A gel plugging agent, its preparation method and application

Abstract

The application discloses a gel blocking agent which is composed of 0.3-1.2 parts of dendritic polymers, 0.2-1.5 parts of cross-linking agents, 0.2-1.5 parts of oxygen scavengers and 80-110 parts of water. The application discloses a preparation method of the gel blocking agent, which comprises the following steps: (1) synthesis of the dendritic polymers; (2) preparation of the gel blocking agent: uniformly mixing formula amount of the dendritic polymers prepared in the step (1), formula amount of the cross-linking agents, formula amount of the oxygen scavengers and formula amount of water, so that the gel blocking agent is obtained. The application further discloses application of the gel blocking agent as a water plugging and profile control agent in thick oil exploitation. The application has the following beneficial effects: (1) high plugging strength; (2) temperature resistance of 120-200 DEG C, good high-temperature stability and long plugging effective period; (3) strong adaptability to oil reservoirs.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of heavy oil exploitation, and particularly relates to a gel plugging agent and a preparation method and application thereof. BACKGROUND

[0002] China is rich in heavy oil resources, and the exploitation of heavy oil reservoirs is mainly by water drive and thermal recovery. For example, Chinese patent application CN110863808A discloses a method for enhancing the efficiency of water drive of heavy oil by electric heating, which first fixes an electric heating pipe or an electric heating cable in a ring-like manner outside an insulated pipe with a groove, and then lowers the pipe string to the target oil reservoir site through the production pipe column, expands the insulated pipe to make the heating pipe closely adhere to the production casing, and heats the near-wellbore formation; after the heating distance reaches the preset value, the heating is continued, and the heating power is adjusted to continuously reduce the viscosity, flow resistance and mobility ratio of heavy oil in the vicinity of the production well; the ordinary heavy oil water drive recovery process is started, and displacement fluid is injected into the injection well to displace the crude oil in the formation to the direction of the production well; the crude oil, water and gas flowing to the production well are lifted to the ground surface by the lifting device in the production well. Chinese patent application CN108868718A discloses a combined thermal recovery method for heavy oil reservoirs with a gas cap, which realizes heating at the top of the oil layer by igniting the gas cap, heats the entire oil layer by using the heat generated by the combustion of the gas layer at the top, reduces the viscosity of the crude oil at the contact surface between the gas cap and the heavy oil layer, and realizes the interwell communication between the vertical well and the horizontal well. At the same time, the flue gas produced after combustion further reduces the viscosity of the heavy oil and provides energy for the entire reservoir.

[0003] For water-driven heavy oil, after years of exploitation, major oilfields have entered the high water cut stage or even the ultra-high water cut stage, high-permeability zones are developed, injected water breaks through, and it is difficult to start the low-permeability oil layers, and the sweep efficiency is low. For thermal recovery of heavy oil, most of the heavy oil reservoirs in Shengli, Xinjiang and Henan oilfields in China have entered the high-cycle huff and puff stage, and steam overlap is serious. At the same time, affected by reservoir heterogeneity, etc., steam is easy to migrate along high-permeability zones, resulting in low oil-steam ratio, and even steam channeling. Water plugging and profile control technology is one of the main technologies for plugging high-permeability zones, improving sweep efficiency and improving reservoir producing degree. Gel plugging and profile control has become one of the leading technologies for water plugging and profile control due to its good injectivity and high plugging strength.

[0004] The gel blocking agent currently applied in China mainly uses "polymer + crosslinking agent", and the polymer used is mainly a linear acrylamide homopolymer or copolymer, which reacts with the crosslinking agent to form a high-strength gel with a three-dimensional network structure. Chinese invention patent application CN 111087992A provides a gel blocking agent composition and its preparation method and application. The gel blocking agent composition comprises: an acrylamide polymer, a water-soluble melamine formaldehyde resin, an oxygen scavenger, a urea compound and water, the urea compound has a structure shown in formula (1) and / or formula (2), wherein R1 and R2 are each independently selected from hydrogen or 2-propynyl; R3, R4 are each independently selected from oxygen, sulfur or imino. The invention mainly solves the problem of realizing water plugging for a long time at a higher temperature, but the gel blocking agent composition provided by the invention is prepared from acrylamide polymers and the like, and has poor shear resistance, large strength loss during entering the deep formation, and limited throughput effect.

[0005] After decades of continuous development, the oil saturation of the near-well region of various heavy oil reservoirs is low, and the remaining oil is enriched in the interwell or deep formation, so it is necessary for the gel blocking agent to enter the deep formation for high-strength plugging. The shear resistance and plugging strength of the gel blocking agent are required to be higher and higher. However, the gel blocking agent formed by polyacrylamide polymer is greatly affected by shear, and the viscosity loss is as high as 40-80% due to the influence of pore throat shear during formation flow, which is difficult to achieve high-strength and long-acting plugging in the deep formation, thereby affecting the development effect of heavy oil. SUMMARY

[0006] The present application discloses a gel blocking agent and its preparation method and application, which can be used for plugging high-permeability channels and improving sweep efficiency during heavy oil exploitation. The gel blocking agent has a viscosity retention rate of 90% or more after high-speed shearing, a plugging strength of 5-20 MPa / m at 50-120℃, can resist temperatures of 120-200℃, and has a plugging strength of 3-10 MPa / m after being aged at 120℃ for 180 days or at 200℃ for 30 days. It is suitable for formation water with a salinity of 0-50000 mg / L, and calcium and magnesium ions of 0-3000 mg / L, and is suitable for reservoir temperatures of 50-120℃. -1

[0007] Technical solution: A gel blocking agent, consisting of the following components in parts by weight:

[0008] 0.3-1.2 parts of dendritic polymer;

[0009] 0.2-1.5 parts of crosslinking agent;

[0010] 0.2-1.5 parts of oxygen scavenger;

[0011] 80-110 parts of water. ​

[0012] Further, it consists of the following components:

[0013] 0.4-0.6 parts of dendritic polymer;

[0014] 0.5-1 part of crosslinking agent;

[0015] 0.5-0.8 parts of oxygen scavenger;

[0016] 90-100 parts of water.

[0017] Further, the structure of the dendritic polymer is shown in formula (1):

[0018]

[0019] wherein: a, b, c, d, e, f, g, h are any integer or decimal number in the range of 400-3800, preferably a, b, c, d, e, f, g, h are any integer or decimal number in the range of 1000-2000;

[0020] • is a polymer chain structure, and the specific structure is shown in formula (2) or formula (3) or formula (4):

[0021]

[0022]

[0023] wherein: x is any integer or decimal number in the range of 210-7800, preferably any integer or decimal number in the range of 500-5300;

[0024] y is any integer or decimal number in the range of 270-10000, preferably any integer or decimal number in the range of 550-6800;

[0025] z is any integer or decimal number in the range of 250-9200, preferably any integer or decimal number in the range of 500-6200.

[0026] Further, the weight average molecular weight of the dendritic polymer is 0.8×10 6 -6×10 6 , preferably 1.6×10 6 -4×10 6 .

[0027] Further, the crosslinking agent is one or more of formaldehyde, paraformaldehyde, hexamethylenetetramine, phenol, m-dihydroxybenzene, p-dihydroxybenzene, water-soluble phenolic resin, urea-formaldehyde resin, and organic chromium, preferably one or more of water-soluble phenolic resin and organic chromium.

[0028] Further, the cross-linking agent is a combination of water-soluble phenolic resin and organic chromium, and the mass ratio of water-soluble phenolic resin to organic chromium is (1-4):1, preferably (2-3):1.

[0029] Further, the organic chromium is one or more of chromium oxalate, chromium acetate, chromium citrate, chromium malonate, chromium propionate, and chromium lactate, preferably chromium lactate.

[0030] Further, the oxygen scavenger is one or more of thiourea, sodium thiosulfate, sodium sulfite, and sodium bisulfite, preferably thiourea.

[0031] Further, the water is water with a total mineralization of less than 50000mg / L.

[0032] The preparation method of the gel blocking agent described above comprises the following steps:

[0033] (1) synthesis of dendritic polymers;

[0034] (2) preparation of the gel blocking agent:

[0035] Mixing the formula amount of the dendritic polymer prepared in step (1), the formula amount of the cross-linking agent, the formula amount of the oxygen scavenger, and the formula amount of the water uniformly, to obtain the gel blocking agent.

[0036] Further, the specific steps of step (1) are as follows in terms of mole fraction:

[0037] (11) Under the conditions of ice bath and protection of nitrogen or inert gas, 1 part of ethylenediamine and 6-10 parts of methyl acrylate are dissolved in an appropriate amount of methanol to obtain a methanol solution of ethylenediamine and a methanol solution of methyl acrylate, respectively, the methanol solution of methyl acrylate is added dropwise to the methanol solution of ethylenediamine, and the reaction is stirred at 20-30℃ for 10-24h to obtain a reaction liquid, and the reaction liquid is distilled at 40-70℃ under reduced pressure to remove methanol and excess methyl acrylate, to obtain a light yellow transparent liquid MA0.5;

[0038] (12) Under the conditions of ice bath and protection of nitrogen or inert gas, an appropriate amount of the light yellow transparent liquid MA0.5 obtained in step (11) is added to an appropriate amount of methanol to obtain a methanol solution of MA0.5, then an excess amount of the methanol solution of ethylenediamine is added dropwise to the methanol solution of MA0.5 to obtain a mixed solution, and the reaction is stirred at 20-30℃ for 10-24h to obtain a reaction liquid, and the reaction liquid is distilled at 40-70℃ under reduced pressure to remove methanol and excess ethylenediamine, then washed with petroleum ether at least once, washed with ethyl acetate at least once, and rotary evaporated to remove unreacted MA0.5, to obtain a light yellow viscous liquid MA1.0;

[0039] (13) under the conditions of ice-bath, nitrogen or inert gas protection, a proper amount of the yellowish viscous liquid MA1.0 obtained in step (12) is added into a proper amount of methanol to obtain a methanol solution of MA1.0, then an excess amount of the methanol solution of methyl acrylate is added dropwise into the methanol solution of MA1.0 to obtain a mixed solution, the mixed solution is stirred at 20-30°C for 10-24h to obtain a reaction liquid, the reaction liquid is distilled under reduced pressure at 40-70°C to remove methanol and excess methyl acrylate, then the reaction liquid is washed with petroleum ether for at least 1 time, washed with ethyl acetate for at least 1 time, and rotary evaporated to remove unreacted MA1.0, to obtain a yellowish viscous liquid MA1.5;

[0040] (14) under the conditions of ice-bath, nitrogen or inert gas protection, a proper amount of the yellowish viscous liquid MA1.5 obtained in step (13) is added into a proper amount of methanol to obtain a methanol solution of MA1.5, then (Z)-3-aminoacrylamide is dissolved in a proper amount of methanol to obtain a methanol solution of (Z)-3-aminoacrylamide, then an excess amount of the methanol solution of (Z)-3-aminoacrylamide is added dropwise into the methanol solution of MA1.5 to obtain a mixed solution, the mixed solution is stirred at 20-30°C for 24-48h to obtain a reaction liquid, the reaction liquid is distilled under reduced pressure at 40-70°C to remove methanol and excess (Z)-3-aminoacrylamide, then the reaction liquid is washed with petroleum ether for at least 1 time, washed with ethyl acetate for at least 1 time, and rotary evaporated to remove unreacted MA1.5, to obtain a dendritic intermediate MAZ;

[0041] (15) under the conditions of nitrogen or inert gas protection, a proper amount of the dendritic intermediate MAZ obtained in step (14) is dissolved in a proper amount of water, then p-carboxystyric acid or p-vinylbenzoic acid or p-vinylphenylacetic acid is added, to obtain a mixed solution A, then an initiator is added into the mixed solution A to obtain a mixed solution B, the mixed solution B is stirred at 50-80°C for 6-12h to obtain a reaction liquid, then the reaction liquid is rotary evaporated to remove water, then the product is washed with ethanol for at least 3 times, dried, and ground into powder, to obtain a dendritic polymer.

[0042] Further, the molar ratio of ethylenediamine to methyl acrylate in step (11) is 1:(7-9);

[0043] The mass ratio of ethylenediamine to methanol in the methanol solution of ethylenediamine in step (11) is 1:(3-15), preferably 1:(8-12);

[0044] The mass ratio of methyl acrylate to methanol in the methanol solution of methyl acrylate in step (11) is 1:(1-2), preferably 1:(1-1.5).

[0045] Further, the molar ratio of ethylenediamine to MA0.5 in the mixture in step (12) is (20-28): 1, preferably (25-27): 1;

[0046] The mass ratio of MA0.5 to methanol in the methanol solution of MA0.5 in step (12) is 1:(1-2), preferably 1:(1-1.5);

[0047] The mass ratio of the amount of petroleum ether to the amount of MA0.5 in step (12) is (3-15): 1, preferably (8-12): 1;

[0048] The mass ratio of the amount of ethyl acetate to the amount of MA0.5 in step (12) is (3-15): 1, preferably (8-12): 1.

[0049] Further, the molar ratio of methyl acrylate to MA1.0 in the mixture in step (13) is (14-18): 1, preferably (15-17): 1;

[0050] The mass ratio of MA1.0 to methanol in the methanol solution of MA1.0 in step (13) is 1:(1-2), preferably 1:(1-1.5);

[0051] The mass ratio of the amount of petroleum ether to the amount of MA1.0 in step (13) is (3-15): 1, preferably (8-12): 1;

[0052] The mass ratio of the amount of ethyl acetate to the amount of MA1.0 in step (13) is (3-15): 1, preferably (8-12): 1.

[0053] Further, the molar ratio of (Z)-3-aminoacrylamide to MA1.5 in the mixture in step (14) is (20-28): 1, preferably (25-27): 1;

[0054] The mass ratio of (Z)-3-aminoacrylamide to methanol in the methanol solution of (Z)-3-aminoacrylamide in step (14) is 1:(3-6), preferably 1:(4-5);

[0055] The mass ratio of MA1.5 to methanol in the methanol solution of MA1.5 in step (14) is 1:(1-3), preferably 1:2;

[0056] The mass ratio of the amount of petroleum ether to the amount of MA1.5 in step (14) is (3-15): 1, preferably (8-12): 1;

[0057] The mass ratio of the amount of ethyl acetate to the amount of MA1.5 in step (14) is (3-15):1, preferably (8-12):1.

[0058] Further, the mass ratio of the p-carboxystyrene acid or p-vinylbenzoic acid or p-vinylphenylacetic acid to the dendritic intermediate MAZ in step (15) is 1:(3-19), preferably 1:(4-9).

[0059] In step (15), the concentration of the sum of the mass of the p-carboxystyrene acid or p-vinylbenzoic acid or p-vinylphenylacetic acid and the dendritic intermediate MAZ, based on the mixed solution A, is 10-30 wt%.

[0060] The initiator in step (15) is one of azobisisobutyronitrile, azobisisobutyramidine hydrochloride and azobisisoheptyl nitrile, preferably azobisisobutyronitrile.

[0061] In step (15), the concentration of the initiator, based on the mixed solution B, is 0.05-0.12 wt%.

[0062] The gel plugging agent is prepared by any one of the preparation methods described above.

[0063] The gel plugging agent is used as a water plugging and profile control agent in thick oil exploitation.

[0064] Further, the specific steps of the application are as follows: under the condition of pre-injection, the gel plugging agent is injected from the wellbore into the formation, so that the gel plugging agent is crosslinked in situ in the formation to form a gel. Further, the high-permeability strip is plugged, the edge and bottom water invasion is inhibited, and the effective sweep of the subsequent injected fluid is expanded.

[0065] The dendritic polymer in the gel plugging agent of the present application has a large number of reactive groups on the surface, and after reaction with a crosslinking agent, an interpenetrating network structure can be formed, so that the prepared gel plugging agent has the advantages of high plugging strength, good shear resistance, long effective plugging period, good reservoir adaptability and the like, and has a good popularization prospect in the exploitation process of thick oil reservoirs.

[0066] Advantages: Compared with the prior art, the present application has the following advantages:

[0067] (1) The gel plugging agent has high plugging strength, and the breakthrough pressure gradient is 5-20 MPa / m under the condition of 50-120℃; the influence of pore throat shear is small, and the viscosity retention rate after 50s -1 high-speed shearing is more than 90%, and the gel plugging agent can be transported to the deep part of the formation for effective plugging;

[0068] (2) The gel plugging agent can resist temperature of 120-200℃, breakthrough pressure gradient of the gel plugging agent is 3-10MPa / m after aging at 120℃ for 180 days or aging at 200℃ for 30 days, high temperature stability is good, and plugging effective period is long;

[0069] (3) The gel plugging agent is suitable for formation water salinity of 0-50000mg / L, wherein calcium and magnesium ion is 0-3000mg / L, and reservoir temperature is 50-120℃, and reservoir adaptability is strong. BRIEF DESCRIPTION OF DRAWINGS

[0070] Figure 1 The flow chart of the preparation method of the gel plugging agent disclosed in the application is shown. DETAILED DESCRIPTION

[0071] The application will be further described in detail with specific examples and with reference to data. It should be understood that these examples are only for illustrating the application, and do not limit the scope of the application in any way.

[0072] The reaction equation for preparing the dendritic polymer is as follows:

[0073]

[0074]

[0075] Example 1

[0076] The gel plugging agent G1 is composed of the following substances in mass fraction:

[0077]

[0078] In another example, the gel plugging agent G1' is composed of the following substances in mass fraction:

[0079]

[0080] Further, the water is formation water, total salinity is 30000mg / L, wherein total concentration of Ca 2+ and Mg 2+ ion is 2000mg / L.

[0081] Further, the dendritic polymer J1 has the following molecular formula:

[0082]

[0083] Wherein ● is polymer chain structure, and is specifically shown in formula (2):

[0084]

[0085] wherein a, b, c, d, e, f, g, h are all 1000, and x is 3000.

[0086] The weight average molecular weight of the dendrimer J1 is 2.1 x 10 6 .

[0087] In another embodiment, the dendrimer J1' has the following formula:

[0088]

[0089] wherein • is a polymer chain structure, specifically as shown in formula (2):

[0090]

[0091] wherein a, b, c, d, e, f, g, h are all 400, and x is 210.

[0092] The weight average molecular weight of the dendrimer J1' is 0.81 x 10 6 .

[0093] In another embodiment, the dendrimer J1* has the following formula:

[0094]

[0095] wherein • is a polymer chain structure, specifically as shown in formula (2):

[0096]

[0097] wherein a, b, c, d, e, f, g, h are all 3800, and x is 7800.

[0098] The weight average molecular weight of the dendrimer J1* is 6.0 x 10 6 .

[0099] In another embodiment, the dendrimer J1" has the following formula:

[0100]

[0101] wherein • is a polymer chain structure, specifically as shown in formula (2):

[0102]

[0103] wherein a, b, c, d, e, f, g, h are all 2000, and x is 500.

[0104] The weight average molecular weight of the dendrimer J1" is 1.62 x 10 6 .

[0105] In another embodiment, the dendrimer J1# has the following formula:

[0106]

[0107] wherein ● is a polymer chain structure, specifically as shown in formula (2):

[0108]

[0109] wherein a, b, c, d, e, f, g, h are all 1500, and x is 5300.

[0110] The dendrimer J1# has a weight average molecular weight of 4.01 x 10 6 .

[0111] The preparation method of the gel blocking agent G1 includes the following steps:

[0112] (1) synthesis of the dendrimer J1;

[0113] (2) preparation of the gel blocking agent G1:

[0114] Mixing the dendrimer J1 prepared in step (1) in a formula amount, a crosslinking agent in a formula amount, an oxygen scavenger in a formula amount, and water in a formula amount uniformly to obtain the gel blocking agent G1.

[0115] Further, in terms of molar parts, the specific steps of step (1) are as follows:

[0116] (11) Under the conditions of ice bath and nitrogen protection, 1 part of ethylenediamine and 6 parts of methyl acrylate are dissolved in an appropriate amount of methanol to obtain a methanol solution of ethylenediamine and a methanol solution of methyl acrylate. Excess methyl acrylate methanol solution is added dropwise to the ethylenediamine methanol solution, and the reaction is stirred at 20°C for 24h to obtain a reaction liquid. The reaction liquid is distilled under reduced pressure at 40°C to remove methanol and excess methyl acrylate, and a light yellow transparent liquid MA0.5 is obtained;

[0117] (12) Under the conditions of ice bath and nitrogen protection, an appropriate amount of light yellow transparent liquid MA0.5 obtained in step (11) is added to an appropriate amount of methanol to obtain a methanol solution of MA0.5. Then, excess methanol solution of ethylenediamine is added dropwise to the methanol solution of MA0.5 to obtain a mixed solution. The reaction is stirred at 2°C for 24h to obtain a reaction liquid. The reaction liquid is distilled under reduced pressure at 40°C to remove methanol and excess ethylenediamine. Then, the reaction liquid is washed once with petroleum ether, washed once with ethyl acetate, and rotary evaporated to remove unreacted MA0.5, and a light yellow viscous liquid MA1.0 is obtained;

[0118] (13) Under the conditions of ice-bath and nitrogen protection, a proper amount of the yellowish viscous liquid MA1.0 obtained in step (12) was added into a proper amount of methanol to obtain a methanol solution of MA1.0, then an excess amount of the methanol solution of methyl acrylate was added dropwise into the methanol solution of MA1.0 to obtain a mixed solution, the mixed solution was stirred at 20℃ for 24h to obtain a reaction liquid, the reaction liquid was distilled under reduced pressure at 40℃ to remove methanol and excess methyl acrylate, then the reaction liquid was washed once with petroleum ether and once with ethyl acetate, and then was rotary evaporated to remove unreacted MA1.0, thereby obtaining a yellowish viscous liquid MA1.5;

[0119] (14) Under the conditions of ice-bath and nitrogen protection, a proper amount of the yellowish viscous liquid MA1.5 obtained in step (13) was added into a proper amount of methanol to obtain a methanol solution of MA1.5, then (Z)-3-aminoacrylamide was dissolved in a proper amount of methanol to obtain a methanol solution of (Z)-3-aminoacrylamide, then an excess amount of the methanol solution of (Z)-3-aminoacrylamide was added dropwise into the methanol solution of MA1.5 to obtain a mixed solution, the mixed solution was stirred at 20℃ for 48h to obtain a reaction liquid, the reaction liquid was distilled under reduced pressure at 40℃ to remove methanol and excess (Z)-3-aminoacrylamide, then the reaction liquid was washed once with petroleum ether and once with ethyl acetate, and then was rotary evaporated to remove unreacted MA1.5, thereby obtaining a dendritic intermediate MAZ.

[0120] (15) Under the condition of nitrogen protection, a proper amount of the dendritic intermediate MAZ obtained in step (14) was dissolved in a proper amount of water, then p-carboxystyrene acid was added to obtain a mixed liquid A, then an initiator was added to obtain a mixed liquid B, the mixed liquid B was stirred at 50℃ for 12h to obtain a reaction liquid, then the reaction liquid was rotary evaporated to remove water, then the product was washed with ethanol for 3 times, dried, and ground into powder, thereby obtaining a dendritic polymer J1.

[0121] In another embodiment, the molar ratio of ethylenediamine to methyl acrylate in step (11) is 1:7.

[0122] Further, the mass ratio of ethylenediamine to methanol in the methanol solution of ethylenediamine in step (11) is 1:3. In another embodiment, the mass ratio of ethylenediamine to methanol in the methanol solution of ethylenediamine in step (11) is 1:8.

[0123] The mass ratio of methyl acrylate to methanol in the methanol solution of methyl acrylate in step (11) is 1:1.

[0124] Further, the molar ratio of ethylenediamine to MA0.5 in the mixture in step (12) is 20:1. In another embodiment, the molar ratio of ethylenediamine to MA0.5 in the mixture in step (12) is 25:1.

[0125] The mass ratio of MA0.5 to methanol in the methanol solution of MA0.5 in step (12) is 1:1.

[0126] Further, the mass ratio of the amount of petroleum ether to the amount of MA0.5 in step (12) is 3:1. In another embodiment, the mass ratio of the amount of petroleum ether to the amount of MA0.5 in step (12) is 8:1.

[0127] The mass ratio of the amount of ethyl acetate to the amount of MA0.5 in step (12) is 3:1. In another embodiment, the mass ratio of the amount of ethyl acetate to the amount of MA0.5 in step (12) is 8:1.

[0128] Further, the molar ratio of methyl acrylate to MA1.0 in the mixture in step (13) is 14:1. In another embodiment, the molar ratio of methyl acrylate to MA1.0 in the mixture in step (13) is 15:1.

[0129] The mass ratio of MA1.0 to methanol in the methanol solution of MA1.0 in step (13) is 1:1.

[0130] Further, the mass ratio of the amount of petroleum ether to the amount of MA1.0 in step (13) is 3:1. In another embodiment, the mass ratio of the amount of petroleum ether to the amount of MA1.0 in step (13) is 8:1.

[0131] The mass ratio of the amount of ethyl acetate to the amount of MA1.0 in step (13) is 3:1. In another embodiment, the mass ratio of the amount of ethyl acetate to the amount of MA1.0 in step (13) is 8:1.

[0132] Further, the molar ratio of (Z)-3-aminopropenamide to MA1.5 in the mixture in step (14) is 20:1. In another embodiment, the molar ratio of (Z)-3-aminopropenamide to MA1.5 in the mixture in step (14) is 25:1.

[0133] The mass ratio of (Z)-3-aminoacrylamide to methanol in the methanol solution of (Z)-3-aminoacrylamide described in step (14) is 1:3. In another embodiment, the mass ratio of (Z)-3-aminoacrylamide to methanol in the methanol solution of (Z)-3-aminoacrylamide described in step (14) is 1:4.

[0134] The mass ratio of MA1.5 to methanol in the methanol solution of MA1.5 described in step (14) is 1:1.

[0135] Further, the mass ratio of the amount of petroleum ether to the amount of MA1.5 described in step (14) is 3:1. In another embodiment, the mass ratio of the amount of petroleum ether to the amount of MA1.5 described in step (14) is 8:1.

[0136] Further, the mass ratio of the amount of petroleum ether to the amount of MA1.5 described in step (14) is 3:1. In another embodiment, the mass ratio of the amount of petroleum ether to the amount of MA1.5 described in step (14) is 8:1.

[0137] Further, the mass ratio of p-carboxystyrene acid to dendritic intermediate MAZ described in step (15) is 1:3. In another embodiment, the mass ratio of p-carboxystyrene acid to dendritic intermediate MAZ described in step (15) is 1:4.

[0138] In step (15), the concentration of the sum of the mass of p-carboxystyrene acid and dendritic intermediate MAZ is 10% by weight, based on the mixed solution A.

[0139] Further, the initiator described in step (15) is azobisisobutyronitrile.

[0140] In step (15), the concentration of the initiator is 0.05% by weight, based on the mixed solution B.

[0141] The gel plugging agent G1 described above is prepared by any one of the preparation methods described above.

[0142] The gel plugging agent G1 described above is used as a water plugging and profile control agent in thick oil exploitation.

[0143] Further, the specific steps of the use are as follows: under the condition of pre-injection, the gel plugging agent G1 is injected from the wellbore into the formation, so that the gel plugging agent G1 is cross-linked in situ in the formation to form a gel. Further, high-permeability channels are plugged, the invasion of edge and bottom water is inhibited, and the effective sweep of injected fluid is expanded.

[0144] Example 2

[0145] The gel plugging agent G2 is composed of the following substances in mass fraction:

[0146]

[0147] In another embodiment, a gel blocking agent G2', consisting of the following substances in mass fraction:

[0148]

[0149]

[0150] Further, the water is formation water, total mineralization 5000 mg / L, wherein Ca 2+ , Mg 2+ ion total concentration 600 mg / L.

[0151] The dendritic polymer J2 has the following formula:

[0152]

[0153] Wherein ● is the polymer chain structure, specifically as follows:

[0154]

[0155] Wherein, a, b, c, d, e, f, g, h are all 1500, and y is 5000.

[0156] Further, the weight average molecular weight of the dendritic polymer J2 is 3.03 x 10 6 .

[0157] In another embodiment, another dendritic polymer is substantially the same as the dendritic polymer J2, the only difference being that y is 270, and the weight average molecular weight of the dendritic polymer is 0.85 x 10 6 .

[0158] In another embodiment, another dendritic polymer is substantially the same as the dendritic polymer J2, the only difference being that y is 10000, and the weight average molecular weight of the dendritic polymer is 4.91 x 10 6 .

[0159] In another embodiment, another dendritic polymer is substantially the same as the dendritic polymer J2, the only difference being that y is 550, and the weight average molecular weight of the dendritic polymer is 1.82 x 10 6 .

[0160] In another embodiment, another dendritic polymer is substantially the same as the dendritic polymer J2, the only difference being that y is 6800, and the weight average molecular weight of the dendritic polymer is 4.42 x 10 6 .

[0161] The preparation method of the gel blocking agent G2 comprises the following steps:

[0162] (1) Synthesis of dendrimer J2;

[0163] (2) Preparation of gel blocking agent G2:

[0164] Mixing the formula amount of the dendrimer J2 prepared in step (1), the formula amount of the crosslinking agent, the formula amount of the oxygen scavenger and the formula amount of water uniformly to obtain the gel blocking agent G2.

[0165] Further, the specific steps of step (1) are as follows in terms of mole fraction:

[0166] (11) Under ice bath and helium gas, 1 part of ethylenediamine and 10 parts of methyl acrylate are dissolved in an appropriate amount of methanol to obtain a methanol solution of ethylenediamine and a methanol solution of methyl acrylate, respectively, the methanol solution of methyl acrylate is added dropwise to the methanol solution of ethylenediamine, and the reaction is stirred at 30°C for 10 hours to obtain a reaction liquid, and the reaction liquid is distilled at 70°C under reduced pressure to remove methanol and excess methyl acrylate, and a light yellow transparent liquid MA0.5 is obtained;

[0167] (12) Under ice bath and helium gas, an appropriate amount of the light yellow transparent liquid MA0.5 obtained in step (11) is added to an appropriate amount of methanol to obtain a methanol solution of MA0.5, and then an excess amount of the methanol solution of ethylenediamine is added dropwise to the methanol solution of MA0.5 to obtain a mixed solution, which is stirred at 30°C for 10 hours to obtain a reaction liquid, and the reaction liquid is distilled at 70°C under reduced pressure to remove methanol and excess ethylenediamine, and then washed with petroleum ether for 3 times, washed with ethyl acetate for 3 times, and rotary evaporated to remove unreacted MA0.5, and a light yellow viscous liquid MA1.0 is obtained;

[0168] (13) Under ice bath and helium gas, an appropriate amount of the light yellow viscous liquid MA1.0 obtained in step (12) is added to an appropriate amount of methanol to obtain a methanol solution of MA1.0, and then an excess amount of the methanol solution of methyl acrylate is added dropwise to the methanol solution of MA1.0 to obtain a mixed solution, which is stirred at 30°C for 10 hours to obtain a reaction liquid, and the reaction liquid is distilled at 70°C under reduced pressure to remove methanol and excess methyl acrylate, and then washed with petroleum ether for 3 times, washed with ethyl acetate for 3 times, and rotary evaporated to remove unreacted MA1.0, and a light yellow viscous liquid MA1.5 is obtained;

[0169] (14) under ice-bath, under helium, a proper amount of the yellowish viscous liquid MA1.5 obtained in step (13) was added into a proper amount of methanol to obtain a methanol solution of MA1.5, then (Z)-3-aminoprop-2-enoic amide was dissolved in a proper amount of methanol to obtain a methanol solution of (Z)-3-aminoprop-2-enoic amide, then a proper amount of the methanol solution of (Z)-3-aminoprop-2-enoic amide was added dropwise into the methanol solution of MA1.5 to obtain a mixed solution, the mixed solution was stirred at 30°C for 24h to obtain a reaction liquid, the reaction liquid was distilled under reduced pressure at 70°C to remove methanol and excess (Z)-3-aminoprop-2-enoic amide, then the reaction liquid was washed with petroleum ether for 3 times, washed with ethyl acetate for 3 times, and rotary evaporated to remove unreacted MA1.5, thus a dendritic intermediate MAZ was obtained;

[0170] (15) under helium, a proper amount of the dendritic intermediate MAZ obtained in step (14) was dissolved in a proper amount of water, then p-vinylbenzoic acid was added to obtain a mixed solution A, then an initiator was added into the mixed solution A to obtain a mixed solution B, the mixed solution B was stirred at 80°C for 6h to obtain a reaction liquid, then the reaction liquid was rotary evaporated to remove water, then the product was washed with ethanol for 5 times, dried, and ground into powder, thus a dendritic polymer J2 was obtained.

[0171] In another embodiment, the molar ratio of ethylenediamine to methyl acrylate in step (11) is 1:9.

[0172] Further, the mass ratio of ethylenediamine to methanol in the methanol solution of ethylenediamine in step (11) is 1:15. In another embodiment, the mass ratio of ethylenediamine to methanol in the methanol solution of ethylenediamine in step (11) is 1:12.

[0173] Further, the mass ratio of methyl acrylate to methanol in the methanol solution of methyl acrylate in step (11) is 1:2.

[0174] Further, the molar ratio of ethylenediamine to MA0.5 in the mixed solution in step (12) is 28:1. In another embodiment, the molar ratio of ethylenediamine to MA0.5 in the mixed solution in step (12) is 27:1.

[0175] The mass ratio of MA0.5 to methanol in the methanol solution of MA0.5 in step (12) is 1:2.

[0176] Further, the mass ratio of the amount of petroleum ether to the amount of MA0.5 in step (12) is 15:1. In another embodiment, the mass ratio of the amount of petroleum ether to the amount of MA0.5 in step (12) is 12:1.

[0177] The mass ratio of the amount of ethyl acetate used in step (12) to the amount of MA0.5 used in step (12) is 15:1. In another embodiment, the mass ratio of the amount of ethyl acetate used in step (12) to the amount of MA0.5 used in step (12) is 12:1.

[0178] Further, the molar ratio of methyl acrylate to MA1.0 in the mixture in step (13) is 18:1. In another embodiment, the molar ratio of methyl acrylate to MA1.0 in the mixture in step (13) is 17:1.

[0179] Further, the mass ratio of MA1.0 to methanol in the methanol solution of MA1.0 in step (13) is 1:2. In another embodiment, the mass ratio of MA1.0 to methanol in the methanol solution of MA1.0 in step (13) is 1:1.5.

[0180] Further, the mass ratio of the amount of petroleum ether used in step (13) to the amount of MA1.0 used in step (13) is 15:1. In another embodiment, the mass ratio of the amount of petroleum ether used in step (13) to the amount of MA1.0 used in step (13) is 12:1.

[0181] Further, the mass ratio of the amount of ethyl acetate used in step (13) to the amount of MA1.0 used in step (13) is 15:1. In another embodiment, the mass ratio of the amount of ethyl acetate used in step (13) to the amount of MA1.0 used in step (13) is 12:1.

[0182] Further, the molar ratio of (Z)-3-aminoacrylamide to MA1.5 in the mixture in step (14) is 28:1. In another embodiment, the molar ratio of (Z)-3-aminoacrylamide to MA1.5 in the mixture in step (14) is 27:1.

[0183] Further, the mass ratio of (Z)-3-aminoacrylamide to methanol in the methanol solution of (Z)-3-aminoacrylamide in step (14) is 1:6. In another embodiment, the mass ratio of (Z)-3-aminoacrylamide to methanol in the methanol solution of (Z)-3-aminoacrylamide in step (14) is 1:5.

[0184] Further, the mass ratio of MA1.5 to methanol in the methanol solution of MA1.5 in step (14) is 1:3.

[0185] Further, the mass ratio of the amount of petroleum ether used in step (14) to the amount of MA1.5 used in step (14) is 15:1. In another embodiment, the mass ratio of the amount of petroleum ether used in step (14) to the amount of MA1.5 used in step (14) is 12:1.

[0186] The mass ratio of the amount of ethyl acetate to the amount of MA1.5 in step (14) is 15:1. In another embodiment, the mass ratio of the amount of ethyl acetate to the amount of MA1.5 in step (14) is 12:1.

[0187] Further, the mass ratio of p-vinylbenzoic acid to dendritic intermediate MAZ in step (15) is 1:19. In another embodiment, the mass ratio of p-vinylbenzoic acid to dendritic intermediate MAZ in step (15) is 1:9.

[0188] In step (15), the concentration of the sum of the mass of p-vinylbenzoic acid and dendritic intermediate MAZ is 30% by weight, based on the mixed solution A.

[0189] Further, the initiator in step (15) is azobisdimethylamidine hydrochloride.

[0190] In step (15), the concentration of the initiator is 0.12% by weight, based on the mixed solution B.

[0191] The gel plugging agent G2 is prepared by any one of the above preparation methods.

[0192] The gel plugging agent G2 is used as a water plugging and profile control agent in thick oil exploitation.

[0193] Further, the specific steps of the application are as follows: under the condition of pre-injection, the gel plugging agent G2 is injected from the wellbore into the formation, so that the gel plugging agent G2 is crosslinked in situ in the formation to form a gel. Further, high permeability zones are plugged, edge and bottom water invasion is inhibited, and the effective sweep of injected fluid is expanded.

[0194] Example 3

[0195] The gel plugging agent G3 is composed of the following substances in mass fraction:

[0196]

[0197] In another embodiment, the gel plugging agent G3' is composed of the following substances in mass fraction:

[0198]

[0199] Further, the water is formation water with a total salinity of 50000 mg / L, wherein the total concentration of Ca 2+ , Mg 2+ ions is 3000 mg / L.

[0200] The dendritic polymer J3 has the following molecular formula:

[0201]

[0202] wherein ● is a polymer chain structure, and is as follows:

[0203]

[0204] wherein a, b, c, d, e, f, g, h are each 2000, and z is 1000.

[0205] Further, the weight average molecular weight of the dendrimer J3 is 3.2 x 10 6 .

[0206] In another embodiment, another dendrimer is substantially the same as the dendrimer J3, except that z is 250, and the weight average molecular weight of the dendrimer is 0.93 x 10 6 .

[0207] In another embodiment, another dendrimer is substantially the same as the dendrimer J3, except that z is 9200, and the weight average molecular weight of the dendrimer is 5.21 x 10 6 .

[0208] In another embodiment, another dendrimer is substantially the same as the dendrimer J3, except that z is 500, and the weight average molecular weight of the dendrimer is 2.18 x 10 6 .

[0209] In another embodiment, another dendrimer is substantially the same as the dendrimer J3, except that z is 6200, and the weight average molecular weight of the dendrimer is 4.51 x 10 6 .

[0210] The preparation method of the gel blocking agent G3 described above comprises the following steps:

[0211] (1) Synthesis of the dendrimer J3;

[0212] (2) Preparation of the gel blocking agent G3:

[0213] Mixing the formula amount of the dendrimer J3 prepared in step (1), the formula amount of the crosslinking agent, the formula amount of the oxygen scavenger, and the formula amount of water uniformly, to obtain the gel blocking agent G3.

[0214] Further, the specific steps of step (1) are as follows in terms of molar parts:

[0215] (11) Under ice-bath, argon atmosphere, 1 part of ethylenediamine and 8 parts of methyl acrylate were dissolved in appropriate amount of methanol to obtain methanol solution of ethylenediamine and methanol solution of methyl acrylate respectively, the excess methanol solution of methyl acrylate was added dropwise into the methanol solution of ethylenediamine, the reaction was carried out at 25℃ for 15h to obtain reaction liquid, the reaction liquid was distilled under reduced pressure at 50℃ to remove methanol and excess methyl acrylate, and a light yellow transparent liquid MA0.5 was obtained;

[0216] (12) Under ice-bath, argon atmosphere, appropriate amount of light yellow transparent liquid MA0.5 obtained in step (11) was added into appropriate amount of methanol to obtain methanol solution of MA0.5, then the excess methanol solution of ethylenediamine was added dropwise into the methanol solution of MA0.5 to obtain a mixed solution, the reaction was carried out at 25℃ for 16h to obtain reaction liquid, the reaction liquid was distilled under reduced pressure at 50℃ to remove methanol and excess ethylenediamine, then the liquid was washed with petroleum ether twice, washed with ethyl acetate twice, and rotary evaporated to remove unreacted MA0.5, and a light yellow viscous liquid MA1.0 was obtained;

[0217] (13) Under ice-bath, argon atmosphere, appropriate amount of light yellow viscous liquid MA1.0 obtained in step (12) was added into appropriate amount of methanol to obtain methanol solution of MA1.0, then the excess methanol solution of methyl acrylate was added dropwise into the methanol solution of MA1.0 to obtain a mixed solution, the reaction was carried out at 25℃ for 16h to obtain reaction liquid, the reaction liquid was distilled under reduced pressure at 60℃ to remove methanol and excess methyl acrylate, then the liquid was washed with petroleum ether twice, washed with ethyl acetate twice, and rotary evaporated to remove unreacted MA1.0, and a light yellow viscous liquid MA1.5 was obtained;

[0218] (14) Under ice-bath, argon atmosphere, appropriate amount of light yellow viscous liquid MA1.5 obtained in step (13) was added into appropriate amount of methanol to obtain methanol solution of MA1.5, then (Z)-3-aminopropenamide was dissolved in appropriate amount of methanol to obtain methanol solution of (Z)-3-aminopropenamide, then the excess methanol solution of (Z)-3-aminopropenamide was added dropwise into the methanol solution of MA1.5 to obtain a mixed solution, the reaction was carried out at 25℃ for 36h to obtain reaction liquid, the reaction liquid was distilled under reduced pressure at 55℃ to remove methanol and excess (Z)-3-aminopropenamide, then the liquid was washed with petroleum ether twice, washed with ethyl acetate twice, and rotary evaporated to remove unreacted MA1.5, and a dendritic intermediate MAZ was obtained;

[0219] (15) under argon, a proper amount of the dendritic intermediate MAZ obtained in step (14) is dissolved in a proper amount of water, then p-vinylphenylacetic acid is added, after complete dissolution, a mixed solution A is obtained, then an initiator is added to the mixed solution A to obtain a mixed solution B, the mixed solution B is stirred at 60°C for 8h to obtain a reaction solution, then the reaction solution is rotary evaporated to remove water, then the product is washed with ethanol for 4 times, dried, ground into powder, and a dendritic polymer J3 is obtained.

[0220] The mass ratio of ethylenediamine to methanol in the methanol solution of ethylenediamine in step (11) is 1:10;

[0221] The mass ratio of methyl acrylate to methanol in the methanol solution of methyl acrylate in step (11) is 1.5.

[0222] Further, in the mixed solution in step (12), the molar ratio of ethylenediamine to MA0.5 is 26:1;

[0223] The mass ratio of MA0.5 to methanol in the methanol solution of MA0.5 in step (12) is 1:1.5.

[0224] Further, in step (12), the mass ratio of the amount of petroleum ether to the amount of MA0.5 is 10:1;

[0225] Further, in step (12), the mass ratio of the amount of ethyl acetate to the amount of MA0.5 is 10:1.

[0226] Further, in the mixed solution in step (13), the molar ratio of methyl acrylate to MA1.0 is 16:1;

[0227] The mass ratio of MA1.0 to methanol in the methanol solution of MA1.0 in step (13) is 1:1.5.

[0228] Further, in step (13), the mass ratio of the amount of petroleum ether to the amount of MA1.0 is 10:1;

[0229] Further, in step (13), the mass ratio of the amount of ethyl acetate to the amount of MA1.0 is 10:1.

[0230] Further, in the mixed solution in step (14), the molar ratio of (Z)-3-aminopropenamide to MA1.5 is 26:1;

[0231] The mass ratio of (Z)-3-aminopropenamide to methanol in the methanol solution of (Z)-3-aminopropenamide in step (14) is 1:4.5;

[0232] The mass ratio of MA1.5 to methanol in the methanol solution of MA1.5 in step (14) is 1:2.

[0233] Further, the mass ratio of the amount of petroleum ether to the amount of MA1.5 in step (14) is 10:1.

[0234] The mass ratio of the amount of ethyl acetate to the amount of MA1.5 in step (14) is 10:1.

[0235] Further, the mass ratio of p-vinylphenylacetic acid to dendritic intermediate MAZ in step (15) is 1:7.

[0236] In step (15), the concentration of the sum of the mass of p-vinylphenylacetic acid and dendritic intermediate MAZ, based on the mixed solution A, is 20% by weight.

[0237] Further, the initiator in step (15) is azobisisoheptane nitrile.

[0238] In step (15), the concentration of the initiator, based on the mixed solution B, is 0.1% by weight.

[0239] The gel blocking agent G3 is prepared by any one of the above preparation methods.

[0240] The gel blocking agent G3 is used as a water plugging and profile control agent in thick oil exploitation.

[0241] Further, the specific steps of the use are as follows: under the condition of pre-injection, the gel blocking agent G3 is injected from the wellbore into the formation, so that the gel blocking agent G3 is cross-linked in situ in the formation to form a gel. Further, high-permeability channels are plugged, edge and bottom water invasion is inhibited, and the effective sweep of injected fluid is expanded.

[0242] Examples 4-21

[0243] The same as Example 1, except that the cross-linking agent is different.

[0244]

[0245]

[0246] Examples 22-26

[0247] The same as Example 1, except that the oxygen scavenger is different.

[0248] Performance evaluation of gel blocking agents G1, G2, and G3

[0249] Test Example 1

[0250] The water used in the experiment is H produced water of a block in Shengli Oilfield, the reservoir temperature is 68℃, the total mineralization is 26680mg / L, among which the Ca 2+ content is 2249mg / L, the Mg 2+ content is 251mg / L.

[0251] The gel blocking agents G1, G2 and G3 prepared in Examples 1-3 and the commercial gel blocking agents KR-1 and KR-2 were placed in a 68℃ oven, and their gelation time, elastic modulus, breakthrough pressure gradient and water plugging rate were evaluated, and the determination method referred to Q / SH10201493-2019 “Performance Index and Test Method of Gel-type Water Shutoff and Profile Control Agent”.

[0252] The shear resistance of the gel blocking agents G1, G2 and G3 prepared in Examples 1-3 and the commercial gel blocking agents KR-1 and KR-2 was evaluated, and the determination method was as follows: first, the initial viscosity μ0 of the gel was determined under the condition of a shear rate of 7.2s -1 , then the gel was sheared for 100s under the condition of a shear rate of 50s -1 , and finally the viscosity μ1 of the gel after shearing was determined under the condition of a shear rate of 7.2s -1 . The viscosity retention rate was calculated according to the formula: viscosity retention rate = (μ0-μ1) / μ0×100%.

[0253]

[0254] The temperature resistance of the gel blocking agents G1, G2 and G3 prepared in Examples 1 and 3 and the commercial gel blocking agent KR-1 was evaluated by placing them in an oven at 200℃ for 30 days, and then the breakthrough pressure gradient was determined. The test results are shown in Table 1.

[0255] Table 1 Performance test results of gel blocking agents G1, G2, G3 and commercial gel blocking agents KR-1 and KR-2

[0256]

[0257] According to the above evaluation results, the gel blocking agents G1, G2 and G3 of the present application have good gelation performance, plugging performance and shear resistance at reservoir temperature, and the gel blocking agents G1 and G3 for thermal recovery of heavy oil also have good temperature resistance.

[0258] ​The gel blocking agent G1, the gel blocking agent G2 and the gel blocking agent G3 of the present application have a gelation time of 21-72h, an elastic modulus greater than 8Pa and a breakthrough pressure gradient greater than 6MPa / m at the reservoir temperature, while the commercial gel blocking agents KR-1 and KR-2 have a gelation time comparable to that of G1, G2 and G3, but an elastic modulus less than 8Pa and a breakthrough pressure gradient less than 5MPa / m, which is significantly lower than that of the present application.

[0259] The gel blocking agent G1, the gel blocking agent G2 and the gel blocking agent G3 of the present application have a water plugging rate greater than 99%, while the commercial gel blocking agents KR-1 and KR-2 have a water plugging rate of 99.2% and 98.7% respectively, and the water plugging rates of the several blocking agents are comparable.

[0260] The gel blocking agent G1, the gel blocking agent G2 and the gel blocking agent G3 of the present application have a viscosity retention rate greater than 90% after shearing for 50s, while the viscosity retention rates of the commercial gel blocking agents KR-1 and KR-2 are 48-62%, which is significantly lower than that of the present application. -1

[0261] The gel blocking agent G1, the gel blocking agent G2 and the gel blocking agent G3 of the present application have a breakthrough pressure gradient maintained above 5MPa / m after being aged at 200℃ for 30d, while the commercial gel blocking agent KR-1 has a strength less than 3MPa / m after high-temperature aging. The gel blocking agent G1, the gel blocking agent G2 and the gel blocking agent G3 of the present application all meet the relevant requirements of oilfields, and have excellent comprehensive performance compared with the commercial gel blocking agents, and can meet the development requirements of multiple rounds of heavy oil reservoirs.

[0262] The above has described the embodiments of the present application in detail. However, the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.​

Claims

1. A gel plug, characterized in that, consists of, by weight fraction, 0.3-1.2 parts of dendritic polymer; 0.2-1.5 parts of cross-linking agent; 0.2-1.5 parts of oxygen scavenger; 80-110 parts of water, wherein: The structure of the dendritic polymer is shown in formula (1): Wherein: a, b, c, d, e, f, g, h are each an integer or decimal number in the range of 400-3800; The polymer chain structure is shown in formula (2) or formula (3) or formula (4). x is any integer or decimal number in the range of 210-7800; y is any integer or decimal number in the range of 270-10000; z is any integer or decimal number in the range of 250-9200; The cross-linking agent is one or more of formaldehyde, paraformaldehyde, hexamethylenetetramine, phenol, m-dihydroxybenzene, p-dihydroxybenzene, water-soluble phenolic resin, urea-formaldehyde resin and organic chromium; The oxygen scavenger is one or more of thiourea, sodium thiosulfate, sodium sulfite and sodium bisulfite.

2. A gel plug according to claim 1, wherein consists of: 0.4-0.6 parts of dendritic polymer; 0.5-1 part of cross-linking agent; 0.5-0.8 parts of oxygen scavenger; 90-100 parts of water.

3. A gel plug according to claim 1, wherein The structure of the dendritic polymer is shown in formula (1): a, b, c, d, e, f, g, h are any integer or decimal number in the range of 1000-2000; The polymer chain structure is, for example, as shown in formula (2) or formula (3) or formula (4): x is any integer or decimal number in the range of 500-5300; y is any integer or decimal number in the range of 550-6800; z is any integer or decimal number in the range of 500-6200.

4. A gel plug according to claim 1, wherein the gel plug is formed from a mixture of a gel and a particulate material. The cross-linking agent is one or more of water-soluble phenolic resin and organic chromium.

5. A gel plug according to claim 1, wherein the gel plug is formed from a mixture of a gel and a particulate material. The oxygen scavenger is thiourea.

6. A gel plug according to claim 1, wherein, The weight average molecular weight of the dendrimer is 0.8 x 10 6 -6 x 10 6 .

7. A gel plug according to claim 6, wherein the gel plug is formed from a gel having a gel strength of at least 1000 Pa. The weight average molecular weight of the dendrimer is 1.6 x 10 6 -4 x 10 6 .

8. A gel plug according to claim 1, wherein, The cross-linking agent is a combination of water-soluble phenolic resin and organic chromium, and the mass ratio of water-soluble phenolic resin to organic chromium is (1-4):

1.

9. A gel plug according to claim 8, wherein the gel plug is formed from a gel having a gel strength of at least 1000 Pa. The cross-linking agent is a combination of water-soluble phenolic resin and organic chromium, and the mass ratio of water-soluble phenolic resin to organic chromium is (2-3):

1.

10. A gel plug according to claim 1, wherein, The organic chromium is one or more of chromium oxalate, chromium acetate, chromium citrate, chromium malonate, chromium propionate and chromium lactate.

11. A gel plug according to claim 10, wherein the gel plug is formed from a mixture of the gel and the particulate material in a ratio of 1 : 1 to 1 :

10. The organic chromium is chromium lactate.

12. A gel plug according to claim 1, wherein, The water is water with a total mineralization degree of less than 50000 mg / L.

13. A method of preparing the gel plug according to any one of claims 1 to 12, characterized in that, The steps include: (1) synthesis of dendritic polymer; (2) preparation of gel plugging agent: Mix the dendritic polymer prepared in step (1) in the formula amount, the cross-linking agent in the formula amount, the oxygen scavenger in the formula amount and the water in the formula amount uniformly to obtain the gel plugging agent.

14. The method for preparing the gel plugging agent as described in claim 13, characterized in that, The specific steps of step (1) are as follows in mole fraction: (11) under the conditions of ice bath and protection of nitrogen or inert gas, dissolve 1 part of ethylenediamine and 6-10 parts of methyl acrylate in appropriate amount of methanol to obtain methanol solution of ethylenediamine and methanol solution of methyl acrylate, drop the excess methanol solution of methyl acrylate into the methanol solution of ethylenediamine, stir at 20-30℃ for 10-24h to obtain reaction liquid, remove methanol and excess methyl acrylate from the reaction liquid under reduced pressure at 40-70℃ to obtain light yellow transparent liquid MA0.5; (12) Under the conditions of ice-bath, protection of nitrogen or inert gas, a proper amount of the yellowish transparent liquid MA0.5 obtained in step (11) is added into a proper amount of methanol to obtain a methanol solution of MA0.5, then an excess amount of methanol solution of the ethylenediamine is added dropwise into the methanol solution of MA0.5 to obtain a mixed solution, the mixed solution is stirred at 20-30℃ for 10-24h to obtain a reaction liquid, the reaction liquid is distilled under reduced pressure at 40-70℃ to remove methanol and excess ethylenediamine, then the reaction liquid is washed with petroleum ether for at least 1 time, washed with ethyl acetate for at least 1 time, and rotary evaporated to remove unreacted MA0.5, to obtain a yellowish viscous liquid MA1.0; (13) Under the conditions of ice-bath, protection of nitrogen or inert gas, a proper amount of the yellowish viscous liquid MA1.0 obtained in step (12) is added into a proper amount of methanol to obtain a methanol solution of MA1.0, then an excess amount of methanol solution of the methyl acrylate is added dropwise into the methanol solution of MA1.0 to obtain a mixed solution, the mixed solution is stirred at 20-30℃ for 10-24h to obtain a reaction liquid, the reaction liquid is distilled under reduced pressure at 40-70℃ to remove methanol and excess methyl acrylate, then the reaction liquid is washed with petroleum ether for at least 1 time, washed with ethyl acetate for at least 1 time, and rotary evaporated to remove unreacted MA1.0, to obtain a yellowish viscous liquid MA1.5; (14) Under the conditions of ice-bath, protection of nitrogen or inert gas, a proper amount of the yellowish viscous liquid MA1.5 obtained in step (13) is added into a proper amount of methanol to obtain a methanol solution of MA1.5, then (Z)-3-aminopropenamide is dissolved in a proper amount of methanol to obtain a methanol solution of (Z)-3-aminopropenamide, then an excess amount of the methanol solution of (Z)-3-aminopropenamide is added dropwise into the methanol solution of MA1.5 to obtain a mixed solution, the mixed solution is stirred at 20-30℃ for 24-48h to obtain a reaction liquid, the reaction liquid is distilled under reduced pressure at 40-70℃ to remove methanol and excess (Z)-3-aminopropenamide, then the reaction liquid is washed with petroleum ether for at least 1 time, washed with ethyl acetate for at least 1 time, and rotary evaporated to remove unreacted MA1.5, to obtain a dendritic intermediate MAZ; (15) Under the conditions of protection of nitrogen or inert gas, a proper amount of the dendritic intermediate MAZ obtained in step (14) is dissolved in a proper amount of water, then p-carboxystyric acid or p-vinylbenzoic acid or p-vinylphenylacetic acid is added, and after complete dissolution, a mixed solution A is obtained, then an initiator is added into the mixed solution A to obtain a mixed solution B, the mixed solution B is stirred at 50-80℃ for 6-12h to obtain a reaction liquid, then the reaction liquid is rotary evaporated to remove water, then the product is washed with ethanol for at least 3 times, dried, and ground into powder, to obtain a dendritic polymer.

15. The method for preparing the gel plugging agent as described in claim 14, characterized in that, The molar ratio of the ethylenediamine to the methyl acrylate in step (11) is 1:(7-9); The mass ratio of the ethylenediamine to methanol in the methanol solution of the ethylenediamine in step (11) is 1:(3-15); The mass ratio of methyl acrylate to methanol in the methyl acrylate methanol solution in step (11) is 1:(1-2).

16. The method of claim 15, wherein the gel plug is prepared by the steps of: The mass ratio of ethylenediamine to methanol in the ethylenediamine methanol solution in step (11) is 1:(8-12); The mass ratio of methyl acrylate to methanol in the methyl acrylate methanol solution in step (11) is 1:(1-1.5).

17. The method for preparing the gel plugging agent as described in claim 14, characterized in that, The molar ratio of ethylenediamine to MA0.5 in the mixed solution in step (12) is (20-28):1; The mass ratio of MA0.5 to methanol in the MA0.5 methanol solution in step (12) is 1:(1-2); The mass ratio of the amount of petroleum ether to the amount of MA0.5 in step (12) is (3-15):1; The mass ratio of the amount of ethyl acetate to the amount of MA0.5 in step (12) is (3-15):

1.

18. The method of claim 17, wherein the gel plug is prepared by the steps of: The molar ratio of ethylenediamine to MA0.5 in the mixed solution in step (12) is (25-27):1; The mass ratio of MA0.5 to methanol in the MA0.5 methanol solution in step (12) is 1:(1-1.5); The mass ratio of the amount of petroleum ether to the amount of MA0.5 in step (12) is (8-12):1; The mass ratio of the amount of ethyl acetate to the amount of MA0.5 in step (12) is (8-12):

1.

19. The method for preparing the gel plugging agent as described in claim 14, characterized in that, The molar ratio of methyl acrylate to MA1.0 in the mixed solution in step (13) is (14-18):1; The mass ratio of MA1.0 to methanol in the MA1.0 methanol solution in step (13) is 1:(1-2); The mass ratio of the amount of petroleum ether to the amount of MA1.0 in step (13) is (3-15):1; The mass ratio of the amount of ethyl acetate to the amount of MA1.0 in step (13) is (3-15):

1.

20. The method of claim 19, wherein the gel plug is prepared by the steps of: The molar ratio of methyl acrylate to MA1.0 in the mixed solution in step (13) is (15-17):1; The mass ratio of MA1.0 to methanol in the MA1.0 methanol solution in step (13) is 1:(1-1.5); The mass ratio of the amount of petroleum ether to the amount of MA1.0 in step (13) is (8-12):1; The mass ratio of the amount of ethyl acetate to the amount of MA1.0 in step (13) is (8-12):

1.

21. The method for preparing the gel plugging agent as described in claim 14, characterized in that, The molar ratio of (Z)-3-aminoacrylamide to MA1.5 in the mixed solution in step (14) is (20-28):1; The mass ratio of (Z)-3-aminoacrylamide to methanol in the (Z)-3-aminoacrylamide methanol solution in step (14) is 1:(3-6); The mass ratio of MA1.5 to methanol in the MA1.5 methanol solution in step (14) is 1:(1-3); The mass ratio of the amount of petroleum ether to the amount of MA1.5 in step (14) is (3-15):1; The mass ratio of the amount of the ethyl acetate to the amount of MA1.5 in step (14) is (3-15):

1.

22. The method of claim 21, wherein the gel plug is prepared by the steps of: The molar ratio of (Z)-3-aminopropenamide to MA1.5 in the mixed solution in step (14) is (25-27):1; The mass ratio of (Z)-3-aminopropenamide to methanol in the methanol solution of (Z)-3-aminopropenamide in step (14) is 1:(4-5); The mass ratio of MA1.5 to methanol in the methanol solution of MA1.5 in step (14) is 1:2; The mass ratio of the amount of the petroleum ether to the amount of MA1.5 in step (14) is (8-12):1; The mass ratio of the amount of the ethyl acetate to the amount of MA1.5 in step (14) is (8-12):

1.

23. The method for preparing the gel plugging agent as described in claim 14, characterized in that, The mass ratio of p-carboxystyrene acid or p-vinylbenzoic acid or p-vinylphenylacetic acid to dendritic intermediate MAZ in step (15) is 1:(3-19); The concentration of the sum of the mass of p-carboxystyrene acid or p-vinylbenzoic acid or p-vinylphenylacetic acid and dendritic intermediate MAZ in step (15) is 10-30% by weight based on the mixed solution A; The initiator in step (15) is one of azobisisobutyronitrile, azobisisobutyramidine hydrochloride and azobisisoheptyl nitrile; The concentration of the initiator in step (15) is 0.05-0.12% by weight based on the mixed solution B.

24. The method for preparing the gel plugging agent as described in claim 23, characterized in that, The mass ratio of p-carboxystyrene acid or p-vinylbenzoic acid or p-vinylphenylacetic acid to dendritic intermediate MAZ in step (15) is 1:(4-9); The initiator in step (15) is azobisisobutyronitrile.

25. A gel plug, comprising: Prepared by the preparation method of any one of claims 13-24.

26. The use of the gel blocking agent of any one of claims 1-12 and 25 as a water plugging and profile control agent in heavy oil exploitation.

Images