Polyacrylamide polymers, processes for their preparation, mobile gels and uses

Abstract

The present application relates to the field of profile control and water plugging in oilfield water injection development, and particularly relates to an acrylamide polymer, a preparation method and application thereof. The polymer contains structural unit A, structural unit B and structural unit C, wherein the structural unit A has a structure shown in formula (1), the structural unit B has a structure shown in formula (2), and the structural unit C has a structure shown in formula (3); wherein R is C5-C12 alkyl, and n is an integer of 8-12. The movable gel formed by the acrylamide polymer has high viscosity under high temperature and high salt conditions, can enter the deep part of the oil reservoir, and can reduce the oil-water surface interfacial tension, has good emulsifying performance, is suitable for being used as a profile control and displacement agent and a profile control and plugging agent in a high-permeability oil reservoir (permeability is higher than 2000 mD), and has high plugging rate.

Description

Technical Field

[0001] This invention relates to the field of profile control and water shut-off in oilfield water injection development, specifically to a polyacrylamide polymer, its preparation method, and its application. Background Technology

[0002] In the process of water injection development in my country's oilfields, water shut-off and profile control techniques are commonly used to improve water production and enhance oilfield efficiency. However, in high-temperature, high-salinity reservoirs and during the later stages of high water cut, ordinary water shut-off and profile control techniques are insufficient to guarantee effective oilfield development. Therefore, to address issues such as severe formation heterogeneity and water cross-contamination, researchers have begun to study other technical methods and novel water shut-off agents. Through long-term research, researchers have discovered that effectively solving the problems of water cross-contamination and bypassing during formation injection can ensure the smooth development of the oilfield.

[0003] In recent years, with the continuous improvement of water injection development in my country's oilfields, the water cut of reservoirs has further increased, reaching over 95%. This has led to the proposal to adjust the water absorption profile in the deep reservoir, forcing fluid flow to change direction, improving the effectiveness of water injection development, and ultimately enhancing oil recovery. With the deepening understanding and technological advancements in formation water injection development, deep reservoir water injection technology has gradually become a new research hotspot, playing a crucial role in stabilizing oil production and controlling water flow. Correspondingly, new chemical agents such as strong gels, weak gels, and particulate gels have been developed. However, these chemical agents generally suffer from poor fluidity, especially in the face of severe water flooding and complex oil-water relationships in ultra-high water-cut stages. They cannot achieve the goal of deep reservoir water injection and can only act in the vicinity of the implementation well, resulting in short implementation cycles and poor effects. Summary of the Invention

[0004] The purpose of this invention is to overcome the aforementioned problems in the prior art and provide a polyacrylamide polymer, its preparation method, a movable gel, and its applications. The movable gel formed by this acrylamide polymer has high viscosity under high temperature and high salt conditions, can penetrate deep into the oil reservoir, and can reduce the interfacial tension between oil and water. It has good emulsification properties and is suitable for use as a modifier and plugging agent in high-permeability reservoirs (permeability higher than 2000 mD), with a high plugging rate.

[0005] One of the objectives of this invention is to provide a polyacrylamide polymer containing structural unit A, structural unit B and structural unit C, wherein structural unit A has the structure shown in formula (1), structural unit B has the structure shown in formula (2) and structural unit C has the structure shown in formula (3).

[0006]

[0007] Where R is a C5-C12 alkyl group and n is an integer from 8 to 12.

[0008] According to the present invention, the content of structural unit A, structural unit B and structural unit C in the acrylamide polymer can be selected within a wide range. In a preferred embodiment of the present invention, based on the total weight of the acrylamide polymer, the content of structural unit A is 80-95% by weight, the content of structural unit B is 2-15% by weight, and the content of structural unit C is 0.5-5% by weight.

[0009] In a more preferred embodiment of the present invention, based on the total weight of the acrylamide polymer, the content of structural unit A is 88-92% by weight, the content of structural unit B is 7-9.5% by weight, and the content of structural unit C is 0.5-3% by weight.

[0010] According to the present invention, R is a C5-C12 alkyl group, for example, it can be an alkyl group with 5, 6, 7, 8, 9, 10, 11 or 12 C atoms. In a preferred embodiment of the present invention, R is a C7-C9 straight-chain alkyl group.

[0011] According to the present invention, n is an integer from 8 to 12. In a preferred embodiment of the present invention, n is an integer from 8 to 10, for example, it can be 8, 9, or 10.

[0012] A second objective of this invention is to provide a method for preparing the polymer described above, comprising: polymerizing a monomer mixture in a solvent under polymerization reaction conditions and in the presence of an initiator to obtain a polymer colloid; and then subjecting the polymer colloid to a hydrolysis reaction.

[0013] The monomer mixture contains acrylamide, monomer X and monomer Y, wherein monomer X has the structure shown in formula (4) and monomer Y has the structure shown in formula (5);

[0014]

[0015] In formula (4), R is a C5-C12 alkyl group and n is an integer from 8 to 12.

[0016] According to the present invention, R is a C5-C12 alkyl group, for example, it can be an alkyl group with 5, 6, 7, 8, 9, 10, 11 or 12 C atoms. In a preferred embodiment of the present invention, R is a C7-C9 straight-chain alkyl group.

[0017] According to the present invention, n is an integer from 8 to 12. In a preferred embodiment of the present invention, n is an integer from 8 to 10, for example, it can be 8, 9, or 10.

[0018] According to the present invention, the range of selection for the amount of each monomer is relatively wide. In a preferred embodiment of the present invention, based on the total mass of the monomer mixture as 100%, the amount of acrylamide is 80-95%, the amount of monomer X is 2-15% by weight, and the amount of monomer Y is 0.5-5% by weight.

[0019] In a more preferred embodiment of the present invention, based on the total mass of the monomer mixture as 100%, the amount of acrylamide is 88-92%, the amount of monomer X is 7-9.5% by weight, and the amount of monomer Y is 0.5-3% by weight.

[0020] In this invention, the content of structural units in the polymer can be obtained through detection in the art. In the examples described below, calculations are performed based on the amount of monomer added.

[0021] In this invention, both monomer X and monomer Y are commercially available.

[0022] In a preferred embodiment of the present invention, the preparation method includes the following steps:

[0023] 1) Under solution polymerization conditions and in the presence of an initiator, a monomer mixture is polymerized in water to obtain a polymer colloid;

[0024] 2) The polymer colloid is subjected to a hydrolysis reaction.

[0025] According to the present invention, the conditions for the solution polymerization reaction can be selected from a wide range. In a preferred embodiment of the present invention, the conditions for the solution polymerization reaction include: the solution polymerization reaction is carried out under an inert atmosphere, such as a nitrogen and / or inert gas atmosphere.

[0026] According to the present invention, the polymerization reaction temperature can be selected over a wide range. In a preferred embodiment of the present invention, the polymerization reaction temperature is 20-30°C.

[0027] According to the present invention, the polymerization reaction time can be selected from a wide range. In a preferred embodiment of the present invention, the time is 8-10 hours.

[0028] According to the present invention, the pH range can be selected widely. In a preferred embodiment of the present invention, the pH value is 6-8. The pH value can be adjusted using methods commonly used in the prior art, such as by adding an alkaline substance like sodium hydroxide.

[0029] In a more preferred embodiment of the present invention, the conditions for the polymerization reaction include: a polymerization temperature of 20-30°C, a time of 8-10 hours, and a pH value of 6-8.

[0030] According to the present invention, the initiator can be selected from multiple sources. In a preferred embodiment of the present invention, the initiator is a redox system initiator, preferably selected from at least one of a persulfate oxidant and a sulfite reductant; preferably, the persulfate oxidant is selected from at least one of potassium persulfate, sodium persulfate, and ammonium persulfate; more preferably, the sulfite is selected from potassium bisulfite and / or sodium bisulfite; and / or, relative to 100 parts by weight of the monomer mixture, the amount of the persulfate oxidant is 0.01-0.1 parts by weight; the amount of the sulfite reductant is 0.005-0.05 parts by weight.

[0031] In a preferred embodiment of the present invention, the solution polymerization reaction is further subjected to the following conditions: the reaction is carried out in the presence of a complexing agent; preferably, the amount of the complexing agent is 0.01-0.1 parts by weight relative to 100 parts by weight of the monomer mixture.

[0032] The complexing agent can be selected from a variety of options, and preferably, the complexing agent is disodium ethylenediaminetetraacetate.

[0033] In a preferred embodiment of the present invention, the solution polymerization reaction is further subjected to the following conditions: the reaction is carried out in the presence of an accelerator; preferably, the amount of the accelerator is 0.05-0.5 parts by weight relative to 100 parts by weight of the monomer mixture.

[0034] The accelerator can be selected from a variety of options, and preferably, the accelerator is (4-bromophenyl)thiourea.

[0035] In this invention, adding an accelerator during the solution polymerization reaction can further improve the thickening and emulsifying properties of the prepared acrylamide polymer, thereby increasing the blocking rate of the product in application.

[0036] In a preferred embodiment of the present invention, the solution polymerization reaction further includes being carried out in the presence of a complexing agent and an accelerator; preferably,

[0037] The complexing agent is 0.01-0.1 parts by weight and the accelerator is 0.05-0.5 parts by weight relative to 100 parts by weight of the monomer mixture; preferably, the complexing agent is disodium ethylenediaminetetraacetate; preferably, the accelerator is (4-bromophenyl)thiourea.

[0038] According to the present invention, the conditions for the hydrolysis reaction can be selected from a wide range. In a preferred embodiment of the present invention, the hydrolysis reaction is carried out under alkaline conditions, preferably by mixing the polymer colloid with a solid alkaline substance, and more preferably the solid alkaline substance is selected from sodium hydroxide and / or potassium hydroxide.

[0039] In this invention, there is no particular limitation on the amount of alkaline substance added, and the mass ratio of the solid alkaline substance to the polymer colloid can be selected from a wide range. In a preferred embodiment of this invention, the mass ratio of the solid alkaline substance to the polymer colloid is 1:(15-44).

[0040] According to the present invention, the conditions for the hydrolysis reaction can be selected from a wide range. In a preferred embodiment of the present invention, the conditions for the hydrolysis reaction include: a temperature of 80-90°C and / or a time of 2-3 hours.

[0041] In a preferred embodiment of the present invention, the preparation method further includes granulating, drying, pulverizing, and sieving the reaction product after the hydrolysis reaction to obtain an acrylamide polymer. The specific process conditions for granulation, drying, pulverizing, and sieving described above are conventional techniques in the art and will not be elaborated further here.

[0042] In a more preferred embodiment of the present invention, the method for preparing acrylamide polymer includes:

[0043] 1) Add acrylamide to the reactor to prepare an aqueous solution, then add monomer X, monomer Y, complex aqueous solution and accelerator, adjust the pH value, and stir thoroughly to make it a stable solution;

[0044] 2) Add an initiator to the redox system, blow in an inert gas to mix it evenly, seal it, and then polymerize to obtain a polymer colloid;

[0045] 3) Remove the colloid, granulate it, add an alkaline substance, mix it evenly, and then carry out a hydrolysis reaction;

[0046] 4) The hydrolysis reaction product is granulated, dried, pulverized and sieved to obtain acrylamide polymer.

[0047] A third objective of this invention is to provide a movable gel containing the polymer described above or the polymer prepared by the method described above, as well as a crosslinking agent and water.

[0048] In practical applications, the acrylamide polymer described above and the acrylamide polymer prepared by the method described above can be prepared on-site with water, and a crosslinking agent can be added. After 2-5 days in the reservoir formation, a mobile gel is formed. This mobile gel can be used as a moderating agent and plugging agent in high-permeability reservoirs (permeability higher than 2000mD).

[0049] According to the present invention, the amount of the polymer and the crosslinking agent can be selected from a wide range. In a preferred embodiment of the present invention, the content of the polymer is 0.2-0.8 parts by weight, preferably 0.3-0.7 parts by weight, relative to 100 parts by weight of water, and the content of the crosslinking agent is 0.004-0.01 parts by weight, preferably 0.006-0.008 parts by weight.

[0050] According to the present invention, the crosslinking agent can be selected from a wide range. In a preferred embodiment of the present invention, the crosslinking agent is selected from at least one of formaldehyde, glyoxal and hexamethylenetetramine.

[0051] The fourth objective of this invention is to provide an application of the polymer described above, or the polymer prepared by the preparation method described above, or the movable gel described above, in oilfield water injection, profile control, and water shut-off.

[0052] The acrylamide polymer of this invention is prepared by mixing a solution with water from the oilfield and a crosslinking agent, and then injected into the oil reservoir formation. It has excellent fluidity and can smoothly enter the deep reservoir to achieve the effects of deep displacement and plugging. Moreover, it forms a movable gel after 2-5 days of well shut-in, which enhances the effective plugging of high-permeability layers in the oil reservoir formation and can significantly improve the oil recovery rate. It is especially suitable for high-permeability reservoirs (permeability higher than 2000mD) and has important significance for increasing oilfield production and efficiency.

[0053] The acrylamide polymer, its preparation method, and the movable gel described in this invention have the following advantages compared with the prior art:

[0054] The mobile gel formed by this acrylamide polymer exhibits high viscosity under high temperature and high salinity conditions, allowing it to penetrate deep into oil reservoirs. It also reduces the interfacial tension between oil and water, demonstrating good emulsification properties. Suitable for use as a modifier and plugging agent in high-permeability reservoirs (permeability greater than 2000 mD), it achieves a high plugging rate. Its application in high-permeability reservoirs (greater than 2000 mD) is of great significance for improving oil recovery.

[0055] This invention introduces monomers X and Y into the macromolecular chain of polyacrylamide to prepare a polyacrylamide polymer that exhibits high viscosity under high temperature (150℃) and high salinity (150000mg / L) conditions. When mixed with a crosslinking agent and injected into the formation, it can penetrate deep into the reservoir and form a mobile gel after 2-5 days to achieve effective plugging. It is particularly suitable for high-permeability reservoirs (permeability higher than 2000mD) and can reduce the interfacial tension between oil and water. It also has good emulsification properties and is especially suitable for high-temperature and high-salinity reservoir conditions. When used as a modifier and plugging agent, it has a high plugging rate.

[0056] The inventors of this invention, through research and verification, believe that the reasons for the above advantages may be as follows:

[0057] This invention introduces functional monomers X and Y simultaneously into the macromolecular chain of polyacrylamide. Functional monomer X contains both superhydrophilic and lipophilic groups, exhibiting excellent emulsifying properties and acting as a self-emulsifier in the polymerization system. The resulting polymer possesses excellent emulsifying and oil-carrying capabilities. Functional monomer Y, under the action of an accelerator, exhibits significantly enhanced polymerization activity, allowing the structural units of the three comonomers to be randomly distributed within the polymer chain, thus providing excellent thickening and emulsifying / washing capabilities. The polymer obtained by copolymerizing the three monomers significantly improves temperature and salt resistance as well as interfacial activity. When mixed with a crosslinking agent, it can effectively penetrate deep into high-temperature, high-salinity oil reservoirs, achieving deep-level regulation and displacement. Furthermore, it forms a mobile gel after 2-5 days, effectively sealing high-permeability layers in the reservoir formation. Detailed Implementation

[0058] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0059] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. 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.

[0060] The present invention will be described in detail below through embodiments. In the following embodiments,

[0061] Unless otherwise specified, all raw materials were purchased commercially. Acrylamide was purchased from Dongying Baomo Environmental Engineering Co., Ltd., monomer X (as shown in formula (4), and the specific substances are described in the corresponding examples. All were purchased from Guangzhou Kede Chemical Co., Ltd., and monomer Y (as shown in formula (5)) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0062]

[0063] The acrylamide polymer was prepared using on-site water (mineralization 150000 mg / L), and its apparent viscosity and surface tension were tested. After being mixed with a crosslinking agent and injected into the core, it was kept stable at 150°C for 90 days, and then the plugging rate was measured.

[0064] The plugging rate was determined through laboratory core model tests. Specifically:

[0065] Determination of plugging rate: The artificial core is loaded into the core holder, saturated with water and then water-driven to measure the permeability (K1). A mixed solution of 0.5 PV acrylamide polymer and crosslinking agent is injected and cured at 150℃ for 48 h. Finally, water-driven is performed to measure the permeability after plugging (K2). (1-K2 / K1)×100% is the plugging rate.

[0066] The apparent viscosity of the acrylamide polymer solution was measured using a Brookfield viscometer with rotor No. 62 at a test temperature of 95°C; the surface tension of the acrylamide polymer solution was measured using a DCAT-21 surface tension meter at a test temperature of 25°C.

[0067] Example 1

[0068] 1) Add 800g of acrylamide to a heat-insulated polymerization reaction flask, add 4000g of deionized water to dissolve and prepare an aqueous solution, then add 150g of functional monomer X (where R is a C5 straight-chain alkyl group, n=8), 50g of functional monomer Y, 0.58g of EDTA-2Na, and 1.8g of (4-bromophenyl)thiourea in sequence. Then add sodium hydroxide to adjust the pH of the solution to 6.9 and stir thoroughly to form a stable solution.

[0069] 2) At 20°C, high-purity nitrogen gas was passed through the above solution to remove oxygen for 30 minutes. Then, 30g of 1% potassium persulfate aqueous solution and 15g of 1% sodium bisulfite aqueous solution were added to initiate the reaction. Nitrogen gas was passed through for another 5 minutes and then stopped. After sealing, the polymerization reaction was carried out for 10 hours to obtain the polymer colloid.

[0070] 3) Remove the colloid, granulate it, add 135g of sodium hydroxide granules and mix well, then carry out the hydrolysis reaction at 85℃ for 2.5 hours;

[0071] 4) Remove the granules, granulate them again, dry them at 60°C to constant weight, crush them, and sieve them to obtain white granular acrylamide polymer NJD1.

[0072] 1000g of on-site water (mineralization 150000mg / L) was taken, and 3g of acrylamide polymer NJD1 sample was added. After stirring, a solution was formed, and its apparent viscosity and surface tension were tested. 0.04g of crosslinking agent formaldehyde was added to the above solution and mixed evenly. The solution was then injected into the core and stabilized at 150℃ for 90 days. The plugging rate was then measured. The specific results are shown in Table 1.

[0073] Example 2

[0074] 1) Add 880g of acrylamide to a heat-insulated polymerization reaction flask, add 4000g of deionized water to dissolve and prepare an aqueous solution, then add 90g of functional monomer X (where R is a C7 straight-chain alkyl group, n=8), 30g of functional monomer Y, 0.75g of EDTA-2Na, and 3.2g of (4-bromophenyl)thiourea in sequence. Then add sodium hydroxide to adjust the pH of the solution to 7.4 and stir thoroughly to form a stable solution.

[0075] 2) At 25°C, high-purity nitrogen gas was passed through the above solution to remove oxygen for 30 minutes. Then, 58g of 1% potassium persulfate aqueous solution and 29g of 1% sodium bisulfite aqueous solution were added to initiate the reaction. Nitrogen gas was passed through for another 5 minutes and then stopped. After sealing, the polymerization reaction was carried out for 9 hours to obtain the polymer colloid.

[0076] 3) Remove the colloid, granulate it, add 140.8g of sodium hydroxide granules and mix well, then carry out the hydrolysis reaction at 90℃ for 2 hours;

[0077] 4) Remove the granules, granulate them again, dry them at 60°C to constant weight, crush them, and sieve them to obtain white granular acrylamide polymer NJD2.

[0078] 1000g of on-site water (mineralization 150000mg / L) was taken, and 4g of acrylamide polymer NJD2 sample was added. After stirring, a solution was formed, and its apparent viscosity and surface tension were tested. 0.06g of crosslinking agent glyoxal was added to the above solution, mixed evenly, and then injected into the core. The solution was stabilized at 150℃ for 90 days, and then the plugging rate was measured. The specific results are shown in Table 1.

[0079] Example 3

[0080] 1) Add 920g of acrylamide to a heat-insulated polymerization reaction flask, add 4000g of deionized water to dissolve and prepare an aqueous solution, then add 70g of functional monomer X (where R is a C9 straight-chain alkyl group, n=10), 10g of functional monomer Y, 0.89g of EDTA-2Na, and 4.4g of (4-bromophenyl)thiourea in sequence. Then add sodium hydroxide to adjust the pH of the solution to 7.1 and stir thoroughly to form a stable solution.

[0081] 2) At 30°C, high-purity nitrogen gas was passed through the above solution to remove oxygen for 30 minutes. Then, 80g of 1% potassium persulfate aqueous solution and 40g of 1% sodium bisulfite aqueous solution were added to initiate the reaction. Nitrogen gas was passed through for another 5 minutes and then stopped. After sealing, the polymerization reaction was carried out for 8.5 hours to obtain the polymer colloid.

[0082] 3) Remove the colloid, granulate it, add 149.3g of sodium hydroxide granules and mix well, then carry out the hydrolysis reaction at 80℃ for 3 hours;

[0083] 4) Remove the granules, granulate them again, dry them at 60°C to constant weight, crush them, and sieve them to obtain white granular acrylamide polymer NJD3.

[0084] 1000g of on-site water (mineralization 150000mg / L) was taken, and 6.2g of acrylamide polymer NJD3 sample was added. After stirring, a solution was formed, and its apparent viscosity and surface tension were tested. 0.075g of crosslinking agent hexamethylenetetramine was added to the above solution, mixed evenly, and then injected into the core. The solution was stabilized at 150℃ for 90 days, and then the plugging rate was measured. The specific results are shown in Table 1.

[0085] Example 4

[0086] 1) Add 900g of acrylamide to a heat-insulated polymerization reaction flask, add 4000g of deionized water to dissolve and prepare an aqueous solution, then add 95g of functional monomer X (where R is a C8 straight-chain alkyl group, n=9), 5g of functional monomer Y, 0.68g of EDTA-2Na, and 3.6g of (4-bromophenyl)thiourea in sequence. Then add sodium hydroxide to adjust the pH of the solution to 6.5 and stir thoroughly to form a stable solution.

[0087] 2) At 22°C, high-purity nitrogen gas was passed through the above solution to remove oxygen for 30 minutes. Then, 76g of 1% potassium persulfate aqueous solution and 38g of 1% sodium bisulfite aqueous solution were added to initiate the reaction. Nitrogen gas was passed through for another 5 minutes and then stopped. After sealing, the polymerization reaction was carried out for 9.5 hours to obtain the polymer colloid.

[0088] 3) Remove the colloid, granulate it, add 123.9g of sodium hydroxide granules and mix well, then carry out the hydrolysis reaction at 85℃ for 2.5 hours;

[0089] 4) Remove the granules, granulate them again, dry them at 60°C to constant weight, crush them, and sieve them to obtain white granular acrylamide polymer NJD4.

[0090] 1000g of on-site water (mineralization 150000mg / L) was taken, and 3.5g of acrylamide polymer NJD4 sample was added. After stirring, a solution was formed, and its apparent viscosity and surface tension were tested. 0.05g of crosslinking agent hexamethylenetetramine was added to the above solution, mixed evenly, and then injected into the core. The solution was stabilized at 150℃ for 90 days, and then the plugging rate was measured. The specific results are shown in Table 1.

[0091] Example 5

[0092] 1) Add 950g of acrylamide to a heat-insulated polymerization reaction flask, add 4000g of deionized water to dissolve and prepare an aqueous solution, then add 20g of functional monomer X (where R is a C12 straight-chain alkyl group, n=12), 30g of functional monomer Y, 0.1g of EDTA-2Na, and 5.0g of (4-bromophenyl)thiourea in sequence. Then add sodium hydroxide to adjust the pH of the solution to 8.0 and stir thoroughly to form a stable solution.

[0093] 2) At 27°C, high-purity nitrogen gas was passed through the above solution to remove oxygen for 30 minutes. Then, 100g of 1% potassium persulfate aqueous solution and 50g of 1% sodium bisulfite aqueous solution were added to initiate the reaction. Nitrogen gas was passed through for another 5 minutes and then stopped. After sealing, the polymerization reaction was carried out for 8 hours to obtain the polymer colloid.

[0094] 3) Remove the colloid, granulate it, add 155g of sodium hydroxide granules and mix well, then carry out the hydrolysis reaction at 90℃ for 2 hours;

[0095] 4) Remove the granules, granulate them again, dry them at 60°C to constant weight, crush them, and sieve them to obtain white granular acrylamide polymer NJD5.

[0096] 1000g of on-site water (mineralization 150000mg / L) was taken, and 8g of acrylamide polymer NJD5 sample was added. After stirring, a solution was formed, and its apparent viscosity and surface tension were tested. 0.1g of crosslinking agent (a mixture of formaldehyde and glyoxal at a mass ratio of 1:1) was added to the above solution, mixed evenly, and then injected into the core. The core was stabilized at 150℃ for 90 days, and then the plugging rate was measured. The specific results are shown in Table 1.

[0097] Example 6

[0098] The polymer and the mobile gel were prepared according to the method of Example 2, except that the monomer ratios were different. The amount of acrylamide used was 850g, functional monomer X was 130g, and functional monomer Y was 20g. That is, with the total mass of the monomer mixture being 100%, the mass ratio of acrylamide was 85%, the mass ratio of functional monomer X was 13%, and the mass ratio of functional monomer Y was 2%, resulting in the acrylamide polymer NJD6. Specific results are shown in Table 1.

[0099] Example 7

[0100] The polymer and the mobile gel were prepared according to the method in Example 2, except that n=8 in the functional monomer X was replaced with n=12, resulting in the acrylamide polymer NJD7. Specific results are shown in Table 1.

[0101] Example 8

[0102] The polymer and the mobile gel were prepared according to the method of Example 2, except that thiourea was used as the accelerator instead of (4-bromophenyl)thiourea in Example 2, to obtain the acrylamide polymer NJD8. The specific results are shown in Table 1.

[0103] Comparative Example 1

[0104] The polymer and the mobile gel were prepared according to the method of Example 2, except that N-phenylmaleimide was used instead of the functional monomer Y in Example 2 to obtain acrylamide polymer D1. The specific results are shown in Table 1.

[0105] Comparative Example 2

[0106] The polymer and the mobile gel were prepared according to the method of Example 2, except that the functional monomer Y was not added, resulting in acrylamide polymer D2. Specific results are shown in Table 1.

[0107] Table 1

[0108] Product No. Apparent Viscosity (mPa-s) Surface Tension (mN / m) Blocking Rate (%) Example 1 92.8 31.5 93.7 Example 2 104.7 31.4 99.2 Example 3 121.2 32.3 99.7 Example 4 134.9 31.2 98.6 Example 5 98.4 33.7 94.9 Example 6 98.9 31.2 95.8 Example 7 96.1 31.3 92.4 Example 8 85.6 32.4 84.9 Comparative Example 1 46.8 34.2 62.3 Comparative Example 2 40.7 35.6 54.1

[0109] As can be seen from the results in Table 1, the acrylamide polymer provided by this invention has higher apparent viscosity and better surface activity at a temperature of 95℃ and a salinity of 150,000 mg / L. It can form a movable gel at a formation temperature of 150℃, exhibiting excellent plugging effect. It can be applied to high-permeability reservoirs (above 2000 mD) and is of great significance for improving crude oil recovery.

[0110] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0111] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0112] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0113] 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.

[0114] 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.

[0115] 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 polymer, which polymer consists of structural units A, structural units B and structural units C, wherein, The structural unit A has a structure shown in formula (1), the structural unit B has a structure shown in formula (2), and the structural unit C has a structure shown in formula (3); Formula (1), Formula (2), Formula (3); In formula (2), R is a C5-C12 alkyl group, and n is an integer of 8-12; The content of the structural unit A is 80-95% by weight, the content of the structural unit B is 2-15% by weight, and the content of the structural unit C is 0.5-5% by weight, based on the total weight of the polyacrylamide polymer; The preparation method of the polyacrylamide polymer comprises the following steps: under polymerization reaction conditions and in the presence of an initiator, a monomer mixture is polymerized in a solvent to obtain a polymer colloid; and then the polymer colloid is subjected to a hydrolysis reaction. The monomer mixture is composed of acrylamide, monomer X and monomer Y, the monomer X has a structure shown in formula (4), and the monomer Y has a structure shown in formula (5). Formula (4), wherein R is a C5-C12 alkyl group, Formula (5).

2. The polymer of claim 1, wherein: The content of the structural unit A is 88-92% by weight, the content of the structural unit B is 7-9.5% by weight, and the content of the structural unit C is 0.5-3% by weight, based on the total weight of the polyacrylamide polymer.

3. The polymer of claim 1, wherein: In formula (2), R is a C7-C9 linear alkyl group; and / or, n is an integer of 8-10.

4. A preparation method of the polymer of any one of claims 1-3, comprising the following steps: under polymerization reaction conditions and in the presence of an initiator, a monomer mixture is polymerized in a solvent to obtain a polymer colloid; and then the polymer colloid is subjected to a hydrolysis reaction. wherein The monomer mixture is composed of acrylamide, monomer X and monomer Y, the monomer X has a structure shown in formula (4), and the monomer Y has a structure shown in formula (5). Formula (4), wherein R is a C5-C12 alkyl group, Formula (5).

5. The method of claim 4, wherein The preparation method comprises the following steps:

1. Under solution polymerization reaction conditions and in the presence of an initiator, a monomer mixture is polymerized in water to obtain a polymer colloid; 2. The polymer colloid is subjected to a hydrolysis reaction.

6. The preparation method of claim 5, wherein: The solution polymerization reaction conditions comprise that the solution polymerization reaction is carried out under an inert atmosphere; and / or, the polymerization reaction temperature is 20-30℃; and / or, the time is 8-10h; and / or, the pH value is 6-8.

7. The preparation method of claim 5, wherein: The initiator is an oxidation-reduction system initiator.

8. The preparation method of claim 5, wherein: The initiator is a persulfate oxidizing agent and a sulfite reducing agent.

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

10. The preparation method according to claim 5, wherein the solution polymerization reaction conditions further comprise: being carried out in the presence of a complexing agent and / or a promoting agent.

11. The preparation method according to claim 10, wherein: the amount of the complexing agent is 0.01-0.1 parts by weight, and / or the amount of the promoting agent is 0.05-0.5 parts by weight, relative to 100 parts by weight of the monomer mixture; and / or the complexing agent is disodium ethylenediaminetetraacetate; and / or the promoting agent is (4-bromophenyl)thiourea.

12. The preparation method according to claim 5, wherein the hydrolysis reaction is carried out under alkaline conditions.

13. The preparation method according to claim 12, wherein the hydrolysis reaction is carried out under alkaline conditions by mixing the polymer colloid with a solid alkaline substance.

14. The preparation method according to claim 13, wherein: 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 polymer colloid is 1: (15-44).

15. The preparation method according to claim 12, wherein the conditions of the hydrolysis reaction comprise: a temperature of 80-90℃, and / or a time of 2-3h.

16. A movable gel comprising the polymer of any one of claims 1-3 or prepared by the preparation method of any one of claims 4-15, and a crosslinking agent and water.

17. The movable gel according to claim 16, wherein: the content of the polymer is 0.2-0.8 parts by weight, and the content of the crosslinking agent is 0.004-0.01 parts by weight, relative to 100 parts by weight of water; and / or the crosslinking agent is selected from at least one of formaldehyde and glyoxal.

18. The movable gel according to claim 16, wherein: the content of the polymer is 0.3-0.7 parts by weight, and the content of the crosslinking agent is 0.006-0.008 parts by weight, relative to 100 parts by weight of water.

19. Use of the polymer of any one of claims 1-3 or prepared by the preparation method of any one of claims 4-15 or the movable gel of any one of claims 16-18 as a raw material in water plugging and profile control in oilfield water injection development. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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