An enhanced oil recovery oil displacement agent, a binary oil displacement system and application thereof

Abstract

The application belongs to the technical field of petroleum chemical industry, and particularly relates to an oil displacement agent for enhanced oil recovery, a binary oil displacement system and application thereof. The oil displacement agent is composed of the following components in parts by weight: alkyl polyglycoside sulfonate 10-50 parts, cyclodextrin 10-25 parts, additive 5-10 parts, and water 15-80 parts. The binary oil displacement system is composed of the following components in percentage by mass: the oil displacement agent 0.2%-0.5%, polymer 0.2%-0.3%, and the rest is injection water. The oil displacement agent and the oil displacement system can improve the recovery ratio of offshore oil reservoirs, and can realize efficient production and stable long-term effect under the condition of large well spacing injection-production well pattern.

Description

Technical Field

[0001] The present invention belongs to the technical field of petrochemical industry, and in particular relates to an oil displacement agent for improving oil recovery, a binary oil displacement system and applications thereof. Background Art

[0002] my country currently faces significant energy shortages and a vast reservoir of untapped oil resources. The importance of offshore resources is gaining increasing attention worldwide. Since their development began in the mid-20th century, my country's offshore oil fields have occupied a crucial position in the nation's energy structure. The main challenge is the significant conflict between low oil production rates and recovery rates, coupled with short platform lifespans, which hinders the full utilization of resources. Therefore, it is necessary to research effective ways to increase oil production rates and recovery rates.

[0003] Binary composite flooding is a more promising new tertiary oil recovery technology after polymer flooding. It is a process of adding surfactants to polymer solutions. On the one hand, it can play the role of polymer viscosity increase and expand the swept volume. On the other hand, it can play the synergistic role of surfactants and reduce the residual oil saturation of water flooding. It can improve the recovery rate more quickly and to a greater extent than single polymer flooding. At the same time, it also avoids the problems of scaling, corrosion, emulsification, etc. caused by the ternary composite flooding system.

[0004] Binary composite flooding has been widely promoted and applied in Shengli Oilfield onshore oilfield, with a cumulative oil production increase of more than 3000×10 4 Tons of oil have been produced, achieving good economic and social benefits. Compared with the reservoir conditions of binary composite flooding units in onshore oilfields, offshore oilfields have favorable conditions for implementing this technology. However, due to the large injection-production well spacing in offshore oilfields (about 1.5 times that of onshore oilfields), the long migration time of the oil displacement agent, the high salinity of the injected water (30,000 mg / L), and the high divalent ion content (1,800 mg / L), the current onshore chemical agents are difficult to promote and apply in offshore oilfields. Therefore, it is necessary to develop efficient, long-lasting oil displacement agents and binary composite flooding systems with strong salt resistance, calcium and magnesium resistance.

[0005] At present, there are many studies on surfactants for oil displacement. Chinese patent CN102504792 A provides an oil displacement agent suitable for ultra-high temperature, high salt, high calcium and magnesium homogeneous oil reservoirs. The oil displacement agent is composed of a dialkyl ether disulfonate surfactant 1,2-bis(sodium 2-oxypropylene sulfonate-3-alkyl ether-propyl) glycol ether, nonylphenol polyoxyethylene ether or fatty alcohol polyoxyethylene ether and anhydrous ethanol. The system is heated at a temperature of 100-130 ° C and a mineralization degree of 5-20×10 4 mg / L, calcium and magnesium ion content is 5~15×10 3mg / L of oil reservoir, has good ability to reduce oil-water interfacial tension and significant performance to change rock wettability, is suitable for ultra-high temperature, high salt, high calcium and magnesium homogeneous oil reservoir, but the long migration time of the oil displacement agent in the formation caused by the large injection-production well spacing of offshore oilfield, so the oil displacement agent requires long-term thermal stability, the long-term thermal stability of the oil displacement agent system described in the patent needs to be further verified.

[0006] Chinese patent CN105368430B provides an oil displacement agent, a preparation method thereof and a method for enhanced oil recovery, the oil displacement agent is composed of surfactant, polymer and alkaline substance, the system can increase the recovery rate by 27.98% on the basis of water flooding for dehydrated crude oil in Henan oilfield, and has good technical effect, but due to the high content of divalent ions in the injected water of Shengli oilfield, the alkaline substance will react to generate precipitate, resulting in serious scaling in the injection system, so the method is not suitable for Shengli offshore oilfield.

[0007] Chinese patent CN104797679B provides a tertiary oil recovery method, the disclosed oil displacement system is composed of water-soluble polyacrylamide polymer, hydrophobic organic liquid, surfactant for stabilizing water-in-oil emulsion and surfactant for stabilizing dispersion system. According to step 1, the surfactant C1 is a surfactant for stabilizing water-in-oil emulsion, and C2 is an oligomer or polymer surfactant, both of which are used to stabilize the polymer system, and the surfactant for improving oil washing efficiency is not mentioned. SUMMARY

[0008] To solve the above problems, the present application provides an oil displacement agent for improving recovery rate, a binary oil displacement system and application thereof. The oil displacement agent and the oil displacement system can improve the recovery rate of offshore oil reservoirs and realize efficient production and stable long-term performance of the system under the condition of large well spacing injection-production well pattern.

[0009] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0010] In a first aspect of the present application, an oil displacement agent for improving recovery rate is provided, which is composed of the following components by weight: alkyl glycoside sulfonate 10-50 parts, cyclodextrin 10-25 parts, additive 5-10 parts, and water 15-80 parts.

[0011] In the present application, the alkyl glycoside sulfonate is obtained by alkalization-etherification reaction of alkyl glycoside.

[0012] Further, the alkyl glycoside sulfonate has the following structure shown in formula (I):

[0013]

[0014] In formula (I), n=1-3, R is a linear or branched alkyl group, and M is Na or K.

[0015] Further, the R is a linear or branched alkyl group with a carbon number of 10-16, and M is Na.

[0016] Further, the cyclodextrin is β-cyclodextrin.

[0017] Further, the additive is one or more of ethanolamine, diethanolamine, and triethanolamine.

[0018] In a second aspect of the present application, a binary oil displacement system is provided, which is composed of the following components in mass percentage: 0.2-0.5% of the oil displacement agent, 0.2-0.3% of the polymer, and the rest being injection water.

[0019] The oil displacement agent is the oil displacement agent described in the first aspect above.

[0020] Further, the polymer is partially hydrolyzed polyacrylamide with a molecular weight of 25-35 million.

[0021] Further, the injection water has a salinity of 5000-30000 mg / L, and the content of divalent ions in the water is 0-1800 mg / L.

[0022] In a third aspect of the present application, a preparation method of the binary oil displacement system described in the second aspect above is provided, which comprises the following steps: mixing the oil displacement agent and the injection water in a certain proportion to prepare an oil displacement agent solution, adding the polymer, continuing to stir to obtain an oil displacement agent-polymer mother liquor, and then aging, and finally diluting with the injection water in a certain proportion to obtain a binary oil displacement system for offshore oil fields, wherein the concentration of the oil displacement agent is 0.2-0.5%, and the concentration of the polymer is 0.2-0.3%.

[0023] In a fourth aspect of the present application, the binary oil displacement system described in the second aspect above is applied in offshore oil reservoir exploitation.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] (1) The oil displacement agent described in the present application is compounded by alkyl glycoside sulfonate, cyclodextrin, and alcohol amine additive. Both alkyl glycoside and β-cyclodextrin have good biodegradability, are non-toxic and non-irritating, and are recognized as "green" surfactants worldwide. The introduction of sulfonic acid group to alkyl glycoside enhances the hydration capacity of alkyl glycoside, greatly improves the water solubility, salt tolerance, and interfacial activity of alkyl glycoside. At the same time, the addition of β-cyclodextrin can reduce the interfacial tension between the binary system and crude oil, and improve the oil washing efficiency.

[0026] (2) The oil displacement agent described in the present application has excellent long-term thermal stability, which meets the technical requirements of long-term effectiveness of the oil displacement agent under the condition of large well spacing in offshore oil fields.

[0027] (3) The binary oil displacement system of the present application, by using alkyl glycoside sulfonate, cyclodextrin and polymer in combination, on the one hand, the viscoelasticity of the system is increased by the polymer to improve the sweep efficiency, and on the other hand, the oil-water interfacial tension is reduced by the oil displacement agent to improve the oil washing efficiency, thereby achieving the effect of greatly improving the recovery rate. DETAILED DESCRIPTION

[0028] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0029] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the term "comprising", "including", etc. is used in the specification, it means that the features, steps, operations, and combinations thereof are present.

[0030] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific examples.

[0031] The polymer described in the following examples of the present application preferably uses partially hydrolyzed polyacrylamide produced by Dongying Baomo Environmental Engineering Co., Ltd., and its solid content is 90%.

[0032] Example 1

[0033] An oil displacement agent A for enhanced oil recovery, the oil displacement agent A is composed of the following components by weight: alkyl glycoside sulfonate 40 parts, β-cyclodextrin 10 parts, ethanolamine 8 parts, water 42 parts.

[0034] The structure of the alkyl glycoside sulfonate is shown in formula (I), wherein R is a linear alkyl group with 12 carbon atoms, M is Na, and n = 1.

[0035] A binary oil displacement system, the binary oil displacement system is composed of the following components by mass percentage: oil displacement agent A 0.4%, polymer 0.25%, and injection water 99.35%.

[0036] The molecular weight of the polymer is 30 million.

[0037] The injection water has a salinity of 30,000 mg / L, and the content of divalent ions in the water is 1,800 mg / L.

[0038] The preparation method of the binary oil displacement system is as follows: first, the oil displacement agent and the injection water are mixed in proportion to prepare an oil displacement agent solution, then the polymer is added and stirring is continued for 2 hours to obtain an oil displacement agent-polymer mother liquor, then the oil displacement agent-polymer mother liquor is aged for 24 hours, and finally the oil displacement agent-polymer mother liquor is diluted with the injection water in proportion.

[0039] Example 2

[0040] An oil displacement agent B for enhanced oil recovery, which is composed of the following components in parts by weight: alkyl glycoside sulfonate 30 parts, β-cyclodextrin 25 parts, diethanolamine 5 parts, and water 40 parts.

[0041] The alkyl glycoside sulfonate has the structure shown in formula (I), wherein R is a linear alkyl group with 14 carbon atoms, M is Na, and n = 2.

[0042] A binary oil displacement system, which is composed of the following components in mass percentage: oil displacement agent B 0.4%, polymer 0.25%, and injection water 99.35%.

[0043] The polymer has a molecular weight of 30 million.

[0044] The injection water has a salinity of 30000 mg / L and a divalent ion content of 1800 mg / L in the water.

[0045] The preparation method of the binary oil displacement system is the same as that in Example 1.

[0046] Example 3

[0047] An oil displacement agent C for enhanced oil recovery, which is composed of the following components in parts by weight: alkyl glycoside sulfonate 30 parts, β-cyclodextrin 10 parts, ethanolamine 5 parts, diethanolamine 5 parts, and water 50 parts.

[0048] The alkyl glycoside sulfonate has the structure shown in formula (I), wherein R is a linear alkyl group with 14 carbon atoms, M is Na, and n = 1.

[0049] A binary oil displacement system, which is composed of the following components in mass percentage: oil displacement agent C 0.4%, polymer 0.25%, and injection water 99.35%.

[0050] The polymer has a molecular weight of 30 million.

[0051] The injection water has a salinity of 30000 mg / L and a divalent ion content of 1800 mg / L in the water.

[0052] The preparation method of the binary oil displacement system is the same as that in Example 1.

[0053] Example 4

[0054] An enhanced oil recovery oil displacement agent D, the oil displacement agent D is composed of the following components by weight: alkyl glycoside sulfonate 50 parts, beta-cyclodextrin 10 parts, ethanolamine 8 parts, water 32 parts.

[0055] The alkyl glycoside sulfonate structure is shown in formula (I), wherein R is a linear alkyl group with 12 carbon atoms, M is Na, and n=2.

[0056] A binary oil displacement system, the binary oil displacement system is composed of the following components by mass percentage: oil displacement agent D 0.4%, polymer 0.25%, injection water 99.35%.

[0057] The polymer has a molecular weight of 300 million.

[0058] The injection water has a salinity of 30000 mg / L, and the content of divalent ions in the water is 1800 mg / L.

[0059] The preparation method of the binary oil displacement system is the same as that of example 1.

[0060] Example 5

[0061] An enhanced oil recovery oil displacement agent E, the oil displacement agent E is composed of the following components by weight: alkyl glycoside sulfonate 40 parts, beta-cyclodextrin 20 parts, ethanolamine 8 parts, water 32 parts.

[0062] The alkyl glycoside sulfonate structure is shown in formula (I), wherein R is a linear alkyl group with 12 carbon atoms, M is Na, and n=1.

[0063] A binary oil displacement system, the binary oil displacement system is composed of the following components by mass percentage: oil displacement agent E 0.4%, polymer 0.25%, injection water 99.35%.

[0064] The polymer has a molecular weight of 300 million.

[0065] The injection water has a salinity of 30000 mg / L, and the content of divalent ions in the water is 1800 mg / L.

[0066] The preparation method of the binary oil displacement system is the same as that of example 1.

[0067] Example 6

[0068] An enhanced oil recovery oil displacement agent F, the oil displacement agent F is composed of the following components by weight: alkyl glycoside sulfonate 10 parts, beta-cyclodextrin 25 parts, ethanolamine 10 parts, water 55 parts.

[0069] The alkyl glycoside sulfonate structure is shown in formula (I), wherein R is a branched alkyl group with 12 carbon atoms, M is Na, and n=1.

[0070] A binary flooding system consisting of the following components in mass percentage: flooding agent F 0.4%, polymer 0.25%, injection water 99.35%.

[0071] The polymer has a molecular weight of 35 million.

[0072] The injection water has a salinity of 5000 mg / L and a divalent ion content of 900 mg / L in water.

[0073] The binary flooding system is prepared in the same way as in Example 1.

[0074] Example 7

[0075] A flooding agent G for enhanced oil recovery, consisting of the following components in weight percentage: alkyl glycoside sulfonate 40 parts, β-cyclodextrin 10 parts, ethanolamine 8 parts, water 42 parts.

[0076] The alkyl glycoside sulfonate has a structure as shown in formula (I), wherein R is a linear alkyl group with 10 carbon atoms, M is K, and n = 1.

[0077] A binary flooding system consisting of the following components in mass percentage: flooding agent G 0.5%, polymer 0.3%, injection water 99.2%.

[0078] The polymer has a molecular weight of 250 million.

[0079] The injection water has a salinity of 30000 mg / L and a divalent ion content of 1800 mg / L in water.

[0080] The binary flooding system is prepared in the same way as in Example 1.

[0081] Example 8

[0082] A flooding agent H for enhanced oil recovery, consisting of the following components in weight percentage: alkyl glycoside sulfonate 40 parts, β-cyclodextrin 10 parts, ethanolamine 8 parts, water 42 parts.

[0083] The alkyl glycoside sulfonate has a structure as shown in formula (I), wherein R is a linear alkyl group with 16 carbon atoms, M is K, and n = 1.

[0084] A binary flooding system consisting of the following components in mass percentage: flooding agent H 0.2%, polymer 0.2%, injection water 99.6%.

[0085] The polymer has a molecular weight of 250 million.

[0086] The injection water has a salinity of 30000 mg / L and a divalent ion content of 1800 mg / L.

[0087] The preparation method of the binary oil displacement system is the same as that of Example 1.

[0088] Comparative Example 1

[0089] An oil displacement agent I, which is different from Example 1 in that the oil displacement agent I does not contain β-cyclodextrin and the weight part of water is 52 parts.

[0090] A binary oil displacement system, which is composed of the following components in mass percentage: 0.4% of the oil displacement agent I, 0.25% of the polymer and 99.35% of the injection water.

[0091] The polymer has a molecular weight of 30 million.

[0092] The injection water has a salinity of 30000 mg / L and a divalent ion content of 1800 mg / L.

[0093] Comparative Example 2

[0094] An oil displacement agent J, which is different from Example 1 in that the oil displacement agent J does not contain ethanolamine and the weight part of water is 50 parts.

[0095] A binary oil displacement system, which is composed of the following components in mass percentage: 0.4% of the oil displacement agent J, 0.25% of the polymer and 99.35% of the injection water.

[0096] The polymer has a molecular weight of 30 million.

[0097] The injection water has a salinity of 30000 mg / L and a divalent ion content of 1800 mg / L.

[0098] Comparative Example 3

[0099] An oil displacement agent K, which is different from Example 1 in that the oil displacement agent K does not contain β-cyclodextrin and ethanolamine and the weight part of water is 60 parts.

[0100] A binary oil displacement system, which is composed of the following components in mass percentage: 0.4% of the oil displacement agent K, 0.25% of the polymer and 99.35% of the injection water.

[0101] The polymer has a molecular weight of 30 million.

[0102] The injection water has a salinity of 30000 mg / L and a divalent ion content of 1800 mg / L.

[0103] The products obtained in the examples and comparative examples are subjected to performance test, and the test conditions and test methods are as follows:

[0104] Test conditions:

[0105] 1. Test instruments mainly include TX-500C interfacial tension meter and MCR301 rheometer

[0106] 2. The test temperature is 65℃

[0107] 3. The test water is offshore injection water, the salinity is 29858 mg / L, and the calcium and magnesium are 1577 mg / L

[0108] 4. The test oil is the dewatered crude oil of a certain block in the sea

[0109] Test method: 1. Interfacial tension performance test: the interfacial tension change between the oil displacement agent and the formation crude oil described in the embodiment is determined by using a TX-500C interfacial tension meter, and the measurement principle is a rotating droplet method.

[0110] 2. Oil washing rate performance test: the simulated formation sand and the target block crude oil are mixed in a ratio of 4:1 (mass ratio), placed in a constant temperature drying box, and aged at 65℃ for 7d, and stirred once a day to make the oil sand mixture uniform. Then the prepared oil sand and the oil displacement agent solution are mixed in a ratio of 1:10, placed in a 65℃ oven for 2d, and the oil washing performance of the oil displacement agent system is tested by using a weighing method.

[0111] 3. Thermal stability test: the filter bottle containing the oil displacement agent-polymer binary system solution is evacuated at-0.1 MPa for 1 hour, then filled with high-purity nitrogen, and placed in a glove box; about 50mL of solution is filled in each ampoule bottle in the glove box, and the ampoule bottle is sealed; after taking out, it is placed in a 65℃ oven, and the apparent viscosity and the interfacial tension between the system and the crude oil of the sample after being placed for 0, 30, 60, 90, 120, 150, 180 days are determined. The results are shown in Tables 1 and 2.

[0112] Table 1: Test results of interfacial tension and oil washing rate of oil displacement agent

[0113] Example Interfacial tension (mN / m) Raffinate rate Example 1 1.0 x 10 -3 ]] 52.6％ Example 2 2.2 x 10 -3 ]]> 50.9％ Example 3 5.6 x 10 -3 ]]> 48.9％ Example 4 1.0 x 10 -3 ]]> 49.9％ Example 5 2.2 x 10 -3 ]] 65.8％ Example 6 4.2 x 10 -3 ]] 40.2％ Example 7 3.1 x 10 -2 ]]> 41.3％ Example 8 2.1 x 10 -3 ]]> 46.8％ Comparative Example 1 6.6 x 10 -2 ]]> 25.6％ Comparative Example 2 1.2 x 10 -2 ]]> 48.6％ Comparative Example 3 2.2 x 10 -1 ]]> 21.2％

[0114] Table 2: Thermal stability test results of binary system (interfacial tension mN / m)

[0115]

[0116]

[0117] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. An enhanced oil recovery oil displacement agent, characterized by, The alkyl glycoside sulfonate 10~50 parts, cyclodextrin 10~25 parts, additives 5~10 parts, water 15~80 parts by weight; The alkyl glycoside sulfonate is shown in the following formula (I): ; wherein n = 1 to 3, R is a linear or branched alkyl group having 10 to 16 carbon atoms, and M is Na or K; The cyclodextrin is β-cyclodextrin. The additive is one or more of ethanolamine, diethanolamine and triethanolamine.

2. A binary oil displacement system characterized in that, The oil displacement agent 0.2%~0.5%, polymer 0.2%~0.3%, and the balance is injection water; The oil displacement agent is the oil displacement agent of claim 1.

3. The binary oil displacement system according to claim 2, wherein, The polymer is partially hydrolyzed polyacrylamide with a molecular weight of 25~35 million.

4. The binary oil displacement system of claim 2, wherein, The injection water has a salinity of 5000~30000 mg / L and a divalent ion content of 0~1800 mg / L.

5. A method of preparing the binary oil displacement system according to any one of claims 2 to 4, characterized in that, The method is: first, the oil displacement agent and the injection water are mixed in proportion to prepare an oil displacement agent solution, the polymer is added, and the stirring is continued to obtain an oil displacement agent-polymer mother liquor; then, the oil displacement agent-polymer mother liquor is aged, and finally, the injection water is diluted in proportion to obtain the oil displacement agent-polymer solution.

6. The use of the binary oil displacement system of any one of claims 2~4 in offshore oil reservoir exploitation.

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