Phosphonic acid type copolymer as well as preparation method and application thereof

Abstract

The invention relates to the field of oil exploitation, and discloses a phosphonic acid type copolymer as well as a preparation method and application thereof. According to the invention, a phosphonic acid group monomer is used as a main construction unit, and amide, tert-butyl benzoate and tertiary carbonate monomer structural units are introduced, so that the hydrolysis rate of amide and tert-butyl benzoate can be controlled, precipitation is inhibited, and the polymer can be used as a polymer for flow regulation of high-temperature and high-salinity oil reservoirs, especially carbonate reservoirs.

Description

Technical Field

[0001] The present invention relates to the technical field of oil extraction, and specifically, to a phosphonic acid copolymer, a preparation method thereof, and an application thereof. Background Art

[0002] Carbonate reservoirs are mainly fracture-cavity type and extremely heterogeneous, resulting in easy water channeling and low recovery rate during water injection development of the reservoir. The polymer gel flow control technology is one of the potential technologies for improving the recovery rate of carbonate reservoirs. However, the carbonate reservoir environment is harsh (temperature 130 - 160 °C, salinity > 200,000 mg / L, calcium and magnesium ion content ≥ 10,000 mg / L). Existing conventional gels use acrylamide monomers as the main building units and have poor adaptability in this reservoir environment, resulting in rapid dehydration and gel breaking of the gel, and it is difficult to meet the water well flow control requirements. Developing high-temperature and high-salt resistant polymers is the key to preparing gels suitable for flow control in carbonate reservoirs.

[0003] 2-Acrylamido-2-methylpropane phosphonic acid is a type of monomer with good Ca 2+ , Mg 2+ chelating properties. In addition, it also has a charge shielding effect, and the electrostatic shielding effect can be used to reduce the hydrolysis of amide groups, preventing the viscosity from dropping sharply or flocculation due to the short-term rapid and large hydrolysis of amide groups after the polymer enters the formation. Therefore, developing copolymers based on 2-acrylamido-2-methylpropane phosphonic acid monomers is expected to improve the temperature resistance, salt resistance, and calcium and magnesium ion resistance of polymers, which is of great significance for developing gels that meet the flow control requirements of carbonate reservoirs. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art and provide a phosphonic acid copolymer, a preparation method thereof, and an application thereof.

[0005] To achieve the above purpose, the first aspect of the present invention provides a phosphonic acid copolymer.

[0006] The second aspect of the present invention provides a method for preparing a phosphonic acid copolymer.

[0007] The third aspect of the present invention provides a phosphonic acid copolymer obtained by the aforementioned preparation method.

[0008] The fourth aspect of the present invention provides a flow control system prepared from the phosphonic acid copolymer as described above.

[0009] Through the above technical solutions, the present invention uses phosphonic acid group monomers as the main building blocks, and the copolymer of the present invention has long-term stability in high salinity and high calcium and magnesium environments. In addition, under the action of electrostatic shielding, the hydrolysis rates of amide groups and tert-butyl benzoate can be controlled, and precipitation can be inhibited at the same time. The copolymer structure of the present invention has strong rigidity and stability. The copolymer of the present invention can form coordination bond crosslinking with a metal crosslinking agent to obtain a high-viscosity fluid with adjustable viscosity, realizing flow channel adjustment. The flow control system prepared from the copolymer of the present invention can be prepared with oxygen-containing sewage and can be stable for 60 days and maintain good viscosity in a reservoir environment at a temperature of 60-130 °C, a salinity of ≤300 g / L, and a calcium and magnesium ion content of ≤10 g / L. Detailed implementation manners

[0010] In the ranges disclosed herein, the endpoints and any value are not limited to the exact range or value, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0011] The first aspect of the present invention provides a phosphonic acid type copolymer, characterized in that the copolymer comprises structural unit A, structural unit B, structural unit C and structural unit D; the structural unit A is The structural unit B is The structural unit C is The structural unit D is

[0012] Wherein, M 1 and M 2 are each independently H or an alkali metal element, R 1 is H or methyl, R 2 and R 3 are each independently an alkyl group with 1-6 carbon atoms, and when R 2 and R 3 are each independently an alkyl group with 2-6 carbon atoms, the total number of carbon atoms of R 2 and R 3 is 6-8.

[0013] According to the present invention, the weight ratio of the structural unit A, the structural unit B, the structural unit C, and the structural unit D is (52-548):(7.5-450):(0.05-30):1, preferably (65-397.5):(10-180):(0.3-10):1, more preferably (75-357):(20-80):(0.5-5):1, and further preferably (80-280):(25-60):(1-3):1.

[0014] In the present invention, based on the total weight of the copolymer, the content of the structural unit A is 65-90% by weight, preferably 70-84% by weight.

[0015] According to the present invention, the viscosity-average molecular weight of the phosphonic acid copolymer is 5 million to 18 million, for example, it can be 5 million, 8 million, 9 million, 10 million, 11 million, 11.6 million, 12 million, 13 million, 14.5 million, 15 million, 16 million, 17 million, 18 million and any value within the range formed by any two of the above values.

[0016] According to the present invention, preferably, M 1 and M 2 are each independently H or Na.

[0017] According to the present invention, preferably, R 1 is H.

[0018] According to the present invention, preferably, R 2 is methyl and R 3 is methyl; or R 2 is methyl and R 3 is n-pentyl; or R 2 is methyl and R 3 is n-hexyl.

[0019] The second aspect of the present invention provides a preparation method of a phosphonic acid copolymer, which is characterized in that the method includes: under solution polymerization reaction conditions, in the presence of an initiator, polymerizing an olefin monomer; wherein, the olefin monomer includes monomer A', monomer B', monomer C' and monomer D'; the monomer A' is The monomer B' is The monomer C' is The monomer D' is

[0020] Wherein, M 1 , M 2 , R 1 , R 2 , R 3 are as described above.

[0021] Based on the total weight of the olefin monomer, the content of the monomer A' is 65-90% by weight, preferably 70-84% by weight.

[0022] According to the present invention, the weight ratio of the monomer A', the monomer B', the monomer C', and the monomer D' is (52 - 548):(7.5 - 450):(0.05 - 30):1, preferably (65 - 397.5):(10 - 180):(0.3 - 10):1, more preferably (75 - 357):(20 - 80):(0.5 - 5):1, and further preferably (80 - 280):(25 - 60):(1 - 3):1.

[0023] According to the present invention, at the start of the solution polymerization reaction, the ratio between the total weight of the vinyl monomer and the total weight of the solvent and the vinyl monomer is (0.3 - 0.55):1, preferably (0.35 - 0.5):1.

[0024] According to the present invention, the solution polymerization reaction conditions can enable the viscosity-average molecular weight of the resulting polymer to be as described above. Preferably, the solution polymerization reaction conditions include: the starting temperature of the polymerization reaction is -10°C to 30°C, the time is 2 - 12 hours, and the pH value is 4 - 8. Preferably, the starting temperature of the polymerization reaction is -5°C to 10°C, the time is 3 - 10 hours, and the pH value is 5 - 7. In the present invention, an alkali metal hydroxide (such as sodium hydroxide, potassium hydroxide), 2-acrylamido-2-methylpropanephosphonic acid, or one or more of them can be used to adjust the pH value of the polymerization reaction. It can be understood that by using an alkali metal hydroxide (such as sodium hydroxide) to adjust the pH value, M 1 and M 2 in the structural unit A (monomer A') can be converted from H to an alkali metal element (such as Na). Moreover, by controlling the amount of the alkali metal hydroxide used, the polymer of the present invention can also have structural units in which M 1 and / or M 2 is H, M 1 and / or M 2 is an alkali metal element.

[0025] According to the present invention, the initiator can be selected from various common initiators in the art. For example, the initiator can be selected from azo initiators and / or redox initiators. The amount of the initiator can be 0.0005 - 0.05% by weight of the weight of the vinyl monomer. Preferably, the amount of the azo initiator is 0.0001 - 0.1% by weight of the weight of the vinyl monomer. Preferably, the amount of the redox initiator is 0.0002 - 0.3% by weight of the weight of the vinyl monomer. According to the present invention, the azo initiator is preferably a water-soluble azo initiator. The redox initiator includes an oxidizing agent and a reducing agent. The reducing agent is an inorganic reducing agent and / or an organic reducing agent, and the weight ratio of the oxidizing agent to the reducing agent is (0.1 - 1):1.

[0026] Preferably, the water-soluble azo initiator is selected from at least one of 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(2-imidazolinopropane) dihydrochloride, and 4,4'-azobis(4-cyanovaleric acid). Preferably, the oxidant is selected from at least one of benzoyl peroxide, hydrogen peroxide, tert-butyl hydroperoxide, 2,5-dimethyl-2,5-bis(hydroperoxy)hexane, ammonium persulfate, sodium persulfate, and potassium persulfate. Preferably, the inorganic reducing agent is selected from at least one of ferrous sulfate, ammonium ferrous sulfate, cuprous chloride, potassium sulfite, sodium sulfite, ammonium bisulfite, potassium bisulfite, sodium thiosulfate, potassium thiosulfate, sodium formaldehyde sulfoxylate (rongalite), and sodium bisulfite. Preferably, the organic reducing agent is selected from at least one of N,N-dimethylethanolamine, N,N'-dimethylpiperazine, N,N,N',N'-tetramethylurea, and N,N,N',N'-tetramethylethylenediamine.

[0027] According to the present invention, in order to better control the induction period and reduce the inhibition effect of dissolved oxygen, the polymerization reaction is preferably carried out in an inert atmosphere, and the inert atmosphere can be provided by nitrogen and / or an inert gas.

[0028] According to the present invention, preferably, the preparation method further contains an emulsifier, and the emulsifier can better disperse monomers C and D and play a role in solubilizing monomers C and D. The emulsifier includes one or more of Tween 60, Tween 80, sodium dodecyl sulfate, and sodium dodecylbenzenesulfonate, and the weight dosage of the emulsifier is 5-30 times the weight dosage of monomers C and D, based on the weight of monomers C and D added.

[0029] According to the present invention, in order to control the foam in the reaction system, the polymerization reaction is carried out in the presence of an antifoaming agent. The dosage of the antifoaming agent can be 0.05-1% by weight of the amount of the vinyl monomer. The antifoaming agent can be selected from various common antifoaming agents in the art.

[0030] According to the present invention, the method may further include: granulating, drying, pulverizing, and screening the polymer colloid to obtain a polymer product.

[0031] According to the present invention, the drying conditions include: the temperature is 40-70°C, preferably 45-65°C. In the present invention, the drying time is not specifically limited, and it can be dried until the solid content reaches 85-95% by weight, preferably 88-90% by weight. Generally, the drying time is 2-24 hours.

[0032] The third aspect of the present invention provides a phosphonic acid type copolymer prepared by the aforementioned preparation method.

[0033] In the present invention, conventional methods in the prior art can be used to test the contents of various structural units in the polymer, such as infrared spectroscopy, nuclear magnetic resonance, and the feeding amounts of monomers during the polymerization process, etc. Preferably, the feeding amounts of monomers are used to determine the contents of various structural units in the polymer. Specifically, by testing the content of unreacted monomers, the feeding ratios of various monomers actually participating in the polymerization are determined, and then the contents of various structural units in the polymer are determined. Further, in the present invention, after testing, the contents of various unreacted monomers in the polymer are all below 0.02% by weight, indicating that all monomers basically participate in the polymerization reaction. Specifically, the content of the residual monomers can be determined by liquid chromatography.

[0034] The fourth aspect of the present invention provides a flow control system, which is characterized in that the flow control system contains a metal crosslinking agent and the phosphonic acid copolymer as described above. The flow control system of the present invention is particularly suitable for adjusting the flow channels in carbonate rock reservoirs.

[0035] According to the present invention, the flow control system may further contain a solvent, and the solvent is water. The content of the solvent can be 97.7 - 99.7% by weight, preferably 98.2 - 99.1% by weight.

[0036] In the present invention, based on the total weight of the flow control system, the content of the phosphonic acid copolymer is preferably 0.3 - 1.5% by weight, more preferably 0.5 - 1.2% by weight.

[0037] In the present invention, based on the total weight of the profile control and flooding system, the content of the metal crosslinking agent is preferably 0.01 - 0.5% by weight, more preferably 0.02 - 0.3% by weight.

[0038] In the present invention, the metal crosslinking agent can be selected from substances commonly used in the art that can crosslink the phosphonic acid copolymer. According to a preferred embodiment of the present invention, the metal crosslinking agent is composed of metal ions and an organic ligand compound. Preferably, the metal ions are selected from at least one of chromium, aluminum, zirconium, and titanium. Preferably, the organic ligand compound is selected from at least one of organic acids and / or organic amines, more preferably selected from at least one of citric acid, oxalic acid, lactic acid, acetic acid, triethanolamine, and polyenepolyamine.

[0039] In the present invention, the flow control system may further contain an oxygen scavenger. The content of the oxygen scavenger can be 0.005 - 0.3% by weight, preferably 0.02 - 0.25% by weight. The type and dosage of the oxygen scavenger can be selected with reference to the prior art. For the present invention, preferably, the oxygen scavenger is at least one of sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium dithionite (insurance powder), isoascorbic acid, and thiourea.

[0040] The fifth aspect of the present invention provides a method for preparing a flow control system, which includes: in the presence of a solvent, mixing a phosphonic acid copolymer with a metal crosslinking agent and an optional deoxidizer, wherein the phosphonic acid copolymer is the aforementioned phosphonic acid copolymer. The specific selection and dosage of the solvent, copolymer, metal crosslinking agent, deoxidizer, etc. are as described above and will not be elaborated here.

[0041] The sixth aspect of the present invention provides an application of the aforementioned flow control system as a flow control agent in oil reservoir exploitation.

[0042] According to the present invention, the oil reservoir is a high-temperature and high-salt oil reservoir, preferably a carbonate rock oil reservoir.

[0043] According to the present invention, preferably, the reservoir temperature of the oil reservoir is 60 - 130 °C, the salinity ≤ 300000 mg / L, and the calcium and magnesium ion concentration ≤ 10000 mg / L; more preferably, the reservoir temperature of the carbonate rock oil reservoir is 70 - 130 °C, the salinity is 1000 - 300000 mg / L, and the calcium and magnesium ion concentration is 100 - 10000 mg / L.

[0044] In the present invention, water serves as the solvent and reaction medium in the phosphonic acid copolymer, and there is no particular limitation on its selection. The water can be natural water and artificially prepared water. Natural water can be river water, lake water, atmospheric water, seawater, groundwater, etc., and artificially prepared water can be tap water, distilled water, deionized water, or heavy water.

[0045] Generally speaking, in the actual application process, the water used is often the water at the oil field location (field water) or its corresponding simulated brine. Preferably, the salinity of the water is 1000 - 300000 mg / L, and the calcium and magnesium ion content is 100 - 10000 mg / L.

[0046] The present invention will be described in detail below through examples. In the following examples and comparative examples:

[0047] Monomer A′ was prepared according to the synthesis method in "Improved Synthesis of AMPP via Ritter Reaction" (He Quanguo, Sun Yuanxi, Liu Ping, etc., Industrial Water Treatment, 2001, 21: 26 - 28). When M = Na, it was prepared by neutralizing the corresponding monomer with M = H with an alkali.

[0048] Monomer B′, the acrylamide monomer, was purchased from Dongying Baomo Environmental Engineering Co., Ltd.

[0049] Monomer C′ was purchased from Sigma - Aldrich Technology Co., Ltd.

[0050] Monomer D′ was purchased from Sigma - Aldrich Technology Co., Ltd.

[0051] Aluminum citrate, zirconium citrate, and zirconium lactate were purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0052] Chromium citrate and chromium lactate were purchased from Shandong Shida Oilfield Technology Service Co., Ltd.

[0053] Unless otherwise specified, the reagents and materials used in the following examples are commercially available. The defoamer used was a silicone defoamer, purchased from Hai'an Petrochemical Factory, Jiangsu Province.

[0054] In the following examples, simulated brine was prepared according to the applicable reservoir environment. The salinity of the simulated brine was 100,000 - 300,000 mg / L, and the calcium and magnesium ion concentration was 5,000 - 10,000 mg / L (it should be understood that the salinity is an approximate value).

[0055] The test methods for the performance of copolymers or flow control systems are as follows:

[0056] 1) The test method for molecular weight is as follows:

[0057] The viscosity-average molecular weight of the polymer was calculated using the formula M = ([η] / K) according to the method specified in GB / T 12005.10 - 92 1 / α where K = 4.75×10 -3 , α = 0.8, and [η] is the intrinsic viscosity; the intrinsic viscosity was determined according to the enterprise standard Q / SH1020 1572 - 2022 "Polyacrylamide for Enhanced Oil Recovery" of Shengli Petroleum Administration Bureau, Sinopec Group.

[0058] 2) The content of crosslinked groups generated by hydrolysis = the content of carboxyl groups + the content of hydroxyl groups. The test method for the content of crosslinked groups (carboxyl and hydroxyl groups): a) For a polymer solution after high-temperature aging with a certain mass, refer to the method for determining the hydrolysis degree in the enterprise standard Q / SH1020 1572 - 2022 "Polyacrylamide for Enhanced Oil Recovery" of Shengli Petroleum Administration Bureau, Sinopec Group to obtain the hydrochloric acid consumption V 1 (total hydrochloric acid consumption of acrylate and p-tert-butylbenzoate structural units); b) For a polymer solution after high-temperature aging with the same mass, first use a dialysis membrane (cut-off molecular weight: 3500, Solabao brand) to purify and remove the sodium formate generated by hydrolysis, then rotary evaporate to remove most of the water, and obtain an aged polymer powder sample after freeze-drying and pulverization. Then, refer to the method for determining the hydrolysis degree in the enterprise standard Q / SH1020 1572 - 2022 "Polyacrylamide for Enhanced Oil Recovery" of Shengli Petroleum Administration Bureau, Sinopec Group to obtain the hydrochloric acid consumption V 2 (hydrochloric acid consumption of acrylate), and calculate the content of carboxyl groups through V 2 . c) Through V 3 = V 1 - V 2The hydrochloric acid consumption of p-tert-butylbenzoate is calculated, and the content of hydrolyzed and released hydroxyl groups is calculated according to the hydrolysis degree formula in Q / SH1020 1572-2022 "Polyacrylamide for Enhanced Oil Recovery".

[0059] 3) The viscosity measurement method of the flow control system uses a Brookfield R / S Rheometer at a temperature of 30 °C to measure the viscosity at a shear rate of 7.34 s -1 -1.

[0060] 4) The high-temperature aging operation method of the flow control system is as follows: The polymer gel formed by the polymer and the cross-linking agent is placed in a sealed stainless steel reaction kettle and reacted in a constant temperature oven at a temperature of 70-130 °C. It is taken out of the constant temperature oven at fixed intervals (60 days) to measure the viscosity.

[0061] Preparation Example 1

[0062] This preparation example is to illustrate the preparation of a phosphonic acid copolymer for flow control in carbonate rock reservoirs by using the preparation method of the present invention.

[0063] (1) Take 91 g of monomer A′, 27.2 g of monomer B′ acrylamide, 1.1 g of monomer C′, and 0.7 g of monomer D′. Among them, monomer A′ is (M 1 is H, M 2 is H), monomer B’ is (R 1 is H); monomer C’ is Monomer D′ is Add 20 g of sodium dodecyl sulfate, dissolve it in 160 g of deionized water, adjust the pH value to 6.5 with sodium hydroxide solution, control the starting temperature at 2 °C, add 0.8 g of defoaming agent, purge nitrogen into the system for 20 min to remove oxygen, and then add 1 g of a 2,2-azobis(2-amidinopropane) dihydrochloride aqueous solution at 0.25 wt%, 1.8 g of an ammonium persulfate aqueous solution at 0.2 wt%, and 1.5 g of a sodium bisulfite aqueous solution at 0.3 wt% to initiate polymerization. After the system temperature rises by 0.5 °C, stop purging nitrogen bubbles and continue the reaction for 6 hours;

[0064] (2) After polymerization, granulate the obtained colloid, dry it at 50 °C until the solid content reaches 89 wt%, crush and screen it to obtain a dry powder product of the phosphonic acid copolymer.

[0065] The viscosity-average molecular weight of the dry powder product is measured to be 11.8 million.

[0066] In addition, it is calculated and determined according to the feeding amount that in the prepared phosphonic acid copolymer, the phosphonic acid copolymer contains:

[0067] Structural unit A( Among them, M 1 and M 2 is Na);

[0068] Structural unit B( Among them, R 1 is H);

[0069] Structural unit C

[0070] Structural unit D

[0071] Among them, based on the total weight of the phosphonic acid copolymer, the content of the structural unit A is 75.8% by weight, the content of the structural unit B is 22.7% by weight, the content of the structural unit C is 0.9% by weight, and the content of the structural unit D is 0.6% by weight.

[0072] The content of the cross-linked groups generated after placing the 5000 mg / L polymer solution (prepared with deionized water) at 130 °C for 15 - 60 days is shown in Table 1.

[0073] Table 1 Content of cross-linked groups generated by high-temperature aging of the sulfonic acid copolymers with controllable hydrolysis rate prepared in Preparation Examples 1 - 5 and the polymers obtained in the Comparative Examples

[0074]

[0075]

[0076] Preparation Example 2

[0077] This preparation example is to illustrate the preparation of the phosphonic acid copolymer for regulating fluid flow in carbonate rock reservoirs by using the preparation method of the present invention.

[0078] (1) Take 100 g of monomer A′, 32.4 g of monomer B′ acrylamide, 1.6 g of monomer C′, and 1.1 g of monomer D′. Among them, monomer A′, monomer B′, and monomer C′ are the same as those in Preparation Example 1, and the structural formula of monomer D′ is R 2 is methyl, and R 3 is n-pentyl); Add 20 g of sodium dodecyl sulfate and 15 g of Tween 60, dissolve them in 165 g of deionized water, adjust the pH value to 6 with sodium hydroxide solution, control the starting temperature at 0 °C, add 1.2 g of defoaming agent, purge nitrogen gas into the system for 20 min to remove oxygen, then add 1 g of 2,2-azobis(2-amidinopropane) dihydrochloride aqueous solution with a concentration of 0.25 wt%, 2.1 g of ammonium persulfate aqueous solution with a concentration of 0.2 wt%, and 2.2 g of sodium bisulfite aqueous solution with a concentration of 0.3 wt% to initiate polymerization. After the system temperature rises by 0.5 °C, stop purging nitrogen gas bubbles and continue the reaction for 6 hours;

[0079] (2) After polymerization, the obtained colloid is granulated, dried at 50 °C until the solid content reaches 89% by weight, pulverized and sieved to obtain a phosphonic acid type copolymer dry powder product.

[0080] The viscosity-average molecular weight of the dry powder product is measured to be 9.5 million.

[0081] In addition, according to the determined feed amount, in the prepared phosphonic acid type copolymer, the phosphonic acid type copolymer contains:

[0082] Structural unit A (the same as in Preparation Example 1);

[0083] Structural unit B (the same as in Preparation Example 1);

[0084] Structural unit C (the same as in Preparation Example 1);

[0085] Structural unit D ( wherein, R 2 is methyl, and R 3 is n-pentyl);

[0086] Among them, based on the total weight of the phosphonic acid type copolymer, the content of the structural unit A is 74% by weight, the content of the structural unit B is 24% by weight, the content of the structural unit C is 1.2% by weight, and the content of the structural unit D is 0.8% by weight.

[0087] The content of the cross-linked groups generated after the 5000 mg / L polymer solution (prepared with deionized water) is placed at 130 °C for 15 - 60 days is shown in Table 1.

[0088] Preparation Example 3

[0089] This preparation example is to illustrate the preparation of a phosphonic acid type copolymer for regulating fluid flow in carbonate rock reservoirs by using the preparation method of the present invention.

[0090] (1) Take 87.3 g of monomer A′, 17 g of monomer B′ acrylamide, 0.53 g of monomer C′, and 0.32 g of monomer D′. Among them, monomer A′, monomer B′, and monomer C′ are the same as in Preparation Example 1, and the structural formula of monomer D′ is; R 2 is methyl, and R 3(where R is methyl and R is n - hexyl); 12.5 g of sodium dodecylbenzenesulfonate was added and dissolved in 182.35 g of deionized water. The pH value was adjusted to 6 with sodium hydroxide solution, and the initial temperature was controlled at 5 °C. 0.8 g of defoamer was added, and nitrogen gas was bubbled into the system for 20 min to remove oxygen. Then, 1 g of an aqueous solution of 2,2 - azobis(2 - amidinopropane) dihydrochloride with a concentration of 0.25 wt%, 2 g of an aqueous solution of ammonium persulfate with a concentration of 0.2 wt%, and 1.5 g of an aqueous solution of sodium bisulfite with a concentration of 0.3 wt% were added to initiate polymerization. After the temperature of the system rose by 0.5 °C, the nitrogen gas bubbling was stopped, and the reaction continued for 4 hours.

[0091] (2) After polymerization, the obtained colloid was granulated, dried at 50 °C until the solid content reached 89 wt%, pulverized and sieved to obtain a dry powder product of the phosphonic acid - type copolymer.

[0092] The viscosity - average molecular weight of the dry powder product was measured to be 11.6 million.

[0093] In addition, according to the calculation based on the feeding amount, in the prepared phosphonic acid - type copolymer, the phosphonic acid - type copolymer contains:

[0094] Structural unit A (same as Preparation Example 1);

[0095] Structural unit B (same as Preparation Example 1);

[0096] Structural unit C (same as Preparation Example 1);

[0097] Structural unit D ( where R 2 is methyl and R 3 is n - hexyl);

[0098] Among them, based on the total weight of the phosphonic acid - type copolymer, the content of structural unit A is 83 wt%, the content of structural unit B is 16.2 wt%, the content of structural unit C is 0.5 wt%, and the content of structural unit D is 0.3 wt%.

[0099] The content of cross - linked groups generated after the polymer solution (prepared with deionized water) at 5000 mg / L was placed at 130 °C for 15 - 60 days is shown in Table 1.

[0100] Preparation Example 4

[0101] This preparation example is to illustrate the preparation of the phosphonic acid - type copolymer for regulating fluid flow in carbonate rock reservoirs by using the preparation method of the present invention.

[0102] (1) Take 78.2 g of monomer A′, 33.1 g of monomer B′ acrylamide, 2.51 g of monomer C′, and 0.17 g of monomer D′. Among them, monomer A′, monomer B′, monomer C′, and monomer D′ are the same as those in Preparation Example 1; add 18 g of Tween 60, dissolve it in 168.02 g of deionized water, adjust the pH value to 6 with sodium hydroxide solution, control the initial temperature at 5 °C, add 0.7 g of defoamer, purge nitrogen into the system for 20 min to remove oxygen, and then add 1 g of 2,2-azobis(2-amidinopropane) dihydrochloride aqueous solution with a concentration of 0.25 wt%, 2 g of ammonium persulfate aqueous solution with a concentration of 0.2 wt%, and 1.5 g of sodium bisulfite aqueous solution with a concentration of 0.3 wt% to initiate polymerization. After the temperature of the system rises by 0.5 °C, stop purging nitrogen bubbles and continue the reaction for 6 hours;

[0103] (2) After the polymerization is completed, granulate the obtained colloid, dry it at 50 °C until the solid content reaches 89 wt%, crush and screen it to obtain a dry powder product of the phosphonic acid copolymer.

[0104] The viscosity-average molecular weight of the dry powder product is measured to be 12.4 million.

[0105] In addition, it is calculated and determined according to the feeding amount that in the prepared phosphonic acid copolymer, the phosphonic acid copolymer contains:

[0106] Structural unit A (the same as in Preparation Example 1);

[0107] Structural unit B (the same as in Preparation Example 1);

[0108] Structural unit C (the same as in Preparation Example 1);

[0109] Structural unit D (the same as in Preparation Example 1);

[0110] Among them, based on the total weight of the phosphonic acid copolymer, the content of structural unit A is 68.6 wt%, the content of structural unit B is 29.05 wt%, the content of structural unit C is 2.2 wt%, and the content of structural unit D is 0.15 wt%.

[0111] The content of crosslinking groups generated after the polymer solution (prepared with deionized water) with a concentration of 5000 mg / L is placed at 130 °C for 15 - 60 days is shown in Table 1.

[0112] Preparation Example 5

[0113] This preparation example is to illustrate the preparation of the phosphonic acid copolymer for regulating fluid flow in carbonate rock reservoirs by using the preparation method of the present invention.

[0114] (1) Take 105 g of monomer A′, 13.2 g of monomer B′ acrylamide, 0.24 g of monomer C′, and 1.56 g of monomer D′. Among them, monomer A′, monomer B′, monomer C′, and monomer D′ are the same as those in Preparation Example 1; add 20 g of sodium dodecylbenzenesulfonate, dissolve it in 160 g of deionized water, adjust the pH value to 6 with sodium hydroxide solution, control the initial temperature at 5 °C, add 0.8 g of defoamer, purge nitrogen into the system for 20 min to remove oxygen, then add 1 g of 2,2 - azobis(2 - amidinopropane) dihydrochloride aqueous solution with a concentration of 0.25 wt%, 2 g of ammonium persulfate aqueous solution with a concentration of 0.2 wt%, and 1.5 g of sodium bisulfite aqueous solution with a concentration of 0.3 wt%. After the system temperature rises by 0.5 °C, stop purging nitrogen bubbles and continue the reaction for 6 hours;

[0115] (2) After polymerization, granulate the obtained colloid, dry it at 50 °C until the solid content reaches 89 wt%, crush and screen it to obtain a phosphonic acid - type copolymer dry powder product.

[0116] The viscosity - average molecular weight of the dry powder product is measured to be 8.5 million.

[0117] In addition, according to the calculation based on the feeding amount, in the prepared phosphonic acid - type copolymer, the phosphonic acid - type copolymer contains:

[0118] Structural unit A (the same as in Preparation Example 1);

[0119] Structural unit B (the same as in Preparation Example 1);

[0120] Structural unit C (the same as in Preparation Example 1);

[0121] Structural unit D (the same as in Preparation Example 1);

[0122] Among them, based on the total weight of the phosphonic acid - type copolymer, the content of structural unit A is 87.5 wt%, the content of structural unit B is 11 wt%, the content of structural unit C is 0.2 wt%, and the content of structural unit D is 1.3 wt%.

[0123] The content of cross - linked groups generated after the 5000 mg / L polymer solution (prepared with deionized water) is placed at 130 °C for 15 - 60 days is as shown in Table 1.

[0124] Example 1

[0125] This example is used to illustrate a polymer flow regulator for carbonate rock reservoirs and its preparation method of the present invention.

[0126] Add 10 g of the phosphonic acid copolymer obtained in Preparation Example 1 to 900 g of simulated brine. Stir at 600 rpm / min until completely dissolved, then add 0.5 g of zirconium citrate and 0.8 g of chromium lactate and stir until completely dissolved. Next, add 0.8 g of sodium thiosulfate and make up to a total weight of 1 kg with simulated brine. Stir evenly to obtain a polymer flow regulator glue solution, and this system can be used as a flow regulator for flow path adjustment.

[0127] Two types of salinity and calcium and magnesium ion contents are selected for the simulated brine. The salinity of the first type of simulated brine is 300000 mg / L, and the calcium and magnesium ion content is 10000 mg / L. The salinity of the second type of simulated brine is 100000 mg / L, and the calcium and magnesium ion content is 5000 mg / L.

[0128] The initial viscosity of the flow regulator system prepared with the simulated brine with a salinity of 300000 mg / L and a calcium and magnesium ion content of 10000 mg / L is 615 mPa·s. The aged viscosities after being placed at 70 °C, 95 °C, and 130 °C for 60 days are measured respectively, and the results are shown in Table 2.

[0129] The initial viscosity of the flow regulator system prepared with the simulated brine with a salinity of 100000 mg / L and a calcium and magnesium ion content of 5000 mg / L is 740 mPa·s. The aged viscosities after being placed at 70 °C, 95 °C, and 130 °C for 60 days are measured respectively, and the results are shown in Table 2.

[0130] Table 2 Viscosities of the flow regulator system obtained in Example 1 after aging for 60 days at different temperatures, different salinities and calcium and magnesium ion contents

[0131]

[0132] Measure the initial viscosity of the said flow regulator system and the high-temperature aged viscosity after being placed at 130 °C for 60 days. The results are shown in Table 3.

[0133] Example 2

[0134] This example is used to illustrate a polymer flow regulator for carbonate rock reservoirs and its preparation method of the present invention.

[0135] Add 9.5 g of the phosphonic acid copolymer obtained in Preparation Example 2 to 900 g of simulated brine (salinity is 300000 mg / L, calcium and magnesium ion content is 10000 mg / L). Stir at 600 rpm / min until completely dissolved, then add 0.5 g of chromium citrate, 0.3 g of aluminum citrate, and 0.3 g of zirconium lactate, and stir until completely dissolved. Next, add 0.6 g of thiourea and make up to a total weight of 1 kg with simulated brine. Stir evenly to obtain a phosphonic acid copolymer flow regulator glue solution.

[0136] Measure the initial viscosity of the flow control system and the high-temperature aging viscosity after being placed at 130 °C for 60 days. The results are shown in Table 3.

[0137] Example 3

[0138] This example is used to illustrate a phosphonic acid copolymer flow control agent of the present invention and its preparation method.

[0139] Add 10.5 g of the phosphonic acid copolymer prepared in Preparation Example 3 to 900 g of simulated brine (salinity is 300000 mg / L, calcium and magnesium ion content is 10000 mg / L). After stirring for 1 h, add 0.4 g of aluminum citrate, 0.8 g of chromium acetate, 0.2 g of zirconium citrate, and 0.8 g of sodium thiosulfate, and make up to a total weight of 1 kg with simulated brine. Stir evenly to obtain the phosphonic acid copolymer flow control agent colloidal solution.

[0140] Measure the initial viscosity of the flow control system and the high-temperature aging viscosity after being placed at 130 °C for 60 days. The results are shown in Table 3.

[0141] Example 4

[0142] This example is used to illustrate a phosphonic acid copolymer flow control agent of the present invention and its preparation method.

[0143] Add 8 g of the acrylamide polymer prepared in Preparation Example 4 to 900 g of simulated brine (salinity is 300000 mg / L, calcium and magnesium ion content is 10000 mg / L). After stirring for 1 h, add 0.5 g of chromium acetate, 0.4 g of zirconium lactate, and 0.5 g of isoascorbic acid, and make up to a total weight of 1 kg with simulated brine. Stir evenly to obtain the phosphonic acid copolymer flow control agent colloidal solution.

[0144] Measure the initial viscosity of the flow control system and the high-temperature aging viscosity after being placed at 120 °C for 60 days. The results are shown in Table 3.

[0145] Example 5

[0146] This example is used to illustrate a phosphonic acid copolymer flow control agent of the present invention and its preparation method.

[0147] Add 9 g of the acrylamide polymer prepared in Preparation Example 5 to 900 g of simulated brine (salinity is 300000 mg / L, calcium and magnesium ion content is 10000 mg / L). After stirring for 1 h, add 0.4 g of aluminum citrate, 0.4 g of chromium acetate, 0.2 g of zirconium lactate, and 0.8 g of sodium thiosulfate, and make up to a total weight of 1 kg with simulated brine. Stir evenly to obtain the phosphonic acid copolymer flow control agent colloidal solution.

[0148] Measure the initial viscosity of the flow control system and the high-temperature aging viscosity after being placed at 120 °C for 60 days. The results are shown in Table 3.

[0149] Comparative Example 1

[0150] This comparative example is used to illustrate a reference polymer flow regulator and its preparation method and application.

[0151] The polymer was prepared in the same manner as Preparation Example 1, except that: the addition amount of monomer A' was 27.2 g, and the addition amount of monomer B' was 91 g. Monomer C' and monomer D' were not added. The viscosity-average molecular weight of the polymer was 17.8 million.

[0152] In addition, based on the calculated feeding amounts, in the polymer obtained, the polymer contained the same structural unit A and structural unit B as in Preparation Example 1; based on the total weight of the polymer, the content of structural unit A was 23% by weight, and the content of structural unit B was 77% by weight.

[0153] The content of crosslinking groups generated after placing a 5000 mg / L polymer solution at 130 °C for 15 - 60 days was measured, and the results are shown in Table 1.

[0154] A flow regulation system was prepared according to the method described in Example 1, except that an equal amount of the above polymer was used to replace the polymer in Example 1. The simulated brine was selected to be 300000 mg / L, and the calcium and magnesium ion content was 10000 mg / L. The initial viscosity of the polymer flow regulation system and the viscosity after aging at 130 °C for 15 days are shown in Table 3.

[0155] Comparative Example 2

[0156] This comparative example is used to illustrate a reference polymer flow regulator and its preparation method and application.

[0157] The polymer was prepared in the same manner as Preparation Example 1, except that: monomer C' and monomer D' were not added. The viscosity-average molecular weight of the polymer was 13.6 million.

[0158] In addition, based on the calculated feeding amounts, in the polymer obtained, the polymer contained the same structural unit A and structural unit B as in Preparation Example 1; based on the total weight of the polymer, the content of structural unit A was 77% by weight, and the content of structural unit B was 23% by weight.

[0159] A flow regulation system was prepared according to the method described in Example 1, except that an equal amount of the above polymer was used to replace the polymer in Example 1. The simulated brine was selected to be 300000 mg / L, and the calcium and magnesium ion content was 10000 mg / L. The initial viscosity of the flow regulation system was measured, and the aged viscosity after placing at 130 °C for 60 days was measured, and the results are shown in Table 3.

[0160] Comparative Example 3

[0161] This comparative example is used to illustrate a reference polymer flow regulator and its preparation method and application.

[0162] The polymer was prepared in the same manner as in Preparation Example 1, except that monomer C' was not added. The viscosity-average molecular weight of the polymer was 12.9 million.

[0163] In addition, based on the feed amount calculation, in the polymer obtained, the polymer contains the same structural units A, B, and D as in Preparation Example 1; based on the total weight of the polymer, the content of structural unit A is 76.5% by weight, the content of structural unit B is 22.9% by weight, and the content of structural unit D is 0.6% by weight.

[0164] The flow control system was formulated in the same manner as in Example 1, except that an equal amount of the above polymer was used to replace the polymer in Example 1. The simulated brine was selected at 300,000 mg / L with a calcium and magnesium ion content of 10,000 mg / L. The initial viscosity of the flow control system was measured, and the aged viscosity was measured after being placed at 130 °C for 60 days. The results are shown in Table 3.

[0165] Comparative Example 4

[0166] This comparative example is used to illustrate a reference polymer flow regulator and its preparation method and application.

[0167] The polymer was prepared in the same manner as in Preparation Example 1, except that monomer D' was not added. The viscosity-average molecular weight of the polymer was 13.4 million.

[0168] In addition, based on the feed amount calculation, in the polymer obtained, the polymer contains the same structural units A, B, and C as in Preparation Example 1; based on the total weight of the polymer, the content of structural unit A is 76.3% by weight, the content of structural unit B is 22.8% by weight, and the content of structural unit C is 0.9% by weight.

[0169] The flow control system was formulated in the same manner as in Example 1, except that an equal amount of the above polymer was used to replace the polymer in Example 1. The simulated brine was selected at 300,000 mg / L with a calcium and magnesium ion content of 10,000 mg / L. The initial viscosity of the flow control system was measured, and the aged viscosity was measured after being placed at 130 °C for 60 days. The results are shown in Table 3.

[0170] Comparative Example 5

[0171] This comparative example is used to illustrate a reference polymer flow regulator and its preparation method and application.

[0172] The polymer was prepared in the same manner as in Preparation Example 1, except that the amount of monomer A' added was 27.2 g and the amount of monomer B' added was 91 g. The viscosity-average molecular weight of the polymer was 14.4 million.

[0173] In addition, it was calculated based on the feed amount that in the polymer obtained, the polymer contained the same structural units A, B, C, and D as in Preparation Example 1; based on the total weight of the polymer, the content of structural unit A was 22.7% by weight, the content of structural unit B was 75.8% by weight, the content of structural unit C was 0.9% by weight, and the content of structural unit D was 0.6% by weight.

[0174] The content of crosslinked groups generated after placing a 5000 mg / L polymer solution (prepared with deionized water) at 130 °C for 15 - 60 days is shown in Table 1.

[0175] A flow control system was prepared according to the method described in Example 1, except that an equal amount of the above polymer was used to replace the polymer in Example 1. The simulated brine was selected to be 300000 mg / L with a calcium and magnesium ion content of 10000 mg / L. The initial viscosity of the flow control system was measured, and the aged viscosity after being placed at 130 °C for 60 days was measured. The results are shown in Table 3.

[0176] Comparative Example 6

[0177] This comparative example is used to illustrate a reference polymer flow control system and its preparation method and application.

[0178] A polymer was prepared in the same manner as in Preparation Example 1, except that monomers C' and D' were replaced with "vinyl acetate", and the structural formula is The viscosity-average molecular weight of the polymer was 13 million.

[0179] In addition, it was calculated based on the feed amount that in the polymer obtained, the polymer contained the same structural units A and B as in Preparation Example 1, and structural unit Based on the total weight of the polymer, the content of structural unit A was 75.8% by weight, the content of structural unit B was 22.7% by weight, and the content of structural unit was 1.5% by weight.

[0180] A flow control system was prepared according to the method described in Example 1, except that an equal amount of the above polymer was used to replace the polymer in Example 1. The simulated brine was selected to be 300000 mg / L with a calcium and magnesium ion content of 10000 mg / L. The initial viscosity of the flow control system was measured, and the aged viscosity after 60 days at 130 °C was measured. The results are shown in Table 3.

[0181] Comparison of the initial viscosity and high-temperature aging viscosity of the flow control systems obtained in the examples and the comparative examples in Table 3

[0182] Number Initial Viscosity (mPa·s) Viscosity after 60 days of high-temperature aging (mPa·s) Example 1 615 2269(130℃) Example 2 550 2051(130℃) Example 3 564 1998(130℃) Example 4 498 1875(120℃) Example 5 442 1660(120℃) Comparative Example 1 760 50 (130℃, 15 days) Comparative Example 2 655 897(130℃) Comparative Example 3 640 1074(130℃) Comparative Example 4 669 1405(130℃) Comparative Example 5 694 140(130℃) Comparative Example 6 650 1580(130℃)

[0183] As can be seen from the results of Table 1 above, compared with the comparative examples, the phosphonic acid-based copolymers prepared in Preparation Examples 1-5 of the present invention have a phosphonic acid group-containing monomer as the main building unit, have strong hydrolysis resistance at a high temperature of 130 °C, and the hydrolysis rate is controllable.

[0184] As can be seen from the results of Table 2 and Table 3 above, compared with Comparative Examples 1-6, the flow control agent formed by the high-temperature and high-salt-resistant phosphonic acid-based copolymer prepared in Preparation Examples 1-5 of the present invention and the metal cross-linking agent has good viscosity after aging for 60 days at 60-130 °C in water with a salinity ≤ 300000 mg / L and a calcium and magnesium ion content ≤ 10000 mg / L, maintains long-term stability, and can be used as a flow control agent for carbonate reservoirs to adjust the flow path.

[0185] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A phosphonic acid type copolymer, characterized in that: The copolymer comprises structural unit A, structural unit B, structural unit C and structural unit D; wherein the structural unit A is The structural unit B is The structural unit C is The structural unit D is Wherein, R1 is H or methyl, M1 and M2 are each independently H or an alkali metal element, R2 and R3 are each independently a C1-C6 alkyl group, and when R2 and R3 are each independently a C2-C6 alkyl group, the total number of carbon atoms of R2 and R3 is 6-8; the viscosity-average molecular weight of the copolymer is 5 million to 18 million; the weight ratio of the structural unit A, the structural unit B, the structural unit C and the structural unit D is (52-548):(7.5-450):(0.05-30):

1.

2. The copolymer according to claim 1, wherein M1 and M2 are each independently H or Na; and / or, R1 is H; And / or, R2 is methyl and R3 is methyl; or R2 is methyl and R3 is n-pentyl; or R2 is methyl and R3 is n-hexyl.

3. The copolymer according to claim 1, wherein The weight ratio of the structural unit A, the structural unit B, the structural unit C and the structural unit D is (65-397.5):(10-180):(0.3-10):

1.

4. The copolymer according to claim 1, 2 or 3, wherein The viscosity average molecular weight of the copolymer is 7 million to 14 million.

5. A method for preparing a phosphonic acid type copolymer, characterized in that: The method comprises: under solution polymerization conditions, in the presence of an initiator, allowing an olefinic monomer to undergo polymerization reaction; wherein the olefinic monomer comprises monomer A', monomer B', monomer C' and monomer D'; the monomer A' is The monomer B' is The monomer C' is The monomer D' is Wherein, M1 and M2 are each independently H or an alkali metal element, R1 is H or a methyl group, R2 and R3 are each independently a C1-C6 alkyl group, and when R2 and R3 are each independently a C2-C6 alkyl group, the total number of carbon atoms of R2 and R3 is 6-8; the weight ratio of the monomer A′, the monomer B′, the monomer C′ and the monomer D′ is (52-548):(7.5-450):(0.05-30):

1.

6. The method according to claim 5, wherein: M1 and M2 are each independently H or Na; and / or, R1 is H; And / or, R2 is methyl and R3 is methyl; or R2 is methyl and R3 is n-pentyl; or R2 is methyl and R3 is n-hexyl.

7. The method according to claim 5, wherein: The weight ratio of the monomer A′, the monomer B′, the monomer C′ and the monomer D′ is (65-397.5):(10-180):(0.3-10):

1.

8. The method according to claim 5, wherein: The initiator is used in an amount of 0.0005-0.05 wt % of the weight of the ethylenic monomer; And / or, the initiator is selected from azo initiators and / or redox initiators.

9. The method according to any one of claims 5 to 8, wherein: The solution polymerization reaction conditions include: a starting temperature of -10°C to 30°C, a reaction time of 2-12 hours, and a pH value of 4-8.

10. A phosphonic acid type copolymer obtained by the method according to any one of claims 5 to 9.

11. A flow regulating system, characterized in that: The flow regulating system contains a metal cross-linking agent and the phosphonic acid type copolymer according to any one of claims 1 to 4 and 10.

12. The flow regulating system according to claim 11, wherein: The content of the phosphonic acid copolymer is 0.3-1.5% by weight.

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