A viscosity reducer composition and its application, a viscosity reducer, and its preparation method and application

Abstract

The present invention relates to the technical field of emulsification viscosity reduction, and discloses an ultra-heavy oil emulsifying viscosity reducer composition and its application, an ultra-heavy oil emulsifying viscosity reducer and its preparation method and application. The viscosity reducer composition contains the following components stored independently or in a mixture of two or more: a nonionic surfactant based on cyclodextrin modification, an amphoteric surfactant, and water; and the nonionic surfactant based on cyclodextrin modification has the structure shown in formula (A). The ultra-heavy oil emulsifying viscosity reducer provided by the present invention has good viscosity reduction and emulsification effects on ultra-heavy oil with a viscosity exceeding 50000 mPa·s under the simulated weak shear action of the formation, and the viscosity reducer has good biocompatibility, is easily biodegradable, does not cause secondary pollution, and has less damage to the formation.

Description

Technical Field

[0001] The present invention relates to the technical field of emulsifying viscosity reduction, and particularly relates to a super heavy oil emulsifying viscosity reducer composition and its application, a super heavy oil emulsifying viscosity reducer, and its preparation method and application. Background Art

[0002] The emulsifying viscosity reduction technology is a viscosity reduction method that uses an externally added surfactant to form an "oil-in-water" emulsion of heavy oil and surfactant aqueous solution, thereby reducing the viscosity of crude oil and improving the fluidity of heavy oil. Due to its strong on-site operability, flexible and diverse technologies, and strong environmental adaptability, the emulsifying viscosity reduction technology has become a commonly used technology for heavy oil exploitation at present. This technology mainly reduces the oil-water interfacial tension through the adsorption of the emulsifying viscosity reducer at the oil-water interface, so that the heavy oil changes from the oil-in-water emulsified state to the oil-in-water emulsion, greatly reducing the viscosity and realizing normal exploitation.

[0003] In recent years, the proportion of heavy oil exploitation in the overall oil exploitation has gradually increased, and the geological conditions have become increasingly complex. The use effect of the emulsifying viscosity reducer is affected by the physical properties of heavy oil and formation conditions. The complex formation conditions increase the dosage of the emulsifier, and the viscosity reduction effect deteriorates or even fails accordingly, resulting in a substantial increase in cost. Most of the existing heavy oil emulsifying viscosity reducers are composed of linear anionic surfactants, non-ionic surfactants, and co-surfactants. Such emulsifying viscosity reducers have good viscosity reduction effects for ordinary heavy oil systems, but for deep super heavy oil reservoirs, especially super heavy oil with a viscosity above 50000 mPa·s, the emulsifying effect is poor.

[0004] Currently, there are few reported super heavy oil emulsifying viscosity reducers in the literature. CN110835522A discloses a temperature and salt-resistant super heavy oil emulsifying viscosity reducer. This emulsifying viscosity reducer is formed by reacting ethylene oxide and dimethylamine to generate an intermediate, and then reacting with 3-chloro-2-phenylsulfonate to form an amphoteric surfactant. This viscosity reducer has strong emulsifying and stripping ability for resins and asphaltenes, and a high viscosity reduction rate, and can reduce the viscosity of super heavy oil at 50 °C by more than 99.0%. However, the raw materials of dimethylamine and ethylene oxide used in the preparation are highly dangerous, are gaseous at room temperature, flammable, and dimethylamine has a strong pungent ammonia odor.

[0005] CN110423600A discloses an aqueous viscosity reducer for highly efficient viscosity reduction of super heavy crude oil, which is composed of a betaine-type surfactant, a biological surfactant, a polyether-type surfactant, and water. The biological surfactant is a ketone surfactant extracted from plants. This viscosity reducer has good solubility in formation water with a salinity of about 200000 mg / L, and can quickly and effectively reduce the viscosity of super heavy oil under the action of stirring and mixing to form an oil-in-water emulsion.

[0006] Most viscosity reducers for extra-heavy oil in the prior art are compositions of ordinary surfactants, which have good emulsifying effects under stirring conditions. However, when actually applied to the process of extra-heavy oil exploitation, there is no violent disturbance in the formation or wellbore. How to achieve emulsifying viscosity reduction of extra-heavy oil with very poor fluidity under weak shear action is highly challenging. It is urgent to develop a new type of extra-heavy oil emulsifying viscosity reduction system that can enhance the permeability of crude oil and achieve viscosity reduction of extra-heavy oil under lower shear action.

[0007] Cyclodextrin is a natural cyclic polysaccharide obtained by fermenting starch with microorganisms. It has a spatial truncated cone structure and is a commonly used functional host molecule. Cyclodextrin can form host-guest complexes with polycyclic aromatic hydrocarbons through host-guest interactions, which is another effective way to solubilize polycyclic aromatic hydrocarbons besides the solubilization effect of surfactants. Therefore, by introducing cyclodextrin structure into the surfactant molecular structure, the synergistic solubilization of the hydrophobic micro-region of the aggregate and the host-guest complexation can be exerted. At present, the relevant reports in the literature and patents mainly focus on the mixed system of surfactants and cyclodextrin, and there are very few reports on obtaining host-guest synergistic surfactants through chemical modification on the cyclodextrin skeleton.

[0008] CN102876309A discloses a viscosity reducer for heavy oil, which includes hydrocarbon oil, β-cyclodextrin, fatty alcohol polyoxyethylene ether and hydrophilic components. The hydrophilic components are selected from one or more of monocarboxylic acids with C1-C4, monohydric alcohols with C1-C4, monoamines with C1-C4 and amides with C1-C4. This viscosity reducer for heavy oil is a solution or microemulsion. However, the viscosity reduction rate of this viscosity reducer for heavy oil is only 15.0% - 51.2%, and the viscosity reduction effect needs to be further improved. Moreover, the composition of the viscosity reducer is relatively complex, which not only increases the complexity of the viscosity reduction operation, but also introduces too many foreign substances into the heavy oil, increasing the difficulty of subsequent treatment processes. Summary of the Invention

[0009] The purpose of the present invention is to overcome the defect that the viscosity reducer in the prior art has poor emulsifying viscosity reduction effect on extra-heavy oil under weak shear action.

[0010] To achieve the above purpose, the first aspect of the present invention provides an extra-heavy oil emulsifying viscosity reducer composition, which contains the following components stored separately or mixed with two or more of them: a non-ionic surfactant modified based on cyclodextrin, an amphoteric surfactant and water; and the non-ionic surfactant modified based on cyclodextrin has the structure shown in formula (A):

[0011]

[0012] Wherein, in formula (A),

[0013] m is any integer selected from 4 to 12;

[0014] One of R1 and R2 is a hydroxyl group, and the other is and each R is independently selected from H, C 1-18 alkyl, C 2-18 alkenyl, C containing at least one oxygen atom 2-18 alkyl.

[0015] The second aspect of the present invention provides a method for preparing an emulsifying viscosity reducer for ultra - heavy oil, the method comprising: mixing the components in the viscosity reducer composition described in the first aspect.

[0016] The third aspect of the present invention provides an emulsifying viscosity reducer for ultra - heavy oil prepared by the method described in the second aspect.

[0017] The fourth aspect of the present invention provides the application of the viscosity reducer composition described in the first aspect and the emulsifying viscosity reducer for ultra - heavy oil described in the third aspect in the exploitation of ultra - heavy oil reservoirs.

[0018] The emulsifying viscosity reducer for ultra - heavy oil provided by the present invention contains a non - ionic surfactant modified by cyclodextrin. The structure of this non - ionic surfactant contains both a cyclodextrin polysaccharide head group and hydroxyl groups on its alkyl chain, has good water solubility, and can accelerate the penetration and dispersion process of the emulsifying viscosity reducer in heavy oil.

[0019] Through the synergistic effect of the non - ionic surfactant modified by cyclodextrin and the amphoteric surfactant, the emulsifying viscosity reducer for ultra - heavy oil of the present invention can effectively reduce the viscosity of ultra - heavy oil under the condition of simulating weak shear in the formation. Moreover, this viscosity reducer has good biocompatibility, is easily biodegradable, does not cause secondary pollution, and has less harm to the formation. Description of the Drawings

[0020] Figure 1 Mass spectrometry spectrum of the non - ionic surfactant 6 - N - β - CD - 2C 12 H 25 modified by cyclodextrin prepared in Preparation Example 1 of the present invention.

[0021] Figure 2 Mass spectrometry spectrum of the non - ionic surfactant 3 - N - β - CD - 2C 12 H 25 modified by cyclodextrin prepared in Preparation Example 2 of the present invention.

[0022] Figure 3 Mass spectrometry spectrum of the non - ionic surfactant 3 - N - α - CD - 2C 12 H 25 modified by cyclodextrin prepared in Preparation Example 3 of the present invention. Detailed Description of the Invention

[0023] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0024] It should be noted that in various aspects of the present invention, for the same components in each aspect, the present invention only describes them once in one aspect without repeating the description. Those skilled in the art should not understand this as a limitation of the present invention.

[0025] The following is an explanation of the terms of the present invention as follows:

[0026] In this article, the wavy line in each group represents the bonding position.

[0027] "An alkyl group of "C 1-18 " means an alkyl group with a total of 1 to 18 carbon atoms, including a straight-chain alkyl group of C 1-18 , and a branched-chain alkyl group of C 1-18 . For example, it can be a straight-chain alkyl group with 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms, or a branched-chain alkyl group with 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms. For example, it can be

[0028] etc. For "an alkyl group of "C 8-18 ", it has a similar explanation, except that the number of carbon atoms is different.

[0029] "An alkenyl group of "C 2-18 " means a hydrocarbon group formed by removing one or more hydrogen atoms from an olefin molecule, and the total number of carbon atoms in this alkenyl group is 2 to 18, and the double bond in this group can be at any position. For example, it can be etc. For "an alkenyl group of "C 6-12 ", it has a similar explanation, except that the number of carbon atoms is different.

[0030] "An alkyl group of "C 2-18 " containing at least one oxygen atom" means an alkyl group with a total of 2 to 18 carbon atoms, including a straight-chain alkyl group and a branched-chain alkyl group, and the carbon atoms in this alkyl group of "C 2-18 " can be interrupted by one or more oxygen atoms. For example, it can be CH3OCH2-, etc. For “alkyl group containing at least one oxygen atom” has a similar explanation, except that the number of carbon atoms is different. 4-16 The alkyl group has a similar explanation, except that the number of carbon atoms is different.

[0031] As described above, the first aspect of the present invention provides an emulsifying viscosity reducer composition for ultra-heavy oil, and the viscosity reducer composition contains the following components stored independently or mixed with two or more of them: a non-ionic surfactant based on cyclodextrin modification, an amphoteric surfactant, and water; and the non-ionic surfactant based on cyclodextrin modification has the structure shown in formula (A):

[0032]

[0033] Wherein, in formula (A),

[0034] m is any integer selected from 4 to 12;

[0035] One of R1 and R2 is a hydroxyl group, and the other is And each R is independently selected from H, C 1-18 alkyl group, C 2-18 alkenyl group, C containing at least one oxygen atom 2-18 alkyl group.

[0036] Preferably, m is any integer selected from 5 to 7;

[0037] Preferably, formula (A) is the structure shown in formula (I) or formula (II),

[0038]

[0039] Preferably, one of R1 and R2 is a hydroxyl group, and the other is And each R is independently selected from H, C 8-18 alkyl group, C 6-12 alkenyl group, C containing at least one oxygen atom 4-16 alkyl group. More preferably, one of R1 and R2 is a hydroxyl group, and the other is And each R is independently selected from n-octyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, 7-octenyl, n-decyl-O-CH2-,

[0040] According to a preferred embodiment, in formula (A),

[0041] m is any integer selected from 5 to 7;

[0042] One of R1 and R2 is a hydroxyl group, and the other is And each R is independently selected from H, C 8-18alkyl group, C 6-12 alkenyl group, C containing at least one oxygen atom 4-16 alkyl group.

[0043] According to another preferred embodiment, in formula (A),

[0044] m is any integer selected from 5 - 7;

[0045] One of R1 and R2 is a hydroxyl group, and the other is and each R is independently selected from n - octyl, n - decyl, n - dodecyl, n - tetradecyl, n - hexadecyl, n - octadecyl, 7 - octenyl, n - decyloxy - CH2 -,

[0046] The present invention has no particular limitation on the method for preparing the cyclodextrin - modified nonionic surfactant. However, in order to obtain better effects, the present invention preferably provides the method for preparing the cyclodextrin - modified nonionic surfactant as described below.

[0047] A method for preparing a cyclodextrin - modified nonionic surfactant, the nonionic surfactant having the structure shown in formula (A); the method includes:

[0048] In the presence of a solvent, contacting the amino - functionalized cyclodextrin shown in formula (B) with the 1,2 - epoxyalkane shown in formula (C);

[0049]

[0050] Wherein, in formula (B), one of R3 and R4 is - OH and the other is - NH2;

[0051] In formula (A), formula (B) and formula (C), the definitions of m, R, R1 and R2 are the same as those in the first aspect. It will not be repeated here, and those skilled in the art should not understand it as a limitation of the present invention.

[0052] Preferably, the amino - functionalized cyclodextrin is selected from at least one of amino - functionalized α - cyclodextrin, amino - functionalized β - cyclodextrin, and amino - functionalized γ - cyclodextrin.

[0053] It should be noted that in the amino - functionalized cyclodextrin, the position of the amino - functionalized cyclodextrin can be at the 3 - hydroxyl position of the cyclodextrin or at the 6 - hydroxyl position.

[0054] More preferably, formula (B) is as shown in formula (III) and (IV):

[0055]

[0056] In the preparation method of the present invention, the amino-functionalized cyclodextrin and the 1,2-epoxyalkane can be prepared by methods known in the art or obtained by purchase.

[0057] Preferably, the 1,2-epoxyalkane is selected from 1,2-epoxydecane, 1,2-epoxydodecane, 1,2-epoxytetradecane, 1,2-epoxyhexadecane, 1,2-epoxyoctadecane, 1,2-epoxyeicosane, 1,2-epoxy-9-decene, octyl glycidyl ether.

[0058] Preferably, the molar ratio of the amount of the amino-functionalized cyclodextrin to the 1,2-epoxyalkane is 1:(1 - 20). More preferably, the molar ratio of the amount of the amino-functionalized cyclodextrin to the 1,2-epoxyalkane is 1:(2.05 - 5).

[0059] Preferably, relative to 1 mmol of the amino-functionalized cyclodextrin, the volume of the solvent used is 10 - 30 mL.

[0060] Preferably, the solvent is selected from at least one of methanol, ethanol, isopropanol, n-butanol, water, tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and ethylene glycol.

[0061] Preferably, the conditions of the contact reaction at least satisfy: the temperature is 60 - 90 °C and the time is 48 - 120 h.

[0062] The contact reaction of the present invention is preferably carried out under stirring, and there is no special requirement for the stirring speed, and parameters known in the art can be used.

[0063] In the foregoing preparation method of the present invention, various post-treatment operations known in the art can also be involved, such as rotary evaporation, extraction, washing, filtration, recrystallization, column chromatography, etc. The present invention has no special limitation on this, and those skilled in the art should not understand it as a limitation to the present invention.

[0064] Exemplarily, after the contact reaction of the amino-functionalized cyclodextrin shown in formula (B) and the 1,2-epoxyalkane shown in formula (C) is completed, the solvent is removed by rotary evaporation, and then recrystallized or purified by column chromatography to obtain the purified target product. The mixed solvent used for recrystallization can be one of methanol-ethyl acetate, methanol-acetone, ethanol-ethyl acetate, and ethanol-acetone; the eluent used for column chromatography is dichloromethane and ethanol with a volume ratio of 5 - 20:1.

[0065] The method for preparing a nonionic surfactant based on cyclodextrin modification provided by the present invention uses amino-functionalized cyclodextrin and 1,2-epoxyalkane as raw materials, and the product can be prepared through a one-pot reaction, which has the advantages of simplicity and high efficiency.

[0066] Preferably, the amphoteric surfactant is selected from at least one of alkyl dimethyl betaine, alkyl hydroxypropyl sulfobetaine, and coconut oil amide propyl betaine.

[0067] Preferably, the number of carbon atoms in the alkyl carbon chain of the alkyl dimethyl betaine and alkyl hydroxypropyl sulfobetaine is independently selected from any integer of 8-20.

[0068] More preferably, the number of carbon atoms in the alkyl carbon chain of the alkyl dimethyl betaine and alkyl hydroxypropyl sulfobetaine is independently selected from any integer of 12-18.

[0069] Preferably, based on the total weight of the super heavy oil emulsifying viscosity reducer composition, the content of the nonionic surfactant based on cyclodextrin modification is 0.05-1.0 wt%, the content of the amphoteric surfactant is 0.1-3.0 wt%, and the content of water is 96.0-99.85 wt%.

[0070] More preferably, based on the total weight of the super heavy oil emulsifying viscosity reducer composition, the content of the nonionic surfactant based on cyclodextrin modification is 0.1-0.8 wt%, the content of the amphoteric surfactant is 0.5-2.5 wt%, and the content of water is 96.7-99.4 wt%.

[0071] As described above, the second aspect of the present invention provides a method for preparing a super heavy oil emulsifying viscosity reducer, which includes: mixing the components in the viscosity reducer composition described in the first aspect.

[0072] The dosages and types of the components involved in the second aspect of the present invention are the same as the contents and types of the corresponding components described in the first aspect of the present invention, and will not be elaborated here. Those skilled in the art should not understand this as a limitation to the present invention.

[0073] Preferably, the conditions for mixing at least satisfy: the temperature is 15-40 °C, the stirring speed is 50-600 rpm, and the stirring time is 10-80 min.

[0074] More preferably, the conditions for mixing at least satisfy: the temperature is 15-30 °C, the stirring speed is 200-400 rpm, and the stirring time is 20-40 min.

[0075] When the viscosity reducer prepared by the present invention is used for reducing the viscosity of ultra-heavy oil, the dosage of the viscosity reducer is more than 40 wt% of the weight of the heavy oil relative to 100 parts by weight of the heavy oil; more preferably, the dosage of the viscosity reducer is 40 wt% - 100 wt% of the weight of the heavy oil.

[0076] As described above, the third aspect of the present invention provides an ultra-heavy oil emulsifying viscosity reducer prepared by the method described in the second aspect.

[0077] As described above, the fourth aspect of the present invention provides the application of the viscosity reducer composition described in the first aspect and the ultra-heavy oil emulsifying viscosity reducer described in the third aspect in the exploitation of ultra-heavy oil reservoirs.

[0078] Preferably, the viscosity of the ultra-heavy oil is 50,000 - 300,000 mPa·s.

[0079] The ultra-heavy oil emulsifying viscosity reducer prepared by the present invention has good viscosity reduction and emulsifying effects on ultra-heavy oil with a viscosity exceeding 50,000 mPa·s under the weak shear action of the simulated formation. Moreover, the viscosity reducer has good biocompatibility, is easily biodegradable, does not cause secondary pollution, and has less damage to the formation.

[0080] The present invention will be described in detail below through preparation examples and examples. In the following preparation examples and examples, the instruments, reagents, materials, etc. involved, unless otherwise specified, are all conventional instruments, reagents, materials, etc. existing in the prior art and can be obtained through regular commercial channels. The experimental methods, detection methods, etc. involved in the following preparation examples and examples, unless otherwise specified, are all conventional experimental methods, detection methods, etc. existing in the prior art.

[0081] The main raw materials used in the preparation examples, examples, and comparative examples are shown in Table 1.

[0082] Table 1

[0083]

[0084] Preparation Example 1

[0085] Preparation of a nonionic surfactant 6-N-β-CD-2C based on cyclodextrin modification based on amino-functionalized β-cyclodextrin 12 H 25 :

[0086] In formula (A), when m = 6, R1 is R2 is a hydroxyl group, and R is a dodecyl group, the structure shown in formula (A) is the nonionic surfactant 6-N-β-CD-2C 12 H 25 ;

[0087]

[0088] Weigh 1.134 g of mono-(6-amino-6-deoxy)-β-cyclodextrin and 0.85 g of 1,2-epoxytetradecane into a reaction flask, then add 20 mL of absolute ethanol and stir evenly. Then, stir and react at 75 °C for 72 h, then stop the reaction and rotary evaporate to remove the solvent. The residue is recrystallized with ethanol / acetone to obtain the product 6-N-β-CD-2C 12 H 25 , with a yield of 97%.

[0089] Characterize the product 6-N-β-CD-2C 12 H 25 by MALDI-TOF-MS. As Figure 1 shown, the peak at 1558.580 ((M+H) + ) in the product spectrum is the highest, which is the molecular ion peak of 6-N-β-CD-2C 12 H 25 , proving that the product has been successfully prepared.

[0090] Preparation Example 2

[0091] Based on the amino-functionalized β-cyclodextrin, prepare the nonionic surfactant 3-N-β-CD-2C 12 H 25 :

[0092] In formula (A), when m = 6, R1 is a hydroxyl group, and R2 is When R is a dodecyl group, the structure shown in formula (A) is the nonionic surfactant 3-N-β-CD-2C 12 H 25 ;

[0093] Weigh 1.134 g of 3A-amino-3A-deoxy-(2AS,3AS)-β-cyclodextrin hydrate and 0.85 g of 1,2-epoxytetradecane into a reaction flask, then add 20 ml of absolute ethanol and stir evenly. Stir and react at 75 °C for 72 h, then stop the reaction and rotary evaporate to remove the solvent. The residue is recrystallized with ethanol / acetone to obtain the product 3-N-β-CD-2C 12 H 25 , with a yield of 98%.

[0094] Characterize the product 3-N-β-CD-2C 12 H 25 by MALDI-TOF-MS. As Figure 2 shown, the peak at 1558.8942 ((M+H) + ) in the product spectrum is the highest, which is the molecular ion peak of 3-N-β-CD-2C 12 H 25The molecular ion peak proves that the product has been successfully prepared.

[0095] Preparation Example 3

[0096] Preparation of a nonionic surfactant 3-N-α-CD-2C based on cyclodextrin modification using amino-functionalized α-cyclodextrin 12 H 25 :

[0097] In formula (A), when m = 5, R1 is a hydroxyl group, and R2 is When R is a dodecyl group, the structure shown in formula (A) is the nonionic surfactant 3-N-α-CD-2C 12 H 25 ;

[0098] Weigh 0.972 g of 3A-amino-3A-deoxy-(2AS,3AS)-α-cyclodextrin hydrate and 0.85 g of 1,2-epoxytetradecane into a reaction flask, then add 20 ml of anhydrous ethanol and stir evenly. Stir and react at 75 °C for 72 h, then stop the reaction and rotary evaporate to remove the solvent. The residue is recrystallized with ethanol / acetone to obtain the product 3-N-α-CD-2C 12 H 25 , with a yield of 95%.

[0099] The product 3-N-α-CD-2C 12 H 25 is characterized by MALDI-TOF-MS. As Figure 3 shown, the peak at 1396.76721 ((M + H) + ) in the product spectrum is the highest, and this is the molecular ion peak of 3-N-α-CD-2C 12 H 25 The molecular ion peak proves that the product has been successfully prepared.

[0100] Example 1

[0101] Add 0.5 g of the nonionic surfactant 6-N-β-CD-2C 12 H 25 prepared in Preparation Example 1 and 1.5 g of tetradecyldimethylbetaine into 98.0 g of water, and stir for 30 min under magnetic stirring conditions of 20 °C and 300 rpm to obtain a super-viscous oil emulsifying viscosity reducer, numbered YA1.

[0102] Example 2

[0103] Add 0.6 g of the nonionic surfactant 3-N-β-CD-2C 12 H 25Add 2.0 g of octadecyl propyl hydroxysulfobetaine to 97.4 g of water, and stir for 40 min under the conditions of magnetic stirring at 25 °C and 200 rpm to obtain a super-viscous oil emulsifying viscosity reducer, numbered YA2.

[0104] Example 3

[0105] Add 0.4 g of the non-ionic surfactant 3-N-α-CD-2C prepared in Preparation Example 3 12 H 25 and 1.2 g of cocamidopropyl betaine to 98.4 g of water, and stir for 20 min under the conditions of magnetic stirring at 30 °C and 400 rpm to obtain a super-viscous oil emulsifying viscosity reducer, numbered YA3.

[0106] Example 4

[0107] Add 0.1 g of the non-ionic surfactant 6-N-β-CD-2C prepared in Preparation Example 1 12 H 25 and 2.5 g of tetradecyl dimethyl betaine to 97.4 g of water, and stir for 30 min under the conditions of magnetic stirring at 20 °C and 300 rpm to obtain a super-viscous oil emulsifying viscosity reducer, numbered YA4.

[0108] Example 5

[0109] Add 0.8 g of the non-ionic surfactant 6-N-β-CD-2C prepared in Preparation Example 1 12 H 25 and 0.5 g of tetradecyl dimethyl betaine to 98.7 g of water, and stir for 30 min under the conditions of magnetic stirring at 20 °C and 300 rpm to obtain a super-viscous oil emulsifying viscosity reducer, numbered YA5.

[0110] Comparative Example 1

[0111] Add 0.5 g of AEO-9 and 1.5 g of tetradecyl dimethyl betaine to 98.0 g of water, and stir for 30 min under the conditions of magnetic stirring at 20 °C and 300 rpm to obtain a super-viscous oil emulsifying viscosity reducer, numbered YA6.

[0112] Comparative Example 2

[0113] Add 2.0 g of the non-ionic surfactant 6-N-β-CD-2C prepared in Preparation Example 1 12 H 25 to 98.0 g of water, and stir for 30 min under the conditions of magnetic stirring at 20 °C and 300 rpm to obtain a super-viscous oil emulsifying viscosity reducer, numbered YA7.

[0114] Comparative Example 3

[0115] Add 2.0 g of tetradecyl dimethyl betaine to 98.0 g of water, and stir for 30 min under the condition of magnetic stirring at 20 °C and 300 rpm to obtain an ultra-heavy oil emulsifying viscosity reducer, numbered YA8.

[0116] Comparative Example 4

[0117] Add 1.0 g of β-cyclodextrin and 1.0 g of tetradecyl dimethyl betaine to 98.0 g of water, and stir for 30 min under the condition of magnetic stirring at 20 °C and 300 rpm to obtain an ultra-heavy oil emulsifying viscosity reducer, numbered YA9.

[0118] Test Example

[0119] The ultra-heavy oil from Shengli Oilfield (viscosity at 50 °C is 125300 mPa·s) was selected for the determination of the emulsifying viscosity and viscosity reduction rate of ultra-heavy oil. The dosage of the heavy oil emulsifying viscosity reducer was uniformly 50 wt% of the weight of the heavy oil.

[0120] The steps of the viscosity reduction test are as follows: In a beaker, add 50 g of the test oil, and then add 25 g of the ultra-heavy oil emulsifying viscosity reducer in the above-mentioned examples or comparative examples, which accounts for 50 wt% of the weight of the ultra-heavy oil. Place the beaker in a 70 °C water bath and keep it static for 1 h. Use a biological shaker to simulate the emulsifying viscosity reduction process under weak shear conditions. The oscillation level is level 1 (oscillation frequency 50 r / min, amplitude 25 mm), and the oscillation time is 30 min. Observe the emulsified form of the heavy oil, and then use a Brookfield DV-II viscometer at 50 °C at a shear rate of 7.34 s -1 to measure the viscosity.

[0121] Calculate the viscosity reduction rate, and the viscosity reduction rate = (viscosity of the heavy oil before viscosity reduction - viscosity of the heavy oil after viscosity reduction) / viscosity of the heavy oil before viscosity reduction × 100%; the results are shown in Table 2.

[0122] Table 2. Emulsifying effects, viscosities of emulsified heavy oil and viscosity reduction rates of different ultra-heavy oil emulsifying viscosity reducers

[0123] Example Emulsification effect Viscosity of emulsified heavy oil (mPa.s) Viscosity reduction rate (%) Example 1 Uniform fine-dispersed emulsion 28.3 99.98 Example 2 Uniform fine-dispersed emulsion 55.6 99.96 Example 3 Uniform fine-dispersed emulsion 102.8 99.92 Example 4 Uniform fine-dispersed emulsion 505.6 99.60 Example 5 Uniform fine-dispersed emulsion 732.5 99.42 Comparative Example 1 Unable to disperse uniformly 18500 85.24 Comparative Example 2 Unable to disperse uniformly 49000 60.89 Comparative Example 3 Unable to disperse uniformly 32000 74.46 Comparative Example 4 Unable to disperse uniformly 38400 69.35

[0124] The results in Table 2 show that in the presence of water, by using a combination of a non-ionic surfactant modified based on cyclodextrin and an amphoteric surfactant to prepare an ultra-heavy oil emulsifying viscosity reducer (YA1 - YA5), it is possible to achieve the emulsifying viscosity reduction of ultra-heavy oil with a viscosity of 125300 mPa·s under simulated weak shear, and the viscosity reduction rate reaches more than 99.42%.

[0125] In contrast, when β-cyclodextrin or nonionic surfactant AEO-9 is used to replace the nonionic surfactant modified based on cyclodextrin and is used in combination with an amphoteric surfactant to prepare a super heavy oil emulsifying viscosity reducer, the uniform emulsification and dispersion of super heavy oil under weak shear force cannot be achieved, and the viscosity reduction effect is poor.

[0126] When YA1 is compared with YA7 and YA8, using only the nonionic surfactant modified based on cyclodextrin or only using the amphoteric surfactant alone cannot achieve the uniform emulsification and dispersion of super heavy oil under weak shear force, and the viscosity reduction effect is poor. Therefore, for the emulsifying viscosity reduction of super heavy oil by the viscosity reducer under weak shear force, neither the nonionic surfactant modified based on cyclodextrin nor the amphoteric surfactant component shown in formula (A) can be missing.

[0127] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope 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. An emulsifying viscosity reducer composition for ultra-heavy oil, characterized in that, The viscosity reducer composition contains the following components stored independently or in a mixture of two or more: a nonionic surfactant modified based on cyclodextrin, an amphoteric surfactant, and water; and the nonionic surfactant modified based on cyclodextrin has the structure shown in formula (A): Wherein, in formula (A), m is any integer selected from 5 to 7; One of R1 and R2 is a hydroxyl group, and the other is and each R is independently selected from n-octyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, 7-octenyl, n-decyl-O-CH2-, 2. The viscosity reducer composition according to claim 1, wherein, The amphoteric surfactant is selected from at least one of alkyl dimethyl betaine, alkyl hydroxypropyl sulfobetaine, and coconut oil amide propyl betaine.

3. The viscosity reducer composition according to claim 2, wherein, The number of carbon atoms in the alkyl carbon chain of the alkyl dimethyl betaine and alkyl hydroxypropyl sulfobetaine is independently any integer selected from 8 to 20.

4. The viscosity reducer composition according to claim 3, wherein The number of carbon atoms in the alkyl carbon chain of the alkyl dimethyl betaine and alkyl hydroxypropyl sulfobetaine is independently any integer selected from 12 to 18.

5. The viscosity reducer composition according to any one of claims 1-4, wherein, Based on the total weight of the ultra-heavy oil emulsifying viscosity reducer composition, the content of the nonionic surfactant modified based on cyclodextrin is 0.05-1.0 wt%, the content of the amphoteric surfactant is 0.1-3.0 wt%, and the content of water is 96.0-99.85 wt%.

6. The viscosity reducer composition according to claim 5, wherein, Based on the total weight of the ultra-heavy oil emulsifying viscosity reducer composition, the content of the nonionic surfactant modified based on cyclodextrin is 0.1-0.8 wt%, the content of the amphoteric surfactant is 0.5-2.5 wt%, and the content of water is 96.7-99.4 wt%.

7. A method for preparing an emulsifying viscosity reducer for ultra-heavy oil, characterized in that, The method includes: mixing the components in the viscosity reducer composition according to any one of claims 1-6.

8. The method according to claim 7, wherein The conditions for the mixing at least satisfy: the temperature is 15-40 °C, the stirring speed is 50-600 rpm, and the stirring time is 10-80 min.

9. An ultra-heavy oil emulsifying viscosity reducer prepared by the method according to claim 7 or 8.

10. The application of the viscosity reducer composition according to any one of claims 1-6 and the ultra-heavy oil emulsifying viscosity reducer according to claim 9 in the exploitation of ultra-heavy oil reservoirs.

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