A pour point depressant and viscosity depressant for oil displacement in a high pour point oil reservoir, a preparation method and application thereof

Abstract

The application provides a pour point depressant and viscosity reducer for high pour point oil reservoir oil displacement, a preparation method and application thereof, and belongs to the field of oil field chemistry. The pour point depressant and viscosity reducer for high pour point oil reservoir oil displacement provided by the application comprises, in percentage by mass, 18-22% of nano surfactant, 20-24% of non-ionic surfactant, 15-20% of Gemini surfactant and 15% of mutual solvent, and the rest is water. The oil displacement agent can be effectively applied to chemical flooding in high pour point oil reservoirs with a waxy crude oil content of ≤40%, a freezing point of ≤55 DEG C, a formation water salinity of ≤100000 mg / L, and a calcium and magnesium ion concentration of ≤2500 mg / L, and the raw materials are easy to purchase, the process is simple, the cost is low, and the application is green and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemistry, and particularly relates to a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs, its preparation method, and its application. Background Technology

[0002] China is one of the countries with the richest high-pour-point oil resources, with known reserves reaching 50 × 10⁻⁶. 8 These high-pour-point oil reservoirs, with reserves exceeding 100 tons, account for 30-40% of the world's high-pour-point oil resources. The crude oil in these reservoirs is characterized by three highs: high wax content, high pour point, and high wax precipitation point. Wax content ranges from 10% to 57%, generally between 20% and 40%; the pour point is generally between 25 and 59 degrees Celsius, with a maximum of 67 degrees Celsius; and the wax precipitation point is generally between 40 and 74 degrees Celsius.

[0003] Currently, over 80% of high-pour-point oil reservoirs are developed using conventional cold water injection. As oilfields continue to develop and the amount of injected water increases, formation temperatures gradually decrease, crude oil undergoes significant wax precipitation, and reservoir cold damage and blockage become increasingly severe. Consequently, the water absorption index of injection wells in the reservoirs declines rapidly. Therefore, reducing the pour point of high-pour-point oil and improving its flow properties are of great significance for enhancing the recovery rate of high-pour-point oil reservoirs.

[0004] CN 115521768 A provides an oil displacement system and method for improving the oil recovery rate of high-pour-point oil reservoirs, including a microbial oil displacement system and a chemical oil displacement system. This system has a significant effect on reducing pour point, viscosity, and preventing wax precipitation in crude oil; however, the process is complex and inconvenient for field use. CN 115368884 A provides a composite oil displacement system for high-pour-point oil reservoirs, its preparation, and application. This system is highly applicable to high-pour-point oils with a wax content of 20-40 wt%, and the composite system can reduce the oil-water interfacial tension to ultra-low levels. This oil displacement system only emphasizes the ability to reduce the oil-water interfacial tension and does not mention the pour point reduction, viscosity reduction performance, or other technical indicators of high-pour-point oil. CN 110776607 A provides a method for preparing a novel active copolymer high-pour-point crude oil displacement agent using rosin amine, α-glycidyl methacrylate, N-vinylcarbazole, and acrylamide as main raw materials. This copolymer has significant pour point reduction and oil displacement capabilities for high-pour-point heavy oils, and the preparation process is reliable. However, the preparation process is relatively complex and carries certain risks, making it unsuitable for widespread application. CN115466607 A provides a microemulsion wax inhibitor, its preparation method, and its application. The microemulsion wax inhibitor comprises an oil phase, fatty alcohol ether salts, fatty alcohol polyethers, fatty acid amide betaine, fatty acid diol amides, a cosolvent, and water. The invented microemulsion wax inhibitor has a high wax prevention rate and surface activity, but its maximum pour point depressant is only 8°C, which does not meet the requirements of general pour point depressants.

[0005] Therefore, in order to address the problems of low single-well productivity and low oil production rate in conventional waterflooding of high-pour-point oil reservoirs, there is an urgent need to develop a new pour point and viscosity reduction flooding system suitable for high-pour-point oil reservoirs. This system should take into account both pour point and viscosity reduction and efficient displacement functions, and have the characteristics of ultra-low interfacial tension and high oil washing rate, thereby significantly improving the recovery rate of high-pour-point oil reservoirs. Summary of the Invention

[0006] This invention provides a pour point and viscosity reducing agent for oil displacement in high pour point oil reservoirs. This agent can be effectively applied to chemical flooding of high pour point oil reservoirs with crude oil wax content ≤40%, pour point ≤55℃, formation water salinity ≤100000mg / L, and calcium and magnesium ion concentration ≤2500mg / L. Moreover, the raw materials are readily available, the process is simple, the cost is low, and it is environmentally friendly.

[0007] To achieve the above objectives, the present invention provides a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs, comprising, by mass percentage, 18%-22% nano-surfactant, 20%-24% nonionic surfactant, 15%-20% Gemini surfactant, 15% miscible solvent, and the remainder being water.

[0008] Preferably, the nanosurfactant is CA601S, a nanosurfactant with a particle size ≤200nm, commercially available from Ningbo Fengcheng Nanotechnology Co., Ltd. The nanosurfactant used exhibits good infeedability and is resistant to temperature and salt.

[0009] Preferably, the nonionic surfactant is cocoyl monoisopropanolamide (MIPA), which is purchased from Shanghai Mailun Daily Chemical Co., Ltd. It is an amidation product of coconut oil and monoisopropanolamine, and has good emulsifying and detergency capabilities, as well as good compatibility and synergistic effects with other surfactants.

[0010] Preferably, the Gemini surfactant is selected from those commercially available from Tianjin Hepfele New Material Co., Ltd. Superwet-360 wetting agent has the chemical composition of 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol polyoxyethylene ether.

[0011] Preferably, the mutual solvent is ethyl acetate.

[0012] As a preferred formulation, when mixed with an aqueous phase with a salinity of 0-100000 mg / L and a total concentration of calcium and magnesium ions of 0-2500 mg / L, the interfacial tension is ≤3.1 × 10⁻⁶ mg / L, according to the general technical conditions for heavy oil viscosity reducers and displacement agents (Q / SH1020 2871-2021) and the determination of pour point of petroleum products (GB / T510-2018). -3mN / m, viscosity reduction rate ≥98.6%, oil washing rate ≥50.8%, pour point reduction range ≥16℃.

[0013] This invention provides a method for preparing a pour point depressant and viscosity reducer for oil displacement in high-pour-point oil reservoirs according to any of the above technical solutions, comprising the following steps:

[0014] Nonionic surfactants are added to the reactor, followed by a co-solvent. After stirring evenly at 30-40℃, water is added and stirred for 30 minutes. Finally, Gemini surfactant and nano surfactant are added and stirred evenly to obtain a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs.

[0015] This invention provides an application of the pour point depressant and viscosity reducer for oil displacement in high-pour-point oil reservoirs according to any of the above technical solutions in chemical flooding of high-pour-point oil reservoirs with crude oil wax content ≤40%, pour point ≤55℃, formation water salinity 0-100000mg / L, and calcium and magnesium ion concentration ≤2500mg / L.

[0016] Preferably, the concentration of the pour point depressant and viscosity reducer used for oil displacement in high-pour-point oil reservoirs is 0.3%.

[0017] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0018] 1. This invention provides a pour point depressant and viscosity reducer for oil displacement in high-pour-point oil reservoirs. This oil displacement agent is mainly composed of a compound of nano-surfactants, nonionic surfactants, and Gemini surfactants. All three surfactants have strong emulsifying effects on high-pour-point crude oil, lowering its pour point, and exhibit significant synergistic effects. Under appropriate formulation conditions, they can reduce the interfacial tension of high-pour-point crude oil to ultra-low levels, increase capillary count, improve the fluidity of high-pour-point crude oil, and enhance oil displacement efficiency.

[0019] 2. This invention provides a pour point depressant and viscosity reducing agent for oil displacement in high-pour-point oil reservoirs, primarily applied to chemical flooding in such reservoirs. While this agent cannot inhibit the precipitation of wax crystals, it can alter their morphology, weakening their ability to form a three-dimensional network structure, thereby improving the low-temperature fluidity of the high-pour-point crude oil. Utilizing the washing function of the agent to strip crude oil from formation sands and reduce its viscosity facilitates its migration within the formation, thus increasing oil recovery. This is a highly promising oil recovery technology for developing high-pour-point oil reservoirs.

[0020] 3. The pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs provided by this invention has a simple production process and readily available raw materials. It is harmless to the environment and personnel from production to use, meets green and environmental protection requirements, and is beneficial to on-site construction. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] All raw materials used in the embodiments of this application were purchased commercially. The nano surfactant CA601S was purchased from Ningbo Fengcheng Nanotechnology Co., Ltd., cocoyl monoisopropanol amide (MIPA) was purchased from Shanghai Mailun Daily Chemical Co., Ltd., and the Gemini surfactant... Superwet-360 wetting agent was purchased from Tianjin Hepufele New Material Co., Ltd., and the mutual solvent is a commercially available product.

[0023] Example 1

[0024] 240 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) was added to the reactor, followed by 150 kg of ethyl acetate. The mixture was stirred thoroughly at 30-40°C, then 230 kg of water was added and stirred for 30 minutes. Finally, 200 kg of [unspecified ingredient] was added. After thoroughly mixing the superwet-360 wetting agent and 180 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0025] Example 2

[0026] Add 230 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) to the reactor, then add 150 kg of ethyl acetate. Stir the mixture thoroughly at 30-40°C, then add 250 kg of water and stir for 30 minutes. Finally, add 180 kg of... After thoroughly mixing the superwet-360 wetting agent and 190 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0027] Example 3

[0028] 220 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) was added to the reactor, followed by 150 kg of ethyl acetate. The mixture was stirred thoroughly at 30-40°C, then 260 kg of water was added and stirred for 30 minutes. Finally, 170 kg of [unspecified ingredient] was added. After thoroughly mixing superwet-360 wetting agent and 200 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0029] Example 4

[0030] 210 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) was added to the reactor, followed by 150 kg of ethyl acetate. The mixture was stirred thoroughly at 30-40°C, then 270 kg of water was added and stirred for 30 minutes. Finally, 160 kg of [unspecified ingredient] was added. After thoroughly mixing the superwet-360 wetting agent and 210 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high-pour-point oil reservoirs is obtained.

[0031] Example 5

[0032] Add 200 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) to the reactor, then add 150 kg of ethyl acetate. Stir the mixture thoroughly at 30-40°C, then add 280 kg of water and stir for 30 minutes. Finally, add 150 kg of... After thoroughly mixing the superwet-360 wetting agent and 220 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high-pour-point oil reservoirs is obtained.

[0033] The pour point depressant and viscosity reducer for oil displacement in high-pour-point oil reservoirs provided by this invention has its components and proportions determined based on a large number of experiments. Any change will result in the failure of the test indicators.

[0034] Comparative Example 1

[0035] Add 150 kg of ethyl acetate and 470 kg of water to the reactor, stir evenly at 30-40°C, and then add 200 kg of... After thoroughly mixing the superwet-360 wetting agent and 180 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0036] Comparative Example 1 is a high-pour-point oil reservoir displacement agent with reduced pour point and viscosity obtained by removing the nonionic surfactant cocoyl monoisopropanolamide (MIPA) from the formulation of Example 1. The amount of nonionic surfactant cocoyl monoisopropanolamide (MIPA) is made up with water.

[0037] Comparative Example 2

[0038] 240 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) was added to the reactor, followed by 150 kg of ethyl acetate. After stirring evenly at 30-40℃, 430 kg of water was added and stirred for 30 min. Finally, 180 kg of nano surfactant CA601S was added and stirred evenly to obtain a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs.

[0039] Comparative Example 2 is the version with the following ingredients removed from the formulation of Example 1. Superwet-360 wetting agent is used as a pour point lowering and viscosity reducing agent for oil displacement in high-pour-point oil reservoirs. Make up the amount of Superwet-360 wetting agent with water.

[0040] Comparative Example 3

[0041] 240 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) was added to the reactor, followed by 150 kg of ethyl acetate. The mixture was stirred thoroughly at 30-40°C, then 410 kg of water was added and stirred for 30 minutes. Finally, 200 kg of [unspecified ingredient] was added. After the superwet-360 wetting agent is thoroughly mixed, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0042] Comparative Example 3 is a high-pour-point oil reservoir displacement agent with reduced pour point and viscosity obtained by removing the nano surfactant CA601S from the formulation of Example 1. The amount of nano surfactant CA601S is made up with water.

[0043] Comparative Example 4

[0044] 190 kg of the nonionic surfactant cocoyl monoisopropanolamide (MIPA) was added to the reactor, followed by 150 kg of ethyl acetate. The mixture was stirred thoroughly at 30-40°C, then 280 kg of water was added and stirred for 30 minutes. Finally, 200 kg of [unspecified ingredient] was added. After thoroughly mixing the superwet-360 wetting agent and 180 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0045] Comparative Example 4 shows that the amount of nonionic surfactant cocoyl monoisopropanolamide (MIPA) in the formulation of Example 1 deviated from the range of 20%-24%. That is, 190 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) (19%) was added to obtain a high pour point oil reservoir oil displacement agent with reduced pour point and viscosity. The amount of nonionic surfactant cocoyl monoisopropanolamide (MIPA) that was added was made up with water.

[0046] Comparative Example 5

[0047] Add 250 kg of the nonionic surfactant cocoyl monoisopropanolamide (MIPA) to the reactor, then add 150 kg of ethyl acetate. Stir the mixture thoroughly at 30-40°C, then add 220 kg of water and stir for 30 minutes. Finally, add 200 kg of... After thoroughly mixing the superwet-360 wetting agent and 180 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0048] Comparative Example 5 shows that the amount of nonionic surfactant cocoyl monoisopropanolamide (MIPA) in the formulation of Example 1 deviated from the range of 20%-24%, that is, 250 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) (25%) was added to obtain a high pour point oil reservoir oil displacement agent with reduced pour point and viscosity. The amount of nonionic surfactant cocoyl monoisopropanolamide (MIPA) added was removed from the amount in water.

[0049] Comparative Example 6

[0050] 240 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) was added to the reactor, followed by 150 kg of ethyl acetate. The mixture was stirred thoroughly at 30-40°C, then 290 kg of water was added and stirred for 30 minutes. Finally, 140 kg of [unspecified ingredient] was added. After thoroughly mixing the superwet-360 wetting agent and 180 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0051] Comparative Example 6 is the formulation of Example 1 The Superwet-360 wetting agent deviated from the 15%-20% range, meaning 140kg was added. Superwet-360 wetting agent (14%) is used as a pour point lowering and viscosity reducing agent for oil displacement in high-pour-point oil reservoirs. A small amount is added... Make up the amount of Superwet-360 wetting agent with water.

[0052] Comparative Example 7

[0053] 240 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) was added to the reactor, followed by 150 kg of ethyl acetate. The mixture was stirred thoroughly at 30-40°C, then 220 kg of water was added and stirred for 30 minutes. Finally, 210 kg of [unspecified ingredient] was added. After thoroughly mixing the superwet-360 wetting agent and 180 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0054] Comparative Example 7 is the formulation of Example 1. The Superwet-360 wetting agent deviated from the 15%-20% range, meaning 210 kg was added. Superwet-360 wetting agent (21%) is used as a pour point lowering and viscosity reducing agent for oil displacement in high-pour-point oil reservoirs. (The additional...) The amount of Superwet-360 wetting agent is removed from the amount of water.

[0055] Comparative Example 8

[0056] 240 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) was added to the reactor, followed by 150 kg of ethyl acetate. The mixture was stirred thoroughly at 30-40°C, then 240 kg of water was added and stirred for 30 minutes. Finally, 200 kg of [unspecified substance] was added. After thoroughly mixing superwet-360 wetting agent and 170 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0057] Comparative Example 8 shows that the nano surfactant CA601S in the formulation of Example 1 deviated from the range of 18%-22%, that is, 170 kg of nano surfactant CA601S (17%) was added to obtain a high pour point oil reservoir oil displacement agent with reduced pour point and viscosity. The amount of nano surfactant CA601S that was added was made up with water.

[0058] Comparative Example 9

[0059] 240 kg of nonionic surfactant cocoyl monoisopropanolamide (MIPA) was added to the reactor, followed by 150 kg of ethyl acetate. The mixture was stirred thoroughly at 30-40°C, then 180 kg of water was added and stirred for 30 minutes. Finally, 200 kg of [unspecified substance] was added. After thoroughly mixing superwet-360 wetting agent and 230 kg of nano surfactant CA601S, a pour point depressant and viscosity reducer for oil displacement in high pour point oil reservoirs is obtained.

[0060] Comparative Example 9 shows that the nano surfactant CA601S in the formulation of Example 1 deviated from the range of 18%-22%, that is, 230 kg of nano surfactant CA601S (23%) was added to obtain a high pour point oil reservoir oil displacement agent with reduced pour point and viscosity. The amount of the added nano surfactant CA601S was removed from the amount of water.

[0061] Performance testing

[0062] The high-pour-point-rate oil displacement agents for oil recovery in high-pour-point oil reservoirs prepared in the above examples and comparative examples were formulated to a concentration of 0.3% for performance testing. The test conditions and methods are as follows:

[0063] Test conditions:

[0064] 1. Testing instruments: Bollerfly DV3T rheometer, constant temperature drying oven, TX-500C full-range rotating drop interfacial tension meter, constant temperature water bath, SYD-510G petroleum product low temperature tester (pouring point tester).

[0065] 2. Test temperature: Formation temperature in a certain block of Shengli Oilfield is 70℃.

[0066] 3. Crude oil used for testing: Dehydrated crude oil from a certain block of Shengli Oilfield, with a wax content of 40%, a pour point of 55℃, and a viscosity of 1578 mPa·s at 70℃.

[0067] 4. Test water: Injection water from a block in Shengli Oilfield, with a salinity of 100,000 mg / L and a calcium and magnesium ion concentration of 2,500 mg / L.

[0068] Test method:

[0069] 1. Interface tension test:

[0070] A solution with a pour point depressant and viscosity reducer was prepared using injection water from a block in the Shengli Oilfield to displace oil from a high-pour-point oil reservoir, resulting in a 0.3% mass concentration solution.

[0071] According to the provisions of 7.3.4 in SY / T 5370-2018, the interfacial tension between the solution and the target block oil sample was measured at 70℃ (rotation speed 5000 r / min, density difference calculated as 0.05), and the minimum value of interfacial tension was recorded.

[0072] 2. Viscosity Reduction Determination: A 0.3% (w / w) solution of a pour point and viscosity reducing agent for oil displacement in a high-pour-point oil reservoir was prepared using injection water from a block in the Shengli Oilfield. 30g of the prepared sample solution was weighed and placed in a small beaker, along with 70g of oil sample from the same block in the Shengli Oilfield. The beaker was sealed and placed in a constant-temperature drying oven at 70℃ for 2 hours. The oil-water mixture was then removed and rapidly stirred with a glass rod to ensure homogeneity. The viscosity of the oil-water mixture at 70℃ was quickly determined using a rheometer according to SY / T0520-2008.

[0073] Calculate the viscosity reduction rate using the following formula:

[0074]

[0075] In the formula:

[0076] —Viscosity reduction;

[0077] — Viscosity of high-pour-point oil sample at 70℃, mPa·s;

[0078] — Viscosity of the oil-water mixture at 70℃, mPa·s.

[0079] 3. Wash oil ratio determination:

[0080] 3.1 The simulated formation sand and the target block crude oil were mixed at a ratio of 4:1 (mass ratio), placed in a constant temperature drying oven, and aged at the reservoir temperature for 7 days, stirring once a day to ensure that the oil and sand were mixed evenly.

[0081] 3.2 Prepare 100g of a 0.3% high-pour-point oil reservoir displacement agent sample solution using injected water from the target block. Stir the solution on a magnetic stirrer at 300r / min for 15min and then test it.

[0082] 3.3 Weigh approximately 5g of the aged oil sand into a 100mL Erlenmeyer flask and weigh it. Accurate to 0.001g.

[0083] 3.4 Add 50g of the prepared sample solution to the sample in 3.3, mix thoroughly, and let stand at the reservoir temperature for 48h.

[0084] 3.5 Using clean cotton gauze, remove the floating crude oil and the crude oil adhering to the bottle wall from the sample after settling in 3.4, and pour out the sample solution. Place the conical flask in an oven at 105℃ and dry it to constant weight to obtain the desired result.

[0085] 3.6 Elute the sample from 3.5 with petroleum ether until the petroleum ether becomes colorless. Place the conical flask from which all crude oil has been eluted in an oven at 120°C until constant weight, and weigh to obtain the final product.

[0086] 3.7 Calculate the wash oil ratio using the following formula:

[0087]

[0088] In the formula:

[0089] —Wash oil ratio;

[0090] —Total mass of the conical flask and oil sand before washing, g;

[0091] —The mass of the conical flask and oil sand after washing, in grams;

[0092] —Total mass of the conical flask and the washed formation sand, in g.

[0093] 4. Determination of pour point range

[0094] 4.1 Prepare the oil-water mixture according to the method for determining viscosity reduction.

[0095] 4.2 The determination of pour point shall be in accordance with GB / T 510—2018 Petroleum Products Determination of Pour Point.

[0096] Pour point drop = initial pour point of crude oil (55℃) - pour point of oil-water mixture.

[0097] The high-pour-point-rate oil displacement agents obtained in Examples 1-5 and Comparative Examples 1-9 were tested for interfacial tension, viscosity reduction rate, oil washing rate, and pour point reduction amplitude in accordance with the above test methods. The test results are shown in Table 1. Among them, the following parameters, specified in Q / SH1020 2871-2021, were used at 70℃: interfacial tension ≤ 5.0 × 10⁻⁶. - 2 mN / m, viscosity reduction rate ≥90%, oil washing rate ≥40%. Pour point depression range is ≥15℃ according to relevant standards for pour point depressants.

[0098] Table 1 Performance Tests of Pour Point Depressants and Viscosity Reducers for Oil Displacement in High-Pour-Point Oil Reservoirs

[0099]

[0100]

[0101] As can be seen from Table 1 above, the formulation provided in this application of the present invention utilizes the nano surfactant CA601S, the nonionic surfactant cocoyl monoisopropanolamide (MIPA), and the Gemini surfactant. The synergistic effect of Superwet-360 wetting agent and its component ratio enables the obtained high-pour-point-rate oil displacement agent for oil displacement in reservoirs to exhibit superior performance compared to the standard parameters, namely, ultra-low interfacial tension ≤3.1×10⁻⁶. -3 With characteristics such as mN / m, viscosity reduction rate ≥98.6%, oil washing rate ≥50.8%, and pour point reduction range ≥16℃, it means that it has the functions of reducing pour point and viscosity and efficient displacement, especially for high pour point oil. When applied to chemical flooding of high pour point oil reservoirs, it can significantly improve the recovery rate of crude oil.

Claims

1. A pour point depressant and viscosity depressant oil displacement agent for high pour point oil reservoirs, characterized by comprising: The nano surfactant, the non-ionic surfactant, the Gemini surfactant, the mutual solvent and the water are in a mass percentage of 18-22%, 20-24%, 15-20%, 15% and the rest, respectively. The nano surfactant is CA601S, the non-ionic surfactant is cocoyl mono-isopropylol amide MIPA, the Gemini surfactant is superwet-360 wetting agent, and the mutual solvent is ethyl acetate.

2. The pour point depressing and viscosity depressing oil displacement agent according to claim 1, wherein The particle size of the nano surfactant is less than or equal to 200 nm.

3. The pour point depressing and viscosity depressing oil displacement agent according to claim 1, wherein When it is matched with a water phase with a mineralization of 0-100000 mg / L, wherein the total concentration of calcium ions and magnesium ions is 0-2500 mg / L, the interfacial tension thereof is ≤3.1*10 -3 mN / m, the viscosity reduction rate is ≥98.6%, the oil washing rate is ≥50.8%, and the pour point reduction amplitude is ≥16℃.

4. A method for preparing the pour point depressant and viscosity depressant oil displacement agent for high pour point oil reservoirs according to any one of claims 1 to 3, characterized by, The method comprises the following steps: The non-ionic surfactant is added into a reaction kettle, then the mutual solvent is added, and after being stirred uniformly at a temperature of 30-40℃, water is added, and stirred for 30 min, and finally the Gemini surfactant and the nano surfactant are added and stirred uniformly, to obtain the high-wax-oil reservoir oil displacement agent.

5. The high-wax-oil reservoir oil displacement agent according to any one of claims 1-3 is applied in the chemical flooding of a high-wax-oil reservoir, wherein the content of wax in crude oil is less than or equal to 40%, the freezing point is less than or equal to 55℃, the formation water salinity is 0-100000 mg / L, and the calcium and magnesium ion concentration is less than or equal to 2500 mg / L.

6. Use according to claim 5, characterized in that, The use concentration of the high-wax-oil reservoir oil displacement agent is 0.3%.

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