Amphoteric polyether carboxylate viscosity reducer containing polyether chain segment as well as preparation method and application of amphoteric polyether carboxylate viscosity reducer

Abstract

The invention discloses an amphoteric polyether carboxylate viscosity reducer containing a polyether chain segment as well as a preparation method and application of the amphoteric polyether carboxylate viscosity reducer. Belongs to the technical field of thickened oil recovery, polyether chain segments in the block polyether carboxylate have oleophylic properties and can be inserted into thickened oil particles to interact with asphalt molecules in the thickened oil particles, and a net structure formed by accumulation of asphaltene on an oil-water interface is destroyed, so that the viscosity of thickened oil is reduced. And the sulfonic acid group and the carboxylic acid group firmly adsorb water molecules on a polyether chain segment under the action of a hydrogen bond to form a water layer, so that the distance between heavy oil particles is further increased, the cohesion of the heavy oil is reduced, and the viscosity of the heavy oil is further reduced. Compared with traditional free radical polymerization, the viscosity reducer has a precise and controllable structure and better viscosity reduction performance, and the viscosity reduction rate of thickened oil can reach 97% or above. The viscosity reducer shows an excellent viscosity reduction effect in practical application, and has important application value in thickened oil recovery and transportation.

Description

Technical Field

[0001] The invention belongs to the technical field of heavy oil recovery, and particularly relates to an amphoteric polyether carboxylate viscosity reducer containing a polyether segment, and a preparation method and application thereof. Background Art

[0002] The high viscosity and low fluidity of heavy oil pose great challenges to its extraction and utilization. In order to overcome the difficulties in heavy oil extraction, the global oil industry has been constantly exploring and innovating extraction technologies. Although traditional thermal extraction methods, such as steam huff and puff and steam flooding, have improved the fluidity of heavy oil to a certain extent, they are energy-intensive and have certain impacts on the environment.

[0003] As a relatively environmentally friendly and economical method, emulsification viscosity reduction technology has received widespread attention worldwide in recent years. By adding specific surfactants to heavy oil, a stable emulsion can be formed, thereby significantly reducing viscosity and improving fluidity. Zwitterionic surfactants, especially block polyether polycarboxylates, show excellent effects in heavy oil viscosity reduction due to their unique structure and properties. This type of surfactant can carry both positive and negative charges, allowing it to form a stable emulsion in heavy oil and effectively reduce viscosity. With the continuous development of polymer chemistry, various advanced polymerization technologies such as RAFT polymerization have been gradually applied to the synthesis of surfactants. These technologies make it possible to precisely control the molecular weight, structure and properties of polymers, thereby hoping to synthesize more efficient heavy oil viscosity reducers. The technical difficulties in the extraction and utilization of heavy oil are not only a problem for one country, but also a common challenge faced by the global oil industry.

[0004] In view of the problems of high viscosity and poor low-temperature fluidity of heavy oil, it is necessary to develop an efficient chemical viscosity reducer to achieve efficient viscosity reduction of heavy oil and solve the technical problems in heavy oil extraction and utilization. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide an amphoteric polyether carboxylate viscosity reducer containing a polyether segment and a preparation method and application thereof, so as to solve the technical problems of high viscosity and poor low-temperature fluidity of heavy oil.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The invention discloses an amphoteric polyether carboxylate viscosity reducer containing a polyether segment. The amphoteric polyether carboxylate viscosity reducer containing a polyether segment is a ternary block polyether carboxylate; the structural formula is:

[0008]

[0009] Among them, a=5~20, b=20~80, c=2~8, n=5~25.

[0010] The invention also discloses a method for preparing the above-mentioned amphoteric polyether carboxylate viscosity reducer containing polyether chain segments, comprising: dividing an initiator into three parts, mixing the first part of the initiator with a chain transfer agent and an allyl polyoxyethylene ether solution, introducing nitrogen, adding the second part of the initiator after the first stirring reaction, then adding a diallyl dimethyl ammonium chloride solution, adding the third part of the initiator after the second stirring reaction, and finally slowly adding an acrylic acid solution, and adjusting the pH value to 7-8 after the third stirring reaction to obtain the amphoteric polyether carboxylate viscosity reducer containing polyether chain segments.

[0011] Preferably, the initiator is one of azobisisobutylamidine hydrochloride, dimethyl azobisisobutyrate and dibenzoyl peroxide; and the chain transfer agent is one of dithiocarbamate, xanthate and trithiocarbonate.

[0012] More preferably, the azobisisobutylamidine hydrochloride is azobisisobutyronitrile; and the trithiocarbonate is S-S'-bis(a,a'-dimethyl-a"-acetic acid)-trithiocarbonate.

[0013] Preferably, the molar ratio of the first initiator: the second initiator: the third initiator is 1:1:(3-5).

[0014] Preferably, the acrylic acid solution is prepared by dissolving 8-10 g of acrylic acid in 18-22 g of water; the diallyldimethylammonium chloride solution is prepared by dissolving 4-6 g of diallyldimethylammonium chloride in 9-14 g of water; and the allyl polyoxyethylene ether solution is prepared by dissolving 15-18 g of allyl polyoxyethylene ether in 35-42 g of water.

[0015] More preferably, the molar ratio of the first initiator:chain transfer agent:allyl polyoxyethylene ether:diallyl dimethyl ammonium chloride:acrylic acid is 1:(4-6):1:1:(3-5).

[0016] Preferably, the nitrogen is introduced for 0.5-1.0 h; the diallyldimethylammonium chloride solution is added for 2.0-4.0 h; and the acrylic acid solution is added for 2.0-4.0 h.

[0017] Preferably, the first stirring reaction temperature is 75-85°C, and the time is 6.0-8.0h; the second stirring reaction temperature is 75-85°C, and the time is 6.0-8.0h; the third stirring reaction temperature is 75-85°C, and the time is 6.0-8.0h.

[0018] Preferably, a 30% by mass NaOH aqueous solution is used to adjust the pH value to 7-8.

[0019] The invention also discloses the application of the amphoteric polyether carboxylate viscosity reducer containing polyether chain segments prepared by the preparation method in heavy oil production and viscosity reduction, and the viscosity reduction rate is 97.04%-99.04%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The invention discloses an amphoteric polyether carboxylate viscosity reducer containing a polyether segment. The polyether segment itself has excellent chemical stability and thermal stability, which enables the amphoteric polyether carboxylate viscosity reducer to maintain its stable performance under extreme environments, thereby having a wider range of applicability in practical applications. The special structure of the ternary block polyether carboxylate gives it unique performance. Specifically, the polyether segment in the block polyether carboxylate has lipophilic properties and can be inserted into heavy oil particles to interact with asphalt molecules therein. This interaction can destroy the network structure formed by the accumulation of asphaltene at the oil-water interface, thereby reducing the viscosity of the heavy oil. The ternary block polyether carboxylate also contains two hydrophilic groups, namely, sulfonic acid groups and carboxylic acid groups. These two groups can firmly adsorb water molecules on the polyether segment through the action of hydrogen bonds to form a water layer. The formation of this water layer further increases the spacing between heavy oil particles, reduces the cohesive force of the heavy oil, and thus further reduces the viscosity of the heavy oil. In practical applications, it shows an excellent viscosity reduction effect and has important application value for heavy oil mining and transportation. Amphoteric block polyether carboxylates can be used to obtain a series of products with different block lengths and contents by adjusting the molecular weight and monomer amount. They have a wide hydrophilic-lipophilic balance (HLB value), and products with different HLB values ​​can be used for various purposes. Moreover, they will not dissociate into ionic states, but rather present ether bonds. The oxygen atoms and hydroxyl groups in the bonds have the ability to form hydrogen bonds with water molecules, so that the stability is not easily affected by the presence of strong electrolytes, and have good washing, emulsification, dispersion, foaming, wetting, solubilization and other properties. The block polymer in the emulsifier system can ensure that the oil phase containing the active ingredients of the pesticide can be evenly and stably dispersed in the water phase. It has a good sustained-release effect on the active ingredients of the microcapsule. It can be used in pesticide collection spray preparations, and the applicability of various dosage forms such as water-dispersible granules and powders is very wide.

[0022] The present invention also discloses a method for preparing the above-mentioned amphoteric polyether carboxylate viscosity reducer containing a polyether segment, comprising: dividing an initiator into three parts, mixing the first part of the initiator with a chain transfer agent and an allyl polyoxyethylene ether solution, introducing nitrogen, stirring and reacting, first adding the second part of the initiator, then adding a diallyl dimethyl ammonium chloride solution, stirring and reacting, then adding the third part of the initiator, and finally slowly adding an acrylic acid solution, and after the stirring and reaction is completed, adjusting the pH value to 7-8 to obtain the amphoteric polyether carboxylate viscosity reducer containing a polyether segment. The molecular structure of the polymer, such as molecular weight, segment length, molecular weight distribution, etc., can be accurately controlled by the RAFT polymerization method. This precise control enables the prepared polyether carboxylate zwitterionic surfactant to have more excellent performance and can better adapt to different requirements for reducing the viscosity of heavy oil. Since the polyether segment has good compatibility with hydrocarbon molecules in the heavy oil, and the carboxylate group can form hydrogen bonds with water molecules, the zwitterionic surfactant can effectively reduce the viscosity of the heavy oil. Polyether carboxylate zwitterionic surfactants can significantly improve the interfacial tension between heavy oil and water, making it easier for heavy oil to be wetted and emulsified by water. This helps to reduce the flow resistance of heavy oil and improve the efficiency of heavy oil extraction and transportation. For heavy oil, fluidity at low temperatures is a major problem in its extraction and transportation. Due to the introduction of polyether segments, this zwitterionic surfactant can improve the fluidity of heavy oil at low temperatures to a certain extent, reduce its freezing point, and thus broaden the window for heavy oil extraction and transportation. The electrostatic repulsion of carboxyl anions contributes to the dispersion of cement particles. Similarly, the relative molecular mass and the content of carboxyl groups have a great influence on the dispersion effect of cement particles. Due to the hydrophobicity of the main chain molecule and the hydrophilicity of the side chain and the presence of the side group -(OCH2CH2)-, a certain stereo stabilization effect is also provided, that is, the surface of the cement particles is stabilized by a block or graft copolymer to prevent random agglomeration, thereby helping the dispersion of cement particles. Compared with traditional chemical viscosity reducers, polyether carboxylate zwitterionic surfactants have better biodegradability and environmental compatibility, and less pollution to the environment. The preparation method has the beneficial effects of precise and controllable structure, excellent viscosity reduction performance, good wetting performance, improved low-temperature fluidity, good environmental protection, high flexibility and theoretical support. It provides a new and efficient viscosity reducer for the extraction and transportation of heavy oil, and can be used in the fields of concrete water reducers, pesticide dispersants, etc.

[0023] Furthermore, the present invention systematically studies the effects of factors such as monomer addition sequence, ratio and chain transfer agent dosage on the performance of polyether carboxylates, determines the optimal synthesis process conditions, and improves the performance and efficiency of the surfactant.

[0024] The invention also discloses the use of the amphoteric polyether carboxylate viscosity reducer containing polyether segments prepared by the above preparation method in the production and viscosity reduction of heavy oil, wherein the viscosity reduction rate is 97.04%-99.04%, and the viscosity of the heavy oil can be significantly reduced, so that the heavy oil can flow more smoothly during the production and transportation process, thereby improving the production efficiency and transportation capacity. Due to the reduction in the viscosity of the heavy oil, the blockage and wear problems of production equipment such as oil pumps and pipelines are effectively alleviated, thereby improving the operating efficiency and life of the equipment. At the same time, the production difficulty and cost caused by excessive viscosity are reduced, making the development of heavy oil resources more economical and efficient. During the transportation of heavy oil, low-viscosity heavy oil is easier to be transported through pipelines, reducing pumping pressure and energy consumption, and reducing transportation costs. In addition, low-viscosity heavy oil is also more convenient and efficient during storage and processing. Compared with traditional viscosity reducers, this type of amphoteric polyether carboxylate viscosity reducer containing polyether segments generally has better biodegradability and environmental compatibility. This helps to reduce environmental pollution during production and transportation, and meets the current requirements of environmental protection and sustainable development. They can be applied to heavy oils of different types and properties, showing good adaptability and versatility. Whether under high or low temperature conditions, they can maintain stable viscosity reduction performance, providing more options for the exploitation and viscosity reduction of heavy oil resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The synthesis steps of the ternary block polyether carboxylate disclosed in Example 4 of the present invention; wherein (a) is the first stage of synthesizing the ternary block polyether carboxylate, (b) is the second stage of synthesizing the ternary block polyether carboxylate, and (c) is the final stage of synthesizing the ternary block polyether carboxylate;

[0026] Figure 2 The synthesis steps of the ternary random polyether carboxylate disclosed in Example 6 of the present invention;

[0027] Figure 3 This is the FT-IR graph of the amphoteric polyether carboxylate viscosity reducer containing polyether segments disclosed in Example 4 of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0031] The invention uses crude oil from the North China Oilfield as a research oil sample, analyzes and studies the composition and physical and chemical properties of the crude oil, characterizes the crude oil by using a gas chromatograph and an infrared spectrometer, determines the composition and content of the crude oil; performs a four-component analysis on the crude oil with reference to industry standards to determine the components of the crude oil; obtains a viscosity-temperature curve of the crude oil; designs and synthesizes a series of novel polyether carboxylates as viscosity reducers, and studies the emulsification and viscosity reduction performance, wetting performance, foaming performance, etc. of the novel polyether carboxylates, and selects the structure of the best polyether carboxylates; selects the novel polyether carboxylates with the best structure, performs a reaction condition optimization experiment, measures the viscosity reduction emulsification performance, examines and evaluates the surface / interfacial tension, wetting performance, etc., to determine the best reaction conditions and infer the viscosity reduction mechanism.

[0032] The invention discloses an amphoteric polyether carboxylate viscosity reducer containing a polyether segment, comprising a ternary block polyether carboxylate and a ternary random polyether carboxylate;

[0033] The structural formula of ternary block polyether carboxylate is:

[0034]

[0035] Wherein, a=5-20, b=20-80, c=2-8, n=5-25;

[0036] The structural formula of ternary random polyether carboxylate is:

[0037]

[0038] Among them, a=5~20, b=20~80, c=2~8, n=5~25.

[0039] The invention discloses a preparation method of a ternary block polyether carboxylate crude oil viscosity reducer, comprising: dividing an initiator into three parts, mixing the first part of the initiator with a chain transfer agent and an allyl polyoxyethylene ether solution, introducing nitrogen for 0.5-1.0h, reacting at 75-85°C for 6.0-8.0h, adding the second part of the initiator after the first stirring reaction, then adding a diallyl dimethyl ammonium chloride solution within 2.0-4.0h, reacting at 75-85°C for 6.0-8.0h, adding the third part of the initiator after the second stirring reaction, and finally slowly adding an acrylic acid solution within 2.0-4.0h, reacting at 75-85°C for 6.0-8.0h, and adjusting the pH value to 7-8 by using a 30% by mass NaOH aqueous solution after the third stirring reaction, so as to obtain an amphoteric polyether carboxylate viscosity reducer containing a polyether segment with a viscosity reduction rate of 97.04%-99.04%.

[0040] Wherein, the initiator is one of azobisisobutylamidine hydrochloride, dimethyl azobisisobutyrate and dibenzoyl peroxide.

[0041] The chain transfer agent is one of dithiocarbamate, xanthate and trithiocarbonate.

[0042] Preferably, the initiator is azobisisobutyronitrile; and the chain transfer agent is S-S'-bis(a,a'-dimethyl-a"-acetic acid)-trithiocarbonate.

[0043] The molar ratio of the first initiator: the second initiator: the third initiator is 1:1:(3-5).

[0044] The acrylic acid solution is prepared by dissolving 8-10 g of acrylic acid in 18-22 g of water.

[0045] The diallyldimethylammonium chloride solution is prepared by dissolving 4-6 g of diallyldimethylammonium chloride in 9-14 g of water.

[0046] The allyl polyoxyethylene ether solution is prepared by dissolving 15-18 g of allyl polyoxyethylene ether in 35-42 g of water.

[0047] The molar ratio of the first initiator: chain transfer agent: allyl polyoxyethylene ether: diallyl dimethyl ammonium chloride: acrylic acid is 1:(4-6):1:1:(3-5).

[0048] The preparation method of the ternary block polyether carboxylate crude oil viscosity reducer disclosed in the present invention comprises the following steps: reacting acrylic acid (AA), diallyl dimethyl ammonium chloride (DADMAC) and allyl polyoxyethylene ether (APEG600) in a molar ratio of AA:DADMAC:APEG600=(3-5):1:1;

[0049] Step 1: Weigh 0.0060-0.0080g of azobisisobutyronitrile (AIBN) and 0.1800-0.2500g of S-S'-bis(a,a'-dimethyl-a"-acetic acid)-trithiocarbonate (BDATT), weigh 15-18g of APEG600, dissolve them in 35-42g of water, add the three together into a 250mL three-necked flask, place the reactor into a magnetic stirring oil bath, pass nitrogen into the flask for half an hour, turn on the condensing water, heat to 75-85°C, and stir to react for 6-8 hours.

[0050] Step 2: Weigh 0.0060-0.0080g of AIBN and add it into a three-necked flask, weigh 3-5g of DADMAC, dissolve it in 7-12g of water and transfer it into a syringe of appropriate size, add DADMAC dropwise within no less than 2 hours, and continue stirring the reaction for 6-8 hours.

[0051] Step 3: Weigh 0.02-0.04g of AIBN and add it into a three-necked flask, weigh 7-10g of AA, dissolve it in 16-23g of water, and transfer it into a syringe of appropriate size. Add AA dropwise within no less than 2 hours, and continue stirring the reaction for 6-8 hours.

[0052] Step 4: Transfer the reaction product into a beaker, cool it to room temperature, and adjust the pH value to between 7 and 8 with a 30% by mass NaOH aqueous solution to obtain a ternary block polyether carboxylate crude oil viscosity reducer.

[0053] Furthermore, the order of the above steps 2 and 3 is exchanged.

[0054] The obtained crude oil viscosity reducer was tested for viscosity, surface tension and contact angle, and the best monomer addition sequence was screened.

[0055] Further: In step 1, the molar ratio of AIBN to BDATT is 1:4.

[0056] Further: In step 1, the molar ratio of AIBN to BDATT is 1:5.

[0057] Further: In step 1, the molar ratio of AIBN to BDATT is 1:6.

[0058] The performance test comparison is carried out again to obtain the best solution for structural characterization.

[0059] The preparation method of the ternary random polyether carboxylate crude oil viscosity reducer disclosed in the present invention comprises the following steps: acrylic acid (AA), diallyl dimethyl ammonium chloride (DADMAC) and allyl polyoxyethylene ether (APEG600) are reacted in a molar ratio of AA:DADMAC:APEG600=(3-5):1:1;

[0060] Step 1: Weigh 15-18g of APEG600, dissolve it in 35-42g of water and add it to a 250mL three-necked flask.

[0061] Step 2: Weigh 0.0300-0.0500 g of AIBN and 0.1550-0.2580 g of BDATT and add them into a three-necked flask together with the reactants in step 1; weigh 8-10 g of AA and dissolve it in 18.70-23.40 g of water; weigh 4-6 g of DADMAC and dissolve it in 10-12 g of water.

[0062] Step 3: Transfer the dissolved monomer in step 2 into a syringe of appropriate size, place the reactor in a magnetic stirring oil bath, introduce 0.5-1h nitrogen into the flask, turn on the condenser, raise the temperature to 75-85°C, turn on the needle, add the monomer dropwise in no less than 2 hours, and stir the reaction for 6-8h.

[0063] Step 4: The product after the reaction is transferred into a beaker, and after cooling to room temperature, a 30% by mass NaOH aqueous solution is used to adjust the pH value to between 7 and 8 to obtain a ternary random polyether carboxylate crude oil viscosity reducer.

[0064] The amphoteric polyether carboxylate viscosity reducer containing polyether chain segments prepared by the preparation method is applied to heavy oil production and viscosity reduction, and the viscosity reduction rate thereof is 97.04%-99.04%.

[0065] The following examples will help to understand the present invention, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0066] Example 1

[0067] A method for preparing an amphoteric polyether carboxylate viscosity reducer containing a polyether segment comprises the following steps:

[0068] 1) Weigh 0.0078 g of AIBN and 0.2418 g of BDATT, weigh 17.151 g of APEG600, dissolve them in 40.02 g of water, add the three together into a 250 mL three-necked flask, place the reactor into a magnetic stirring oil bath, pass nitrogen into the flask for half an hour, turn on the condenser, raise the temperature to 80°C, and stir the reaction for 6 hours.

[0069] 2) Weigh 0.0313 g of AIBN and add it into a three-necked flask. Weigh 8.2325 g of AA, dissolve it in 19.21 g of water, and transfer it into a syringe of suitable size. Add AA dropwise within no less than 2 hours, and continue stirring the reaction for 6 hours.

[0070] 3) Weigh 0.0078 g of AIBN and add it into a three-necked flask. Weigh 4.6165 g of DADMAC, dissolve it in 10.77 g of water and transfer it into a syringe of suitable size. Add DADMAC dropwise within no less than 2 hours and continue stirring the reaction for 6 hours.

[0071] 4) The reaction product is transferred into a beaker, and after cooling to room temperature, a 30% by mass NaOH aqueous solution is used to adjust the pH to 7.5 to obtain an amphoteric polyether carboxylate viscosity reducer containing polyether segments, namely a ternary block polyether carboxylate crude oil viscosity reducer.

[0072] Example 2

[0073] A method for preparing an amphoteric polyether carboxylate viscosity reducer containing a polyether segment comprises the following steps:

[0074] 1) Weigh 0.0078 g of AIBN and 0.2418 g of BDATT, weigh 17.151 g of APEG600, dissolve them in 40.02 g of water, add the three together into a 250 mL three-necked flask, place the reactor into a magnetic stirring oil bath, pass nitrogen into the flask for half an hour, turn on the condenser, raise the temperature to 80°C, and stir the reaction for 6 hours.

[0075] 2) Weigh 0.0078 g of AIBN and add it into a three-necked flask. Weigh 4.6165 g of DADMAC, dissolve it in 10.77 g of water and transfer it into a syringe of suitable size. Add DADMAC dropwise within no less than 2 hours and continue stirring the reaction for 6 hours.

[0076] 3) Weigh 0.0313 g of AIBN and add it into a three-necked flask. Weigh 8.2325 g of AA, dissolve it in 19.21 g of water, and transfer it into a syringe of suitable size. Add AA dropwise within no less than 2 hours, and continue stirring and reacting for 6 hours.

[0077] 4) The reaction product is transferred into a beaker, and after cooling to room temperature, a 30% by mass NaOH aqueous solution is used to adjust the pH to 7.5 to obtain an amphoteric polyether carboxylate viscosity reducer containing polyether segments, namely a ternary block polyether carboxylate crude oil viscosity reducer.

[0078] Example 3

[0079] A method for preparing an amphoteric polyether carboxylate viscosity reducer containing a polyether segment comprises the following steps:

[0080] 1) Weigh 0.0078 g of AIBN and 0.3224 g of BDATT (the molar ratio of AIBN to BDATT is 1:4), weigh 17.151 g of APEG600, dissolve them in 40.02 g of water, add the three together into a 250 mL three-necked flask, place the reactor into a magnetic stirring oil bath, pass nitrogen into the flask for half an hour, turn on the condenser, heat to 80°C, and stir to react for 6 hours.

[0081] 2) Weigh 0.0313 g of AIBN and add it into a three-necked flask. Weigh 8.2325 g of AA, dissolve it in 19.21 g of water, and transfer it into a syringe of suitable size. Add AA dropwise within no less than 2 hours, and continue stirring the reaction for 6 hours.

[0082] 3) Weigh 0.0078 g of AIBN and add it into a three-necked flask. Weigh 4.6165 g of DADMAC, dissolve it in 10.77 g of water and transfer it into a syringe of suitable size. Add DADMAC dropwise within no less than 2 hours and continue stirring the reaction for 6 hours.

[0083] 4) The reaction product is transferred into a beaker, and after cooling to room temperature, a 30% by mass NaOH aqueous solution is used to adjust the pH to 7.5 to obtain an amphoteric polyether carboxylate viscosity reducer containing polyether segments, namely a ternary block polyether carboxylate crude oil viscosity reducer.

[0084] Example 4

[0085] A method for preparing an amphoteric polyether carboxylate viscosity reducer containing a polyether segment comprises the following steps:

[0086] 1) Weigh 0.0078 g of AIBN and 0.4030 g of BDATT (the molar ratio of AIBN to BDATT is 1:5), weigh 17.151 g of APEG600, dissolve them in 40.02 g of water, add the three together into a 250 mL three-necked flask, place the reactor into a magnetic stirring oil bath, pass nitrogen into the flask for half an hour, turn on the condenser, raise the temperature to 80°C, and stir the reaction for 6 hours.

[0087] 2) Weigh 0.0313 g of AIBN and add it into a three-necked flask. Weigh 8.2325 g of AA, dissolve it in 19.21 g of water, and transfer it into a syringe of suitable size. Add AA dropwise within no less than 2 hours, and continue stirring the reaction for 6 hours.

[0088] 3) Weigh 0.0078 g of AIBN and add it into a three-necked flask. Weigh 4.6165 g of DADMAC, dissolve it in 10.77 g of water and transfer it into a syringe of suitable size. Add DADMAC dropwise within no less than 2 hours and continue stirring the reaction for 6 hours.

[0089] 4) The reaction product is transferred into a beaker, and after cooling to room temperature, a 30% by mass NaOH aqueous solution is used to adjust the pH to 7.5 to obtain an amphoteric polyether carboxylate viscosity reducer containing polyether segments, namely a ternary block polyether carboxylate crude oil viscosity reducer.

[0090] See also Figure 1 The synthesis steps of the ternary block polyether carboxylate disclosed in Example 4 of the present invention; wherein, (a) is the first stage of synthesizing the ternary block polyether carboxylate, (b) is the second stage of synthesizing the ternary block polyether carboxylate, and (c) is the final stage of synthesizing the ternary block polyether carboxylate; as can be seen from the figure, the synthesis of the ternary block polyether carboxylate requires attention to the order of adding substances, the initiator is divided into three parts, the initiator of the current stage is added at different stages, the corresponding intermediate products are synthesized respectively, the intermediate products are involved in the next stage reaction, and the ternary block polyether carboxylate viscosity reducer is obtained.

[0091] Figure 2 This is the synthesis step of the ternary random polyether carboxylate disclosed in Example 6 of the present invention; as can be seen from the figure, to synthesize the ternary random polyether carboxylate, it is only necessary to put all the required reactants together and react together without paying attention to the order of adding the substances to obtain the ternary random polyether carboxylate viscosity reducer.

[0092] Figure 3 This is the FT-IR image of the amphoteric polyether carboxylate viscosity reducer containing polyether segments disclosed in Example 4 of the present invention; it can be seen from the figure that 3318.24 cm -1 The stretching vibration absorption peak of carboxyl hydroxyl group is 2878.18cm -1 The stretching vibration absorption peak of methyl group is 1453.09cm -1 The bending vibration absorption peak of methylene is 1106.51cm -1 The absorption peak at is the stretching vibration absorption peak of C=S bond. From the above absorption characteristic peaks, we can basically confirm that the target viscosity reducer has been obtained.

[0093] Example 5

[0094] A method for preparing an amphoteric polyether carboxylate viscosity reducer containing a polyether segment comprises the following steps:

[0095] 1) Weigh 0.0078 g of AIBN and 0.4836 g of BDATT (the molar ratio of AIBN to BDATT is 1:6), weigh 17.151 g of APEG600, dissolve them in 40.02 g of water, add the three together into a 250 mL three-necked flask, place the reactor into a magnetic stirring oil bath, pass nitrogen into the flask for half an hour, turn on the condenser, heat to 80°C, and stir to react for 6 hours.

[0096] 2) Weigh 0.0313 g of AIBN and add it into a three-necked flask. Weigh 8.2325 g of AA, dissolve it in 19.21 g of water, and transfer it into a syringe of suitable size. Add AA dropwise within no less than 2 hours, and continue stirring the reaction for 6 hours.

[0097] 3) Weigh 0.0078 g of AIBN and add it into a three-necked flask. Weigh 4.6165 g of DADMAC, dissolve it in 10.77 g of water and transfer it into a syringe of suitable size. Add DADMAC dropwise within no less than 2 hours and continue stirring the reaction for 6 hours.

[0098] 4) The reaction product is transferred into a beaker, and after cooling to room temperature, a 30% by mass NaOH aqueous solution is used to adjust the pH to 7.5 to obtain an amphoteric polyether carboxylate viscosity reducer containing polyether segments, namely a ternary block polyether carboxylate crude oil viscosity reducer.

[0099] Example 6

[0100] A method for preparing an amphoteric polyether carboxylate viscosity reducer containing a polyether segment comprises the following steps:

[0101] 1) Weigh 17.151 g of APEG600, dissolve it in 40.02 g of water and add it to a 250 mL three-necked flask.

[0102] 2) Weigh 0.0469 g of AIBN and 0.2418 g of BDATT and add them together with the mixture in step 1) into a three-necked flask; weigh 8.2325 g of AA and dissolve it in 19.21 g of water; weigh 4.6165 g of DADMAC and dissolve it in 10.77 g of water.

[0103] 3) The monomer dissolved in step 2 is transferred into a syringe of appropriate size. After the reactor is placed in a magnetic stirring oil bath, nitrogen is introduced into the flask for half an hour, condensation water is turned on, the temperature is raised to 80°C, the needle is turned on, and the monomer is added dropwise within a period of not less than 2 hours, and the reaction is stirred for 6 hours.

[0104] 4) The product after the reaction is transferred into a beaker, and after cooling to room temperature, a 30% by mass NaOH aqueous solution is used to adjust the pH to 7.5 to obtain an amphoteric polyether carboxylate viscosity reducer containing polyether segments, namely a ternary random polyether carboxylate crude oil viscosity reducer.

[0105] Example 7

[0106] A method for preparing an amphoteric polyether carboxylate viscosity reducer containing a polyether segment comprises the following steps:

[0107] 1) Weigh 0.0060 g of dimethyl azobisisobutyrate and 0.1800 g of dithiocarbamate, weigh 15 g of APEG600, dissolve them in 35 g of water, add the three together into a 250 mL three-necked flask, place the reactor into a magnetic stirring oil bath, pass nitrogen into the flask for 0.5 hours, turn on the condensation water, raise the temperature to 75°C, and stir the reaction for 6 hours.

[0108] 2) Weigh 0.0060 g of dimethyl azobisisobutyrate and add it into a three-necked flask, weigh 3 g of DADMAC, dissolve it in 7 g of water and transfer it into a syringe of appropriate size, add DADMAC dropwise within 2 hours, and continue stirring and reacting for 6 hours.

[0109] 3) Weigh 0.02 g of dimethyl azobisisobutyrate and add it into a three-necked flask, weigh 8 g of AA, dissolve it in 18 g of water and transfer it into a syringe of appropriate size, add AA dropwise within no less than 2 hours, and continue stirring and reacting for 6 hours.

[0110] 4) The product after the reaction is transferred into a beaker, and after cooling to room temperature, a 30% by mass NaOH aqueous solution is used to adjust the pH to 7 to obtain an amphoteric polyether carboxylate viscosity reducer containing polyether segments, namely a ternary block polyether carboxylate crude oil viscosity reducer.

[0111] Example 8

[0112] A method for preparing an amphoteric polyether carboxylate viscosity reducer containing a polyether segment comprises the following steps:

[0113] 1) Weigh 0.0078 g of AIBN and 0.2418 g of BDATT, weigh 17.151 g of APEG600, dissolve them in 40.02 g of water, add the three together into a 250 mL three-necked flask, place the reactor into a magnetic stirring oil bath, pass nitrogen into the flask for 1 hour, turn on the condenser, raise the temperature to 80°C, and stir the reaction for 7 hours.

[0114] 2) Weigh 0.0078 g of AIBN and add it into a three-necked flask, weigh 4.6165 g of DADMAC, dissolve it in 10.77 g of water and transfer it into a syringe of suitable size, add DADMAC dropwise within 3 hours, and continue stirring and reacting for 7 hours.

[0115] 3) Weigh 0.0313 g of AIBN and add it into a three-necked flask. Weigh 9 g of AA, dissolve it in 20 g of water and transfer it into a syringe of suitable size. Add AA dropwise within 3 hours and continue stirring the reaction for 7 hours.

[0116] 4) The reaction product is transferred into a beaker, and after cooling to room temperature, a 30% by mass NaOH aqueous solution is used to adjust the pH to 7.5 to obtain an amphoteric polyether carboxylate viscosity reducer containing polyether segments, namely a ternary block polyether carboxylate crude oil viscosity reducer.

[0117] Example 9

[0118] A method for preparing an amphoteric polyether carboxylate viscosity reducer containing a polyether segment comprises the following steps:

[0119] 1) Weigh 0.0080 g of dibenzoyl peroxide and 0.2500 g of xanthate, weigh 18 g of APEG600, dissolve them in 42 g of water, add the three together into a 250 mL three-necked flask, place the reactor into a magnetic stirring oil bath, pass nitrogen into the flask for 1 hour, turn on the condensation water, raise the temperature to 85°C, and stir the reaction for 8 hours.

[0120] 2) Weigh 0.0080 g of dibenzoyl peroxide and add it into a three-necked flask, weigh 5 g of DADMAC, dissolve it in 12 g of water and transfer it into a syringe of appropriate size, add DADMAC dropwise within 4 hours, and continue stirring and reacting for 8 hours.

[0121] 3) Weigh 0.04 g of dibenzoyl peroxide and add it into a three-necked flask, weigh 10 g of AA, dissolve it in 22 g of water and transfer it into a syringe of appropriate size, add AA dropwise within 4 hours, and continue stirring and reacting for 8 hours.

[0122] 4) The product after the reaction is transferred into a beaker, and after cooling to room temperature, a 30% by mass NaOH aqueous solution is used to adjust the pH to 8 to obtain an amphoteric polyether carboxylate viscosity reducer containing polyether segments, namely a ternary block polyether carboxylate crude oil viscosity reducer.

[0123] Example Effect Description

[0124] The selected heavy oil is North China heavy oil, and its viscosity is 4893 mPa·s at a reservoir temperature of 50°C.

[0125] Test temperature: 50℃.

[0126] Emulsion concentration: 10g / L.

[0127] Test method: The viscosity reduction and wetting properties of the obtained polyether carboxylate are characterized by using a viscometer, a surface tension meter and a contact angle meter, and then the structure is characterized by using an infrared spectrometer, a nuclear magnetic resonance hydrogen spectrometer, etc.

[0128] Apparent viscosity test of North China crude oil:

[0129] The digital viscometer produced by Brookfield Co., Ltd. in the United States was used to measure the crude oil in North China. Since the viscosity is greatly affected by temperature, the crude oil needs to be heated to the temperature to be measured and stabilized for 5 to 10 minutes before measurement to prevent temperature fluctuations from interfering with the viscosity measurement. The viscosity reduction rate was determined with reference to the enterprise standard Q / HS2052-2009 "Specifications for the Implementation of Chemical Viscosity Reduction Process for Heavy Oil" of China National Offshore Oil Corporation. Take the oil sample from the wellhead of the target well, dehydrate and degas it, and measure the viscosity η1 of the crude oil at a certain temperature; prepare the viscosity reducer with the water sample of the target well to prepare a solution of the target concentration; fully mix the crude oil and the prepared solution in a certain proportion, and measure the viscosity η2 of the crude oil emulsion at the temperature. The viscosity reduction rate M is calculated as follows.

[0130] M=(η1-η2) / η1×100%

[0131] Surface tension test of crude oil viscosity reducer:

[0132] The surface tension of surfactant solutions of various concentrations was tested using the platinum plate method. The test steps are as follows: hang a platinum plate that has been burned red with an alcohol lamp, and pour the liquid to be tested into the surface dish on the workbench; press the "up" button, and the workbench will slowly rise, so that the platinum plate is immersed in the liquid to be tested; when equilibrium is reached, read and record the number.

[0133] Contact angle test of crude oil viscosity reducer:

[0134] Evenly apply a layer of the oil sample to be tested on the slide, heat it with an alcohol lamp to melt it, and cool it until it solidifies. Ensure that the coating surface is flat and parallel to the lens angle of view, so that relatively reliable results can be obtained; adjust the sample stage to a suitable position, adjust the focus, and prepare for measurement; use a micro-injection needle to slowly drop the solution to be tested onto the surface of the oil sample, and freeze and save the image when the droplet is in stable contact with the rock oil surface; use the five-point method to measure its contact angle, where the adjustment accuracy is 0.05°.

[0135] Table 1 Comparison of emulsion properties of the amphoteric polycarboxylate viscosity reducer containing polyether segments prepared in Examples 1-6 and thick oil

[0136] Example Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Viscosity value (mPa·s) 67 108 55 47 49 145 Viscosity reduction rate (%) 98.67 97.80 98.88 99.04 99.00 97.04 Surface tension (mN / m) 61.26 61.90 60.02 59.18 59.96 63.16 Contact angle (°) 111.89 113.68 108.76 102.71 104.09 117.83

[0137] See Table 1 for a comparison of the performance of the emulsions formed by the amphiphilic polycarboxylate viscosity reducers containing polyether segments and heavy oil obtained in Examples 1-6; it can be seen from Table 1 that the viscosity reducing effect of the synthesized amphiphilic polycarboxylate heavy oil viscosity reducers containing polyether segments is obvious, and the viscosity reducing rate exceeds 97%. Comparison of the data of Example 1 and Example 2 shows that the best monomer addition order is viscosity reducer No. ①, i.e. APEG600, AA and DADMAC. Comparison of the data of Example 1, Example 3, Example 4 and Example 5 shows that the best chain transfer agent dosage is the viscosity reducer of Example 4 (molar ratio of AIBN: BDATT = 1:5), i.e. the chain transfer agent dosage accounts for 0.83% of the total monomer molar amount. Comparison of the data of the examples in Table 1 shows that the performance of the block copolymers is better than that of the random copolymers.

[0138] The present invention uses RAFT polymerization to synthesize a series of zwitterionic surfactants containing polyether carboxylates from water-soluble monomers acrylic acid (AA), polyoxyethylene ether (PEG) and cationic olefin monomers under the action of initiator azobisisobutyronitrile (AIBN) and chain transfer agent. Compared with traditional free radical polymerization, the polycarboxylic acid dispersant generated by this technology has a precisely controllable structure and better viscosity reduction performance. The viscosity reduction rate of this zwitterionic polyether carboxylate for heavy oil can reach more than 97%. A new and efficient viscosity reducer is provided for the exploitation and transportation of viscous crude oil. The present invention provides a theoretical basis for the application of polycarboxylate polymer surfactants in the viscosity reduction of heavy oil. This research can not only provide a theoretical basis for applying more polymer surfactants to the viscosity reduction of heavy oil, but also provide a new method for the viscosity reduction of heavy oil exploitation. Block-type polyether polycarboxylate zwitterionic surfactants have the advantages of both anionic surfactants and cationic surfactants, and can be used as an efficient emulsified viscosity reducer for heavy oil. RAFT reversible addition-fragmentation chain transfer radical polymerization is becoming a research hotspot in the field of free radical polymerization due to its unique advantages such as mild operating conditions and a wide range of monomer options.

[0139] Aiming at the characteristics of high viscosity and poor low-temperature fluidity of heavy oil in North China Oilfield, the present invention attempts to use RAFT polymerization to prepare a series of polyether carboxylate zwitterionic surfactants according to different monomer addition sequences and chain transfer agent dosages by using three monomers, namely acrylic acid (AA), allyl polyoxyethylene ether (APEG) 600 and diallyl dimethyl ammonium chloride (DADMAC), under the action of initiator azobisisobutyronitrile (AIBN) and chain transfer agent S-S'-bis(a,a'-dimethyl-a"-acetic acid)-trithiocarbonate (BDATT). Viscometer, surface tension meter and contact angle meter are used to characterize the viscosity reduction and wetting properties of the obtained polyether carboxylate, and then infrared light is used to analyze the viscosity of the obtained polyether carboxylate. The structure of the polyether carboxylate was characterized by spectrometer, nuclear magnetic resonance hydrogen spectrometer, etc., and the monomer addition order, ratio and chain transfer agent dosage were analyzed and compared with traditional random copolymers. The study determined the optimal synthesis process conditions and structure: the optimal monomer addition order of polyether carboxylate crude oil viscosity reducer is APEG600, AA and DADMAC; according to the optimal monomer addition order, the optimal amount of chain transfer agent is 0.83% of the total molar amount of monomers. Compared with the performance of traditional random copolymers, the performance is greatly improved. The best polyether carboxylate prepared can be applied to the heavy oil in the North China Oilfield to achieve a viscosity reduction rate of up to 99.04%, exploring a feasible polymerization method for the development of new chemical viscosity reducers.

[0140] In summary, the content of the present invention is not limited to the embodiments listed, and any equivalent changes made to the technical solution of the present invention by ordinary technicians in this field after reading the specification of the present invention are covered by the claims of the present invention.

[0141] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An amphoteric polyether carboxylate viscosity reducer containing a polyether segment, characterized in that: The amphoteric polyether carboxylate viscosity reducer containing polyether chain segments is a ternary block polyether carboxylate; the structural formula is: Among them, a=5~20, b=20~80, c=2~8, n=5~25.

2. The method for preparing the amphoteric polyether carboxylate viscosity reducer containing polyether chain segments according to claim 1, characterized in that: include: The initiator is divided into three parts, the first part of the initiator is mixed with the chain transfer agent and the allyl polyoxyethylene ether solution, and nitrogen is introduced. After the first stirring reaction is completed, the second part of the initiator is added first, and then the diallyl dimethyl ammonium chloride solution is added. After the second stirring reaction is completed, the third part of the initiator is added, and finally the acrylic acid solution is slowly added. After the third stirring reaction is completed, the pH value is adjusted to 7-8 to obtain an amphoteric polyether carboxylate viscosity reducer containing a polyether segment.

3. The method for preparing the amphoteric polyether carboxylate viscosity reducer containing polyether segments according to claim 2, characterized in that: The initiator is one of azobisisobutylamidine hydrochloride, dimethyl azobisisobutyrate and dibenzoyl peroxide; the chain transfer agent is one of dithiocarbamate, xanthate and trithiocarbonate.

4. The method for preparing the amphoteric polyether carboxylate viscosity reducer containing polyether segments according to claim 2, characterized in that: The molar ratio of the first initiator: the second initiator: the third initiator is 1:1:(3-5).

5. The method for preparing the amphoteric polyether carboxylate viscosity reducer containing polyether segments according to claim 2, characterized in that: The acrylic acid solution is prepared by dissolving 8-10g of acrylic acid in 18-22g of water; the diallyldimethylammonium chloride solution is prepared by dissolving 4-6g of diallyldimethylammonium chloride in 9-14g of water; and the allyl polyoxyethylene ether solution is prepared by dissolving 15-18g of allyl polyoxyethylene ether in 35-42g of water.

6. The method for preparing the amphoteric polyether carboxylate viscosity reducer containing polyether segments according to claim 5, characterized in that: The molar ratio of the first initiator: chain transfer agent: allyl polyoxyethylene ether: diallyl dimethyl ammonium chloride: acrylic acid is 1:(4-6):1:1:(3-5).

7. The method for preparing the amphoteric polyether carboxylate viscosity reducer containing polyether segments according to claim 2, characterized in that: The nitrogen gas is introduced for 0.5-1.0 h; the diallyldimethylammonium chloride solution is added for 2.0-4.0 h; and the acrylic acid solution is added for 2.0-4.0 h.

8. The method for preparing the amphoteric polyether carboxylate viscosity reducer containing polyether chain segments according to claim 2, characterized in that: The temperature of the first stirring reaction is 75-85°C, and the time is 6.0-8.0h; the temperature of the second stirring reaction is 75-85°C, and the time is 6.0-8.0h; the temperature of the third stirring reaction is 75-85°C, and the time is 6.0-8.0h.

9. The method for preparing the amphoteric polyether carboxylate viscosity reducer containing polyether segments according to claim 2, characterized in that: The pH value was adjusted to 7-8 using a 30% by mass NaOH aqueous solution.

10. Use of the amphoteric polyether carboxylate viscosity reducer containing polyether segments prepared by the preparation method according to any one of claims 2 to 9 in heavy oil recovery and viscosity reduction, characterized in that: The viscosity reduction rate is 97.04%-99.04%.

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