Nonionic surfactants, oil flushing agents, and methods of making and use

Abstract

The application discloses a non-ionic surfactant and a preparation method, an oil washing agent and a preparation method, an oil displacement method and application thereof. The non-ionic surfactant is selected from at least one of structural formulas shown in the following formula (1): in the formula (1), R1 is selected from at least one of fatty groups of C 11 ~C 17 ; x is an integer between 1 and 4; y is an integer between 1 and 4; -Polym1- is selected from at least one of -(PO) m1 , -(EO) n1 , and -(BO) j1 ; -Polym2- is selected from at least one of -(PO) m2 , -(EO) n2 , and -(BO) j2 , wherein m1+m2=2-10, n1+n2=2-15, j1+j2=0-8; R2, R3, R4 are the same or different, and each is independently selected from at least one of hydrogen, C1-C4 alkyl and aromatic groups. The non-ionic surfactant provided by the application has super strong interfacial properties and wetting change properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oilfield exploitation, in particular to a non-ionic surfactant and a preparation method, an oil washing agent and a preparation method, an oil displacement method and application thereof. BACKGROUND

[0002] At present, the development of some large oil reservoirs in China has entered the late stage, and the comprehensive water cut is as high as 80% or more. A large amount of data shows that the exploitation stage in high water cut is the most difficult period in the development process of an oilfield. At this time, the underground oil-water movement and distribution are more complex, the remaining oil is dispersed, the well condition is gradually deteriorated, the water consumption rises sharply, and the late exploitation becomes more and more difficult. However, from the annual oil production and the remaining recoverable reserves, there is still a large amount of crude oil geological reserves in the underground that has not been exploited, and such considerable remaining oil is a rich foundation for increasing reserves and production and an important basis for enhancing oil recovery in old oilfields in China.

[0003] However, how to economically exploit these remaining oils under the existing economic and technical conditions has become a very important and urgent technical problem faced by old oilfields with high water cut in the new development stage.

[0004] At present, chemical flooding or miscible gas flooding is generally used to enhance oil recovery in China. Chemical flooding helps to improve oil washing efficiency, and miscible gas flooding helps to improve sweep efficiency. However, both methods have disadvantages, for example, the sweep efficiency of chemical flooding is often low, and the miscible gas flooding cannot effectively improve the oil washing efficiency in many cases. When the oil washing agent and carbon dioxide are used for recovery, the oil washing agent and carbon dioxide gas are injected alternately on the basis of water flooding, the oil washing agent is used to change the wettability of the reservoir and improve the oil washing efficiency, and the carbon dioxide is used to reduce the viscosity of the underground crude oil to improve the flow capacity of the crude oil. At the same time, the oil washing agent and carbon dioxide can be used for synergistic viscosity reduction, mixed mass transfer and energy enhancement to expand the swept area and more effectively develop high water cut reservoirs.

[0005] However, the formation water becomes weakly acidic during the injection of carbon dioxide, and the properties of ionic surfactants are greatly affected by pH. Although the commonly used polyoxyethylene non-ionic surfactants are not affected by acid and alkali, they are not soluble in water due to the influence of the cloud point with the increase of temperature.

[0006] In summary, it is of great economic significance to develop a temperature-resistant and efficient oil washing agent that is not affected by acid and alkali. SUMMARY

[0007] To address the aforementioned problems in the existing technology, this invention provides a nonionic surfactant and its preparation method, an oil-dissolving agent containing the nonionic surfactant and its preparation method, an oil displacement method using the oil-dissolving agent, and its application. The nonionic surfactant provided by this invention has superior interfacial properties and wetting modification properties, and the oil-dissolving agent containing the nonionic surfactant is acid-resistant and high-temperature resistant, thus expanding the application environment and application range.

[0008] The first aspect of the present invention provides a nonionic surfactant, said nonionic surfactant being selected from at least one of the structural formulas shown in formula (1):

[0009]

[0010] In equation (1), R1 is selected from C 11 ~C 17 At least one of the aliphatic groups; x is an integer between 1 and 4; y is an integer between 1 and 4; -Polym1- is selected from -(PO) m1 -、-(EO) n1 -、-(BO) j1 - at least one of the following, -Polym2- is selected from -(PO) m2 -、-(EO) n2 -、-(BO) j2 At least one of the following: m1+m2=2~10, n1+n2=2~15, j1+j2=0~8; R2, R3, and R4 may be the same or different, and each is independently selected from at least one of hydrogen, C1~C4 alkyl and aromatic groups.

[0011] In the above formula (1), -(PO)- is propylene oxide, -(EO)- is ethylene oxide, and -(BO)- is butyl oxide.

[0012] The nonionic surfactant provided by this invention, through ethoxylation and silane modification of alkyl diethanolamide, exhibits superior interfacial and wetting-modifying properties. Specifically, by controlling the length of the alkyl chain and the number of ethoxy groups, the interfacial properties between the nonionic surfactant and crude oil can be adjusted. Furthermore, by introducing silane groups into the molecular structure, the surface tension of the nonionic surfactant can be reduced, thus improving its wetting properties.

[0013] According to some embodiments of the nonionic surfactant of the present invention, in the above formula (1), x is an integer between 2 and 4, preferably x is 2.

[0014] According to some embodiments of the non-ionic surfactant of the present application, in the above formula (1), the y is an integer between 2 and 4, preferably, the y is 2.

[0015] According to some embodiments of the non-ionic surfactant of the present application, the -Polym1- is selected from -(PO) m1 - and -(EO) n1 -.

[0016] According to some embodiments of the non-ionic surfactant of the present application, the -Polym2- is selected from -(PO) m2 - and -(EO) n2 -.

[0017] According to preferred embodiments of the non-ionic surfactant of the present application, the non-ionic surfactant is selected from at least one of the following formula (2):

[0018]

[0019] According to some embodiments of the non-ionic surfactant of the present application, the R2, R3, R4 are the same or different, each independently selected from at least one of hydrogen, methyl, ethyl and phenyl.

[0020] The second aspect of the present application provides a method for preparing a non-ionic surfactant, the method comprising steps of:

[0021] Step A, mixing at least one of ethylene oxide, propylene oxide, butylene oxide, a starter and a catalyst to react, to obtain an alkoxylation reaction product;

[0022] Step B, mixing the alkoxylation reaction product with a silanol, to obtain the non-ionic surfactant.

[0023] According to some embodiments of the method of the present application, the starter is selected from at least one of C 11 ~ C 17 alkyl alkanolamide. For example, the starter can be selected from at least one of undecyl alkanolamide, dodecyl alkanolamide, tridecyl alkanolamide, tetradecyl alkanolamide, pentadecyl alkanolamide, hexadecyl alkanolamide and heptadecyl alkanolamide.

[0024] According to some embodiments of the method for preparing a non-ionic surfactant of the present application, the catalyst is selected from at least one of alkali metal hydroxide, DMC bimetallic polyether catalyst and phosphazene catalyst.

[0025] According to some embodiments of the method for preparing non-ionic surfactant according to the present application, the alkali metal hydroxide is selected from at least one of sodium hydroxide, potassium hydroxide and calcium hydroxide.

[0026] According to some embodiments of the method for preparing non-ionic surfactant according to the present application, the silanol is selected from at least one of trimethylsilanol, triethylsilanol and triphenylsilanol.

[0027] According to some embodiments of the method for preparing non-ionic surfactant according to the present application, the reaction condition in step A includes that the reaction temperature is 140-200℃ and the reaction pressure is 0-5MPa. For example, the reaction temperature can be 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, and any value and any combination range between them. The reaction pressure can be 0MPa, 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa, 4.5MPa, 5MPa, and any value and any combination range between them.

[0028] According to some embodiments of the method for preparing non-ionic surfactant according to the present application, the reaction condition in step B includes that the reaction temperature is 100-150℃ and the reaction pressure is 0-4MPa. For example, the reaction temperature can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, and any value and any combination range between them. The reaction pressure can be 0MPa, 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa, and any value and any combination range between them.

[0029] According to some embodiments of the method for preparing non-ionic surfactant according to the present application, the molar ratio of the starter to at least one of the added ethylene oxide, propylene oxide and butylene oxide is 1:(1-50). For example, the molar ratio of the starter to at least one of the added ethylene oxide, propylene oxide and butylene oxide is 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, and any value and any combination range between them.

[0030] According to some embodiments of the method for preparing the non-ionic surfactant according to the present application, the weight ratio of the catalyst to the initiator is (0.001% to 2.0%): 1. For example, the weight ratio of the catalyst to the initiator can be 0.001%: 1, 0.01%: 1, 0.02%: 1, 0.03%: 1, 0.04%: 1, 0.05%: 1, 0.06%: 1, 0.07%: 1, 0.08%: 1, 0.09%: 1, 0.1%: 1, 0.2%: 1, 0.3%: 1, 0.4%: 1, 0.5%: 1, 0.6%: 1, 0.7%: 1, 0.8%: 1, 0.9%: 1, 1.0%: 1, 1.5%: 1, 2.0%: 1, and any value and any combination range therebetween.

[0031] According to some embodiments of the method for preparing the non-ionic surfactant according to the present application, the weight ratio of the alkoxylated reaction product to the silanol is (1 to 50): 1. For example, the weight ratio of the alkoxylated reaction product to the silanol can be 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, 10: 1, 15: 1, 20: 1, 25: 1, 30: 1, 35: 1, 40: 1, 45: 1, 50: 1, and any value and any combination range therebetween.

[0032] According to some embodiments of the method for preparing the non-ionic surfactant according to the present application, the weight ratio of the catalyst to the initiator is (0.001% to 2.0%): 1. For example, the weight ratio of the catalyst to the initiator can be 0.001%: 1, 0.01%: 1, 0.02%: 1, 0.03%: 1, 0.04%: 1, 0.05%: 1, 0.06%: 1, 0.07%: 1, 0.08%: 1, 0.09%: 1, 0.1%: 1, 0.2%: 1, 0.3%: 1, 0.4%: 1, 0.5%: 1, 0.6%: 1, 0.7%: 1, 0.8%: 1, 0.9%: 1, 1.0%: 1, 1.5%: 1, 2.0%: 1, and any value and any combination range therebetween.

[0033] The third aspect of the present application provides a flushing oil agent, which comprises a co-agent and a non-ionic surfactant, wherein the non-ionic surfactant is the non-ionic surfactant described above or prepared by the method for preparing the non-ionic surfactant described above.

[0034] According to some embodiments of the flushing oil agent according to the present application, the co-agent is selected from at least one of ethanolamine, diethanolamine, ethylene glycol butyl ether, diethylene glycol butyl ether, and propylene glycol butyl ether.

[0035] According to some embodiments of the flushing oil agent according to the present application, the weight ratio of the non-ionic surfactant to the co-agent is 1:(0.01 to 10). For example, the weight ratio can be 1:0.01, 1:0.05, 1:0.1, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, and any value and any combination range therebetween.

[0036] According to a preferred embodiment of the oil washing agent of the present application, the weight ratio of the non-ionic surfactant and the auxiliary agent is 1:(0.05-2).

[0037] According to a preferred embodiment of the oil washing agent of the present application, the weight ratio of the non-ionic surfactant and the auxiliary agent is 1:(0.05-0.5).

[0038] According to some embodiments of the oil washing agent of the present application, the oil washing agent further comprises water.

[0039] According to a preferred embodiment of the oil washing agent of the present application, the salinity of the water is 0-25wt%. For example, the salinity of the water in the present application can be 0wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, and any value and any combination range therebetween.

[0040] According to some embodiments of the oil washing agent of the present application, the mass concentration of the oil washing agent is ≤10%, preferably, the mass concentration of the oil washing agent is ≤1%, more preferably, the mass concentration of the oil washing agent is ≤0.3%.

[0041] The present application provides a preparation method of the oil washing agent, which comprises mixing the auxiliary agent with the non-ionic surfactant and optionally water.

[0042] The present application provides a method for oil displacement, which comprises alternately injecting the oil washing agent and CO2 for displacement after the oil reservoir is displaced to be oil-free, wherein the oil washing agent is the oil washing agent described above or prepared by the preparation method described above.

[0043] According to some embodiments of the method for oil displacement of the present application, the process of displacing the oil reservoir to be oil-free is to displace the oil reservoir to be oil-free by using the formation water.

[0044] According to some embodiments of the method for oil displacement of the present application, the temperature of the displacement process is 60-120℃. For example, the temperature of the displacement process can be 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, and any value and any combination range therebetween.

[0045] According to some embodiments of the method for oil displacement of the present application, the oil washing agent is mixed with water before the displacement.

[0046] According to a preferred embodiment of the oil displacement method of the present application, the pH of the mixed oil displacement agent and water is 3-8.

[0047] According to a specific embodiment of the oil displacement method of the present application, the oil displacement method comprises mixing the oil displacement agent with a required amount of water to obtain a temperature-resistant and acid-resistant oil displacement agent with a pH of 3-8. Under the temperature condition of the oil reservoir, the oil displacement agent is first displaced with the formation water until no oil is present, then the above oil displacement agent is injected, and then CO2 is injected, and the oil displacement agent and CO2 are injected alternately.

[0048] The sixth aspect of the present application provides the use of the above-mentioned non-ionic surfactant, the above-mentioned preparation method of the non-ionic surfactant, the above-mentioned oil displacement agent, the above-mentioned preparation method of the oil displacement agent, or the above-mentioned oil displacement method in the oil extraction process, preferably in the development of high water cut reservoirs. But not limited to this.

[0049] The beneficial effects of the present application are:

[0050] (1) The non-ionic surfactant provided by the present application can make the obtained non-ionic surfactant have super strong interfacial properties and wetting change properties by ethoxy modification and silane modification of alkyl diethanolamide. By controlling the length of the alkyl chain and the number of ethoxyl groups, the interfacial properties between the non-ionic surfactant and crude oil can be adjusted. At the same time, by introducing silane groups into the molecular structure, the surface tension of the non-ionic surfactant can be reduced, and the wetting properties can be improved.

[0051] (2) The oil displacement agent provided by the present application can ensure the solubilizing properties and interfacial properties of the surfactant at a lower concentration, and can further improve the spreading ability of the oil displacement agent and improve its wetting effect. Moreover, the oil displacement agent provided by the present application can resist high temperature and acid, greatly expanding its application range and use environment. DETAILED DESCRIPTION

[0052] In order to make the present application easier to understand, the present application will be described in detail below in conjunction with examples, which are only illustrative and do not limit the application range of the present application.

[0053] The test method of the present application and the equipment used in the test are as follows:

[0054] (1) The method for measuring the oil-water interfacial tension adopts the American TX-500C rotary drop interfacial tension meter.

[0055] (2) The core damage rate is calculated by measuring the permeability change before and after core damage using a core displacement device.

[0056] (3) Oil washing rate determination method is based on the China Petroleum and Chemical Corporation Enterprise Standard Q / SHCG 11-2017 "Oil Layer Cleaning Agent Technical Requirements".

[0057] The reagent raw materials used in the embodiments of the present application can be obtained by market purchase or prepared according to the preparation methods disclosed in the prior art.

[0058]

Example 1

[0059] (1) Preparation of non-ionic surfactant

[0060] The ethylene oxide, dodecyl alcohol amide and sodium hydroxide are mixed, and the obtained alkoxylation reaction product is mixed with trimethylsilanol to perform condensation reaction, thereby obtaining the non-ionic surfactant.

[0061] The weight ratio of the ethylene oxide, dodecyl alcohol amide, sodium hydroxide and trimethylsilanol is 30:100:1:30; n1+n2=4; the temperature of the alkoxylation reaction is 170°C, and the pressure is 1 MPa; the temperature of the condensation reaction is 135°C, and the pressure is 1 MPa.

[0062] (2) Preparation of oil washing agent

[0063] The above non-ionic surfactant is mixed with diethanolamine according to a weight ratio of 1:0.1, and is dissolved in a 20000mg / L NaCl aqueous solution at a temperature of 20°C, thereby obtaining an oil washing agent with a mass concentration of 0.3wt%.

[0064] The oil washing agent obtained in this example is tested for performance under different pH conditions at 70°C, and the test results are shown in Table 1, which shows that the oil washing agent provided in this example has little change in performance under different acid-base conditions, and has good performance, i.e. good acid resistance.

[0065] Table 1

[0066]

[0067]

[0068]

Example 2

[0069] (1) Preparation of non-ionic surfactant

[0070] The ethylene oxide, dodecyl alcohol amide and sodium hydroxide are mixed, and the obtained alkoxylation reaction product is mixed with trimethylsilanol to perform condensation reaction, thereby obtaining the non-ionic surfactant.

[0071] The weight ratio of ethylene oxide, dodecyl alcohol amide, sodium hydroxide and trimethylsilanol is 75:100:1:30; n1+n2=10; the temperature of alkoxylation reaction is 170℃, and the pressure is 1MPa; the temperature of condensation reaction is 135℃, and the pressure is 1MPa.

[0072] (2) Preparation of the oil washing agent

[0073] The non-ionic surfactant and diethylene glycol butyl ether are mixed according to the weight ratio of 1:0.2, and are dissolved in 35000mg / L NaCl aqueous solution at 25℃ to obtain the oil washing agent with a mass concentration of 0.2wt%.

[0074] The oil washing agent obtained in this example is tested for performance at 120℃ and pH 7, and the test results are shown in Table 2, indicating that the oil washing agent provided in this example has good temperature resistance.

[0075] Table 2

[0076] Surface tension mN / m Solubilisation parameter Oil-water interfacial tension mN / m Oil displacement efficiency % 25.2 20 3.12 x 10 -3 ]]> 95.2

[0077]

Example 3

[0078] The preparation process is the same as that of Example 1, except that the ethylene oxide is replaced by propylene oxide, and in the obtained non-ionic surfactant, m1+m2=3. The oil washing agent obtained in this example is tested for performance at 120℃ and different pH conditions, and the test results are shown in Table 3. Among them, the lower pH condition cannot be realized at a higher temperature.

[0079] Table 3

[0080]

[0081]

[0082]

Example 4

[0083] The preparation process is the same as that of Example 1, except that the ethylene oxide is replaced by butylene oxide. In the obtained non-ionic surfactant, j1+j2=2. The oil washing agent obtained in this example is tested for performance at 55℃ and different pH conditions, and the test results are shown in Table 4.

[0084] Table 4

[0085] pH Surface tension mN / m Solubilisation parameter Oil-water interfacial tension mN / m Oil displacement efficiency % 4 24.1 17 1.12 x 10 -3 ]] 84.1 5 25.2 18 2.14 x 10 -3 ]] 82.5 6 26.1 16 1.78 x 10 -3 ]]> 83.1 8 25.5 17 2.36 x 10 -3 ]] 84.0

[0086]

Example 5

[0087] The preparation process is the same as that of Example 1, except that the ethylene oxide is replaced by butylene oxide. The oil washing agent obtained in this example is tested for performance at 140°C and pH 7, and the test results are shown in Table 5.

[0088] Table 5

[0089] Surface tension mN / m Solubilisation parameter Oil-water interfacial tension mN / m Oil displacement efficiency % 24.6 19 4.18 x 10 -3 ]]> 90.0

[0090]

Example 6

[0091] The preparation process is the same as that of Example 1, except that the trimethylsilanol is replaced by triphenylsilanol. The oil washing agent obtained in this example is tested for performance at 240°C and different pH, and the test results are shown in Table 6.

[0092] Table 6

[0093]

[0094]

[0095]

Example 7

[0096] The preparation process is the same as that of Example 1, except that the weight ratio of ethylene oxide, dodecyl alcohol amide, sodium hydroxide, and trimethylsilanol is 45:100:1:30. The oil washing agent obtained in this example is tested for performance at 50°C and different pH, and the test results are shown in Table 7.

[0097] Table 7

[0098] pH Surface tension mN / m Solubilisation parameter Oil-water interfacial tension mN / m Oil displacement efficiency % 4 25.9 21 1.2 x 10 -3 ]]> 87.1 5 27.5 22 2.13 x 10 -3 ]]> 88.9 6 26.1 19 2.89 x 10 -3 ]] 87.9 8 26.8 20 3.01 x 10 -3 ]] 88.0

[0099]

Example 8

[0100] The preparation process is the same as that of Example 1, except that the weight ratio of ethylene oxide, dodecyl alcohol amide, sodium hydroxide, and trimethylsilanol is 90:100:1:30. The oil washing agent obtained in this example is tested for performance at 50°C and different pH, and the test results are shown in Table 8.

[0101] Table 8

[0102] pH Surface tension mN / m Solubilisation parameter Oil-water interfacial tension mN / m Oil displacement efficiency % 4 26.2 17 4.2 x 10 -3 ]]> 83.1 5 25.9 18 5.3 x 10 -3 ]]> 84.7 6 26.7 16 4.9 x 10 -3 ]]> 85.1 8 27.1 17 3.9 x 10 -3 ]]> 87.2

[0103]

Example 9

[0104] The preparation process is the same as that of Example 1, except that the weight ratio of ethylene oxide, dodecyl alcohol amide, sodium hydroxide, and trimethylsilanol is 150:100:1:30. The oil washing agent obtained in this example is tested for performance at 50°C and different pH, and the test results are shown in Table 9.

[0105] Table 9

[0106]

[0107]

[0108]

Example 10

[0109] The nonionic surfactant prepared in step (1) of Example 1 was mixed with diethanolamine in different weight ratios. The different weight ratios of nonionic surfactant to diethanolamine are shown in Table 10 below. The mixtures were dissolved in 20000 mg / L NaCl aqueous solution at 20°C to obtain a washing agent with a mass concentration of 0.3 wt%. Performance tests were conducted at 70°C and pH=8, and the test results are shown in Table 10.

[0110] Table 10

[0111] Weight ratio Surface tension mN / m Solubilisation parameter Oil-water interfacial tension mN / m Oil displacement efficiency % 1：0 26.5 16 2.84 x 10 -3 ]] 90.2 1：0.1 26.4 18 9.21 x 10 -4 ]]> 91.5 1：0.2 26.3 10 1.9 x 10 -2 ]]> 92.1 1：1 26.2 7 4.7 x 10 -2 ]]> 93.1

[0112] Table 10 shows that, without the addition of additives, the nonionic surfactant alone exhibits strong emulsifying and solubilizing abilities and low interfacial tension. The best interfacial performance of the resulting washing agent is achieved when the weight ratio of the nonionic surfactant to diethanolamine is 1:0.1. Subsequently, the interfacial performance deteriorates with increasing weight percentage of the added additives. Different weight ratios have little effect on surface tension and washing efficiency, all exhibiting low surface tension and high washing efficiency.

[0113]

Example 11

[0114] The nonionic surfactant obtained in Example 1 was mixed with diethanolamine at a weight ratio of 1:0.1 to obtain an oil washing agent. This oil washing agent was then used in a core alternating flooding experiment with carbon dioxide. After injecting 1.5 PV (pore volume) of water, the recovery rate was 55%. Alternating flooding with the oil washing agent / CO2 was then employed, with the injection pressure increased to 0.035 MPa. The rate of water cut increase was relatively slow. At a total injection volume of 2.15 PV, the recovery rate reached 72%; at a total injection volume of 2.85 PV, the recovery rate reached 80%; and with continued flooding up to 3.6 PV, the recovery rate reached 88.8%.

[0115] In this embodiment, during the alternating flooding process of the wash agent / CO2, multiple alternating flooding operations expand the sweep range of the liquid and gas phases, increasing the displacement pressure. As the alternating flooding proceeds, the water saturation in the core pores gradually increases, and the injected water begins to occupy the large channels, forming a continuous phase in the center of the pores, while the gas phase seeps in the form of smaller bubbles. Oil accumulates around the gas in the form of an oil film; while water drives the gas, it also extracts the oil, thereby further improving the oil recovery rate.

[0116] Comparative Example 1

[0117] The nonionic surfactant shown in the following formula (3) was mixed with diethanolamine at a weight ratio of 1:0.1, and dissolved in a 20000 mg / L NaCl aqueous solution at a temperature of 20°C to obtain a mass concentration of 0.3wt% of the oil washing agent.

[0118] The performance of the obtained oil washing agent was tested at 70°C, pH=8, and the test results are shown in Table 11, and compared with the performance of the oil washing agent obtained in Example 1 at 70°C, pH=8.

[0119]

[0120] Comparative Example 2

[0121] The nonionic surfactant shown in the following formula (4) was mixed with diethanolamine at a weight ratio of 1:0.1, and dissolved in a 20000 mg / L NaCl aqueous solution at a temperature of 20°C to obtain a mass concentration of 0.3wt% of the oil washing agent.

[0122] The performance of the obtained oil washing agent was tested at 70°C, pH=8, and the test results are shown in Table 11, and compared with the performance of the oil washing agent obtained in Example 1 at 70°C, pH=8.

[0123]

[0124] Table 11

[0125] Surface tension mN / m Solubilisation parameter Oil-water interfacial tension mN / m Oil displacement efficiency % Comparative Example 1 28.5 2 7.82 x 10 -1 ]] 76.2 Comparative Example 2 28.9 5 1.9 x 10 -3 ]] 82.4 Example 1 26.4 18 9.21 x 10 -4 ]]> 91.5

[0126] As can be seen from Table 11, the nonionic surfactant in Example 1 has lower surface tension and oil-water interfacial tension after introducing silane, which can greatly improve the wettability of oil sand and increase the oil washing rate. Moreover, the introduction of ethoxy in the nonionic surfactant can effectively adjust the interfacial properties of the oil washing agent and crude oil.

[0127] Test Example

[0128] (1) The determination method of oil-water interfacial tension is:

[0129] Phase behavior experiments were mainly conducted by glass capillary method. A certain amount of surfactant solution and crude oil were added into a sealed capillary tube in the order of water to oil ratio (WOR) 1:1, and the liquid level of surfactant solution and crude oil and the mass of each added were recorded. Then the glass capillary tube was sealed by acetylene flame or epoxy resin glue and immersed in a 10-milliliter capacity oil bath glass test tube filled with silicone oil, and placed in a metal bath (Hanuo Instruments) for heating at a reservoir temperature of 52°C. The test tube was first shaken manually or mechanically to mix the oil and water phases uniformly, and then equilibrated in the constant temperature metal bath for several days to several weeks until the oil and water liquid levels no longer changed. According to the change of the oil-water interface liquid level in the microemulsion, the solubilization parameter (SP) of the oil phase and the water phase can be calculated:

[0130]

[0131] where V i is the volume of the water phase or the oil phase in the microemulsion, V s is the volume of the surfactant. The calculation of the SP parameter has three assumptions: the total volume does not change after the oil and water are mixed; all the surfactant is in the microemulsion phase; and the volume of the surfactant is equal to its mass.

[0132] (2) Oil washing rate determination method includes the following steps:

[0133] 1) Preparation of standard oil solution

[0134] 0.5 g (accurate to 0.0001 g) of artificial oil stain was weighed into a 100 mL volumetric flask, dissolved and diluted to the mark with petroleum ether with a boiling range of 60°C-90°C. The oil concentration of this solution was 5.0 mg / mL.

[0135] 2) Preparation of standard curve

[0136] 0.0 mL, 0.2 mL, 0.4 mL, 0.6 mL, 0.8 mL, 1.0 mL, 1.2 mL, and 1.4 mL of the standard oil solution were respectively taken with a pipette into 8 clean 50 mL volumetric flasks, diluted to the mark with petroleum ether with a boiling range of 90°C-120°C, and the absorbance was measured on a spectrophotometer with a wavelength of 225 nm and a 1 cm cuvette, using petroleum ether with a boiling range of 90°C-120°C as a blank. The standard curve was plotted according to the measured absorbance values and the corresponding oil content.

[0137] 3) Preparation of oil sand

[0138] Take 3.675 g crude oil in a 250 mL beaker, add 10 mL petroleum ether with boiling range of 60-90°C to dissolve the artificial oil stain, add 156.260 g quartz sand to the solution, stir well to mix the sand and oil stain, heat and stir in a water bath at 80-90°C for more than 0.5 h, evaporate the petroleum ether, and the oil sand is obtained.

[0139] 4) Sample preparation

[0140] Prepare the sample of the oil washing agent into a 0.3% and 1% mass fraction solution in distilled water for use.

[0141] 5) Take 3.0 g oil sand in a 50 mL blue cap bottle, add 10 mL of the prepared sample, place the blue cap bottle in a 60°C constant temperature water bath, take out the blue cap bottle every 15 min, gently turn it 10 times, and then place it in the water bath, after 1 h of total placement, take it out, shake it, and place it on a colorimetric rack. Carefully pour off the washing liquid.

[0142] 6) Rinse the residual cleaning agent solution in the blue cap bottle with distilled water until the rinsing liquid is transparent.

[0143] 7) Place the rinsed blue cap bottle with oil sand in an oven at (105±1) °C for 4 h, and then take it out and place it in a desiccator until it reaches room temperature.

[0144] 8) Add 50 mL petroleum ether with boiling range of 90-120°C to the blue cap bottle, shake well, and then pipette the petroleum ether solution, measure the absorbance on a spectrophotometer, and find the residual oil content in the blue cap bottle on a standard curve.

[0145] 9) Calculation of oil washing rate

[0146] The oil washing rate is calculated according to the following formula:

[0147]

[0148] In the formula, X is the oil washing rate, K is the mass fraction of oil in the oil sand, %, W0 is the mass of the oil sand, g, and W1 is the residual oil content in the oil sand in the blue cap bottle, g.

[0149] The above is only a preferred example of the present application. It should be noted that for those skilled in the art, under the technical inspiration provided by the present application, other equivalent variants and improvements as common knowledge in the art can also be made, and should be considered as the protection scope of the present application.

Claims

1. A non-ionic surfactant, the non-ionic surfactant is selected from at least one of the following formula (1) : wherein, x is an integer between 2 and 4; and / or, y is an integer between 2 and 4; and / or, R 2, R 3, R 4 are the same or different, each independently selected from any one of hydrogen, methyl, ethyl and phenyl. Formula (1) In formula (1), R1is selected from at least one of C 11 ~C 17 fatty groups; x is an integer between 1 and 4; y is an integer between 1 and 4; -Polym1- is selected from at least one of -(PO) m1 -, -(EO) n1 -, and -(BO) j1 -; -Polym2- is selected from at least one of -(PO) m2 -, -(EO) n2 -, and -(BO) j2 -; wherein, when -Polym1- is selected from -(PO) m1 - and / or -Polym2- is selected from -(PO) m2 - m1+m2=2-10 when -Polym1- is selected from -(EO) n1 - and / or -Polym2- is selected from -(EO) n2 - n1+n2=2-15 when -Polym1- is selected from -(BO) j1 - and / or -Polym2- is selected from -(BO) j2 - j1+j2=2-8; R2, R3, R4 are the same or different, each independently selected from any one of hydrogen, C1-C4 alkyl and phenyl.

2. The nonionic surfactant according to claim 1, characterized in that, x is 2; and / or, y is 2. said -Polym1- is selected from the group consisting of -(PO) m1 - and -(EO) n1 - at least one of; and / or, said -Polym2- is selected from the group consisting of - (PO) m2 - and - (EO) n2 - at least one of; and / or, The preparation method comprises the following steps:

3. The nonionic surfactant according to claim 2, characterized in that, Step A, mixing at least one of ethylene oxide, propylene oxide, butylene oxide, a starting agent and a catalyst to react, to obtain an alkoxylation reaction product; Step B, mixing the alkoxylation reaction product with a silanol to obtain the non-ionic surfactant; 4. A process for the preparation of a nonionic surfactant as claimed in any one of claims 1 to 3, characterised in that, The catalyst is selected from at least one of alkali metal hydroxide, DMC bimetallic polyether catalyst and phosphazene catalyst; and / or, The silanol is selected from at least one of trimethylsilanol, triethylsilanol and triphenylsilanol; and / or, The reaction conditions in step A include: the reaction temperature is 140-200 ℃, and the reaction pressure is 1-5 MPa; and / or, The starter is selected from at least one of a C 11 ~C 17 alkanolamide.

5. The production method according to claim 4, characterized by, The reaction conditions in step B include: the reaction temperature is 100-150 ℃, and the reaction pressure is 1-4 MPa; and / or, The molar ratio of the starting agent to the added at least one of ethylene oxide, propylene oxide and butylene oxide is 1: (1-50) ; and / or, The weight ratio of the catalyst to the starting agent is (0.001%-2.0%) : 1; and / or, The weight ratio of the alkoxylation reaction product to the silanol is (1-50) :

1. The oil washing agent comprises an auxiliary agent and a non-ionic surfactant, wherein the non-ionic surfactant is the non-ionic surfactant of any one of claims 1-3 or the non-ionic surfactant prepared by the preparation method of claim 4 or 5. The auxiliary agent is selected from at least one of ethanolamine, diethanolamine, ethylene glycol butyl ether, diethylene glycol butyl ether and propylene glycol butyl ether; and / or, The weight ratio of the non-ionic surfactant to the auxiliary agent is 1: (0.01-10).

6. A wash oil agent characterized by, The weight ratio of the non-ionic surfactant to the auxiliary agent is 1: (0.05-2) ; and / or, 7. The oil wash of claim 6, wherein, The oil washing agent further comprises water. The weight ratio of the non-ionic surfactant to the auxiliary agent is 1: (0.05-0.5) ; and / or, 8. The oil wash of claim 7, wherein, The salinity of the water is 0-25 wt%; and / or, The mass concentration of the oil washing agent is ≤10%.

9. The oil wash of claim 8, wherein, The mass concentration of the oil washing agent is ≤1%. The mass concentration of the oil washing agent is ≤0.3%. The preparation method is to mix the auxiliary agent and the non-ionic surfactant.

10. The oil wash of claim 9, wherein, The oil displacement method is to inject the oil washing agent and CO 2 alternately for displacement after the oil reservoir is displaced to be oil-free, wherein the oil washing agent is the oil washing agent of any one of claims 6-11 or the oil washing agent prepared by the preparation method of claim 12.

11. The oil wash of claim 10, wherein, The process of displacing the oil reservoir to be oil-free is to use formation water to displace the oil reservoir to be oil-free; and / or, 12. A process for the preparation of the oil washing agent according to any one of claims 6 to 11, characterized in that, The temperature of the displacement process is 60-120 ℃; and / or, 13. A method of oil recovery, characterized by, ​ 14. The method of flooding according to claim 13, wherein, ​ ​ The oil displacing agent is mixed with water.

15. The method of flooding according to claim 14, wherein, The oil displacing agent has a pH of 3 to 8 when mixed with water.

16. Use of a nonionic surfactant as defined in any one of claims 1 to 3, a method of preparing a nonionic surfactant as defined in claim 4 or 5, a flushing oil as defined in any one of claims 6 to 11, a method of preparing a flushing oil as defined in claim 12, or an oil displacement method as defined in any one of claims 13 to 15 in an oil recovery process.

17. Use according to claim 16, characterized in that, The use is in the development of high water cut reservoirs. The use is in the development of high water cut reservoirs.

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