Polyacrylamide copolymer and preparation method thereof, profile control and flooding movable gel and application

Abstract

The present application relates to the field of profile control and water plugging in oilfield water injection development, and discloses a polyacrylamide copolymer, a preparation method thereof, a profile control and flooding movable gel and application. The polyacrylamide copolymer contains a structural unit shown in formula (1), a structural unit shown in formula (2) and a structural unit shown in formula (3); wherein R is C4-C10 alkyl, n is an integer of 6-15, and M is a metal element; the profile control and flooding movable gel formed by the acrylamide copolymer can enter the deep part of an oil reservoir, has a relatively high viscosity under high-temperature and high-salt conditions, can reduce the oil-water surface interfacial tension, is suitable for being used as a profile control and flooding agent and a profile control and plugging agent in a high-permeability oil reservoir (permeability is higher than 2000 mD), has a relatively high plugging rate and has good emulsifying performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of profile control and water plugging in oilfield water injection development, in particular, to a polyacrylamide copolymer, a preparation method thereof, a profile control and flooding movable gel and application. BACKGROUND

[0002] With the development of oilfields in China into the middle and late stages, many domestic oilfields have entered the high water cut stage, and water control and oil stabilization and enhanced oil recovery have become the main problems currently faced. In addition, with the deepening of oilfield development, the recoverable reserves of conventional oilfields are becoming less and less, and the value of deep potential is becoming lower and lower, and people have to turn their attention to unconventional and harsh condition oilfields such as high temperature and high salt. For example, most of the main chemical flooding units in Shengli Oilfield currently belong to the first class resources, the resource production rate has reached more than 75%, and the remaining recoverable geological reserves are small, and the situation is serious, while the second and third class high temperature and high salt reservoirs are rich in chemical flooding resources, but the reservoir conditions are much harsher than the first class reservoirs.

[0003] There are high temperature and high salt reservoirs with abundant reserves in Northwest Oilfield, Shengli Oilfield, North China Oilfield, Central Plains Oilfield and Tarim Oilfield, and with the development, these high temperature and high salt main blocks gradually enter the high water cut stage. However, for high temperature and high salt reservoirs, due to the poor temperature resistance and salt resistance of conventional profile control and flooding agents, the effective time is short, and the profile control and flooding effect is obviously poor, and the enhanced oil recovery is limited. In order to better improve the development effect of high temperature and high salt reservoirs, it is urgent to explore the deep profile control and flooding system of high temperature and high salt reservoirs, and to explore the temperature-resistant and salt-resistant deep profile control and flooding system suitable for high temperature and high salt reservoirs. SUMMARY

[0004] The purpose of the present application is to overcome the above-mentioned problems existing in the prior art, provide a polyacrylamide copolymer, a preparation method thereof, a profile control and flooding movable gel and application. The profile control and flooding movable gel formed by the polyacrylamide copolymer can enter the deep part of the reservoir, has high viscosity under high temperature and high salt conditions, and can reduce the oil-water interfacial tension, is suitable for being used as a profile control and flooding agent and a profile control and plugging agent in high permeability reservoirs (permeability is higher than 2000 mD), has high plugging rate, and has good emulsifying performance.

[0005] The first aspect of the present application is to provide a polyacrylamide copolymer containing a structural unit represented by formula (1), a structural unit represented by formula (2) and a structural unit represented by formula (3);

[0006] In the formula, R is C4-C10 alkyl, n is an integer of 6-15, and M is a metal element.

[0007]

[0008] In the structural unit shown in formula (2) of the present application, R is C4-C10 alkyl, which can be linear alkyl or branched alkyl. In order to further improve the performance of the obtained polymer in application, preferably, R is C4-C10 linear alkyl, more preferably C7-C9 linear alkyl. In the present application, the C7-C9 linear alkyl can be at least one of C7 linear alkyl, C8 linear alkyl, and C9 linear alkyl.

[0009] In the structural unit shown in formula (2) of the present application, n is an integer of 6-15. In a preferred embodiment of the present application, n is an integer of 8-12, for example, 8, 9, 10, 11, 12, or any two values or any interval of any two values.

[0010] In the present application, M is a metal element. In a preferred embodiment of the present application, M is an alkali metal element, preferably potassium or sodium.

[0011] In the present application, the content of each structural unit in the copolymer can be selected in multiple ways. In order to further improve the performance of the obtained polymer in application, preferably, the content of the structural unit shown in formula (1) is 84-97 wt%, the content of the structural unit shown in formula (2) is 2-10 wt%, and the content of the structural unit shown in formula (3) is 1-6 wt%, based on the total weight of the polyacrylamide copolymer being 100%.

[0012] More preferably, the content of the structural unit shown in formula (1) is 88-94 wt%, the content of the structural unit shown in formula (2) is 4-8 wt%, and the content of the structural unit shown in formula (3) is 2-4 wt%, based on the total weight of the polyacrylamide copolymer being 100%.

[0013] The second aspect of the present application provides a preparation method of the polyacrylamide copolymer of the first aspect, comprising polymerizing a monomer mixture in a solvent in the presence of an initiator to obtain a copolymer colloid; and then hydrolyzing the copolymer colloid.

[0014] The monomer mixture contains acrylamide, a monomer shown in formula (4), and a monomer shown in formula (5).

[0015] In the present application, R is C4-C10 alkyl, n is an integer of 6-15, and M is a metal element.

[0016] In a preferred embodiment of the present application, the method for preparing the acrylamide copolymer comprises:

[0017] 1) polymerizing a monomer mixture in water under solution polymerization reaction conditions and in the presence of an initiator to obtain a copolymer colloid; wherein the monomer mixture contains acrylamide, monomer X and monomer Y, the monomer X has a structure shown in formula (4), the monomer Y has a structure shown in formula (5); and the acrylamide is used in an amount of 84-97% by weight, the monomer X is used in an amount of 2-10% by weight, and the monomer Y is used in an amount of 1-6% by weight;

[0018]

[0019] wherein R is a C4-C10 linear alkyl group, n is an integer of 6-15, and M is potassium or sodium.

[0020] 2) hydrolyzing the copolymer colloid, and obtaining an acrylamide copolymer after drying and crushing.

[0021] In the monomer shown in formula (4) in the present application, R is a C4-C10 alkyl group, which can be a linear alkyl group or a branched alkyl group. In order to further improve the performance of the obtained polymer in application, preferably, R is a C4-C10 linear alkyl group, and more preferably, R is a C7-C9 linear alkyl group. In the present application, the C7-C9 linear alkyl group can be at least one of a C7 linear alkyl group, a C8 linear alkyl group, and a C9 linear alkyl group.

[0022] In the monomer shown in formula (4) in the present application, n is an integer of 6-15. In a preferred embodiment of the present application, n is an integer of 8-12, for example, 8, 9, 10, 11, 12, or any two values or any interval of any two values.

[0023] In the monomer shown in formula (4) in the present application, M is a metal element. In a preferred embodiment of the present application, M is an alkali metal element, and preferably, M is potassium or sodium.

[0024] In the present application, the amount of each monomer in the copolymer can be selected in multiple ways. In order to further improve the performance of the obtained polymer in application, preferably, the amount of each monomer is such that, based on the total weight of the polyacrylamide copolymer being 100%, the content of the structural unit shown in formula (1) is 84-97% by weight, the content of the structural unit shown in formula (2) is 2-10% by weight, and the content of the structural unit shown in formula (3) is 1-6% by weight.

[0025] More preferably, the amount of each monomer is such that, based on the total weight of the polyacrylamide copolymer being 100%, the content of the structural unit shown in formula (1) is 88-94% by weight, the content of the structural unit shown in formula (2) is 4-8% by weight, and the content of the structural unit shown in formula (3) is 2-4% by weight.

[0026] In the present application, the content of the structural unit in the polymer can be obtained by the detection in the art. In the following examples, the content is calculated by the amount of the monomer.

[0027] In a preferred embodiment of the present application, the preparation method comprises the following steps:

[0028] 1) performing solution polymerization of the monomer mixture in water in the presence of an initiator to obtain a copolymer colloid;

[0029] 2) hydrolyzing the copolymer colloid under alkaline conditions.

[0030] The initiator in the present application can be the common initiator in the art. In order to further improve the performance of the obtained polymer in application, preferably, the initiator is an oxidation-reduction system initiator.

[0031] The amount of the initiator in the present application can be selected in a wide range. In a preferred embodiment of the present application, the amount of the oxidation-reduction system initiator is 0.015-0.15 parts by weight, relative to 100 parts by weight of the monomer mixture.

[0032] More preferably, the oxidation-reduction system initiator comprises a persulfate and a sulfite.

[0033] As to the persulfate, there can be a variety of choices. Preferably, the persulfate is selected from at least one of ammonium persulfate, potassium persulfate and sodium persulfate.

[0034] The sulfite in the present application can be selected in a wide range. In a preferred embodiment of the present application, the sulfite is selected from potassium bisulfite and / or sodium bisulfite.

[0035] In a more preferred embodiment of the present application, the amount of the sulfite is 0.005-0.05 parts by weight, and the amount of the persulfate is 0.01-0.1 parts by weight, relative to 100 parts by weight of the monomer mixture.

[0036] In order to further improve the performance of the obtained polymer in application, preferably, the solution polymerization system further comprises a complexing agent and / or an accelerator.

[0037] The amount of the complexing agent and the accelerator in the present application can be selected in a wide range. In a preferred embodiment of the present application, the amount of the complexing agent is 0.01-0.1 parts by weight, and / or the amount of the accelerator is 0.05-0.3 parts by weight, relative to 100 parts by weight of the monomer mixture.

[0038] Preferably, the accelerator is phenylthiocarbamide, in this preferred embodiment, the polymer of the present application has better performance and plugging rate in application. The inventors of the present application have found that adding accelerator during the solution polymerization reaction can further improve the tackiness and emulsifying performance of the prepared acrylamide copolymer.

[0039] In the present application, the complexing agent can be selected from a wide range, in a preferred embodiment of the present application, the complexing agent is disodium ethylenediaminetetraacetate.

[0040] In the present application, "and / or" means either one of the two cases, or both cases can exist.

[0041] The conditions of the solution polymerization reaction include: the polymerization reaction temperature is 10-20℃; and / or, the polymerization time is 8-10h.

[0042] Preferably, the solution polymerization reaction is carried out in an inert atmosphere, for the inert atmosphere, the conventional inert atmosphere in the art can be used, for example, nitrogen and / or inert gas, preferably, the inert atmosphere in the present application is provided by nitrogen.

[0043] In the present application, the pH value of the solution polymerization can be selected from a wide range, in a preferred embodiment of the present application, the pH value is 6-8. In this preferred embodiment, the polymer obtained by the present application has better performance. The adjustment of the pH value can be carried out by using the means commonly used in the prior art, for example, by adding alkali such as sodium hydroxide.

[0044] The hydrolysis reaction can be selected from a wide range. In order to further improve the performance of the obtained polymer in application, preferably, the hydrolysis reaction is carried out by mixing the copolymer colloid with solid alkali, and further preferably, the solid alkali is selected from sodium hydroxide and / or potassium hydroxide.

[0045] For the amount of solid alkali, the present application can be selected from a wide range, in a preferred embodiment of the present application, the mass ratio of the solid alkali to the copolymer colloid is 1:(15-44).

[0046] For the conditions of the hydrolysis reaction, the conditions can be adjusted in a wide range, preferably, the conditions of the hydrolysis reaction include: the temperature is 80-90℃, and / or, the time is 2-4h.

[0047] Preferably, the preparation method of the present application further comprises: after the hydrolysis reaction, the reaction product is granulated, dried, crushed and sieved to obtain the acrylamide copolymer.

[0048] According to a preferred specific embodiment provided by the present application, the method for preparing the acrylamide copolymer comprises:

[0049] 1) acrylamide is added into a reactor to form an aqueous solution, then monomer X, monomer Y, an aqueous solution of a complex and an accelerator are added, the pH value is adjusted, and the solution is stirred sufficiently to form a stable solution;

[0050] 2) an oxidation-reduction system initiator is added, inert gas is blown to mix the solution uniformly, and the polymer colloid is obtained after sealing and polymerization;

[0051] 3) the colloid is taken out, granulated, and then an alkaline substance is added to mix uniformly, and the hydrolysis reaction is carried out;

[0052] 4) the hydrolysis reaction product is granulated, dried, crushed, and sieved to obtain the acrylamide copolymer.

[0053] A third aspect of the present application provides a profile control and displacement movable gel, which contains the polyacrylamide copolymer of the first aspect or the polyacrylamide copolymer prepared by the preparation method of the second aspect, water and a crosslinking agent.

[0054] The profile control and displacement movable gel in the present application can be prepared by the following method: the acrylamide copolymer of the first aspect of the present application and / or the acrylamide prepared by the method of the second aspect of the present application are prepared by using field water, and then a crosslinking agent is added to form a movable gel after 2-5 days in a reservoir formation. The movable gel is used as a profile control and displacement agent and a profile control and plugging agent in a high permeability reservoir (permeability is higher than 2000 mD).

[0055] The present application introduces two kinds of monomers into the macromolecular chain of polyacrylamide to prepare a polyacrylamide copolymer, which has high viscosity under high temperature (150℃) and high salinity (150000 mg / L) conditions. After mixing with a crosslinking agent and being injected into a formation, the polyacrylamide copolymer can enter the deep part of a reservoir to form a movable gel to achieve effective plugging after 2-5 days, especially in a high permeability reservoir (permeability is higher than 2000 mD), and can reduce the oil-water surface interfacial tension and has good emulsifying performance.

[0056] The amounts of the polyacrylamide copolymer, the crosslinking agent and water can be adjusted in a wide range. In order to further improve the performance of the obtained polymer in application, preferably, the content of the polyacrylamide copolymer is 0.2-0.6 parts by weight, preferably 0.3-0.5 parts by weight, and the content of the crosslinking agent is 0.004-0.01 parts by weight, preferably 0.006-0.008 parts by weight, relative to 100 parts by weight of water.

[0057] For the crosslinking agent, the present application can also have multiple choices. In a preferred embodiment of the present application,

[0058] The crosslinking agent is selected from at least one of glyoxal, hexamethylenetetramine and formaldehyde.

[0059] The fourth aspect of the present application provides an application of the polyacrylamide copolymer of the first aspect or the polyacrylamide copolymer prepared by the preparation method of the second aspect or the profile control movable gel of the third aspect in oilfield water injection development.

[0060] The polyacrylamide copolymer prepared by simultaneously introducing two monomers into the macromolecular chain of polyacrylamide has high viscosity under high temperature (150 DEG C) and high salinity (150000 mg / L) conditions, can enter the deep part of the oil reservoir after being mixed with a crosslinking agent and injected into the formation, and forms a movable gel to achieve effective plugging after 2-5 days, is especially suitable for high permeability oil reservoirs (permeability is higher than 2000 mD), and can reduce the oil-water surface interfacial tension and has good emulsifying performance.

[0061] The polyacrylamide copolymer and the preparation method thereof have the following advantages and effects compared with the prior art in performance:

[0062] The present application simultaneously introduces two specific functional monomers X and functional monomer Y into the macromolecular chain of polyacrylamide, greatly improves the temperature resistance and salt resistance of the copolymer and the surface interfacial activity, can effectively enter the deep part of the high temperature and high salinity oil reservoir after being mixed with a crosslinking agent, achieves the purpose of deep profile control, and forms a movable gel to effectively plug the high permeability layer in the oil reservoir formation after 2-5 days. The inventor of the present application found through research and verification that the functional monomer X (shown in formula 4) in the present application contains a super hydrophilic group and an oleophilic group, has good emulsifying effect, plays a self-emulsifying role in the polymerization system, and the formed copolymer has good emulsifying and oil carrying effect. The functional monomer Y (shown in formula 5) in the present application has excellent performance, especially under the action of a promoter, the polymerization activity is significantly improved, the structure units of the three copolymer monomers are randomly distributed in the high molecular chain, and the polymer has excellent tackifying and emulsifying and oil washing capacity. The polyacrylamide copolymer of the present application is prepared into a solution by using oilfield site water, mixed with a crosslinking agent, and injected into the oil reservoir formation together, has good fluidity, can smoothly enter the deep part of the oil reservoir, achieves the effect of deep profile control and plugging, forms a movable gel after 2-5 days of well shut-in, enhances the effective plugging of the high permeability layer in the oil reservoir formation, greatly improves the oil recovery rate, is especially suitable for high permeability oil reservoirs (permeability is higher than 2000 mD), and has important significance for oilfield production increase and efficiency improvement. DETAILED DESCRIPTION

[0063] The application will be described in detail below with specific examples. It is necessary to point out here that the following examples are only used to further illustrate the application and cannot be understood as limiting the protection scope of the application. Some non-essential improvements and adjustments to the application made by those skilled in the art according to the content of the application still fall within the protection scope of the application.

[0064] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited. The endpoints of the ranges and the values are approximations that are understood to encompass values approximating these.

[0065] The application will be described in detail below with specific examples. It is necessary to point out here that the following examples are only used to further illustrate the application and cannot be understood as limiting the protection scope of the application. Some non-essential improvements and adjustments to the application made by those skilled in the art according to the content of the application still fall within the protection scope of the application.

[0066] Unless otherwise specified, all raw materials are commercially available. Among them, acrylamide is purchased from Dongying Baomo Environmental Engineering Co., Ltd., functional monomer X is as shown in formula (4), M is Na, R and n are described in the examples, and are purchased from Shenzhen Aituo Chemical Co., Ltd., functional monomer Y is as shown in formula (5), and is prepared according to the method described in (Tsaur S.L., Fitch R.M.. Preparation and properties of polystyrene model colloids: I. Preparation of surface-active monomer and model colloids derived therefrom. Journal of Colloid and Interface Science, 1987, 115(2): 450-462).

[0067]

[0068] The apparent viscosity of the acrylamide copolymer solution is determined by a Brookfield viscometer with a No. 62 rotor, and the test temperature is 95℃; the surface tension of the acrylamide copolymer solution is determined by a DCAT-21 surface tension meter, and the test temperature is 25℃.

[0069] The apparent viscosity and surface tension of the acrylamide copolymer are tested after being prepared with field water (mineralization 150000 mg / L), and after being mixed with a crosslinking agent and injected into a core, the plugging rate is determined after being stably kept at 150℃ for 90 days.

[0070] The plugging rate is determined by a laboratory core physical model test. Specifically:

[0071] Plugging rate determination: The artificial core is loaded into a core holder, saturated with water, and the permeability (K1) is measured. A mixture of 0.5 PV of acrylamide and crosslinking agent is injected, and the core is cured at 150°C for 48 hours. The permeability (K2) is then measured after water flooding. The plugging rate is calculated as (1-K2 / K1) x 100%.

[0072] Example 1

[0073] 1) 739.2 g of acrylamide is added to a polymerization reaction bottle, and deionized water 3120 g is added to dissolve and form an aqueous solution. Functional monomer X (wherein R is a linear alkyl group with C4, and n = 6) 88.0 g, functional monomer Y 55.8 g, EDTA-2Na 0.15 g, and phenylthiosemicarbazide 0.44 g are sequentially added. Sodium hydroxide is then added to adjust the pH of the solution to 6.4, and the solution is thoroughly stirred to form a stable solution;

[0074] 2) The solution is deoxygenated by purging with high-purity nitrogen gas at 10°C for 30 minutes. Then, 1 wt% potassium persulfate aqueous solution 20 g and 1 wt% sodium bisulfite aqueous solution 10 g are added to initiate the reaction. Nitrogen gas is continuously purged for five minutes, and then the polymerization reaction is stopped. The solution is sealed and polymerized for 10 hours to obtain a polymer colloid;

[0075] 3) The colloid is taken out, granulated, and mixed with 99.2 g of sodium hydroxide granules to form a uniform mixture. The mixture is then hydrolyzed at 80°C for 3 hours;

[0076] 4) The granules are taken out, granulated again, dried at 60°C to a constant weight, crushed, and sieved to obtain white granular acrylamide copolymer NJD1.

[0077] 1000 g of field water (salinity 150000 mg / L) is taken, and 2.5 g of acrylamide copolymer NJD1 sample is added. After stirring, a solution is formed, and its apparent viscosity and surface tension are tested. 0.042 g of crosslinking agent (a mixture of formaldehyde and glyoxal with a mass ratio of 1:1) is added to the solution and mixed uniformly. The mixture is injected into a core, and the core is kept stable at 150°C for 90 days. Then, the plugging rate is measured. The results are shown in Table 1.

[0078] Example 2

[0079] 1) 774.4 g of acrylamide is added to a polymerization reaction bottle, and deionized water 3120 g is added to dissolve and form an aqueous solution. Functional monomer X (wherein R is a linear alkyl group with C9, and n = 10) 70.4 g, functional monomer Y 35.2 g, EDTA-2Na 0.22 g, and phenylthiosemicarbazide 1.4 g are sequentially added. Sodium hydroxide is then added to adjust the pH of the solution to 7.2, and the solution is thoroughly stirred to form a stable solution;

[0080] 2) After the above solution was deoxygenated by passing high purity nitrogen gas for 30 minutes at 20°C, 1 wt% potassium persulfate aqueous solution 36 g and 1 wt% sodium bisulfite aqueous solution 18 g were added to initiate the reaction. Nitrogen gas was continued to be passed for 5 minutes and then stopped. The polymer colloid was obtained after the polymerization reaction for 8.5 hours under sealing;

[0081] 3) The colloid was taken out, granulated, and mixed with 109.1 g of sodium hydroxide granules. After uniform mixing, the hydrolysis reaction was carried out at 90°C for 2 hours;

[0082] 4) The colloid granules were taken out, granulated again, dried to constant weight at 60°C, crushed, and sieved to obtain white granular acrylamide copolymer NJD2.

[0083] 1000 g of field water (salinity 150000 mg / L) was taken, 3.3 g of acrylamide copolymer NJD2 sample was added, and after stirring, a solution was formed. The apparent viscosity and surface tension were tested, respectively. 0.068 g of crosslinking agent glyoxal was added to the above solution and mixed uniformly, then injected into the core. After being kept at 150°C for 90 days, the plugging rate was determined. The results are shown in Table 1.

[0084] Example 3

[0085] 1) 792.0 g of acrylamide was added to a heat-preservation polymerization reaction bottle, deionized water 3120 g was added to dissolve and prepare an aqueous solution, functional monomer X (wherein R is a linear alkyl group with 7 carbons, n = 12) 61.6 g, functional monomer Y 26.4 g, EDTA-2Na 0.48 g, phenylaminothiourea 2.2 g were added in sequence, sodium hydroxide was added to adjust the pH of the solution to 7.1, and the solution was stirred thoroughly to become a stable solution;

[0086] 2) After the above solution was deoxygenated by passing high purity nitrogen gas for 30 minutes at 18°C, 1 wt% potassium persulfate aqueous solution 56 g and 1 wt% sodium bisulfite aqueous solution 28 g were added to initiate the reaction. Nitrogen gas was continued to be passed for 5 minutes and then stopped. The polymer colloid was obtained after the polymerization reaction for 8 hours under sealing;

[0087] 3) The colloid was taken out, granulated, and mixed with 123.9 g of sodium hydroxide granules. After uniform mixing, the hydrolysis reaction was carried out at 85°C for 2 hours;

[0088] 4) The colloid granules were taken out, granulated again, dried to constant weight at 60°C, crushed, and sieved to obtain white granular acrylamide copolymer NJD3.

[0089] Take the field water (mineralization 150000 mg / L) 1000 g, add acrylamide copolymer NJD3 sample 4.2 g, after stirring to form a solution, respectively, test its apparent viscosity and surface tension, in the above solution, add 0.074 g crosslinking agent hexamethyl tetramine mixed evenly after injection into the core, at 150 ℃ stable for 90 days, then determine the plugging rate. Results are shown in Table 1.

[0090] Example 4

[0091] 1) 827.2 g of acrylamide was added to a heat-preservation polymerization reaction bottle, deionized water 3120 g was added to dissolve and form an aqueous solution, functional monomer X (wherein R is a linear alkyl group of C8, n = 8) 35.2 g, functional monomer Y 17.6 g, EDTA-2Na 0.45 g, phenylthiohydantoin 1.8 g were added in turn, sodium hydroxide was added to adjust the solution pH to 6.9, and the solution was fully stirred to become a stable solution;

[0092] 2) At 20 ℃, high-purity nitrogen was blown into the above solution for 30 minutes to remove oxygen, then 1% by weight of potassium persulfate aqueous solution 88 g and 1% by weight of sodium bisulfite aqueous solution 44 g were added to initiate the reaction, and the nitrogen blowing was continued for five minutes and then stopped. After sealing, the polymerization reaction was carried out for 9 hours to obtain a polymer colloid;

[0093] 3) The colloid was taken out, granulated, and then mixed with 121.5 g of sodium hydroxide granules to hydrolyze at 85 ℃ for 3 hours;

[0094] 4) The granules were taken out, granulated again, dried at 60 ℃ to constant weight, crushed, and sieved to obtain white granular acrylamide copolymer NJD4.

[0095] Take the field water (mineralization 150000 mg / L) 1000 g, add acrylamide copolymer NJD4 sample 3.2 g, after stirring to form a solution, respectively, test its apparent viscosity and surface tension, in the above solution, add 0.062 g crosslinking agent hexamethyl tetramine mixed evenly after injection into the core, at 150 ℃ stable for 90 days, then determine the plugging rate. Results are shown in Table 1.

[0096] Example 5

[0097] 1) 853.6 g of acrylamide was added to a heat-preservation polymerization reaction bottle, deionized water 3120 g was added to dissolve and form an aqueous solution, functional monomer X (wherein R is a linear alkyl group of C10, n = 15) 17.6 g, functional monomer Y 8.8 g, EDTA-2Na 0.88 g, phenylthiohydantoin 2.6 g were added in turn, sodium hydroxide was added to adjust the solution pH to 8.0, and the solution was fully stirred to become a stable solution;

[0098] 2) After the above solution was deoxygenated by passing high purity nitrogen gas at 15°C for 30 minutes, 1% by weight of potassium persulfate aqueous solution 70 g and 1% by weight of sodium bisulfite aqueous solution 35 g were added to initiate the reaction, and the nitrogen gas was passed for another 5 minutes and then stopped. The polymerization was carried out for 10 hours after the solution was sealed.

[0099] 3) The gel was taken out, granulated, and mixed with 119.0 g of sodium hydroxide granules. After the mixture was uniformly mixed, the hydrolysis reaction was carried out at 90°C for 2.5 hours.

[0100] 4) The gel particles were taken out, granulated, dried at 60°C to a constant weight, crushed, and sieved to obtain white granular acrylamide copolymer NJD5.

[0101] 1000 g of field water (salinity 150000 mg / L) was taken, 6.0 g of acrylamide copolymer NJD5 sample was added, and the solution was formed after stirring. The apparent viscosity and surface tension of the solution were tested, respectively. 0.010 g of crosslinking agent hexamethyl tetramine was added to the above solution and mixed uniformly, and then injected into the core. The plugging rate was measured after the core was kept at 150°C for 90 days. The results are shown in Table 1.

[0102] Example 6

[0103] The polymer and the mobile gel were prepared according to the method of Example 3, except that the monomer ratio was different. The amount of acrylamide was 844.8 g, the amount of functional monomer X was 17.6 g, and the amount of functional monomer Y was 17.6 g. That is, the mass ratio of acrylamide was 96%, the mass ratio of functional monomer X was 2%, and the mass ratio of functional monomer Y was 2% based on the total mass of all monomers being 100%. Acrylamide copolymer NJD6 was obtained. The results are shown in Table 1.

[0104] Example 7

[0105] The polymer and the mobile gel were prepared according to the method of Example 3, except that n=10 in functional monomer X was replaced by n=15. Acrylamide copolymer NJD7 was obtained. The results are shown in Table 1.

[0106] Example 8

[0107] The polymer was prepared according to the method of Example 3, except that 4-methyl amino thiourea was used as a promoter instead of phenyl amino thiourea in Example 3. Acrylamide copolymer NJD8 was obtained. The results are shown in Table 1.

[0108] Comparative Example 1

[0109] The polymer was prepared according to the method of Example 3, except that (N-(4-aminophenyl) maleimide) was used instead of functional monomer Y in Example 2. Acrylamide copolymer D1 was obtained. The results are shown in Table 1.

[0110] Comparative Example 2

[0111] The polymer was prepared according to the method of Example 3, except that no functional monomer Y was added, to obtain acrylamide copolymer D2. The results are shown in Table 1.

[0112] Table 1

[0113]

[0114] As can be seen from the results in Table 1, the acrylamide copolymer provided by the present application has higher apparent viscosity and good surface activity under the conditions of a temperature of 95°C and a salinity of 150,000 mg / L, and can form a movable gel at a formation temperature of 150°C, and has excellent plugging effect, and can be applied to high permeability reservoirs (higher than 2,000 mD), and is of great significance for improving the recovery of crude oil.

[0115] It should be noted that the above-described examples are only used to explain the present application and do not constitute any limitation on the present application. The present application is described by referring to typical examples, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified as specified within the scope of the claims of the present application, and the present application can be revised within the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and examples, it does not mean that the present application is limited to the specific examples disclosed therein, on the contrary, the present application can be extended to all other methods and applications having the same function.

[0116] All publications, patent applications, patents and other references mentioned in this specification are hereby incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present specification will control.

[0117] When the specification derives material, substances, methods, steps, devices or components, etc. with the word head "known to those skilled in the art", "prior art" or similar language, the word head derived objects cover those commonly used in the art at the time of filing this application, but also include those not commonly used at present, but will become recognized as suitable for similar purposes in the art.

[0118] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0119] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0120] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. A polyacrylamide copolymer, said polyacrylamide copolymer being composed of structural units shown in formula (1), structural units shown in formula (2), and structural units shown in formula (3); in, In the structural unit shown in formula (2): R is a C4-C10 alkyl group, n is an integer from 6 to 15, and M is a metal element; Equation (1), Equation (2), Equation (3); With the total weight of the polyacrylamide copolymer as 100%, the content of the structural unit shown in formula (1) is 84-97% by weight, the content of the structural unit shown in formula (2) is 2-10% by weight, and the content of the structural unit shown in formula (3) is 1-6% by weight; A method for preparing polyacrylamide copolymers includes polymerizing a monomer mixture in a solvent in the presence of an initiator to obtain a copolymer colloid; and then subjecting the copolymer colloid to a hydrolysis reaction. The monomer mixture is composed of acrylamide, the monomer shown in formula (4), and the monomer shown in formula (5); Formula (4), where R is a C4-C10 alkyl group. Equation (5).

2. The polyacrylamide copolymer according to claim 1, characterized in that: In the structural unit shown in equation (2): R is a C4-C10 straight-chain alkyl group; and / or, n is an integer between 8 and 12; and / or, M is an alkali metal element.

3. The polyacrylamide copolymer according to claim 1, characterized in that: In the structural unit shown in equation (2): R is a C7-C9 straight-chain alkyl group; and / or, M represents potassium or sodium.

4. The polyacrylamide copolymer according to claim 1, characterized in that: With the total weight of the polyacrylamide copolymer as 100%, the content of the structural unit shown in formula (1) is 88-94% by weight, the content of the structural unit shown in formula (2) is 4-8% by weight, and the content of the structural unit shown in formula (3) is 2-4% by weight.

5. A method for preparing the polyacrylamide copolymer according to any one of claims 1-4, comprising: polymerizing a monomer mixture in a solvent in the presence of an initiator to obtain a copolymer colloid; and then subjecting the copolymer colloid to a hydrolysis reaction; in, The monomer mixture consists of acrylamide, the monomer shown in formula (4), and the monomer shown in formula (5); Formula (4), where R is a C4-C10 alkyl group. Equation (5).

6. The preparation method according to claim 5, characterized in that... Includes the following steps: 1) In the presence of an initiator, a monomer mixture is subjected to solution polymerization in water to obtain a copolymer colloid; 2) The copolymer colloid is subjected to hydrolysis under alkaline conditions.

7. The preparation method according to claim 5 or 6, characterized in that: The initiator is a redox initiator, and / or, relative to 100 parts by weight of the monomer mixture, the amount of the redox initiator is 0.015-0.15 parts by weight.

8. The preparation method according to claim 7, characterized in that: The initiators of the redox system include persulfate and sulfite.

9. The preparation method according to claim 8, characterized in that: The persulfate is selected from at least one of ammonium persulfate, potassium persulfate, and sodium persulfate; and / or, the sulfite is selected from potassium bisulfite and / or sodium bisulfite; and / or, The amount of sulfite used is 0.005-0.05 parts by weight relative to 100 parts by weight of the monomer mixture; the amount of persulfate used is 0.01-0.1 parts by weight.

10. The preparation method according to claim 6, characterized in that: The solution polymerization reaction system also contains a complexing agent and / or a accelerator.

11. The preparation method according to claim 10, characterized in that: The amount of the complexing agent is 0.01-0.1 parts by weight relative to 100 parts by weight of the monomer mixture, and / or the amount of the accelerator is 0.05-0.3 parts by weight; The accelerator is phenylaminothiourea; and / or, the complexing agent is disodium ethylenediaminetetraacetate.

12. The preparation method according to claim 6, characterized in that: The conditions for the solution polymerization reaction include: a polymerization temperature of 10-20℃; and / or a time of 8-10h; And / or, the solution polymerization reaction is carried out under an inert atmosphere; And / or, pH value is 6-8.

13. The preparation method according to claim 6, characterized in that: The hydrolysis reaction is performed by mixing the copolymer colloid with a solid alkaline substance.

14. The preparation method according to claim 13, characterized in that: The solid alkaline substance is selected from sodium hydroxide and / or potassium hydroxide; and / or, the mass ratio of the solid alkaline substance to the copolymer colloid is 1:(15-44).

15. The preparation method according to claim 13, characterized in that: The conditions for the hydrolysis reaction include a temperature of 80-90℃ and / or a time of 2-4 hours.

16. A modulated movable gel, comprising the polyacrylamide copolymer according to any one of claims 1-4 or the polyacrylamide copolymer prepared by the preparation method according to any one of claims 5-15, water, and a crosslinking agent.

17. The modulated movable gel according to claim 16, characterized in that: The content of the polyacrylamide copolymer relative to 100 parts by weight is 0.2-0.6 parts by weight, and the content of the crosslinking agent is 0.004-0.01 parts by weight; and / or, The crosslinking agent is selected from at least one of glyoxal and formaldehyde.

18. The modulated movable gel according to claim 16, characterized in that: The content of the polyacrylamide copolymer is 0.3-0.5 parts by weight relative to 100 parts by weight of water, and the content of the crosslinking agent is 0.006-0.008 parts by weight.

19. The application of the polyacrylamide copolymer according to any one of claims 1-4 as a raw material, or the polyacrylamide copolymer prepared by the preparation method according to any one of claims 5-15 as a raw material, or the movable gel according to any one of claims 16-18 in water injection development in oilfields.

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