Multicomponent copolymer scale inhibitor used in high-salinity oilfield water environment and preparation method thereof

Abstract

The present application relates to a kind of high salinity oilfield water environment used multi-component copolymer scale inhibitor and preparation method.The existing scale inhibitor has problems such as high-temperature decomposition failure, molecular structure stability decline when treating high salinity oilfield exploitation water.The multi-component copolymer scale inhibitor provided by the present application is prepared from isoamylene alcohol polyoxyethylene ether, itaconic acid, 2-acrylamide-2-methylpropane sulfonic acid, initiator and chain transfer agent.The unsaturated dibasic organic acid itaconic acid used contains two carboxyl groups, has excellent scale inhibition dispersibility and water solubility, and has good chelating capacity for cations in water.Meanwhile, 2-acrylamide-2-methylpropane sulfonic acid containing sulfonic acid group and isoamylene alcohol polyoxyethylene ether containing ether bond are introduced into itaconic acid for copolymerization modification, which further improves the performance of synthesized scale inhibitor such as high-temperature resistance, high salinity resistance and solubility in water.

Description

Technical Field

[0001] This invention relates to the field of oilfield water treatment technology, specifically to a multi-component copolymer scale inhibitor and its preparation method for use in high-salinity oilfield water environments. Background Technology

[0002] Oilfield production water is groundwater with extremely high salt concentrations that is generated during oil extraction and coexists with oil and natural gas in oil reservoirs. Due to its extreme chemical properties, it must be strictly treated before being discharged or reused; otherwise, it will cause serious environmental pollution and equipment damage. The treatment objectives are oil removal, suspended solids removal, scale prevention, and corrosion prevention.

[0003] Traditional scale inhibitors used in oilfield water treatment often have organophosphorus compounds and nitrogen-containing copolymers as core components, resulting in poor environmental compatibility. After the agents are reinjected or discharged with produced water, phosphorus and nitrogen elements continuously enter the water body, easily leading to eutrophication, algal blooms, and water quality deterioration. Furthermore, nitrogen-containing intermediates are prone to biotoxicity, damaging the aquatic ecosystem and failing to meet green mining environmental control standards. In addition, oilfield formation water has high temperatures and extremely high mineralization, with complex contents of calcium and magnesium ions, sulfates, and corrosive ions. Conventional scale inhibitors are prone to decomposition and inactivation at high temperatures, resulting in decreased molecular structural stability. In high-mineralization environments, they are prone to salt precipitation and flocculation, significantly reducing their dispersion and chelation capabilities, thus worsening their inhibitory effect on insoluble scale such as calcium carbonate and barium strontium sulfate, leading to recurring scaling problems in pipelines and formations.

[0004] Therefore, it is necessary to propose new measures to overcome the above-mentioned shortcomings. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-component copolymer scale inhibitor and its preparation method for use in high-salinity oilfield water environments, in order to solve the problems of existing scale inhibitors being prone to high-temperature decomposition and failure, and decreased molecular structure stability when treating high-salinity oilfield production water.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments is provided. The multi-component copolymer scale inhibitor is prepared from isopentenyl alcohol polyoxyethylene ether, itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, initiator, and chain transfer agent.

[0008] in:

[0009] The molar ratio of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid is 1.0:(6.8-7.15):(2.7-3.2).

[0010] The initiator added is 7.0% to 8.5% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid.

[0011] The chain transfer agent is added at a mass of 5.2% to 6.5% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid.

[0012] Furthermore, the molecular weight of the isopentenyl alcohol polyoxyethylene ether is selected from 800 to 2400.

[0013] Furthermore, the initiator is selected from ammonium persulfate and potassium persulfate.

[0014] Furthermore, the chain transfer agent is selected from sodium bisulfite and sodium hypophosphite.

[0015] On the other hand, a method for preparing a multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments as described above is provided, the method comprising:

[0016] Dissolve isopentenyl alcohol polyoxyethylene ether in deionized water, and after complete dissolution, transfer it to a four-necked flask equipped with a magnetic rotor.

[0017] Itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, initiator, and chain transfer agent are dissolved simultaneously in deionized water. After complete dissolution, the solution is transferred to a constant pressure dropping funnel. The constant pressure dropping funnel and reflux condenser are then installed on a four-necked flask.

[0018] Place the four-necked flask in an oil bath, turn on the cooling water, introduce nitrogen gas into the four-necked flask, and start stirring.

[0019] Open the constant pressure dropping funnel to drip the liquid. After the dripping is complete, increase the oil bath temperature, keep it warm and stir to obtain a multi-component copolymer scale inhibitor.

[0020] Furthermore, the initial temperature of the oil bath is 80℃.

[0021] Furthermore, after opening the constant pressure dropping funnel, control the dropping rate to complete the dropping in 45-60 minutes.

[0022] Furthermore, after the dripping is complete, the oil bath temperature is increased to 90~100℃.

[0023] Furthermore, after increasing the oil bath temperature, maintain the temperature and stir for 2.5 to 4 hours.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention provides a multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments and its preparation method. The inhibitor is synthesized via multi-component copolymerization. The unsaturated dibasic organic acid itaconic acid used contains two carboxyl groups, exhibiting excellent scale inhibition, dispersibility, and water solubility, as well as good chelating ability for cations in water. Furthermore, itaconic acid is modified by copolymerization with 2-acrylamido-2-methylpropanesulfonic acid containing sulfonic acid groups and isopentenyl alcohol polyoxyethylene ether containing ether bonds, further enhancing the synthesized scale inhibitor's resistance to high temperatures and high salinity, as well as its solubility in water. Detailed Implementation

[0026] To facilitate understanding of the present invention, a more comprehensive description is provided below, in which preferred embodiments of the invention are shown. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0027] In the description of this invention, it should be understood that all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the definitions in this specification shall prevail. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art, the reagents used in the embodiments are commercially available products, and the devices used in the embodiments are existing devices. The limitation on the means, reagents, or devices should not be construed as a limitation on the present invention. Means, reagents, or devices of the same type that solve the same technical problem are all within the protection scope of the present invention.

[0028] In the description of this invention, it should be understood that when a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0029] In the description of this invention, it should be understood that the method involves multiple steps and should not be construed as a limitation on the order of the steps. Technical solutions obtained by changing the order of steps when solving the same technical problem are also within the protection scope of this invention.

[0030] This invention provides a multi-component copolymer scale inhibitor for use in high-mineralization oilfield water environments. It is suitable for high-temperature, high-mineralization, and high-hardness water environments in oilfield production water. It is phosphorus-free, nitrogen-free, and has good biodegradability. It effectively improves high-temperature stability, high-mineralization tolerance, and broad-spectrum scale inhibition performance, making it suitable for complex oilfield water environments.

[0031] Specifically, the multi-component copolymer scale inhibitor is prepared from isopentenyl polyoxyethylene ether (TPEG), itaconic acid (IA), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), an initiator, and a chain transfer agent, and deionized water is used for dissolution during the preparation process.

[0032] in:

[0033] The molar ratio of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid is 1.0:(6.8-7.15):(2.7-3.2). The isopentenyl polyoxyethylene ether has a molecular weight of 800-2400. This monomer introduces a highly hydrophilic ether bond into the multi-component copolymer scale inhibitor of this invention, which improves the copolymer's tolerance to calcium ions, making the synthesized scale inhibitor more suitable for use in high-mineralization water environments. Itaconic acid contains two carboxyl groups (-COOH), exhibiting excellent scale inhibition, dispersibility, and water solubility. It reacts with other monomers to generate a biodegradable scale inhibitor, making it environmentally friendly. The sulfonic acid groups introduced by 2-acrylamido-2-methylpropanesulfonic acid significantly improve the salt resistance and high-temperature resistance of the synthesized scale inhibitor.

[0034] The initiator is added at a mass of 7.0% to 8.5% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid (i.e., the total mass of monomers). It is selected from ammonium persulfate and potassium persulfate. Its molecular structure contains unstable peroxy bonds. It is a free radical initiator with good solubility in the aqueous phase. It starts the chain polymerization reaction of monomers by decomposing to generate highly active free radicals.

[0035] The chain transfer agent is added at a mass of 5.2% to 6.5% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid (i.e., the total mass of monomers), and is selected from sodium bisulfite and sodium hypophosphite. It can effectively control the molecular weight of the polymerization reaction and optimize the structure, thereby improving the dispersibility and stability of the synthesized scale inhibitor.

[0036] The preparation method of the above-mentioned multi-component copolymer scale inhibitor specifically includes the following steps:

[0037] S1: Dissolve isopentenyl alcohol polyoxyethylene ether in deionized water, and after complete dissolution, transfer it to a four-necked flask equipped with a magnetic rotor.

[0038] S2: Dissolve itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, initiator, and chain transfer agent simultaneously in deionized water. After complete dissolution, transfer the solution into a constant pressure dropping funnel. Then, install the constant pressure dropping funnel and the reflux condenser on a four-necked flask.

[0039] S3: Place the four-necked flask in an oil bath, turn on the cooling water, adjust the initial temperature of the oil bath to 80°C, introduce nitrogen gas into the four-necked flask, and start stirring.

[0040] S4: Open the constant pressure dropping funnel and control the dropping rate to complete the dropping process in 45-60 minutes. After the dropping process is complete, increase the oil bath temperature to 90-100℃, keep it at this temperature and stir for 2.5-4 hours to obtain the multi-component copolymer scale inhibitor.

[0041] During the preparation process, the amount of deionized water used should be sufficient to completely dissolve the solute.

[0042] The multi-component copolymer scale inhibitor prepared by this invention uses phosphorus-free and nitrogen-free raw materials, which are green and environmentally friendly. During use, it avoids eutrophication of water bodies and harm to water bodies. The multi-component polymerization method increases the functionality and applicability of the synthesized scale inhibitor. The use of biodegradable itaconic acid can effectively alleviate the precipitation caused by the formation of gel with calcium ions in water.

[0043] The following specific examples further illustrate the performance improvement of the multi-component copolymer scale inhibitor prepared by the present invention in the treatment of high-salinity oilfield water.

[0044] Example 1:

[0045] S1: Dissolve isopentenyl alcohol polyoxyethylene ether in deionized water, and after complete dissolution, transfer it to a four-necked flask equipped with a magnetic rotor.

[0046] S2: Dissolve itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, initiator, and chain transfer agent simultaneously in deionized water. After complete dissolution, transfer the solution into a constant pressure dropping funnel. Then, install the constant pressure dropping funnel and the reflux condenser on a four-necked flask.

[0047] The molar ratio of isopentenyl alcohol polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid is 1.0:6.8:3.2.

[0048] The molecular weight of isopentenyl alcohol polyoxyethylene ether was selected as 800.

[0049] The initiator added is 8.5% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid (i.e., the total mass of monomers), and ammonium persulfate is selected.

[0050] The chain transfer agent added is 5.2% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid (i.e., the total mass of monomers), and sodium hypophosphite is selected.

[0051] S3: Place the four-necked flask in an oil bath, turn on the cooling water, adjust the initial temperature of the oil bath to 80°C, introduce nitrogen gas into the four-necked flask, and start stirring.

[0052] S4: Open the constant pressure dropping funnel and control the dropping rate to complete the dropping process in 60 minutes. After the dropping process is complete, increase the oil bath temperature to 90℃, maintain the temperature and stir for 4 hours to obtain the multi-component copolymer scale inhibitor.

[0053] Example 2:

[0054] S1: Dissolve isopentenyl alcohol polyoxyethylene ether in deionized water, and after complete dissolution, transfer it to a four-necked flask equipped with a magnetic rotor.

[0055] S2: Dissolve itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, initiator, and chain transfer agent simultaneously in deionized water. After complete dissolution, transfer the solution into a constant pressure dropping funnel. Then, install the constant pressure dropping funnel and the reflux condenser on a four-necked flask.

[0056] The molar ratio of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid is 1.0:7:2.9.

[0057] The molecular weight of isopentenyl alcohol polyoxyethylene ether was selected as 1600.

[0058] The initiator added is 7.7% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid (i.e., the total mass of monomers), and potassium persulfate is selected.

[0059] The chain transfer agent added is 5.8% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid (i.e., the total mass of monomers), and sodium bisulfite is selected.

[0060] S3: Place the four-necked flask in an oil bath, turn on the cooling water, adjust the initial temperature of the oil bath to 80°C, introduce nitrogen gas into the four-necked flask, and start stirring.

[0061] S4: Open the constant pressure dropping funnel and control the dropping rate to complete the dropping process in 52 minutes. After the dropping process is complete, increase the oil bath temperature to 95℃, keep it at this temperature and stir for 3 hours to obtain the multi-component copolymer scale inhibitor.

[0062] Example 3:

[0063] S1: Dissolve isopentenyl alcohol polyoxyethylene ether in deionized water, and after complete dissolution, transfer it to a four-necked flask equipped with a magnetic rotor.

[0064] S2: Dissolve itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, initiator, and chain transfer agent simultaneously in deionized water. After complete dissolution, transfer the solution into a constant pressure dropping funnel. Then, install the constant pressure dropping funnel and the reflux condenser on a four-necked flask.

[0065] The molar ratio of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid is 1.0:7.15:2.7.

[0066] The molecular weight of isopentenyl alcohol polyoxyethylene ether was selected as 2400.

[0067] The initiator added is 7.0% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid (i.e., the total mass of monomers), and ammonium persulfate is selected.

[0068] The chain transfer agent added is 6.5% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid (i.e., the total mass of monomers), and sodium hypophosphite is selected.

[0069] S3: Place the four-necked flask in an oil bath, turn on the cooling water, adjust the initial temperature of the oil bath to 80°C, introduce nitrogen gas into the four-necked flask, and start stirring.

[0070] S4: Open the constant pressure dropping funnel and control the dropping rate to complete the dropping process in 45 minutes. After the dropping process is complete, increase the oil bath temperature to 100℃, keep it at this temperature and stir for 2.5 hours to obtain the multi-component copolymer scale inhibitor.

[0071] Currently, most oilfields in my country have production depths exceeding 4,000 meters, corresponding to common bottom temperatures of 150°C. As temperature dissipates, the produced water often reaches 100°C or even higher. Meanwhile, it is understood that the hardness of produced water in major domestic oilfields ranges from 500 to 2000 ppm, with some high-salinity oilfields having hardness below 3000 ppm.

[0072] To fully demonstrate the effectiveness of the scale inhibitor with good adaptability described in this invention, its scale inhibition effect on high-mineralized water with a hardness of 3000ppm under high-temperature conditions was tested using a static scale inhibition test method.

[0073] (1) Preparation of high-mineralization water samples:

[0074] A water sample with a total hardness of 3000 ppm (calculated as CaCO3) was prepared using calcium chloride and magnesium chloride, with a calcium ion concentration of 2100 ppm and a magnesium ion concentration of 900 ppm.

[0075] (2) Determination of scale inhibition rate:

[0076] Take nine 500mL conical flasks, and transfer 50mL of the above water sample into each flask. One flask serves as a blank sample, while the others are treated with different amounts of the scale inhibitor of this invention. After thorough mixing, the flasks are sealed and placed in water baths at different temperatures, and allowed to stand for 24 hours. Filter the scale samples from the conical flasks, and determine the residual calcium and magnesium ion concentrations in the nine filtrates using titration.

[0077] (3) Calculate the scale inhibition rate:

[0078] Scale inhibition rate = (calcium and magnesium ion concentration in treated water sample - calcium and magnesium ion concentration in blank water sample) / (calcium and magnesium ion concentration in initial water sample - calcium and magnesium ion concentration in blank water sample) × 100%;

[0079] (4) Experimental results:

[0080] The scale inhibition rate of the scale inhibitor under different temperatures and different addition amounts in Example 2 is shown in the table below.

[0081]

[0082] Results analysis:

[0083] As shown in the table above, when the dosage of the scale inhibitor in Example 2 of this invention is 40ppm~70ppm, the scale inhibition rate of calcium and magnesium ion water samples with high mineralization is maintained at over 90% in the high temperature range of 80℃~100℃, demonstrating excellent scale inhibition performance in high temperature and high mineralization environments.

[0084] Parallel comparative tests were conducted to determine the scale inhibition effects of Examples 1 and 3. The test results were comparable to those of the scale inhibitor in Example 2, and both showed excellent scale inhibition effects.

[0085] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments, characterized in that: The multi-component copolymer scale inhibitor is prepared from isopentenyl polyoxyethylene ether, itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, initiator, and chain transfer agent. in: The molar ratio of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid is 1.0:(6.8-7.15):(2.7-3.2). The initiator added is 7.0% to 8.5% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid. The chain transfer agent is added at a mass of 5.2% to 6.5% of the total mass of isopentenyl polyoxyethylene ether, itaconic acid, and 2-acrylamido-2-methylpropanesulfonic acid.

2. The multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments according to claim 1, characterized in that: The molecular weight of the isopentenyl alcohol polyoxyethylene ether is selected from 800 to 2400.

3. The multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments according to claim 2, characterized in that: The initiator is selected from ammonium persulfate and potassium persulfate.

4. The multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments according to claim 3, characterized in that: The chain transfer agent is selected from sodium bisulfite and sodium hypophosphite.

5. The preparation method of the multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments as described in claim 4, characterized in that: The method includes: Dissolve isopentenyl alcohol polyoxyethylene ether in deionized water, and after complete dissolution, transfer it to a four-necked flask equipped with a magnetic rotor. Itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid, initiator, and chain transfer agent are dissolved simultaneously in deionized water. After complete dissolution, the solution is transferred to a constant pressure dropping funnel. The constant pressure dropping funnel and reflux condenser are then installed on a four-necked flask. Place the four-necked flask in an oil bath, turn on the cooling water, introduce nitrogen gas into the four-necked flask, and start stirring. Open the constant pressure dropping funnel to drip the liquid. After the dripping is complete, increase the oil bath temperature, keep it warm and stir to obtain a multi-component copolymer scale inhibitor.

6. The method for preparing the multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments according to claim 5, characterized in that: The initial temperature of the oil bath is 80℃.

7. The method for preparing the multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments according to claim 6, characterized in that: After opening the constant pressure dropping funnel, control the dropping rate to complete the dropping in 45-60 minutes.

8. The method for preparing the multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments according to claim 7, characterized in that: After the dripping is complete, raise the oil bath temperature to 90~100℃.

9. The method for preparing the multi-component copolymer scale inhibitor for use in high-salinity oilfield water environments according to claim 8, characterized in that: After increasing the oil bath temperature, maintain the temperature and stir for 2.5 to 4 hours.

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