branched hydroxylamine cross-linked jelly is prepared by the above-mentioned preparation method.

[0085] The above-mentioned environmentally friendly branched hydroxylamine cross-linked gel is used as a water plugging and profile control agent in medium and high permeability oil reservoirs.

[0086] Example 3

[0087] An environmentally friendly branched hydroxylamine cross-linked gel, composed of the following components by mass percentage:

[0088] 1.0% water-soluble polymer, 0.8% branched hydroxylamine crosslinking agent, 0.3% gelling accelerator, 1.0% nanoparticle stabilizer, 0.5% deoxidizer, and the balance is water.

[0089] Furthermore, the water-soluble polymer is acrylamide-(2-acrylamide-2-methylpropanesulfonic acid) copolymer.

[0090] Furthermore, the viscosity average molecular weight of the acrylamide-(2-acrylamide-2-methylpropane sulfonic acid) copolymer is 8 million. In another embodiment, the viscosity average molecular weight of the acrylamide-(2-acrylamide-2-methylpropane sulfonic acid) copolymer is 20 million. In another embodiment, the viscosity average molecular weight of the acrylamide-(2-acrylamide-2-methylpropane sulfonic acid) copolymer is 12 million. In another embodiment, the viscosity average molecular weight of the acrylamide-(2-acrylamide-2-methylpropane sulfonic acid) copolymer is 15 million. In another embodiment, the viscosity average molecular weight of the acrylamide-(2-acrylamide-2-methylpropane sulfonic acid) copolymer is 14 million.

[0091] Furthermore, the structural formula of the branched hydroxylamine crosslinking agent is as follows:

[0092] in:

[0093] R is s-triazine;

[0094] R' is methyl.

[0095] Furthermore, the gelling accelerator is acetic acid. In another embodiment, the gelling accelerator is ammonium chloride.

[0096] Furthermore, the nanoparticle stabilizer is silica sol Sw-30.

[0097] Furthermore, the median particle size of the nanoparticle stabilizer is 20 nm.

[0098] Furthermore, the deoxidizer is urea.

[0099] Furthermore, the water has a mineralization degree of less than 2×104 mg / L of water.

[0100] The method for preparing the environmentally friendly branched hydroxylamine cross-linked jelly described in any one of the above items comprises the following steps:

[0101] (1) Divide the amount of water in the formula into two parts;

[0102] (2) adding a water-soluble polymer in a formula amount to one portion of the water, and stirring at room temperature for 8 hours until the water is completely dissolved to obtain a water-soluble polymer solution;

[0103] (3) adding a formulated amount of a branched hydroxylamine crosslinker, a formulated amount of a gelling accelerator, a formulated amount of a nanoparticle stabilizer, and a formulated amount of an oxygen scavenger to another portion of water, dissolving and mixing the mixture to obtain a mixed solution;

[0104] (4) Pour the mixed solution obtained in step (3) into the water-soluble polymer solution obtained in step (2), and continue stirring for 2 hours to obtain an environmentally friendly branched hydroxylamine cross-linked gel solution.

[0105] An environmentally friendly branched hydroxylamine cross-linked jelly is prepared by the above-mentioned preparation method.

[0106] The above-mentioned environmentally friendly branched hydroxylamine cross-linked gel is used as a water plugging and profile control agent in medium and high permeability oil reservoirs.

[0107] Comparative Example 1

[0108] The preparation method of the environmentally friendly branched hydroxylamine cross-linked jelly comprises the following steps:

[0109] Add 0.4 g of partially hydrolyzed polyacrylamide to 79.6 g of water and stir at room temperature for 4 hours until the polymer is completely dissolved;

[0110] 0.3 g of branched hydroxylamine crosslinking agent, 0 g of lactic acid, 0.5 g of silica sol Sw-30, and 0.1 g of thiourea were added to 19.1 g of water, and the solution was poured into the above polymer solution, and stirring was continued for 1 hour to obtain an environmentally friendly branched hydroxylamine crosslinking gel.

[0111] in:

[0112] The structural formula of the branched hydroxylamine cross-linking agent is as follows:

[0113] in:

[0114] R is pyrimidine;

[0115] R' is methyl.

[0116] Comparative Example 2

[0117] The preparation method of the environmentally friendly branched hydroxylamine cross-linked jelly comprises the following steps:

[0118] Add 0.6 g of partially hydrolyzed polyacrylamide to 79.4 g of water and stir at room temperature for 4 hours until the polymer is completely dissolved;

[0119] 0.5 g of branched hydroxylamine crosslinking agent and 0.1 g of lactic acid were added to 19.4 g of water, and the solution was poured into the above polymer solution, and stirring was continued for 1 hour to obtain an environmentally friendly branched hydroxylamine crosslinking gel, wherein:

[0120] The structural formula of the branched hydroxylamine cross-linking agent is as follows:

[0121] in:

[0122] R is pyrazine;

[0123] R' is ethyl.

[0124] Performance characterization:

[0125] The branched hydroxylamine crosslinking agent jelly prepared by the methods described in Examples 1 to 3 and Comparative Examples 1 to 2 was used to measure the jelly gelling time, storage modulus after gelling, and dehydration rate after aging for 180 days.

[0126] (1) Pour 50g of gelling liquid into a stoppered heat-resistant glass tube and age it in an oven. Take out the glass tube at regular intervals and invert it; it can be observed that the fluidity of the gel gradually decreases with the aging time. When the upper edge of the gel cannot touch the glass tube stopper after the glass tube is inverted, the gel is considered to be gelled, and the aging time at this time is recorded as the gelling time, where:

[0127] The environmentally friendly branched hydroxylamine cross-linked gel solution prepared in Example 1 was poured into a stoppered heat-resistant glass tube, and placed in a 60° C. oven to age into gel;

[0128] The environmentally friendly branched hydroxylamine cross-linked gel solution prepared in Example 2 was poured into a stoppered heat-resistant glass tube, and placed in a 75° C. oven to age into gel;

[0129] The environmentally friendly branched hydroxylamine cross-linked gel prepared in Example 3 was poured into a stoppered heat-resistant glass tube, and placed in a 90° C. oven to age into gel;

[0130] The environmentally friendly branched hydroxylamine cross-linked gel prepared in Comparative Example 1 was poured into a stoppered heat-resistant glass tube, and placed in a 60° C. oven to age into gel;

[0131] The environmentally friendly branched hydroxylamine cross-linked jelly prepared in Comparative Example 2 was poured into a stoppered heat-resistant glass tube, and placed in a 90° C. oven to age into a gel.

[0132] (2) After aging for 5 days, the gel was taken out and the storage modulus of the gel was measured at 1% strain and 1 Hz frequency using an Anton Paar MCR 101 shear rheometer.

[0133] (3) After aging for 180 days, the glass tube was taken out, the mass of water in the glass tube was weighed, and the dehydration rate of the gel was measured:

[0134] Dehydration rate = water mass / 50g×100%

[0135] The experimental results are shown in Table 1.

[0136] Table 1 Experimental results

[0137] serial number Gelation time / h Storage modulus / Pa 180-day dehydration rate / % Example 1 280 3.9 4.5％ Example 2 184 15.2 5.3％ Example 3 118 22.5 8.8％ Comparative Example 1 No glue - - Comparative Example 2 136 14.6 32％

[0138] It can be seen from the experimental results in Table 1 that in Examples 1 to 3, as the concentration of the polymer and the crosslinking agent in the gel increases and the aging time increases, the gelling time of the gel decreases, the storage modulus increases, and the dehydration rate increases. The gelling time of the environmentally friendly branched hydroxylamine crosslinked gel of the present invention is between 118 hours and 280 hours, the storage modulus after gelling is 3.9Pa-22.5Pa, and the dehydration rate is less than 10% after aging for 180 days at 60℃-90℃.

[0139] In Comparative Example 1, no gelling accelerator lactic acid was added, and the frozen gel could not be gelled at 60°C;

[0140] In Comparative Example 2, no nanoparticle stabilizer and deoxidizer were added, and the dehydration rate of the gel after aging for 180 days reached 32%, which was much higher than that of Examples 1 to 3.

[0141] The above describes the embodiments of the present invention in detail. However, the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. An environmentally friendly branched hydroxylamine cross-linked gel, It is characterized in that In terms of mass percentage, it is composed of the following components: The invention comprises 0.3%-1.0% of water-soluble polymer, 0.3%-0.8% of branched hydroxylamine crosslinking agent, 0.1%-0.3% of gelling accelerator, 0.5%-1.0% of nanoparticle stabilizer, 0.1%-0.5% of deoxidizer, and the balance is water.

2. An environmentally friendly branched hydroxylamine cross-linked jelly as claimed in claim 1, It is characterized in that The water-soluble polymer is partially hydrolyzed polyacrylamide or acrylamide-(2-acrylamide-2-methylpropanesulfonic acid) copolymer.

3. An environmentally friendly branched hydroxylamine cross-linked jelly as claimed in claim 2, It is characterized in that The viscosity average molecular weight of the partially hydrolyzed polyacrylamide is 8 million to 20 million, preferably 12 million to 15 million.

4. An environmentally friendly branched hydroxylamine cross-linked jelly as claimed in claim 2, It is characterized in that The degree of hydrolysis of the partially hydrolyzed polyacrylamide is 3%-20%, preferably 10-15%.

5. An environmentally friendly branched hydroxylamine cross-linked jelly as claimed in claim 2, It is characterized in that The viscosity average molecular weight of the acrylamide-(2-acrylamide-2-methylpropanesulfonic acid) copolymer is 8 million to 20 million, preferably 12 million to 15 million.

6. An environmentally friendly branched hydroxylamine cross-linked jelly as claimed in claim 1, It is characterized in that The structural formula of the branched hydroxylamine cross-linking agent is as follows: in: R is one of pyrimidine, pyrazine, and s-triazine; R' is methyl or ethyl.

7. An environmentally friendly branched hydroxylamine cross-linked jelly as claimed in claim 1, It is characterized in that The gelling accelerator is one of citric acid, lactic acid, acetic acid and ammonium chloride, preferably lactic acid.

8. An environmentally friendly branched hydroxylamine cross-linked jelly as claimed in claim 1, It is characterized in that The nanoparticle stabilizer is silica sol, preferably silica sol Sw-30.

9. The environmentally friendly branched hydroxylamine cross-linked jelly according to claim 1, It is characterized in that The median particle size of the nanoparticle stabilizer is 10nm-20nm.

10. The environmentally friendly branched hydroxylamine cross-linked jelly according to claim 1, It is characterized in that The deoxidizer is one of thiourea, sodium sulfite and urea, preferably thiourea.

11. An environmentally friendly branched hydroxylamine cross-linked jelly as claimed in claim 1, It is characterized in that The water has a mineralization of less than 2×10 4 mg / L of water.

12. A method for preparing the environmentally friendly branched hydroxylamine cross-linked jelly according to any one of claims 1 to 11, It is characterized in that Here are the steps: (1) Divide the amount of water in the formula into two parts; (2) adding a water-soluble polymer in a formula amount to one portion of the water, and stirring at room temperature for at least 4 hours until the water is completely dissolved to obtain a water-soluble polymer solution; (3) adding a formulated amount of a branched hydroxylamine crosslinker, a formulated amount of a gelling accelerator, a formulated amount of a nanoparticle stabilizer, and a formulated amount of an oxygen scavenger to another portion of water, dissolving and mixing the mixture to obtain a mixed solution; (4) Pour the mixed solution obtained in step (3) into the water-soluble polymer solution obtained in step (2), and continue stirring for at least 1 hour to obtain an environmentally friendly branched hydroxylamine cross-linked gel solution.

13. An environmentally friendly branched hydroxylamine cross-linked gel, It is characterized in that Prepared by the preparation method described in claim 12.

14. Use of the environmentally friendly branched hydroxylamine cross-linked gel according to claims 1-11 and 13 as a water plugging and profile control agent in medium and high permeability oil reservoirs.

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