Polyacrylamide polymers for mobile gels, process for their preparation and use

Abstract

The present application relates to the field of profile control and water plugging in oilfield water injection development, and discloses a mobile gel polyacrylamide polymer and a preparation method and application thereof. The polymer contains structural unit A shown in formula (1), structural unit B shown in formula (2) and structural unit C shown in formula (3); wherein R is C8-C18 alkyl, and M is a metal element. The acrylamide copolymer can form a mobile gel after adding a crosslinking agent, has a relatively high viscosity under high-temperature and high-salt conditions, can enter the deep part of an oil reservoir, can reduce the oil-water surface interfacial tension, has a good emulsifying performance, is suitable for being applied 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 a relatively high plugging rate.

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 mobile gel polyacrylamide polymer and a preparation method and application thereof. BACKGROUND

[0002] In the process of oilfield water injection development in China, water plugging and profile control technology is usually used to improve the problem of serious water production, thereby improving oilfield production. However, in high-temperature and high-salt reservoirs and in the late high-water-cut stage of oilfield development, ordinary water plugging and profile control agents cannot meet the requirements of field application, resulting in poor implementation effect. Therefore, in order to cope with the problems of serious heterogeneity of high-temperature and high-salt reservoirs and ineffective water injection circulation, researchers have begun to study other technical methods and new water plugging agent products. Through long-term research, researchers have found that effectively solving the problem of stratum water injection channeling and bypassing can promote the guarantee of oilfield development.

[0003] In recent years, with the continuous improvement of the degree of oilfield water injection development in China, large areas of high-permeability zones have appeared in the stratum, and water injection cannot reach the high-oil-bearing zones, resulting in the water cut of part of the produced liquid of the oil well reaching more than 98%. Therefore, it is proposed to adjust the water injection profile in the deep part of the reservoir, force the flow to turn, improve the water injection development effect, and achieve the purpose of improving the oil recovery. In the early stage of profile control and water plugging, high-strength plugging agents are mainly used, and the mechanism is mainly a physical barrier or plugging in the near-wellbore zone. However, with the increase of the number of oilfield profile control and water plugging, it is gradually difficult to control water and stabilize oil and improve oil recovery, and conventional shallow adjustment and near-wellbore zone modification cannot meet the needs of oilfield development.

[0004] Deep profile control and fluid diversion technology as a technical measure to improve development effect and control water and stabilize oil has achieved good application effect in many domestic and foreign oilfields, but its application in high-temperature and high-salt reservoirs is limited, and the oil displacement plugging effect needs to be further improved. SUMMARY

[0005] The present application aims to overcome the above-mentioned problems in the prior art and provide a mobile gel polyacrylamide polymer and a preparation method and application thereof. The acrylamide copolymer can form a mobile gel after adding a crosslinking agent, has high viscosity under high-temperature and high-salt conditions, can enter the deep part of the reservoir, can reduce the oil-water interfacial tension, has good emulsifying performance, is suitable for being used as a profile control and plugging agent in high-permeability reservoirs (permeability higher than 2000 mD), and has high plugging rate.

[0006] One of the purposes of the present application is to provide a mobile gel polyacrylamide polymer, which contains a structural unit A represented by formula (1), a structural unit B represented by formula (2), and a structural unit C represented by formula (3);

[0007] wherein R is C8-C18 alkyl, and M is a metal element.

[0008] In the present application, R is C8-C18 alkyl, which can be linear alkyl or branched alkyl, preferably, R is C8-C18 linear alkyl, more preferably C10-C14 linear alkyl.

[0009] In the present application, M is a metal element, preferably, M is an alkali metal element, more preferably potassium or sodium.

[0010] In the present application, the content of the structural unit A, the structural unit B and the structural unit C in the polymer has a wide selection range, preferably, the content of the structural unit A is 85-98.5 wt%, the content of the structural unit B is 1-10 wt%, and the content of the structural unit C is 0.5-5 wt%, based on 100% of the total weight of the acrylamide polymer.

[0011] More preferably, the content of the structural unit A is 90-95 wt%, the content of the structural unit B is 4-8 wt%, and the content of the structural unit C is 1-3 wt%, based on 100% of the total weight of the acrylamide polymer.

[0012] The second object of the present application is to provide a preparation method of the polymer described above, comprising polymerizing a monomer mixture in a solvent under the presence of an initiator and under polymerization conditions to obtain a copolymer colloid; and then hydrolyzing the copolymer colloid.

[0013] The monomer mixture contains acrylamide, a monomer represented by formula (4) and a monomer represented by formula (5).

[0014] wherein R is C8-C18 alkyl, and M is a metal element.

[0015] In the present application, R is C8-C18 alkyl, which can be linear alkyl or branched alkyl, preferably, R is C8-C18 linear alkyl, more preferably C10-C14 linear alkyl.

[0016] In the present application, M is a metal element, preferably, M is an alkali metal element, more preferably potassium or sodium.

[0017] The amount of each monomer in the present application has a wide selection range, preferably, the amount of acrylamide is 85-98.5 wt%, the amount of monomer represented by formula (4) is 1-10 wt%, and the amount of monomer represented by formula (5) is 0.5-5 wt% based on the total weight of the monomer mixture being 100%; more preferably, the amount of acrylamide is 90-95 wt%, the amount of monomer represented by formula (4) is 4-8 wt%, and the amount of monomer represented by formula (5) is 1-3 wt% based on the total weight of the monomer mixture being 100%.

[0018] In the present application, the content of the structural unit in the polymer can be obtained by detection in the art. In the following examples, it is calculated by the amount of monomer fed.

[0019] In a preferred embodiment of the present application, the preparation method comprises the following steps:

[0020] 1) polymerizing the monomer mixture in water under the presence of an initiator and solution polymerization conditions to obtain a copolymer colloid;

[0021] 2) hydrolyzing the copolymer colloid under alkaline conditions.

[0022] The initiator in the present application can be a conventional initiator, for example, the initiator is an oxidation-reduction system initiator, a persulfate oxidant and a sulfite reducing agent; preferably, the persulfate oxidant is selected from at least one of potassium persulfate, ammonium persulfate and sodium persulfate; more preferably, the sulfite is selected from potassium bisulfite and / or sodium bisulfite.

[0023] The ratio of the initiator can refer to the prior art, and the present application has a wide selection range, preferably, the sulfite reducing agent is 0.005-0.05 parts by weight and the persulfate oxidant is 0.01-0.1 parts by weight relative to 100 parts by weight of the monomer mixture.

[0024] The solution polymerization conditions in the present application have a wide selection range, preferably, the solution polymerization is carried out under an inert atmosphere, and the inert atmosphere is preferably provided by nitrogen and / or an inert gas such as argon.

[0025] The polymerization temperature, polymerization time and pH in the present application can have a wide selection range, preferably, the polymerization temperature is 30-40°C.

[0026] Preferably, the polymerization time is 8-10h.

[0027] Preferably, the pH value is 6-8. The adjustment of the pH value can be carried out by means commonly used in the prior art, for example, by adding alkaline substances such as sodium hydroxide.

[0028] More preferably, the polymerization temperature is 30-40℃, the polymerization time is 8-10h, and the pH value is 6-8.

[0029] The hydrolysis reaction in the present application has a wide selection range, preferably, the hydrolysis reaction is carried out by mixing the copolymer colloid with a solid alkaline substance, and more preferably, the solid alkaline substance is selected from sodium hydroxide and / or potassium hydroxide.

[0030] The mass ratio of the solid alkaline substance to the copolymer colloid in the present application has a wide selection range, preferably, the mass ratio of the solid alkaline substance to the copolymer colloid is 1:(15-44).

[0031] The conditions of the hydrolysis reaction in the present application have a wide selection range, preferably, the conditions of the hydrolysis reaction include: the temperature is 80-90℃, and / or the time is 2-4h.

[0032] In order to further improve the high plugging effect of the obtained polymer in application, preferably, the solution polymerization 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, and / or the complexing agent is disodium ethylenediaminetetraacetate.

[0033] In a more preferred embodiment of the present application, the solution polymerization reaction is further added with an accelerator; preferably, the amount of the accelerator is 0.05-0.5 parts by weight; more preferably, the accelerator is p-nitrophenyl thiourea.

[0034] In a further more preferred embodiment of the present application, the conditions of the solution polymerization reaction further include: being carried out in the presence of a complexing agent and an accelerator.

[0035] The addition of the accelerator during the solution polymerization reaction can further improve the tackiness and emulsifying performance of the prepared acrylamide copolymer. The complexing agent is disodium ethylenediaminetetraacetate (EDTA-2Na). The accelerator is p-nitrophenyl thiourea.

[0036] In a further more preferred embodiment of the present application, the amount of the redox system initiator is 0.015-0.15 parts by weight, the amount of the complexing agent is 0.01-0.1 parts by weight, and the amount of the accelerator is 0.05-0.5 parts by weight, relative to 100 parts by weight of the monomer mixture.

[0037] In a preferred embodiment of the present application, the preparation method further comprises: after the hydrolysis reaction, the reaction product is granulated, dried, crushed, and sieved to obtain the acrylamide copolymer.

[0038] According to the application, a preferred embodiment is provided:

[0039] The method for preparing the acrylamide copolymer comprises:

[0040] 1) acrylamide is added into a reactor to form an aqueous solution, then monomer X, monomer Y, an aqueous solution of a complex and a promoter are added, the pH value is adjusted, and the solution is stirred sufficiently to form a stable solution;

[0041] 2) an oxidation-reduction system initiator is added, inert gas is blown to mix the solution uniformly, the solution is sealed, and a polymer colloid is obtained after polymerization;

[0042] 3) the colloid is taken out, granulated, and then an alkaline substance is added, the mixture is mixed uniformly, and a hydrolysis reaction is performed;

[0043] 4) the hydrolysis reaction product is granulated, dried, crushed, and sieved to obtain the acrylamide copolymer.

[0044] The third object of the application is to provide a mobile gel containing the polymer prepared by the method described above or the polymer prepared by the method described above, and a crosslinking agent and water.

[0045] The acrylamide copolymer prepared by the method described in the first aspect of the application and the acrylamide prepared by the method described in the second aspect of the application are mixed with water on site, a crosslinking agent is added, and a mobile gel is formed after 2-5 days in the oil reservoir formation. The mobile gel is used as a profile control agent and a plugging agent in a high-permeability oil reservoir (permeability is higher than 2000 mD).

[0046] The amount of the polymer and the crosslinking agent in the application has a wide selection range. Preferably, the content of the polymer is 0.2-0.8 parts by weight, preferably 0.3-0.6 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 0.005-0.008 parts by weight.

[0047] In the application, the crosslinking agent can be selected from at least one of glyoxal, formaldehyde and hexamethylenetetramine.

[0048] The fourth object of the application is to provide an application of the polymer described above or the polymer prepared by the method described above or the mobile gel described above in profile control and water shutoff in oilfield water injection development.

[0049] The acrylamide copolymer and the mobile gel described in the application have the following advantages and effects compared with the prior art:

[0050] The polyacrylamide copolymer prepared by simultaneously introducing two specific functional monomers in the macromolecular chain of polyacrylamide, preferably prepared by using the preferred ratio in the application, has high viscosity under high temperature (150℃) and high salinity (150000mg / 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, and is especially suitable for high permeability oil reservoirs (permeability higher than 2000mD), has high plugging rate, and can reduce the oil-water surface interfacial tension and has good emulsifying performance.

[0051] The inventors of the application have found through research and verification that the application has the above advantages because:

[0052] The specific functional monomer represented by formula (4) in the application contains a super-hydrophilic group and an oleophilic group, has good emulsifying effect, and plays a self-emulsifying role in the polymerization system, and the copolymer formed has good emulsifying and oil-carrying effect. The functional monomer represented by formula (5) has good performance, especially under the action of a promoter, the polymerization activity is significantly improved, and the structure units of the three copolymerization monomers are randomly distributed in the high molecular chain, thereby the polymer has excellent tackifying and emulsifying and oil-washing capacity. Thus, the application simultaneously introduces two specific functional monomers in the macromolecular chain of polyacrylamide, greatly improves the temperature resistance and salt resistance of the copolymer and the surface interfacial activity, and after being mixed with a crosslinking agent, can effectively enter the deep part of the high temperature and high salinity oil reservoir to achieve the purpose of deep profile control and flooding, and can form a movable gel to effectively plug the high permeability layer in the oil reservoir formation after 2-5 days. In application, the acrylamide copolymer of the application is prepared into a solution by using oilfield site water, mixed with a crosslinking agent, and injected into the oil reservoir formation, has good flowability, can smoothly enter the deep part of the oil reservoir to achieve the effect of deep profile control and plugging, and forms a movable gel after the well is closed for 2-5 days to enhance the effective plugging of the high permeability layer in the oil reservoir formation, thereby greatly improving the oil recovery rate, especially suitable for high permeability oil reservoirs (permeability higher than 2000mD), and has important significance for increasing production and efficiency of oilfields. DETAILED DESCRIPTION

[0053] The application will be specifically described below in combination with specific examples, and 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, and some non-essential improvements and adjustments of the application made by those skilled in the art based on the content of the application still fall within the protection scope of the application.

[0054] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the practice of the application. The endpoints of the ranges and any values are provided as a separate point or as a range with each separate point being a separate embodiment of the application. The ranges are provided as a convenience to the reader and are not intended to be limiting of the application.

[0055] The application will be described in detail by way of examples. In the following examples,

[0056] Unless otherwise specified, all raw materials are commercially available. Among them, acrylamide is purchased from Dongying Baomo Environmental Engineering Co., Ltd., the structure of functional monomer X is shown in formula (4), M is Na in formula (4), and R is as described in the examples, which are purchased from Shanghai Jizisheng Chemical Technology Co., Ltd.; the structure of functional monomer Y is shown in formula (5), which is prepared according to the method described in (Bistline R.G, Synthetic detergents from animal fats. VI. Polymerizable ester of alpha-sulfonated fatty acids. Journal of the American Oil Chemists Society, 1956, 33(1): 44-45).

[0057]

[0058] The apparent viscosity and surface tension of the acrylamide copolymer are tested after being prepared with field water (salinity 150000 mg / L), and the plugging rate is determined after the acrylamide copolymer mixed with crosslinking agent is injected into the core and kept stable at 150℃ for 90 days.

[0059] The plugging rate is determined by laboratory core physical model test. Specifically:

[0060] Determination of plugging rate: the artificial core is loaded into the core holder, saturated with water, and the permeability (K1) is measured by water flooding. Then, 0.5 PV of the mixed solution of acrylamide polymer and crosslinking agent is injected, and the permeability (K2) is measured by water flooding after curing at 150℃ for 48h. (1-K2 / K1) x 100% is the plugging rate.

[0061] The apparent viscosity of the acrylamide copolymer solution is determined by Brookfield viscometer No. 62 rotor, and the test temperature is 95℃; the surface tension of the acrylamide copolymer solution is determined by DCAT-21 surface tension instrument, and the test temperature is 25℃.

[0062] Example 1

[0063] 1) Put 935 g of acrylamide into a polymerization bottle, add 3900 g of deionized water to dissolve and form a solution, then add functional monomer X (wherein R is a linear alkyl group with 8 carbon atoms) 110 g, functional monomer Y 55 g, EDTA-2Na 0.25 g, p-nitrophenylthiourea 0.68 g, and sodium hydroxide to adjust the pH of the solution to 6.2, and stir well to form a stable solution;

[0064] 2) At 30°C, introduce high-purity nitrogen into the above solution to remove oxygen for 30 minutes, then add 40 g of 1% potassium persulfate aqueous solution and 20 g of 1% sodium bisulfite aqueous solution, initiate the reaction, continue to introduce nitrogen for five minutes, then stop, seal and polymerize for 10 hours to obtain a polymer colloid;

[0065] 3) Take out the colloid, granulate, then add 148.7 g of sodium hydroxide granules and mix well, and then perform hydrolysis reaction at 80°C for 4 hours;

[0066] 4) Take out the granules, granulate again, dry at 60°C to constant weight, crush and sieve to obtain white granular acrylamide copolymer NJD1.

[0067] Take 1000 g of field water (salinity 150000 mg / L), add 3.2 g of acrylamide copolymer NJD1 sample, stir to form a solution, and then test the apparent viscosity and surface tension, respectively. Add 0.043 g of crosslinking agent glyoxal to the above solution and mix well, then inject into the core, and then keep it stable at 150°C for 90 days, and then measure the plugging rate. The results are shown in Table 1.

[0068] Example 2

[0069] 1) Put 990 g of acrylamide into a polymerization bottle, add 3900 g of deionized water to dissolve and form a solution, then add functional monomer X (wherein R is a linear alkyl group with 12 carbon atoms) 88 g, functional monomer Y 22 g, EDTA-2Na 0.45 g, p-nitrophenylthiourea 2.8 g, and sodium hydroxide to adjust the pH of the solution to 7.4, and stir well to form a stable solution;

[0070] 2) At 40°C, introduce high-purity nitrogen into the above solution to remove oxygen for 30 minutes, then add 72 g of 1% potassium persulfate aqueous solution and 36 g of 1% sodium bisulfite aqueous solution, initiate the reaction, continue to introduce nitrogen for five minutes, then stop, seal and polymerize for 8 hours to obtain a polymer colloid;

[0071] 3) Take out the colloid, granulate, then add 154.9 g of sodium hydroxide granules and mix well, and then perform hydrolysis reaction at 90°C for 2 hours;

[0072] 4) Take out the gel particles, granulate, dry at 60°C to constant weight, crush, and sieve to obtain white granular acrylamide copolymer NJD2.

[0073] Take 1000 g of field water (salinity 150000 mg / L), add 5.2 g of acrylamide copolymer NJD2 sample, stir to form a solution, and test the apparent viscosity and surface tension, respectively. Add 0.072 g of crosslinking agent (mixture of formaldehyde and glyoxal, mass ratio 1:1) to the above solution, mix uniformly, and inject into the core. Keep at 150°C for 90 days, and then measure the plugging rate. The results are shown in Table 1.

[0074] Example 3

[0075] 1) Add 1012 g of acrylamide to a heat-preservation polymerization reaction bottle, add 3900 g of deionized water to dissolve and prepare an aqueous solution, and then add 55 g of functional monomer X (wherein R is a linear alkyl group with 14 carbons), 33 g of functional monomer Y, 0.72 g of EDTA-2Na, and 3.2 g of p-nitrophenylthiourea, and then add sodium hydroxide to adjust the pH of the solution to 7.2, and stir thoroughly to form a stable solution;

[0076] 2) At 35°C, deoxygenate the above solution by passing high-purity nitrogen for 30 minutes, then add 60 g of 1% by weight potassium persulfate aqueous solution and 30 g of 1% by weight sodium bisulfite aqueous solution, initiate the reaction, continue to pass nitrogen for five minutes, then stop, seal, and polymerize for 9 hours to obtain a polymer colloid;

[0077] 3) Take out the colloid, granulate, and then add 139.4 g of sodium hydroxide granules, mix uniformly, and then hydrolyze at 90°C for 2.5 hours;

[0078] 4) Take out the gel particles, granulate, dry at 60°C to constant weight, crush, and sieve to obtain white granular acrylamide copolymer NJD3.

[0079] Take 1000 g of field water (salinity 150000 mg / L), add 3.5 g of acrylamide copolymer NJD3 sample, stir to form a solution, and test the apparent viscosity and surface tension, respectively. Add 0.067 g of crosslinking agent hexamethylenetetramine to the above solution, mix uniformly, and inject into the core. Keep at 150°C for 90 days, and then measure the plugging rate. The results are shown in Table 1.

[0080] Example 4

[0081] 1) 1045 g of acrylamide was added to a polymerization flask, and deionized water 3900 g was added to dissolve and form an aqueous solution, functional monomer X (wherein R is a linear alkyl group of C10) 44 g, functional monomer Y 11 g, EDTA-2Na 0.69 g, p-nitrophenylthiourea 4.1 g were added in sequence, and sodium hydroxide was added to adjust the pH of the solution to 7.0, and the solution was stirred to form a stable solution;

[0082] 2) After the solution was deoxygenated by high-purity nitrogen at 32°C for 30 minutes, 1% by weight of potassium persulfate aqueous solution 50 g and 1% by weight of sodium bisulfite aqueous solution 25 g were added to initiate the reaction, and the nitrogen was stopped after five minutes of continuous nitrogen blowing, and the polymerization reaction was carried out for 9 hours after sealing to obtain a polymer colloid;

[0083] 3) The colloid was taken out, granulated, and mixed with 130.1 g of sodium hydroxide granules to form a uniform mixture, and the hydrolysis reaction was carried out at 85°C for 3 hours;

[0084] 4) The granules were taken out, granulated again, dried at 60°C to constant weight, crushed, and sieved to obtain white granular acrylamide copolymer NJD4.

[0085] 1000 g of field water (salinity 150000 mg / L) was taken, 4.0 g of acrylamide copolymer NJD4 sample was added, and the solution was formed after stirring, and the apparent viscosity and surface tension were tested respectively, 0.058 g of crosslinking agent (hexamethyl tetramine and glyoxal, mass ratio 2:1) was added to the above solution and mixed uniformly, and then injected into the core, and the plugging rate was measured after being kept at 150°C for 90 days. The results are shown in Table 1.

[0086] Example 5

[0087] 1) 1083.5 g of acrylamide was added to a polymerization flask, and deionized water 3900 g was added to dissolve and form an aqueous solution, functional monomer X (wherein R is a linear alkyl group of C8) 11 g, functional monomer Y 5.5 g, EDTA-2Na 1.1 g, p-nitrophenylthiourea 5.0 g were added in sequence, and sodium hydroxide was added to adjust the pH of the solution to 8.0, and the solution was stirred to form a stable solution;

[0088] 2) After the solution was deoxygenated by high-purity nitrogen at 36°C for 30 minutes, 1% by weight of potassium persulfate aqueous solution 110 g and 1% by weight of sodium bisulfite aqueous solution 55 g were added to initiate the reaction, and the nitrogen was stopped after five minutes of continuous nitrogen blowing, and the polymerization reaction was carried out for 10 hours after sealing to obtain a polymer colloid;

[0089] 3) The colloid was taken out, granulated, and mixed with 161.1 g of sodium hydroxide granules to form a uniform mixture, and the hydrolysis reaction was carried out at 805°C for 3 hours;

[0090] 4) The gel particles were taken out and granulated, dried at 60°C to constant weight, pulverized, and sieved to obtain white granular acrylamide copolymer NJD5.

[0091] 1000 g of field water (salinity 150000 mg / L) was taken, 8.0 g of acrylamide copolymer NJD5 sample was added, and after stirring, a solution was formed. The apparent viscosity and surface tension of the solution were tested, respectively. 0.1 g of crosslinking agent hexamethyl tetramine was added into the above solution and mixed uniformly, then injected into the core. The core was kept at 150°C for 90 days, and then the plugging rate was measured. The results are shown in Table 1.

[0092] Example 6

[0093] The polymer and the movable gel were prepared according to the method of Example 2, except that the monomer ratio was different, wherein the amount of acrylamide was 957 g, the amount of functional monomer X was 99 g, and the amount of functional monomer Y was 44 g, i.e. the mass ratio of acrylamide was 87%, the mass ratio of functional monomer X was 9%, and the mass ratio of functional monomer Y was 4%. Acrylamide copolymer NJD6 was obtained. The results are shown in Table 1.

[0094] Example 7

[0095] The polymer and the movable gel were prepared according to the method of Example 2, except that the straight-chain alkyl group of C12 in functional monomer X was replaced by a straight-chain alkyl group of C18 to obtain acrylamide copolymer NJD7.

[0096] Example 8

[0097] The polymer was prepared according to the method of Example 2, except that N,N'-dimethyl urea was used instead of p-nitrophenyl thiourea in Example 2 to obtain acrylamide copolymer NJD8. The results are shown in Table 1.

[0098] Comparative Example 1

[0099] The polymer was prepared according to the method of Example 2, except that N-phenyl maleimide was used instead of functional monomer Y in Example 2 to obtain acrylamide copolymer D1. The results are shown in Table 1.

[0100] Comparative Example 2

[0101] The polymer was prepared according to the method of Example 2, except that no functional monomer Y was added to obtain acrylamide copolymer D2. The results are shown in Table 1.

[0102] Table 1

[0103]

[0104]

[0105] 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℃ and a salinity of 150000 mg / L, can form a movable gel at a formation temperature of 150℃, has excellent plugging effect, and can be applied to high permeability reservoirs (higher than 2000 mD), which is of great significance for improving the recovery of crude oil.

[0106] It should be noted that the above-described embodiments 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 embodiments, 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 embodiments, 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.

[0107] 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 definition in this specification prevails.

[0108] When the specification derives materials, substances, methods, steps, devices or components, etc. with the word head "known to those skilled in the art", "prior art" or similar words, the objects derived by the word head cover those commonly used in the art at the time of the present application, but also include those which are not commonly used at present, but will be recognized as suitable for similar purposes in the art.

[0109] The endpoints of the ranges and any values disclosed in this application document are not limited to the precise values stated. The ranges and values should be interpreted as being approximate. For numeric values, the endpoints of each range, the endpoints of each range and individual point values, and individual point values can be combined with each other to obtain one or more new numeric ranges, which should be considered as specifically disclosed herein. In the following, each technical solution can be combined with each other to obtain a new technical solution in principle, which should also be considered as specifically disclosed herein.

[0110] In the context of the present specification, except for the explicitly stated content, any unmentioned matter or matter directly applies to those known in the art without any change.

[0111] Moreover, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas are considered to be part of the original disclosure or original description of the present application, and should not be considered as new content that has not been disclosed or anticipated herein, unless the combination is considered to be obviously unreasonable by those skilled in the art.

Claims

1. A mobile gel polyacrylamide polymer, the polymer consisting of structural unit A shown in formula (1), structural unit B shown in formula (2) and structural unit C shown in formula (3); Formula (1), Formula (2), Formula (3), wherein In structural unit B shown in formula (2): R is C8-C18 alkyl, and M is a metal element; The content of structural unit A is 85-98.5 wt%, the content of structural unit B is 1-10 wt%, and the content of structural unit C is 0.5-5 wt% based on the total weight of the acrylamide polymer being 100%; A method for preparing a mobile gel polyacrylamide polymer, comprising polymerizing a monomer mixture in a solvent under the presence of an initiator and polymerization conditions to obtain a copolymer colloid; and then hydrolyzing the copolymer colloid; The monomer mixture consists of acrylamide, a monomer represented by formula (4), and a monomer represented by formula (5). Formula (4), wherein R is an alkyl group of C8-C18, Formula (5).

2. The polymer of claim 1, wherein: In structural unit B shown in formula (2): R is C8-C18 linear alkyl; and / or, M is an alkali metal element.

3. The polymer of claim 1, wherein: In structural unit B shown in formula (2): R is C10-C14 linear alkyl; and / or, M is potassium or sodium.

4. The polymer of claim 1, wherein: The content of structural unit A is 90-95 wt%, the content of structural unit B is 4-8 wt%, and the content of structural unit C is 1-3 wt% based on the total weight of the acrylamide polymer being 100%.

5. A method for preparing the polymer of any one of claims 1-4, comprising polymerizing a monomer mixture in a solvent under the presence of an initiator and polymerization conditions to obtain a copolymer colloid; and then hydrolyzing the copolymer colloid; wherein, The monomer mixture consists of acrylamide, a monomer represented by formula (4), and a monomer represented by formula (5); Formula (4), in which R is an alkyl group of C8-C18, Formula (5).

6. The method of claim 5, wherein comprising the following steps: 1) polymerizing a monomer mixture in water under the presence of an initiator and solution polymerization conditions to obtain a copolymer colloid; 2) hydrolyzing the copolymer colloid under alkaline conditions.

7. The method of claim 5 or 6, wherein: The initiator is an oxidation-reduction system initiator.

8. The method of claim 5 or 6, wherein: The initiator is a persulfate oxidant and a sulfite reducing agent.

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

10. The method of claim 6, wherein: The solution polymerization conditions include a polymerization temperature of 30-40°C, a time of 8-10 h, a pH value of 6-8, and / or the solution polymerization is carried out under an inert atmosphere.

11. The method of claim 6, wherein: The hydrolysis is carried out by mixing the copolymer colloid with a solid alkaline substance.

12. The preparation method according to claim 11, 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 copolymer colloid is 1: (15-44).

13. The preparation method according to claim 11, wherein: the reaction conditions of the hydrolysis reaction include a temperature of 80-90℃ and / or a time of 2-4h.

14. The preparation method according to claim 6, wherein: the solution polymerization reaction conditions further include being carried out in the presence of a complexing agent and / or a promoting agent.

15. The preparation method according to claim 14, wherein: the complexing agent is used in an amount of 0.01-0.1 parts by weight and / or the promoting agent is used in an amount of 0.05-0.5 parts by weight, relative to 100 parts by weight of the monomer mixture; and / or, the promoting agent is p-nitrophenylthiourea; and / or, the complexing agent is disodium ethylenediaminetetraacetate.

16. A mobile gel comprising the polymer of any one of claims 1-4 or prepared by the preparation method of any one of claims 5-15, and a crosslinking agent and water.

17. The mobile 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 glyoxal and formaldehyde.

18. The mobile gel according to claim 16, wherein: the content of the polymer is 0.3-0.6 parts by weight and the content of the crosslinking agent is 0.005-0.008 parts by weight, relative to 100 parts by weight of water.

19. Use of the polymer of any one of claims 1-4 as a raw material or the polymer prepared by the preparation method of any one of claims 5-15 as a raw material or the mobile gel of any one of claims 16-18 in water shutoff and profile control in oilfield water injection development.

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