Oil displacement compositions and oil displacement agents and their applications

Abstract

This invention relates to the field of oilfield chemistry, and discloses an oil displacement composition and an oil displacement agent, as well as their applications. The oil displacement composition comprises component A and component B, wherein component A has the structure shown in Formula I, and component B has the structure shown in Formula II; wherein R1 is a C1-C8 alkanol or a C6-C8 aromatic alcohol; PO is a polyoxypropylene segment; EO is a polyoxyethylene segment; m = 1-30; n = 1-15; Y ‑ R1 is an acid radical ion; M is an alkali metal or alkaline earth metal; R2 is a C1-C8 alkyl group or a C6-C8 aryl group. The oil displacement agent prepared from the oil displacement composition of this invention can be used in chemical oil displacement. This oil displacement agent is an ultra-low interfacial tension spreading type oil displacement agent, with simple composition, good solubility, and cost advantage. R1-O-(PO) m -(EO) n -Y ‑ M + Formula I; R2-OH Formula II.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemistry, and more specifically to oil displacement compositions and oil displacement agents and their applications. Background Technology

[0002] Various enhanced oil recovery technologies have been developed to improve oil recovery rates, including chemical flooding, thermal flooding, gas flooding, and microbial flooding. Chemical flooding is currently the main method for improving oil recovery rates; by using appropriate surfactants, the interfacial tension between crude oil and water can be effectively reduced. When the interfacial tension between crude oil and water reaches an ultra-low value (IFT < 10), the oil recovery rate is significantly improved. -2 When the oil recovery rate is (mN / m), the oil recovery rate will be greatly improved.

[0003] However, with further crude oil extraction, reservoir conditions are becoming increasingly demanding. In high-salt, high-calcium-magnesium reservoirs, traditional surfactants struggle to reduce the crude oil / water interfacial tension to ultra-low levels. Therefore, designing and synthesizing salt-resistant, efficient, and inexpensive multifunctional surfactants for high-salt reservoirs to effectively improve the recovery rate of existing oilfields is of great significance. Extended surfactants contain polyethylene oxide (EO) and polypropylene oxide (PO) groups. The EO groups endow extended surfactants with salt and calcium-magnesium resistance. The semi-flexible EO segments and flexible PO segments provide the surfactant with a certain interfacial strength at the oil-water interface, giving extended surfactants controllable emulsifying properties, which is beneficial for oil-water migration in rock pores, improving microscopic sweep efficiency and microscopic oil washing efficiency. Furthermore, extended surfactants can effectively regulate the hydrophilic-lipophilic balance and size of surfactant molecules through their weakly hydrophobic polypropylene oxide (PO) and weakly hydrophilic polyoxyethylene oxide (EO) segments, potentially reducing interfacial tension to ultra-low levels and exhibiting excellent interfacial properties and phase behavior. However, the introduction of hydrophobic PO segments reduces the water solubility of surfactant molecules. Long-chain extended surfactants have poor water solubility, making them difficult to apply in waterflooding to enhance oil recovery. Therefore, it is of great significance to find a balance between the water solubility, interfacial activity, and production cost of extended surfactants so that they can be practically applied to oil extraction in high-salinity reservoirs. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of existing technologies that make it difficult to balance the water solubility, interfacial activity, and production cost of extended surfactants, and to provide an oil displacement composition and an oil displacement agent and their application. The oil displacement composition includes a short-chain extended surfactant and a short-chain alcohol agent, which can adjust the hydrophilic-lipophilic balance and size of surfactant molecules and reduce interfacial tension to an ultra-low level. At the same time, the added short-chain alcohol agent has solubilizing properties and can also adjust the hydrophilic-lipophilic balance (HLB) value of the oil displacement agent.

[0005] To achieve the above objectives, a first aspect of the present invention provides an oil displacement composition comprising component A and component B, wherein component A has the structure shown in Formula I and component B has the structure shown in Formula II;

[0006] R1-O-(PO) m -(EO) n -Y - M + Formula I;

[0007] R2-OH formula II;

[0008] Wherein, R1 is a C1-C8 alkanol or a C6-C8 aromatic alcohol;

[0009] PO stands for polyoxypropylene segment; EO stands for polyoxyethylene segment;

[0010] m = 1 - 30; n = 1 - 15;

[0011] Y - It is an acid radical ion;

[0012] M is an alkali metal or an alkaline earth metal;

[0013] R2 is a C1-C8 alkyl group or a C6-C8 aryl group.

[0014] A second aspect of the present invention provides an oil displacement agent comprising water and the oil displacement composition described in the first aspect.

[0015] The third aspect of the present invention provides the application of the oil displacement composition described in the first aspect or the oil displacement agent described in the second aspect in chemical oil displacement.

[0016] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0017] (1) The oil displacement composition of the present invention includes a short-chain extended surfactant and a short-chain alcohol agent. The short-chain extended surfactant has the characteristics of salt resistance and calcium and magnesium resistance, and is suitable for crude oil extraction in high-salt oil reservoirs. It can adjust the hydrophilic-lipophilic balance and size of surfactant molecules, and reduce the interfacial tension to an ultra-low level. It can form an interfacial film with a certain interfacial strength at the crude oil-water interface, and has controllable emulsification properties, which is conducive to the migration of oil and water in rock pores and can effectively improve the micro-sweeping efficiency and micro-washing efficiency. At the same time, the added short-chain alcohol agent has solubilizing properties and can also adjust the hydrophilic-lipophilic balance (HLB) value of the oil displacement agent.

[0018] (2) The oil displacement agent made from the oil displacement composition of the present invention can be used in chemical oil displacement. The oil displacement agent is an ultra-low interfacial tension extended type oil displacement agent with simple composition, good solubility, and cost advantage. Attached Figure Description

[0019] Figure 1 The diagram shows the interfacial tension data between formation water 1 and the oil displacement agent and crude oil in Examples 1-5.

[0020] Figures 2a-2f The oil-water-solid three-phase contact angle diagrams are shown for formation water 1 and the oil displacement agents of Examples 1-5, respectively.

[0021] Figures 3a-3f The figures show the emulsification performance test results of formation water 1 and the oil displacement agents prepared in Examples 1-5, respectively.

[0022] Figures 4a-4f The images show the microscopic visualization of the oil displacement effects of formation water 1 and the oil displacement agents in Examples 1-5, respectively. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] The first aspect of the present invention provides an oil displacement composition comprising component A and component B, wherein component A has the structure shown in Formula I and component B has the structure shown in Formula II;

[0025] R1-O-(PO) m -(EO) n -Y - M + Formula I;

[0026] R2-OH formula II;

[0027] Wherein, R1 is a C1-C8 alkanol or a C6-C8 aromatic alcohol;

[0028] PO stands for polyoxypropylene segment; EO stands for polyoxyethylene segment;

[0029] m = 1 - 30; n = 1 - 15;

[0030] Y - It is an acid radical ion;

[0031] M is an alkali metal or an alkaline earth metal;

[0032] R2 is a C1-C8 alkyl group or a C6-C8 aryl group.

[0033] Component A of this invention is a short-chain extended surfactant. The hydrophobic alkyl short chain of component A not only allows for the introduction of more flexible PO groups into the extended structure, but its short-chain alcohol structure is also cheaper than long-chain alcohols, potentially yielding a highly efficient and inexpensive salt-resistant surfactant. This surfactant molecule contains at least three types of functional groups: a short-chain alcohol structure, a flexible, weakly hydrophobic PO segment, and a semi-flexible, weakly hydrophilic EO segment, thereby endowing the surfactant with high efficiency, low cost, salt and calcium / magnesium resistance, and the ability to achieve ultra-low interfacial tension. This is beneficial for improving the recovery rate of high-salt oil fields.

[0034] According to some embodiments of the present invention, R1 is a C4-C8 alkanol or a C6-C8 aromatic alcohol.

[0035] According to some embodiments of the present invention, m = 5-15; n = 1-10.

[0036] According to some embodiments of the present invention, Y - SO3 - COO - or SO4 2- .

[0037] According to some embodiments of the present invention, M is Na, K, Ca, or Mg.

[0038] According to some embodiments of the present invention, R2 is a C4-C8 alkyl group or a C6-C8 aryl group.

[0039] According to some embodiments of the present invention, R1 is ethylhexyl alcohol, isobutanol, or phenol;

[0040] According to some embodiments of the present invention, R2 is ethylhexyl, isobutyl or phenyl.

[0041] According to some embodiments of the present invention, the mass ratio of component A to component B is 0.5-50:1, preferably 1-10:1, and more preferably 1-5:1.

[0042] According to some embodiments of the present invention, based on the total mass of the oil displacement composition, the mass content of component A is 0.05-0.5 wt%, and the mass content of component B is 0.01-0.1 wt%.

[0043] A second aspect of the present invention provides an oil displacement agent comprising water and the oil displacement composition described in the first aspect.

[0044] According to some embodiments of the present invention, the mass concentration of the oil displacement composition in the oil displacement agent is 0.06-0.6 wt%.

[0045] The oil displacement composition of the present invention can be used to prepare an oil displacement agent, which can be used to improve the recovery rate of high-salinity oil reservoirs.

[0046] The present invention also provides a method for preparing an oil displacement agent, the method comprising: mixing component A and component B described in the first aspect above with water.

[0047] Specifically, the following steps are included:

[0048] (1) Pre-treat component A, that is, grind and crush it;

[0049] (2) Weigh out the amount of component A and component B in the formula, mix them evenly and add them to a clean container;

[0050] (3) Add water to the above container and stir or shake thoroughly to obtain the oil displacement agent.

[0051] According to some embodiments of the present invention, the water is formation water or simulated formation water.

[0052] According to some embodiments of the present invention, the oil-water interfacial tension of the oil displacement agent is 1.0 × 10⁻⁶. -3 -1.0×10 - 2 mN / m.

[0053] The third aspect of the present invention provides the application of the oil displacement composition described in the first aspect or the oil displacement agent described in the second aspect in chemical oil displacement.

[0054] The present invention will be described in detail below through examples. Unless otherwise specified in the following examples and comparative examples, conditions were performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0055] The ethylhexanol raw material is a commercially available product from Shanghai Maclean Biochemical Technology Co., Ltd., CAS No. 104-76-7. The isobutanol raw material is a commercially available product from Shanghai Maclean Biochemical Technology Co., Ltd., CAS No. 78-83-1.

[0056] In the following examples and comparative examples, the composition of formation water 1, formation water 2 and formation water 3 is shown in Table 1.

[0057] Table 1. Composition of Formation Water 1, Formation Water 2, and Formation Water 3

[0058]

[0059] Example 1

[0060] By weight percentage, the carboxylate-based extended displacement agent based on ethylhexanol comprises the following components: 0.5 wt% C8PO 15 EO5COONa, 0.1 wt% ethylhexanol, and the remainder being formation water. Among them, C8PO 15 The preparation steps of EO5COONa are as follows:

[0061] 1) Add 0.1 mol of ethylhexanol and 0.25 g of potassium hydroxide powder to a reactor equipped with heating, temperature control and electric stirring device. Heat the temperature to 120°C, blow the reactor with high-purity nitrogen for 15 min, evacuate for 15 min, and then raise the temperature to 150°C. Add 1.5 mol of propylene oxide vaporized into the reactor. After the reaction is complete, connect it to a tank containing 0.5 mol of ethylene oxide and continue the reaction. After the reaction is complete, age for 2 h and cool to obtain 2-ethyl-hexyl polyoxypropylene (15) polyoxyethylene (5) ether alcohol.

[0062] 2) Add 0.1 mol of the 2-ethylhexyl polyoxypropylene (15) polyoxyethylene (5) ether alcohol prepared above to a reactor equipped with heating, temperature control and electric stirring device, heat to about 70°C, and slowly add 0.3 mol of solid sodium hydroxide under stirring. After the addition is complete, heat to about 75°C and continue the reaction at this temperature for 1 hour; then add 0.15 mol of chloroacetic acid to the reactor in batches. After the addition is complete, heat to about 85°C and react at a constant temperature for 2 hours to obtain the carboxylate-type extended oil displacement agent of 2-ethylhexanol, the specific structural formula of which is as follows:

[0063]

[0064] Example 2

[0065] By weight percentage, isobutanol-based sulfonate-type extended displacement agents comprise the following components: 0.1 wt% C4PO4. 10 EO 10 SO3Na, 0.02wt% isobutanol, and the remainder is formation water. C4PO4 10 EO 10 The preparation steps of SO3Na are as follows:

[0066] 1) Add 0.2 mol of isobutanol and 0.3 g of sodium methoxide to a reactor equipped with heating, temperature control and electric stirring device, evacuate for 15 min, then heat to 100℃, vaporize 2.0 mol of propylene oxide and add it to the reactor, after the reaction is completed, connect to a tank containing 2.0 mol of ethylene oxide to continue the reaction; after the reaction is completed, age for 2 h, cool to obtain a yellow oily substance isobutyl polyoxypropylene (10)polyoxyethylene (10) ether alcohol;

[0067] 2) Add 0.1 mol of the prepared isobutyl polyoxypropylene (10)polyoxyethylene (10) ether alcohol to a reactor equipped with heating, temperature control and electric stirring device, heat to about 70°C, and slowly add 0.3 mol of solid sodium hydroxide while stirring. After the addition is complete, heat to about 75°C and continue the reaction at this temperature for 2 hours. Then add 0.15 mol of 2-chloroethyl sulfonic acid to the reactor in batches. After the addition is complete, heat to about 85°C and continue the reaction at a constant temperature for 5 hours to obtain the isobutanol sulfonate type extended oil displacement agent, the specific structural formula of which is as follows:

[0068]

[0069] Example 3

[0070] By weight percentage, phenol-based carboxylate-based extended displacement agents comprise the following components: 0.3 wt% PhPO 15 EO 10 COONa, 0.06 wt% phenol, the remainder being formation water 3. PhPO 15 EO 10 The preparation steps of COONa are as follows:

[0071] 1) Add 0.1 mol of phenol and 0.25 g of powdered potassium hydroxide to a reactor equipped with heating, temperature control and electric stirring device. Heat the reactor to 120°C, blow the reactor with high-purity nitrogen for 15 min, evacuate for 15 min, and then raise the temperature to 150°C. Add 1.5 mol of vaporized propylene oxide to the reactor. After the reaction is complete, connect the reactor to a tank containing 1.0 mol of ethylene oxide to continue the reaction. After the reaction is complete, age for 2 h and cool to obtain a yellow oily substance phenoxy polyoxypropylene (15) polyoxyethylene (5) ether alcohol.

[0072] 2) Add 0.1 mol of the prepared phenoxy polyoxypropylene (15) polyoxyethylene (5) ether alcohol to a reactor equipped with heating, temperature control and electric stirring device, heat to about 70°C, and slowly add 0.3 mol of solid sodium hydroxide while stirring. After the addition is complete, heat to about 75°C and continue the reaction at this temperature for 1.5 hours. Then add 0.15 mol of chloroacetic acid to the reactor in batches. After the addition is complete, heat to about 85°C and continue the reaction at a constant temperature for 3 hours to obtain a phenol-based carboxylate-type extended oil displacement agent with the following specific structural formula:

[0073]

[0074] Example 4

[0075] By weight percentage, the isobutanol-based sulfate-based extended displacement agent comprises the following components: 0.2 wt% C4PO4.15 EO3SO4Na, 0.04wt% isobutanol, and the remainder is formation water. C4PO4 15 The preparation steps of EO3SO4Na are as follows:

[0076] 1) The preparation process of isobutyl polyoxypropylene (15) polyoxyethylene (3) ether alcohol is the same as in Example 2;

[0077] 2) Add 0.1 mol of isobutyl polyoxypropylene (15) polyoxyethylene (3) ether alcohol and 300 mL of dichloromethane to the reactor, cool to 0-5℃, and gradually add 0.12 mol of chlorosulfonic acid dropwise. The system temperature should not exceed 10℃ during the reaction. After the addition is complete, raise the temperature to room temperature and continue the reaction for 2 hours. After the reaction is complete, pour the mixture onto crushed ice, and then neutralize it with 30 wt% sodium hydroxide aqueous solution to a pH of about 7-8. Remove dichloromethane and water from the solution to obtain a sulfate-based extended oil displacement agent based on isobutanol. The specific structural formula is as follows:

[0078]

[0079] Example 5

[0080] By weight percentage, the ethylhexanol-based sulfonate-type extended displacement agent comprises the following components: 0.2 wt% C8PO5EO5SO3Na, 0.04 wt% ethylhexanol, and the remainder being formation water. The preparation steps of C8PO5EO5SO3Na are as follows:

[0081] 1) The preparation process of 2-ethyl-hexyl polyoxypropylene (15) polyoxyethylene (5) ether alcohol is the same as in Example 1;

[0082] 2) The preparation process of the sulfonate-based extended oil displacement agent based on ethylhexanol is the same as step 2) in Example 2, and the specific structural formula is as follows:

[0083]

[0084] Comparative Example 1

[0085] The oil displacement agent comprises the following components by weight percentage: 0.5 wt% sodium dodecyl sulfate, with the remainder being formation water.

[0086] Comparative Example 2

[0087] The oil displacement agent comprises the following components by weight percentage: 0.5 wt% sodium dodecylbenzenesulfonate, 0.1 wt% ethylhexanol, and the remainder being formation water. The structural formula of sodium dodecylbenzenesulfonate is as follows:

[0088]

[0089] Test Example 1

[0090] Interfacial tension measurement method: The interfacial tension between oil and water was measured in accordance with the "SY / T 5370-2018 Interfacial Tension Measurement Method".

[0091] The interfacial tension between crude oil and the test sample was determined using the spin drop method at a temperature of 70℃ and a rotation speed of 5000 rpm. The interfacial tension between the oil displacement agents of Examples 1-5 and Comparative Examples 1-2, as well as between formation water 1-3 and crude oil, was measured. To observe the salt and calcium-magnesium resistance of the oil displacement agent solution, the oil displacement agent was prepared using simulated formation water with three different salinities and calcium-magnesium contents. The formulation and composition of the simulated formation water are shown in Table 1, and the steady-state interfacial tension values ​​are shown in Table 2. The dynamic interfacial tension data between formation water 1 and the oil displacement agent of Examples 1-5 and crude oil are shown in Table 2. Figure 1 As shown, from Figure 1 As can be seen from the data in Table 2, the oil displacement agents of Examples 1-5, when used alone at a concentration of only 0.06wt%-0.6wt%, exhibit an oil-water interfacial tension of less than 10. -1 mN / m, down to as low as 10 -3 The results show that the oil displacement agent of this invention has excellent interfacial tension reduction ability and salt and calcium-magnesium resistance properties, making it suitable for crude oil extraction in high-salt reservoirs.

[0092] Test Example 2

[0093] Method for determining interfacial modulus: An expansion rheological experiment was conducted using an interfacial expansion rheology and dynamic contact angle measuring instrument. A suspended droplet was subjected to periodic oscillations, and the instantaneous changes in liquid surface area were captured by a camera. The periodic changes in interfacial tension were measured using droplet shape analysis, and the interfacial modulus value was obtained through theoretical calculation. A higher interfacial modulus value indicates greater interfacial film strength.

[0094] Interfacial expansion rheological experiments were conducted on the oil displacement agents of Examples 1-5 and Comparative Examples 1-2, as well as formation water 1-3. The interfacial modulus data are shown in Table 2. The results show that the oil displacement agent of the present invention can form an interfacial film with a certain interfacial strength at the crude oil / water interface.

[0095] Test Example 3

[0096] Oil-water-solid three-phase contact angle test method: The seat drop method is used. The temperature is kept constant for 0.5h. 4μL of crude oil is dropped onto a clean quartz surface. The quartz plate is placed upside down on a support in the solution. The shape of the droplet is captured by a camera. After processing by software, the contact angle formed by the test sample on the quartz plate over time can be obtained. The experimental temperature is kept constant at 70℃.

[0097] The oil-water-solid three-phase contact angles of the oil displacement agents of Examples 1-5 and Comparative Examples 1-2, as well as formation water 1-3, were measured. The oil-water-solid three-phase contact angle data are shown in Table 2. The effects of formation water 1 and the oil displacement agents of Examples 1-5 on the oil-water-solid three-phase contact angle (inverted) on the quartz surface are shown in Table 2. Figures 2a-2f As shown, 2a is the oil-water-solid three-phase contact angle test diagram for formation water 1, 2b is the oil-water-solid three-phase contact angle test diagram for Example 1, 2c is the oil-water-solid three-phase contact angle test diagram for Example 2, 2d is the oil-water-solid three-phase contact angle test diagram for Example 3, 2e is the oil-water-solid three-phase contact angle test diagram for Example 4, and 2f is the oil-water-solid three-phase contact angle test diagram for Example 5. The test results show that, compared with the formation water phase, the oil displacement agents of Examples 1-5 can all increase the three-phase contact angle to varying degrees. The oil displacement agent of the present invention can effectively increase the separation pressure near the triple point based on electrostatic repulsion, which is beneficial to oil film stripping. Therefore, the oil displacement agent of the present invention has good oil film stripping ability.

[0098] Test Example 4

[0099] Emulsification performance test method: First, place the sample to be tested and crude oil in a constant temperature oven at 70℃ for 30 minutes. Then, take 5 grams of each of oil and water at a ratio of 1:1 and add them to a 25mL stoppered test tube in the order of water first and then oil. Seal the tube and shake it vigorously up and down 100 times to ensure that it is fully emulsified to obtain the desired emulsion. Keep it in an oven at a constant temperature and record the demulsification and water separation at different times.

[0100] The emulsification properties of the oil displacement agents of Examples 1-5 and formation water 1 were tested respectively. The stability of the emulsions of formation water 1 and the oil displacement agents of Examples 1-5 is as follows: Figures 3a-3f As shown, 3a is the emulsification performance test diagram of formation water 1, 3b is the emulsification performance test diagram of Example 1, 3c is the emulsification performance test diagram of Example 2, 3d is the emulsification performance test diagram of Example 3, 3e is the emulsification performance test diagram of Example 4, and 3f is the emulsification performance test diagram of Example 5. The test results show that the oil displacement agent of the present invention has strong emulsification ability, slow water separation and cannot completely separate phases after long-term storage, and the emulsion formed with crude oil has good stability.

[0101] Test Example 5

[0102] Microscopic visualization method for oil displacement experiment: Diluted crude oil of suitable viscosity is injected into a water-wetted model with simulated pore structure characteristics at a rate of 20 μL / min until the crude oil fills the entire glass model and no air bubbles are present in the pore throat. In the experiment, the sample to be tested is injected into the chip model at a constant injection rate of 0.1 μL / min, and the process of crude oil displacement in the model is recorded by microscopy video recording mode.

[0103] Microscopic visualization tests were conducted on the oil displacement agents of Examples 1-5 and Comparative Examples 1-2, as well as formation water 1-3. The oil displacement efficiency data are shown in Table 2, and the oil displacement effect is as follows: Figures 4a-4f As shown, 4a is the oil displacement effect of formation water 1, 4b is the oil displacement effect of Example 1, 4c is the oil displacement effect of Example 2, 4d is the oil displacement effect of Example 3, 4e is the oil displacement effect of Example 4, and 4f is the oil displacement effect of Example 5. The test results show that the oil displacement agent of the present invention has a better microscopic oil displacement effect, which is >18% higher than that of water displacement.

[0104] Table 2 Performance data of formation water and oil displacement agents

[0105]

[0106]

[0107] Test Example 6

[0108] Indoor physical simulation experiment method: Following GB / T 29172-2012 Core Analysis Methods, the new sandstone core was first dried, and the core length and diameter were measured and recorded. Then, porosity, pore volume, gas permeability, and other data were obtained according to SY / T 6385-2016 Methods for Determining Porosity of Rocks Under Overburden. The core was placed in a sealed container, saturated with formation water for more than 12 hours, then saturated with crude oil and 9.1% jet fuel. Finally, a core displacement experiment was conducted at 70℃, and the experiment was stopped after reaching 50 times the pore volume.

[0109] Indoor physical simulation oil displacement tests were conducted on the oil displacement agents of Examples 1-5 respectively, and the oil displacement efficiency data are shown in Table 3.

[0110] Table 3. Indoor physical simulation data of oil displacement efficiency for formation water and different oil displacement agents.

[0111] Oil displacement system Water drive Example 1 Example 2 Example 3 Example 4 Example 5 Oil displacement efficiency (%) 56.5％ 78.6％ 74.3％ 80.1％ 77.7％ 81.2％

[0112] As can be seen from the results in Table 3, the oil displacement efficiency of the indoor physical simulation oil displacement agents in Examples 1-5 is increased by 22.1%, 17.8%, 23.6%, 21.2% and 24.7% respectively compared with water displacement; the test results show that the oil displacement agent of the present invention has a good oil displacement effect, which is >17% higher than that of water displacement.

[0113] The results above show that the oil displacement agent of the present invention has a very good oil displacement effect.

[0114] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An oil displacement composition, characterized in that, The oil displacement composition comprises component A and component B, wherein component A has the structure shown in Formula I and component B has the structure shown in Formula II; R1-O-(PO) m -(EO) n -Y - M + Formula I; R2-OH formula II; Wherein, R1 is a C1-C8 alkanol or a C6-C8 aromatic alcohol; PO stands for polyoxypropylene segment; EO stands for polyoxyethylene segment; m = 1 - 30; n = 1 - 15; Y - It is an acid radical ion; M is an alkali metal or an alkaline earth metal; R2 is a C1-C8 alkyl group or a C6-C8 aryl group.

2. The oil displacement composition according to claim 1, wherein, R1 is a C4-C8 alkanol or a C6-C8 aromatic alcohol; And / or, m = 5-15; n = 1-10; And / or, Y - SO3 - COO - or SO4 2- ; And / or, M is Na, K, Ca, or Mg; And / or, R2 is a C4-C8 alkyl group or a C6-C8 aryl group.

3. The oil displacement composition according to claim 2, wherein, R1 is ethylhexyl alcohol, isobutanol, or phenol; And / or, R2 is ethylhexyl, isobutyl or phenyl.

4. The oil displacement composition according to any one of claims 1-3, wherein, The mass ratio of component A to component B is 1-10:1, preferably 1-5:

1.

5. The oil displacement composition according to any one of claims 1-4, wherein, Based on the total mass of the oil displacement composition, the mass content of component A is 0.05-0.5 wt%, and the mass content of component B is 0.01-0.1 wt%.

6. An oil displacement agent, characterized in that, The oil displacement agent comprises water and the oil displacement composition according to any one of claims 1-5.

7. The oil displacement agent according to claim 6, wherein, The oil displacement composition has a mass concentration of 0.06-0.6 wt% in the oil displacement agent.

8. The oil displacement agent according to claim 6 or 7, wherein, The water is either formation water or simulated formation water.

9. The oil displacement agent according to any one of claims 6-8, wherein, The oil-water interfacial tension of the oil displacement agent is 1×10⁻⁶. -3 -1×10 -2 mN / m.

10. The use of the oil displacement composition according to any one of claims 1-5 or the oil displacement agent according to any one of claims 6-9 in chemical flooding.

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