Acrylamide comb polymers, methods for their preparation, mobile gels and uses

Abstract

The present application relates to the research field of oilfield profile control and water plugging materials and the improvement of oil well productivity in high water cut reservoirs, and discloses a kind of acrylamide comb polymer and its preparation method, movable gel and application, the polymer contains structural unit A shown in formula (1), structural unit B shown in formula (2), structural unit C shown in formula (3);Wherein, M in formula (2) is H or metal element;R in formula (3) is C n Alkyl, n is 5-10.The acrylamide polymer in the present application is a comb functional polymer with excellent temperature resistance and salt resistance, further improving the tackiness and stability of profile control and plugging polymers, thereby achieving the effect of stabilizing oil and controlling water, adjusting structure and improving recovery efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oilfield profile control and water plugging materials and the field of improving oil well productivity in high water cut reservoirs, and in particular, the present application relates to an acrylamide comb polymer, a preparation method thereof, a movable gel and application. BACKGROUND

[0002] At present, due to the heterogeneity of the formation, different fluid velocities, long-term water drive development, and broken ethyl sleeve, many domestic oilfields are facing problems such as well leakage and high water cut, and the crude oil recovery rate of water injection or gas injection technology is decreasing year by year, and the oil production cost is continuously rising. In the tertiary oil recovery of oilfields, partially hydrolyzed polyacrylamide (HPAM) is widely used as a polymer oil displacement agent, profile control and water plugging material. The polymer gel system has flowability before gelation. Under the action of the crosslinking agent, the linear polymer molecular chain is cross-linked at multiple positions, thereby forming a gel body with a spatial network structure. The gel body has partial solid properties, has certain viscoelasticity, strength and pressure bearing capacity, and can play a role in plugging water channels, thereby achieving the purpose of water plugging and further improving the crude oil recovery rate.

[0003] However, the linear molecular structure and ultrahigh molecular weight of HPAM lead to easy shear degradation of the polymer, and the salt resistance of the solution is poor, the gelation reaction in the formation is affected, the plugging rate is low, and its application is limited to high temperature and high salt reservoir conditions.

[0004] Therefore, how to provide an acrylamide polymer gel to improve the plugging rate under high temperature and high salt reservoir conditions is a technical problem to be solved at present. SUMMARY

[0005] In view of the defects in the prior art, based on the above findings and research in the present application, the purpose of the present application is to provide an acrylamide comb polymer, a preparation method thereof, a movable gel and application. The acrylamide polymer in the present application is a comb functional polymer with excellent temperature resistance and salt resistance, which further improves the viscosity and stability of the profile control and plugging polymer, thereby achieving the effects of stabilizing oil, controlling water, adjusting structure and improving recovery rate.

[0006] One of the purposes of the present application is to provide an acrylamide polymer containing 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]

[0008] wherein M in formula (2) is H or a metal element; R in formula (3) is a C n alkyl group, and n is 5-10.

[0009] The content of each structural unit in the polymer in the present application is selected in a wide range, and in a preferred embodiment, the content of the structural unit A is 88-98 wt%, the content of the structural unit B is 1-10 wt%, and the content of the structural unit C is 0.5-2 wt% based on the total weight of the polymer.

[0010] In a more preferred embodiment, the content of the structural unit A is 89-92 wt%, the content of the structural unit B is 7-10 wt%, and the content of the structural unit C is 0.8-2 wt% based on the total weight of the polymer.

[0011] In a preferred embodiment of the present application, the percentage contents of the structural unit A, the structural unit B and the structural unit C add up to 100%.

[0012] The content of the above structural unit can be detected by direct means or calculated by the amount of feed, and in the present application, the content of the structural unit of the polymer in the present application is calculated by the amount of feed.

[0013] In the present application, when M in formula (2) is a metal element, M can be selected in a wide range, and in a preferred embodiment, M in formula (2) is selected from alkali metal elements, preferably Na or K.

[0014] In a preferred embodiment, R in formula (3) is a linear alkyl group of C n , n is 5-10, for example, can be C5, C6, C7, C8, C 10 , a combination of a plurality of the above, and preferably n is 6-8.

[0015] In a preferred embodiment of the present application, the acrylamide comb polymer contains the structural unit A, the structural unit B and the structural unit C, wherein the structural unit A is a structural unit having the structure shown in formula (1), the structural unit B is a structural unit having the structure shown in formula (2), and the structural unit C is a structural unit having the structure shown in formula (3); wherein the content of the structural unit A is 88-98 wt%, the content of the structural unit B is 1-10 wt%, and the content of the structural unit C is 0.5-2 wt% based on the total weight of the polymer.

[0016]

[0017] R in formula (3) is a linear alkane of C n , and n is 5-10.

[0018] The second object of the present application is to provide a preparation method of the polymer as described above, comprising polymerizing acrylamide, functional monomer X and functional monomer Y in water in the presence of an initiator and an accelerator to obtain a polymer colloid; and then hydrolyzing the polymer colloid; wherein the functional monomer X is a compound represented by formula (4), and the functional monomer Y is a compound represented by formula (5).

[0019] M in formula (4) is H or a metal element, and R in formula (5) is a linear alkyl group, and n is 5-10. n

[0020] In a preferred embodiment, R in formula (5) is a linear alkyl group of C n , n is 5-10, for example, can be C5, C6, C7, C8, C9, C 10 , or a combination of the above. Preferably, n is 6-8.

[0021] The ratio of water to monomers in the present application can be selected within a wide range. In a preferred embodiment, the total amount of acrylamide, functional monomer X and functional monomer Y is 12-20 parts by mass per 100 parts by mass of water.

[0022] The ratio of the monomers in the present application can be selected within a wide range. In a preferred embodiment, the total mass of acrylamide, functional monomer X and functional monomer Y is 100%, of which functional monomer X accounts for 1%-10%, functional monomer Y accounts for 0.5%-2%, and the balance is acrylamide.

[0023] In a more preferred embodiment, the total mass of acrylamide, functional monomer X and functional monomer Y is 100%, of which functional monomer X accounts for 7%-10%, functional monomer Y accounts for 0.8%-2%, and the balance is acrylamide.

[0024] In a preferred embodiment, at least one of an emulsifier and a complexing agent is further added to the polymerization system.

[0025] In the present application, the addition of an emulsifier to the polymerization system can form stable micelles in the polymerization system, and initiate the copolymerization of acrylamide and functional monomers in the micelles, so that the polymer is more uniform and has better plugging effect in application.

[0026] In a more preferred embodiment, the preparation method comprises:

[0027] Step 1: mixing acrylamide and functional monomer X with water, then adding functional monomer Y, an emulsifier, a complexing agent, an accelerator, and adjusting the pH value to 6-8 to obtain a stable micelle solution; ​

[0028] Step 2, adding initiator to the micelle solution obtained in Step 1, mixing, and then polymerizing under a protective atmosphere to obtain a polymer colloid;

[0029] Step 3, granulating the polymer colloid, mixing with a solid alkaline substance, and performing hydrolysis.

[0030] In the present application, the polymerization conditions in Step 2 can be selected within a wide range, and in a preferred embodiment, the polymerization conditions in Step 2 include a temperature of 30-45℃ and / or a polymerization time of 8-12 hours.

[0031] The protective atmosphere in the present application can be provided by nitrogen and / or an inert gas.

[0032] In the present application, the hydrolysis conditions in Step 3 can be selected within a wide range, and in a preferred embodiment, the hydrolysis conditions in Step 3 include a temperature of 80-90℃ and / or a time of 2-3 hours.

[0033] In the present application, the emulsifier can be selected within a wide range, and in a preferred embodiment, the emulsifier is at least one selected from Tween 20, Tween 40, Tween 60, Span 20, Span 40, and Span 60.

[0034] In the present application, the amount of emulsifier can be selected within a wide range, and in a preferred embodiment, the amount of emulsifier is 0.05-1 parts by mass relative to 100 parts by mass of water.

[0035] In the present application, the complexing agent can be selected within a wide range, and in a preferred embodiment, the complexing agent is EDTA-2Na.

[0036] In the present application, the amount of complexing agent can be selected within a wide range, and in a preferred embodiment, the amount of complexing agent is 0.01-0.1 parts by mass relative to 100 parts by mass of water; preferably, the complexing agent is in the form of an aqueous solution of EDTA-2Na.

[0037] In a preferred embodiment, the accelerator is 1,3-bis(4-methoxyphenyl)thiourea. In this preferred embodiment, the obtained polymer exhibits better plugging effect in oilfield profile control applications.

[0038] In the present application, the ratio of the total mass of acrylamide, functional monomer X, and functional monomer Y to the mass of the accelerator can be selected within a wide range, and in a preferred embodiment, the ratio of the total mass of acrylamide, functional monomer X, and functional monomer Y to the mass of the accelerator is 100:(0.01-0.2).

[0039] The initiator in the present application can be selected from the common initiators in the art. In a preferred embodiment, the initiator is an oxidation-reduction initiation system composed of a persulfate oxidant and a sulfite reducing agent. Preferably, the persulfate oxidant is added in an amount of 0.01%-0.1% of the total mass of acrylamide and functional monomers X and Y, and the sulfite reducing agent is added in an amount of 0.005%-0.05% of the total mass of acrylamide and functional monomers X and Y.

[0040] In the present application, the solid alkaline substance in the third step has a wide selection range. In a preferred embodiment, the solid alkaline substance in the third step is a strong base, preferably sodium hydroxide.

[0041] In the present application, the mass ratio of the solid alkaline substance to the polymer colloid has a wide selection range. In a preferred embodiment, the mass ratio of the solid alkaline substance to the polymer colloid is 1:(44-65).

[0042] In a more preferred embodiment of the present application, the preparation method of the acrylamide comb polymer comprises the following steps:

[0043] In the first step, acrylamide and functional monomer X are mixed with water, and then functional monomer Y, emulsifier, complexing agent, and accelerator are added, and the pH value is adjusted to 6-8 to obtain a stable micellar solution. The functional monomer X is a compound represented by formula (4):

[0044] In formula (4), M is H or a metal element;

[0045] The functional monomer Y is a compound represented by formula (5):

[0046] In formula (5), R is a linear alkane of C n n is 5-10;

[0047] The accelerator is a compound represented by formula (6):

[0048]

[0049] In the second step, the initiator is added to the mixed solution (micellar solution) obtained in the first step, and then mixed and polymerized under a protective atmosphere to obtain a polymer colloid.

[0050] In the third step, the polymer colloid obtained in the second step is granulated and mixed with a solid alkaline substance to perform hydrolysis, and then hydrolyzed colloidal particles are obtained.

[0051] In the fourth step, the hydrolyzed colloidal particles are granulated, dried, crushed, and sieved to obtain an acrylamide comb polymer.

[0052] On the basis of the above technical solution, the total mass of acrylamide and the two functional monomers in water in the first step is 12%-20% according to the mass percentage of water in the system being 100%; according to the total mass percentage of acrylamide and the functional monomers being 100%, the functional monomer X accounts for 1%-10%, the functional monomer Y accounts for 0.5%-2%, and the balance is acrylamide.

[0053] On the basis of the above technical solution, the base in the first step is sodium hydroxide or sodium carbonate;

[0054] On the basis of the above technical solution, the emulsifier in the first step is one of Tween 20, Tween 40, Tween 60, Span 20, Span 40, and Span 60, and the addition amount is 0.05%-1% in mass concentration in the aqueous solution; the complexing agent is an EDTA-2Na aqueous solution, the addition amount of EDTA-2Na in the complexing agent is 0.01%-0.1% of the total mass of acrylamide and the functional monomers, the complexing agent is an EDTA-2Na aqueous solution with a mass concentration of 1%; the accelerator is 1,3-bis(4-methoxyphenyl)thiourea, and the addition amount is 0.01%-0.2% of the total mass of acrylamide and the two functional monomers;

[0055] On the basis of the above technical solution, the complex initiator in the second step is an oxidation-reduction initiation system composed of a persulfate oxidizing agent and a sulfite reducing agent, the addition amount of the persulfate oxidizing agent is 0.01%-0.1% of the total mass of acrylamide and the functional monomers, and the addition amount of the sulfite reducing agent is 0.005%-0.05% of the total mass of acrylamide and the functional monomers;

[0056] On the basis of the above technical solution, the particle base in the third step is sodium hydroxide particle base.

[0057] The third object of the present application is to provide a movable gel containing the polymer prepared by the above method or the polymer prepared by the above method, water and a crosslinking agent.

[0058] The ratio of the polymer, water and the crosslinking agent in the present application has a wide selection range, in a preferred embodiment, the content of the polymer is 0.3-0.7 parts by weight, preferably 0.3-0.5 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 0.004-0.08 parts by weight.

[0059] The crosslinking agent in the present application has a wide selection range, in a preferred embodiment, the crosslinking agent is selected from at least one of water-soluble phenolic resin, N,N-methylene bisacrylamide and hexamethylenetetramine.

[0060] The movable gel in the present application can be prepared according to the following method: after the acrylamide comb polymer described above is prepared by using field water, a crosslinking agent is added, and the movable gel is formed after 2-5 days in the oil reservoir formation.

[0061] On the basis of the above technical solutions, the salinity of the field water used for preparing the movable gel can be 150000 mg / L, or can be lower or higher, and the present application does not have particular limitations, and the present application wants to explain that the polymer of the present application can be suitable for high salinity field water. Preferably, the content of the acrylamide comb polymer in the acrylamide comb polymer solution is 0.3-0.7 parts by weight relative to 100 parts by weight of the field water; the crosslinking agent comprises one of water-soluble phenolic resin, N,N-methylene bisacrylamide and hexamethylenetetramine, and the content of the crosslinking agent is 0.004-0.01 parts by weight.

[0062] The fourth object of the present application 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 water injection development profile control and water plugging in oilfields.

[0063] The multi-functional polymer is prepared by water solution polymerization or micellar copolymerization process under certain conditions to initiate the polymerization of the comonomer, and the functional polymer is obtained after colloid treatment. The polymer aqueous solution and the crosslinking agent solution are mixed and injected into the well, the mixed liquid is rapidly pumped into the well, and the crosslinking occurs through the shear of the drill bit water eye or at the formation temperature. The crosslinked gel is a rubber-like gel plugging agent with good elasticity, which is suitable for gel plugging agents for near-wellbore zones and deep profile control.

[0064] The acrylamide comb polymer, the preparation method thereof and the movable gel described in the present application have the following advantages and effects compared with the prior art:

[0065] The comb polymer of the present application is prepared into a solution by using field water in oilfields, mixed with a crosslinking agent, and injected into the oil reservoir formation, has good fluidity, can smoothly enter the deep part of the oil reservoir, and has the effects of deep profile control and profile control and plugging. After the well is closed for 2-5 days, the movable gel is formed, the effective plugging of the high permeable layer in the oil reservoir formation is enhanced, the oil recovery rate can be greatly improved, and it is especially suitable for high permeability oil reservoirs (permeability is higher than 2000 mD), which has important significance for increasing production and efficiency of oilfields.

[0066] The reason why the acrylamide comb polymer and the movable gel have the above advantages is that the inventors of the present application believe that the reason is that:

[0067] The inventor of the present application finds that for high-temperature and high-salt reservoir conditions, the structure of the polymer molecule is a key factor affecting the temperature resistance and salt resistance of the aqueous solution of the polymer and the stability, thereby further affecting the gelation reaction, coping with engineering problems such as high water content and well leakage, and selecting a temperature-resistant and salt-resistant polymer gel can play an effective plugging role. The present application introduces specific functional monomer X and functional monomer Y into the macromolecular structure of polyacrylamide through terpolymerization, greatly improves the temperature resistance and salt resistance and surface and interface activity of the copolymer, and the structural units of the polymer in the present application can also improve the hydrophobic association of the polymer, further improving the viscosity of the aqueous solution of the polymer. The addition of the preferred accelerator can improve the polymerization activity of the functional monomers, especially the functional monomer Y, so that the macromolecular chain distribution is more uniform, forming a comb-shaped polymer.

[0068] The inventor of the present application finds that by further research, introducing the long-chain group in the present application into the linear molecule of polyacrylamide makes the polymer molecule present a comb structure, which is more conducive to the gelation reaction after injection into the underground, enhances the viscoelasticity of the polymer gel, can effectively adjust the heterogeneity of the reservoir formation, and can effectively plug the water flow channel even under high-temperature and high-salt reservoir conditions, thereby reducing the water permeability, improving the water injection development effect and the oil recovery rate. DETAILED DESCRIPTION

[0069] The following specific embodiments of the present application will be described in detail, and it is necessary to point out here that the following embodiments are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments of the present application made by those skilled in the art according to the content of the present application still fall within the protection scope of the present application.

[0070] The following are several specific embodiments.

[0071] Unless otherwise specified, all raw materials are commercially available. Among them, acrylamide is from Dongying Baomo Environmental Engineering Co., Ltd., functional monomer X (M is H) shown in formula (4) is purchased from Shanghai Xianghui Pharmaceutical Technology Co., Ltd., and functional monomer Y (R is C n The straight-chain alkyl group of n value is shown in the corresponding embodiment, and all are purchased from Heping Bio-Technology Co., Ltd.

[0072]

[0073] The apparent viscosity and surface tension of the acrylamide copolymer are tested after being prepared with field water (mineralization degree 150000 mg / L), the plugging rate is measured after the copolymer is mixed with a crosslinking agent and injected into a core, and then stably kept at 150℃ for 90 days.

[0074] The apparent viscosity of the acrylamide comb polymer solution was determined by a Brookfield viscometer with a No. 62 rotor, and the test temperature was 95°C; the surface tension of the acrylamide copolymer solution was determined by a DCAT-21 surface tension meter, and the test temperature was 25°C.

[0075] The plugging rate was determined by a laboratory core physical model test. Specifically:

[0076] Determination of the plugging rate: The artificial core was loaded into a core holder, saturated with water first, then saturated with oil, water-flooded to 90% water content, the permeability (K1) was measured, 0.5 PV of a mixed solution of the acrylamide comb polymer and the crosslinking agent was injected, and after curing at 130°C for 48 hours, the water was finally injected again to determine the permeability (K2) after plugging, and (1-K2 / K1) x 100% was the plugging rate.

[0077] Example 1

[0078] 1) 270 g of acrylamide and 24 g of functional monomer X were added to a polymerization reaction bottle, and deionized water 1200 g was added to dissolve and form an aqueous solution, 6 g of functional monomer Y (n is 8), 0.21 g of Tween 400, 21 g of 1% mass fraction EDTA-2Na aqueous solution, 0.6 g of 1,3-bis(4-methoxyphenyl)thiourea were added in turn, and then sodium hydroxide was added to adjust the pH of the solution to 6.9, and the solution was fully stirred to form a stable micellar solution;

[0079] 2) At 38°C, the above solution was deoxygenated by passing high-purity nitrogen for 30 minutes, then 6 g of 1% mass fraction potassium persulfate aqueous solution and 3 g of 1% mass fraction sodium bisulfite aqueous solution were added to initiate the reaction, and the nitrogen was continued for five minutes and then stopped, and the polymerization reaction was carried out for 10 hours after sealing;

[0080] 3) The colloid was taken out, granulated, and then mixed uniformly with 33.8 g of sodium hydroxide granules, and then hydrolysis reaction was carried out at 85°C for 2.5 hours;

[0081] 4) The granules were taken out and granulated again, dried at 60°C to constant weight, crushed, and sieved to obtain white granular acrylamide comb polymer.

[0082] 500 g of field water (mineralization 150000 mg / L) was taken, 2.5 g of acrylamide comb polymer sample was added, and after stirring, a solution was formed, and the apparent viscosity and surface tension were tested, respectively. 0.02 g of water-soluble phenolic resin crosslinking agent (Puyang Ruicheng Chemical Co., Ltd.) was added to the above solution and mixed uniformly, then injected into the core, and kept stable at 150°C for 90 days, and then the plugging rate was determined. The results are shown in Table 1.

[0083] Example 2

[0084] 1) Put 200.7 g of acrylamide and functional monomer X 22.5 g into a heat-preservation polymerization reaction bottle, add deionized water 1275 g to dissolve and prepare an aqueous solution, then add functional monomer Y (n is 7) 1.8 g, Tween 601.05 g, 1% by mass EDTA-2Na aqueous solution 11.25 g, 1,3-bis(4-methoxyphenyl) thiourea 0.225 g, and then add sodium hydroxide to adjust the pH of the solution to 6.5, and fully stir to form a stable micellar solution;

[0085] 2) At 40°C, after the above solution is deoxygenated by high-purity nitrogen for 30 minutes, 1% by mass potassium persulfate aqueous solution 13.5 g and 1% by mass sodium bisulfite aqueous solution 6.75 g are added to initiate the reaction, and the nitrogen gas is continued for five minutes and then stopped, and the polymerization reaction is carried out for 10 hours after sealing to obtain a polymer colloid;

[0086] 3) The colloid is taken out, granulated, and then mixed uniformly with 22.8 g of sodium hydroxide granules, and then hydrolysis reaction is carried out at 85°C for 2.5 hours;

[0087] 4) The granules are taken out, granulated again, dried at 60°C to constant weight, crushed, and sieved to obtain white granular acrylamide comb polymer.

[0088] Take 500 g of field water (salinity 150000 mg / L), add 2.5 g of acrylamide comb polymer sample, stir to form a solution, and then test the apparent viscosity and surface tension, respectively. Add 0.04 g of water-soluble phenolic resin (Puyang Ruicheng Chemical Co., Ltd.) to the above solution and mix uniformly, then inject into the core, and then keep stable at 150°C for 90 days, and then measure the plugging rate. The results are shown in Table 1.

[0089] Example 3

[0090] 1) Put 250.8 g of acrylamide and functional monomer X 18.9 g into a heat-preservation polymerization reaction bottle, add deionized water 1230 g to dissolve and prepare an aqueous solution, then add functional monomer Y (n is 6) 0.3 g, Span 600.9 g, 1% by mass EDTA-2Na aqueous solution 8.1 g, 1,3-bis(4-methoxyphenyl) thiourea 0.27 g, and then add sodium hydroxide to adjust the pH of the solution to 7, and fully stir to form a stable micellar solution;

[0091] 2) At 35°C, after the above solution is deoxygenated by high-purity nitrogen for 30 minutes, 1% by mass potassium persulfate aqueous solution 13.5 g and 1% by mass sodium bisulfite aqueous solution 6.75 g are added to initiate the reaction, and the nitrogen gas is continued for five minutes and then stopped, and the polymerization reaction is carried out for 10 hours after sealing to obtain a polymer colloid;

[0092] 3) Take out the colloid, granulate, add 33.5 g of sodium hydroxide granular alkali, mix uniformly, and then carry out hydrolysis reaction at 85°C for 2.5 hours;

[0093] 4) Take out the colloid, granulate, dry at 60°C to constant weight, crush, and sieve to obtain white granular acrylamide comb polymer.

[0094] Take 500 g of field water (salinity 150000 mg / L), add 1.5 g of acrylamide comb polymer sample, stir to form a solution, and then test the apparent viscosity and surface tension, respectively. Add 0.035 g of crosslinking agent N,N-methylene bisacrylamide to the above solution, mix uniformly, and then inject into the core. Keep stable at 150°C for 90 days, and then determine the plugging rate. The results are shown in Table 1.

[0095] Example 4

[0096] 1) Put 166.5 g of acrylamide and 12.6 g of functional monomer X into a heat-preservation polymerization reaction bottle, add 1320 g of deionized water to dissolve and prepare an aqueous solution, then add 0.9 g of functional monomer Y (n is 10), 0.75 g of Span 400, 14.4 g of 1% EDTA-2Na aqueous solution, 0.09 g of 1,3-bis(4-methoxyphenyl)thiourea, and then add sodium hydroxide to adjust the pH of the solution to 7.2. Stir thoroughly to form a stable micellar solution;

[0097] 2) At 30°C, deoxygenate the above solution by passing high-purity nitrogen for 30 minutes, then add 18 g of 1% potassium persulfate aqueous solution and 9 g of 1% sodium bisulfite aqueous solution, initiate the reaction, continue to pass nitrogen for five minutes, then stop, seal, and polymerize for 10 hours to obtain a polymer colloid;

[0098] 3) Take out the colloid, granulate, add 23.3 g of sodium hydroxide granular alkali, mix uniformly, and then carry out hydrolysis reaction at 85°C for 2.5 hours;

[0099] 4) Take out the colloid, granulate, dry at 60°C to constant weight, crush, and sieve to obtain white granular acrylamide comb polymer.

[0100] Take 500 g of field water (salinity 150000 mg / L), add 3.5 g of acrylamide comb polymer sample, stir to form a solution, and then test the apparent viscosity and surface tension, respectively. Add 0.05 g of crosslinking agent water-soluble phenolic resin (Puyang Ruicheng Chemical Co., Ltd.) to the above solution, mix uniformly, and then inject into the core. Keep stable at 150°C for 90 days, and then determine the plugging rate. The results are shown in Table 1.

[0101] Example 5

[0102] 1) Put 233.5 g of acrylamide and functional monomer X 4.8 g into a polymerization flask, dissolve in deionized water 1260 g to form an aqueous solution, add functional monomer Y (n is 5) 1.7 g, Span 201.5 g, 1% by mass EDTA-2Na aqueous solution 4.8 g, 1,3-bis(4-methoxyphenyl) thiourea 0.072 g, then add sodium hydroxide to adjust the pH of the solution to 7.6, and stir to form a stable micellar solution;

[0103] 2) At 45°C, after deoxygenating the above solution with high-purity nitrogen for 30 minutes, add 1% by mass potassium persulfate aqueous solution 7.2 g and 1% by mass sodium bisulfite aqueous solution 3.6 g to initiate the reaction, continue to pass nitrogen for five minutes and then stop, seal and polymerize for 10 hours to obtain a polymer colloid;

[0104] 3) Take out the colloid, granulate, add 33.8 g of sodium hydroxide granules, mix uniformly, and then hydrolyze at 85°C for 2.5 hours;

[0105] 4) Take out the granules, granulate again, dry at 60°C to constant weight, crush and sieve to obtain white granular acrylamide comb polymer.

[0106] Take 500 g of field water (salinity 150000 mg / L), add 1.5 g of acrylamide comb polymer sample, stir to form a solution, and then test the apparent viscosity and surface tension, respectively. Add 0.025 g of crosslinking agent hexamethylene tetramine to the above solution and mix uniformly, then inject into the core, and then measure the plugging rate after keeping at 150°C for 90 days. The results are shown in Table 1.

[0107] Example 6

[0108] Prepare the polymer and mobile gel according to the method of Example 2, except that the mass ratio of the monomers is replaced by acrylamide: functional monomer X: functional monomer Y as 98.5:1:0.5 under the premise that the total amount of monomers remains unchanged. The results are shown in Table 1.

[0109] Example 7

[0110] Prepare the polymer and mobile gel according to the method of Example 2, except that amidinothiourea is used instead of 1,3-bis(4-methoxyphenyl) thiourea in Example 2. The results are shown in Table 1.

[0111] Example 8

[0112] Prepare the polymer and mobile gel according to the method of Example 2, except that no accelerator (1,3-bis(4-methoxyphenyl) thiourea) is added. The results are shown in Table 1.

[0113] Comparative Example 1

[0114] The polymer and the mobile gel were prepared according to the method of Example 2, except that 1-(2-vinylphenyl)ethanone was used instead of the functional monomer Y in Example 2. The results are shown in Table 1.

[0115] Comparative Example 2

[0116] The polymer and the mobile gel were prepared according to the method of Example 2, except that no monomer X was added. The results are shown in Table 1.

[0117] Comparative Example 3

[0118] The polymer and the mobile gel were prepared according to the method of Example 2, except that no monomer Y was added. The results are shown in Table 1.

[0119] Test Example Results

[0120] Table 1

[0121] Example No. Apparent viscosity (mPa-s) Surface tension (mN / m) Blocking rate (%) Example 1 138.4 33.2 98.2 Example 2 128.3 31.8 99.6 Example 3 132.6 31.3 97.3 Example 4 100.2 32.1 94.5 Example 5 116.7 32.7 93.1 Example 6 105.4 30.6 93.3 Example 7 80.1 27.3 60.8 Example 8 48.3 26.8 50.2 Comparative Example 1 81.7 26.6 37.2 Comparative Example 2 88.6 28.7 38.1 Comparative Example 3 75.1 25.3 34.4

[0122] 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 salinity of 150,000 mg / L and a temperature of 95°C, and can form a mobile gel at a formation temperature of 150°C, and can remain stable for 90 days at 150°C, and still has excellent plugging effect, and can be applied to high permeability reservoirs (more than 2000 mD), and is of great significance for improving oil recovery.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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. An acrylamide polymer comprising structural unit A of formula (1), structural unit B of formula (2), and structural unit C of formula (3); Equation (1); Equation (2); Equation (3); in, In equation (2), M is H or a metallic element; in equation (3), R is C. n Alkyl groups, where n is 5-10; Based on the total weight of the polymer (100%), the content of structural unit A is 88-98% by weight, the content of structural unit B is 1-10% by weight, and the content of structural unit C is 0.5-2% by weight. The method for preparing the polymer includes polymerizing acrylamide, functional monomer X, and functional monomer Y in water in the presence of an initiator and a accelerator to obtain a polymer colloid; and then hydrolyzing the polymer colloid. Wherein, the functional monomer X is the compound shown in formula (4), and the functional monomer Y is the compound shown in formula (5); Equation (4); Equation (5); M in Equation (4) is H or a metallic element, and R in Equation (5) is C. n Alkyl groups, where n is 5-10; The accelerator is 1,3-bis(4-methoxyphenyl)thiourea.

2. The polymer according to claim 1, characterized in that: Based on the total weight of the polymer (100%), the content of structural unit A is 89-92% by weight, the content of structural unit B is 7-10% by weight, and the content of structural unit C is 0.8-2% by weight.

3. The polymer according to claim 1, characterized in that: In the case where M is a metallic element in equation (2), M in equation (2) is selected from alkali metal elements; and / or, In equation (3), R is C n Straight-chain alkyl groups, n is 5-10.

4. The polymer according to claim 1, characterized in that: In the case where M is a metallic element in equation (2), M in equation (2) is Na or K; and / or, In equation (3), R is C n Straight-chain alkyl groups, n is 6-8.

5. A method for preparing the polymer according to any one of claims 1-4, comprising: polymerizing acrylamide, functional monomer X and functional monomer Y in water in the presence of an initiator and a accelerator to obtain a polymer colloid; and then hydrolyzing the polymer colloid; in, The functional monomer X is the compound shown in formula (4), and the functional monomer Y is the compound shown in formula (5); Equation (4); Equation (5); M in Equation (4) is H or a metallic element, and R in Equation (5) is C. n The alkyl group, n is 5-10; the accelerator is 1,3-bis(4-methoxyphenyl)thiourea.

6. The preparation method according to claim 5, characterized in that: The total amount of the acrylamide, functional monomer X, and functional monomer Y is 12-20 parts by weight relative to 100 parts by weight of water; and / or, Based on the total mass of acrylamide, functional monomer X and functional monomer Y as 100%, functional monomer X accounts for 1%-10%, functional monomer Y accounts for 0.5%-2%, and the balance is acrylamide.

7. The preparation method according to claim 5 or 6, characterized in that: At least one of emulsifiers and complexing agents is also added to the polymerization system.

8. The preparation method according to claim 5 or 6, characterized in that: The preparation method includes: Step 1: Mix acrylamide and functional monomer X with water, then add functional monomer Y, emulsifier, complexing agent, and accelerator, and adjust the pH to 6-8. After mixing, a micelle solution is obtained. Step 2: Add an initiator to the micelle solution obtained in Step 1, mix, and polymerize under a protective atmosphere to obtain a polymer colloid. Step 3 involves granulating the polymer colloid and mixing it with a solid alkaline substance for hydrolysis.

9. The preparation method according to claim 8, characterized in that: The polymerization conditions in step 2 include: a temperature of 30-45°C, and / or a polymerization time of 8-12 hours, and / or a protective atmosphere of nitrogen and / or an inert gas; and / or, The hydrolysis conditions in step 3 include a temperature of 80-90°C and / or a time of 2-3 hours.

10. The preparation method according to claim 8, characterized in that: The emulsifier is selected from at least one of Tween 20, Tween 40, Tween 60, Span 20, Span 40, and Span 60; and / or, The amount of the emulsifier is 0.05-1 parts by weight relative to 100 parts by weight of water.

11. The preparation method according to claim 8, characterized in that: The complexing agent is EDTA-2Na; and / or, The amount of the complexing agent is 0.01-0.1 parts by weight relative to 100 parts by weight of water.

12. The preparation method according to claim 11, characterized in that: The complexing agent is derived from an aqueous solution of EDTA-2Na.

13. The preparation method according to claim 8, characterized in that: The ratio of the total mass of acrylamide, functional monomer X, and functional monomer Y to the mass of the accelerator is 100:(0.01-0.2).

14. The preparation method according to claim 8, characterized in that: The initiator is a redox initiation system composed of a persulfate oxidant and a sulfite reductant.

15. The preparation method according to claim 14, characterized in that: The amount of persulfate oxidant added is 0.01%-0.1% of the total mass of acrylamide and functional monomers X and Y, and the amount of sulfite reducing agent added is 0.005%-0.05% of the total mass of acrylamide and functional monomers X and Y.

16. The preparation method according to claim 8, characterized in that: The solid alkaline substance mentioned in step 3 is a strong base; and / or, The mass ratio of the solid alkaline substance to the polymer colloid is 1:(44-65).

17. The preparation method according to claim 8, characterized in that: The solid alkaline substance mentioned in step 3 is sodium hydroxide granules.

18. A movable gel comprising the polymer according to any one of claims 1-4 or the polymer prepared by any one of claims 5-17, as well as water and a crosslinking agent.

19. The movable gel according to claim 18, characterized in that: The polymer content is 0.3-0.7 parts by weight relative to 100 parts by weight of water, and the crosslinking agent content is 0.004-0.01 parts by weight; and / or, The crosslinking agent is selected from at least one of water-soluble phenolic resin, N,N-methylenebisacrylamide, and hexamethylenetetramine.

20. The movable gel according to claim 18, characterized in that: The polymer content is 0.3-0.5 parts by weight relative to 100 parts by weight of water, and the crosslinking agent content is 0.004-0.08 parts by weight.

21. The application of the polymer according to any one of claims 1-4, or the polymer prepared by the preparation method according to any one of claims 5-17, or the movable gel according to any one of claims 18-20, in oilfield water injection, profile control, and water shut-off.

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