Thickened oil viscosity reducing and oil displacement agent resistant to temperature and salt and preparation method thereof

Abstract

The application belongs to the technical field of oil exploitation, and particularly relates to a temperature-resistant and salt-resistant thick oil viscosity-reducing and oil-displacing agent and a preparation method thereof. The preparation method comprises the following steps: under the condition of 80-90 DEG C, 4,4'-difluorobenzophenone in a first solvent and ammonium formate are subjected to Leuckart-Wallach reaction; secondly, under the action of a catalyst, in a second solvent, in an oxygen-isolated environment and under the condition of high temperature and high pressure, the reaction product and ethylene oxide are subjected to etherification reaction. The viscosity-reducing and oil-displacing agent has the advantages of simple synthesis process, low dosage and good effect.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent and its preparation method. Background Technology

[0002] Improving oil recovery rates in old oilfields through new methods and technologies is a crucial means of increasing oil and gas production and ensuring national energy security. Chemical flooding, a primary method of enhanced oil recovery, has made significant contributions to the stable production and increased output of oilfields in my country over the past 30 years. For example, chemical flooding in Daqing Oilfield has resulted in a cumulative oil production of 260 million tons, while chemical flooding in Shengli Oilfield has resulted in a cumulative increase in crude oil production of 34.58 million tons. Currently, chemical flooding technology has achieved full coverage of Class I and II reservoirs, but there is a lack of highly efficient displacement agents for Class III and IV high-temperature, high-salinity heavy oil reservoirs. This is because displacement agents used in Class I and II reservoirs undergo structural changes under high-temperature and high-salinity environments, significantly reducing their displacement performance. Therefore, developing temperature- and salt-resistant viscosity-reducing displacement agents for heavy oil is of great significance for improving oil recovery rates in Class III and IV heavy oil reservoirs.

[0003] High-temperature, high-salinity heavy oil reservoirs contain a high proportion of gum and asphaltenes in their crude oil, resulting in high viscosity and a large oil-water mobility ratio, making them prone to waterflooding. To effectively suppress waterflooding, the most common method is to reduce the crude oil viscosity using viscosity reducers to lower the mobility ratio. Viscosity reducers include water-soluble and oil-soluble types. Water-soluble viscosity reducers have advantages such as low cost and wide applicability, making them the main research focus for heavy oil viscosity reducers.

[0004] CN20181104172.6 discloses a water-soluble viscosity reducer for heavy oil composed of humic acid condensate and N-dialkylN'N-dialkyldimethylpyridinium salt. This type of viscosity reducer possesses good interfacial participation ability and viscosity-reducing effect. Through strong penetration and dispersion, it enters between the lamellar molecules of gum and asphaltenes, partially breaking down the planar overlapping aggregates and forming a randomly stacked, loosely structured aggregate of gum, asphaltenes, and viscosity reducer molecules, thereby reducing the viscosity of heavy oil. This invention's heavy oil viscosity reducer is applicable in the temperature range of 40–80℃, but in reality, the temperature of most high-temperature, high-salinity oil reservoirs exceeds 85℃, thus limiting the applicable reservoir range. Furthermore, this invention uses quaternary ammonium salt cationic surfactants, which are severely adsorbed in the reservoir, causing chromatographic separation and affecting oil displacement performance.

[0005] CN20111044108.8 discloses a fluorinated amphiphilic polymer crude oil viscosity reducer. It is prepared by dissolving a water-soluble monomer and a perfluoroalkyl acrylate monomer in water to obtain an aqueous solution, followed by the addition of cyclohexane, an emulsifier, and an initiator, and stirring to obtain a water-in-oil emulsion. The water-in-oil emulsion is then adjusted to alkaline pH and subjected to reverse emulsion polymerization to obtain the final product. Viscosity reduction experiments show that this agent has good emulsifying effects on heavy oil, with a viscosity reduction rate ≥90%. However, the heavy oil viscosity reducer prepared by this invention is a compound product, and its adsorption during well displacement can cause chromatographic separation problems, affecting the oil displacement effect. Summary of the Invention

[0006] This invention addresses the problem of poor reservoir environmental adaptability of viscosity reducers encountered in current heavy oil extraction by providing a temperature- and salt-resistant viscosity reducer and its preparation method. This viscosity reducer has the advantages of simple synthesis process, low dosage, and good effect.

[0007] Therefore, in order to achieve the above objectives, on the one hand, the present invention discloses a temperature-resistant and salt-resistant heavy oil viscosity-reducing displacement agent, the molecular structural formula of which is as follows:

[0008]

[0009] Where: m = 2 - 50;

[0010] n = 5 - 100.

[0011] On the other hand, the present invention provides a method for preparing the above-mentioned temperature-resistant and salt-resistant heavy oil viscosity-reducing and displacement agent, the preparation method comprising: 4,4'-difluorobenzophenone reacting with ammonium formate in a first solvent at 80-90°C in a Leuckart-Wallach reaction; and then, under the action of a catalyst, in a second solvent, in an oxygen-isolated environment, and under high temperature and high pressure conditions, the reaction product undergoing an etherification reaction with ethylene oxide.

[0012] The third objective of this invention is to disclose the application of the above-mentioned temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent in the development of heavy oil reservoirs.

[0013] This invention relates to a temperature- and salt-resistant heavy oil viscosity reducer and displacement agent, which is a special fluorinated composite surfactant. Two polyether groups are nonionic hydrophilic groups, and two fluorophenyl groups are lipophilic groups. The structure of this invention does not contain anionic hydrophilic groups, thus exhibiting good salt resistance. To address the poor temperature resistance of the polyether groups, highly polar fluorophenyl groups are introduced to reduce the precipitation of polyethers caused by hydrogen bonding at high temperatures, significantly improving the temperature resistance of the molecule. This invention has higher surface / interfacial activity and a lower critical micelle concentration than conventional heavy oil viscosity reducers, thus requiring a lower dosage. The fluorophenyl groups have good lipophilic properties and can spontaneously insert into the aggregated structure of gums and asphaltenes in crude oil, disrupting the π-π conjugation of gums and asphaltenes, weakening their aggregation force, and easily combining with large aromatic ring compounds in crude oil. This allows for easier stripping of gums and asphaltenes adsorbed at the oil-water interface of W / O type heavy oil emulsions, converting the W / O emulsion into an O / W emulsion, thereby significantly reducing the viscosity of the emulsion. Polyether groups have strong hydrophilicity, and the external phase can easily form a continuous water film. Moreover, polyether groups have good flexibility and can easily entangle with crude oil, thus enabling the entire oil-water system to form a stable O / W emulsion under low dynamic conditions, which greatly improves the crude oil permeability and enhances the water drive efficiency of heavy oil.

[0014] Compared with the prior art, the present invention has the following beneficial effects and advantages:

[0015] (1) The temperature-resistant and salt-resistant heavy oil viscosity reducer and oil displacement agent of the present invention has the characteristics of wide availability of raw materials, simple synthesis process, and clean and pollution-free process.

[0016] (2) The temperature-resistant and salt-resistant heavy oil viscosity reducer and oil displacement agent of the present invention has good temperature and salt resistance performance, with a temperature resistance of up to 210℃, a salt resistance concentration of up to 120000mg / L, and a calcium and magnesium ion resistance concentration of up to 2000mg / L.

[0017] (3) The temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent of the present invention has good surface / interfacial properties, with the surface tension reduced to below 27 mN / m and the interfacial tension reduced to 6.5 × 10⁻⁶. -2 Below mN / m;

[0018] (4) The temperature-resistant and salt-resistant heavy oil viscosity reducer and oil displacement agent of the present invention has the characteristics of high activity. Under the condition of using a concentration of 500 mg / L, it can reduce the viscosity of heavy oil by more than 96%.

[0019] (5) The temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent of the present invention can significantly improve the wettability of the reservoir and reduce the contact angle of the core model from 89.6 degrees to 16.5 degrees. Attached Figure Description

[0020] Figure 1The contact angle variation diagram of the viscosity-reducing and oil displacement agent B5 of this invention and the petroleum sulfonate treatment rock model of Shengli Chemical Plant. Detailed Implementation

[0021] 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.

[0022] According to a first aspect of the present invention, a temperature-resistant and salt-resistant heavy oil viscosity-reducing displacement agent is disclosed, the molecular structural formula of which is as follows:

[0023]

[0024] Where: m = 2-50, more preferably m = 5-10;

[0025] n = 5-100, more preferably n = 25-50.

[0026] Secondly, the present invention provides a method for preparing a temperature- and salt-resistant heavy oil viscosity-reducing and displacement agent, the preparation method comprising: 4,4'-difluorobenzophenone reacting with ammonium formate in a first solvent at 80-90℃; and then, under the action of a catalyst, in a second solvent, in an oxygen-isolated environment, and under high temperature and high pressure conditions, the reaction product undergoing an etherification reaction with ethylene oxide.

[0027] In this invention, preferably, based on 1 mole of 4,4'-difluorobenzophenone, the amounts of ammonium formate and ethylene oxide are 1-3 moles and 4-100 moles, respectively.

[0028] More preferably, based on 1 mole of 4,4'-difluorobenzophenone, the amounts of ammonium formate and ethylene oxide are 2-3 moles and 10-100 moles, respectively.

[0029] In this invention, preferably, the first solvent is one of ethanol, propanol, and isopropanol, and the mass ratio of the first solvent to 4,4'-difluorobenzophenone is 3-5:1.

[0030] In this invention, preferably, the Leuckart-Wallach reaction time is 2-4 hours.

[0031] More preferably, the Leuckart-Wallach reaction time is 2-3 hours.

[0032] In this invention, preferably, the catalyst is one of sodium hydroxide solid, potassium hydroxide solid, calcium hydroxide solid, and sodium ethoxide solid, and the mass ratio of the catalyst to 4,4'-difluorobenzophenone is 0.05-0.2:1.

[0033] In this invention, preferably, the second solvent is one of benzene or toluene, and the mass ratio of the solvent to 4,4'-difluorobenzophenone is 2-3:1.

[0034] In this invention, preferably, the high temperature condition is a temperature of 110-180℃, and the high pressure condition is a pressure of 0.02-0.4MPa.

[0035] More preferably, the high temperature condition is a temperature of 120-150℃, and the high pressure condition is a pressure of 0.05-0.2MPa.

[0036] In this invention, preferably, the etherification reaction time is 1-8 hours.

[0037] More preferably, the etherification reaction time is 2-5 hours.

[0038] According to a more specific preferred embodiment, the preparation method of the temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent specifically includes the following steps:

[0039] (1) Add 4,4'-difluorobenzophenone, the first solvent, and ammonium formate to a flask equipped with a stirrer, condenser, and thermometer. Stir to dissolve and keep the temperature at 80-90℃ for 2-4 hours.

[0040] (2) The above mixture was distilled under reduced pressure to 100°C until no fraction was obtained, resulting in a viscous solid. The solid was dissolved in a second solvent and transferred to an autoclave.

[0041] (3) Add the catalyst to the autoclave, purge the autoclave and pipelines with nitrogen, seal the autoclave, evacuate, introduce ethylene oxide, heat to 110-180℃, pressurize to 0.02-0.4MPa, keep the reaction at the temperature for 1-8h, cool the circulating water to below 40℃, distill the mixture under reduced pressure to obtain a viscous solid, dissolve the viscous solid with 30% by weight of methanol, and adjust the pH to 8-9 with 10wt% hydrochloric acid to obtain the product, a temperature-resistant and salt-resistant heavy oil viscosity reducer and displacement agent.

[0042] The reaction equation for the synthesis of the temperature-resistant and salt-resistant heavy oil viscosity reducer and displacement agent of the present invention is as follows:

[0043]

[0044] The third objective of this invention discloses the application of the aforementioned temperature-resistant and salt-resistant heavy oil viscosity-reducing and displacement agent in the development of heavy oil reservoirs. No specific requirements are specified for the application; conventional applications in the field are acceptable and will not be elaborated upon further here.

[0045] More preferably, the heavy oil reservoir in the application has a temperature of less than 90°C and a salinity of less than 120,000 mg / L.

[0046] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0047] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

[0048] The present invention will be further described below with reference to specific embodiments.

[0049] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0050] Unless otherwise specified, all reagents used in the following examples and comparative examples are commercially available chemically pure reagents.

[0051] Example 1

[0052] (1) Add 0.5 mol of 4,4'-difluorobenzophenone, 327 g of ethanol and 0.5 mol of ammonium formate to a flask equipped with a stirrer, condenser and thermometer, stir to dissolve, and keep the temperature at 80℃ for 2 h.

[0053] (2) The above mixture was distilled under reduced pressure to 100°C until no fraction was obtained, resulting in a viscous solid. The solid was dissolved in 218g of toluene and transferred to a high-pressure reactor.

[0054] (3) Add 5.5g of sodium hydroxide to the autoclave, purge the autoclave and pipelines with nitrogen, seal the autoclave, evacuate, introduce 2mol of ethylene oxide, heat to 110℃, pressurize to 0.02MPa, keep the reaction at the temperature for 1h, cool the circulating water to below 40℃, distill the mixture under reduced pressure to obtain a viscous solid, dissolve the viscous solid with 30% by weight of methanol, and adjust the pH to 8-9 with 10wt% hydrochloric acid to obtain the product, temperature-resistant and salt-resistant heavy oil viscosity reducer B1.

[0055] Example 2

[0056] (1) Add 0.5 mol of 4,4'-difluorobenzophenone, 414 g of propanol and 0.7 mol of ammonium formate to a flask equipped with a stirrer, condenser and thermometer, stir to dissolve, and keep the temperature at 90℃ for 2 h.

[0057] (2) The above mixture was distilled under reduced pressure to 100°C until no fraction was obtained, resulting in a viscous solid. The solid was dissolved in 249g of toluene and transferred to an autoclave.

[0058] (3) Add 9.4g of sodium hydroxide to the autoclave, purge the autoclave and pipelines with nitrogen, seal the autoclave, evacuate, introduce 5mol of ethylene oxide, heat to 122℃, pressurize to 0.05MPa, keep the reaction at the temperature for 2h, cool the circulating water to below 40℃, distill the mixture under reduced pressure to obtain a viscous solid, dissolve the viscous solid with 30% by weight of methanol, and adjust the pH to 8-9 with 10wt% hydrochloric acid to obtain the product, temperature-resistant and salt-resistant heavy oil viscosity reducer B2.

[0059] Example 3

[0060] (1) Add 0.5 mol of 4,4'-difluorobenzophenone, 366 g of isopropanol and 1 mol of ammonium formate to a flask equipped with a stirrer, condenser and thermometer, stir to dissolve, and keep the temperature at 85℃ for 3 h.

[0061] (2) The above mixture was distilled under reduced pressure to 100°C until no fraction was obtained, resulting in a viscous solid. The solid was dissolved in 300g of toluene and transferred to a high-pressure reactor.

[0062] (3) Add 10.3g of potassium hydroxide to the autoclave, purge the autoclave and pipelines with nitrogen, seal the autoclave, evacuate, introduce 10mol of ethylene oxide, heat to 132℃, pressurize to 0.1MPa, keep the reaction at the temperature for 3h, cool the circulating water to below 40℃, distill the mixture under reduced pressure to obtain a viscous solid, dissolve the viscous solid with 30% by weight of methanol, and adjust the pH to 8-9 with 10wt% hydrochloric acid to obtain the product, temperature-resistant and salt-resistant heavy oil viscosity reducer B3.

[0063] Example 4

[0064] (1) Add 0.5 mol of 4,4'-difluorobenzophenone, 465 g of propanol and 1.2 mol of ammonium formate to a flask equipped with a stirrer, condenser and thermometer, stir to dissolve, and keep the reaction at 82℃ for 3 h.

[0065] (2) The above mixture was distilled under reduced pressure to 100°C until no fraction was obtained, resulting in a viscous solid. The solid was dissolved in 327g of toluene and transferred to an autoclave.

[0066] (3) Add 13.3g of calcium hydroxide to the autoclave, purge the autoclave and pipelines with nitrogen, seal the autoclave, evacuate, introduce 20mol of ethylene oxide, heat to 144℃, pressurize to 0.17MPa, keep the reaction at the temperature for 4h, cool the circulating water to below 40℃, distill the mixture under reduced pressure to obtain a viscous solid, dissolve the viscous solid with 30% by weight of methanol, and adjust the pH to 8-9 with 10wt% hydrochloric acid to obtain the product, temperature-resistant and salt-resistant heavy oil viscosity reducer B4.

[0067] Example 5

[0068] (1) Add 0.5 mol of 4,4'-difluorobenzophenone, 433 g of ethanol and 1.2 mol of ammonium formate to a flask equipped with a stirrer, condenser and thermometer, stir to dissolve, and keep the reaction at 86℃ for 4 h.

[0069] (2) The above mixture was distilled under reduced pressure to 100°C until no fraction was obtained, resulting in a viscous solid. The solid was dissolved in 265g of benzene and transferred to an autoclave.

[0070] (3) Add 17.6g of sodium ethoxide to the autoclave, purge the autoclave and pipelines with nitrogen, seal the autoclave, evacuate, introduce 30mol of ethylene oxide, heat to 158℃, pressurize to 0.26MPa, keep the reaction at the temperature for 6h, cool the circulating water to below 40℃, distill the mixture under reduced pressure to obtain a viscous solid, dissolve the viscous solid with 30% by weight of methanol, and adjust the pH to 8-9 with 10wt% hydrochloric acid to obtain the product, temperature-resistant and salt-resistant heavy oil viscosity reducer B5.

[0071] Example 6

[0072] (1) Add 0.5 mol of 4,4'-difluorobenzophenone, 545 g of ethanol and 1.4 mol of ammonium formate to a flask equipped with a stirrer, condenser and thermometer, stir to dissolve, and keep the reaction at 83℃ for 4 h.

[0073] (2) The above mixture was distilled under reduced pressure to 100°C until no fraction was obtained, resulting in a viscous solid. The solid was dissolved in 308g of benzene and transferred to an autoclave.

[0074] (3) Add 18.9g of sodium hydroxide to the autoclave, purge the autoclave and pipelines with nitrogen, seal the autoclave, evacuate, introduce 40mol of ethylene oxide, heat to 170℃, pressurize to 0.34MPa, keep the reaction at the temperature for 7h, cool the circulating water to below 40℃, distill the mixture under reduced pressure to obtain a viscous solid, dissolve the viscous solid with 30% by weight of methanol, and adjust the pH to 8-9 with 10wt% hydrochloric acid to obtain the product, temperature-resistant and salt-resistant heavy oil viscosity reducer B6.

[0075] Example 7

[0076] (1) Add 0.5 mol of 4,4'-difluorobenzophenone, 515 g of ethanol and 1.5 mol of ammonium formate to a flask equipped with a stirrer, condenser and thermometer, stir to dissolve, and keep the reaction at 87°C for 4 h.

[0077] (2) The above mixture was distilled under reduced pressure to 100°C until no fraction was obtained, resulting in a viscous solid. The solid was dissolved in 313g of benzene and transferred to an autoclave.

[0078] (3) Add 21.8g of potassium hydroxide to the autoclave, purge the autoclave and pipelines with nitrogen, seal the autoclave, evacuate, introduce 50mol of ethylene oxide, heat to 180℃, pressurize to 0.4MPa, keep the reaction at the temperature for 8h, cool the circulating water to below 40℃, distill the mixture under reduced pressure to obtain a viscous solid, dissolve the viscous solid with 30% by weight of methanol, and adjust the pH to 8-9 with 10wt% hydrochloric acid to obtain the product, temperature-resistant and salt-resistant heavy oil viscosity reducer B7.

[0079] Example 8: Testing of Surface Tension and Interfacial Tension

[0080] The oil displacement agent of the present invention and the petroleum sulfonate of Shengli Chemical Plant were prepared into a 500 mg / L solution. The surface tension was determined according to the pull-ring method in SY / T 5370-2018 "Methods for Determination of Surface and Interfacial Tension". The interfacial tension was tested by the pendant drop method. The crude oil used to test the interfacial tension was heavy oil from a block of Shengli Oilfield. The viscosity of the crude oil at 50°C was 23560 mPa·s. The test results of the surface and interfacial tension are shown in Table 1.

[0081] As shown in Table 1, the surface tension of the oil displacement agents B1-B7 of this invention is all less than 26.5 mN / m, with B5 having the lowest surface tension at 23.6 mN / m. In contrast, the surface tension of the comparative petroleum sulfonate is 29.4 mN / m, significantly higher than that of this invention. Furthermore, the interfacial tension of the oil displacement agents B1-B7 of this invention is all less than 6.5 × 10⁻⁶ mN / m. -2 mN / m, with B5 reaching a minimum of 2.5×10 mN / m. -2 The surface tension of the comparative petroleum sulfonate was 8.69 × 10 mN / m. -2 The mN / m ratio is significantly higher than that of this invention.

[0082] Example 9: Determination of viscosity reduction rate

[0083] The crude oil used in this experiment was the same as in Example 8. The oil displacement agent of this invention and Shengli Chemical Plant petroleum sulfonate were prepared into a 500 mg / L solution. The evaluation method referred to Q / SH10201519—2016 "General Technical Conditions for Heavy Oil Viscosity Reducers".

[0084]

[0085] In the formula:

[0086] f—viscosity reduction rate, %;

[0087] μ0 — Initial viscosity of crude oil at 50℃, mPa·s;

[0088] μ——Crude oil viscosity after viscosity reduction, mPa·s.

[0089] The test results are shown in Table 1.

[0090] As can be seen from Table 1, the viscosity reduction rate of the oil displacement agents B1-B7 of the present invention is greater than 96% when the concentration is 500 mg / L, with B5 reaching the highest at 99.2%. In contrast, the viscosity reduction rate of the comparative petroleum sulfonates is 69.8%, which is significantly lower than that of the present invention.

[0091] Table 1. Results of surface tension, interfacial tension, and viscosity reduction tests.

[0092]

[0093] Example 10: Contact Angle Test

[0094] The viscosity-reducing and oil displacement agent B5 of this invention was prepared into a 500 mg / L solution with petroleum sulfonate from Shengli Chemical Plant. A hydrophobic core model was placed in the above solution in a sealed container and placed in a 90°C oven for 12 hours. The core model was then removed, dried in a 100°C oven for 4 hours, and after cooling, the contact angle was tested with distilled water. The results are shown below. Figure 1 .

[0095] from Figure 1 It can be seen that the contact angle of the hydrophobic core model before treatment was 89.6°, and after treatment with the viscosity-reducing oil displacement agent B5 of this invention, the contact angle decreased to 16.5°, while the contact angle after treatment with petroleum sulfonate was reduced to 51.0°. The reduction in contact angle was significantly lower than that of this invention.

[0096] 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. A method for preparing a temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent, characterized in that, The preparation method includes: 4,4'-difluorobenzophenone undergoes a Leuckart-Wallach reaction with ammonium formate in a first solvent at 80-90℃; then, under the action of a catalyst, the reaction product undergoes an etherification reaction with ethylene oxide in a second solvent, in an oxygen-isolated environment, and under high temperature and high pressure conditions. The first solvent is one of ethanol, propanol, and isopropanol, and the mass ratio of it to 4,4'-difluorobenzophenone is 3-5:

1. The second solvent is either benzene or toluene, and the mass ratio of it to 4,4'-difluorobenzophenone is 2-3:1; The high-temperature conditions are 110-180℃, and the high-pressure conditions are 0.02-0.4MPa.

2. The preparation method of the temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent as described in claim 1, characterized in that, Based on 1 mole of 4,4'-difluorobenzophenone, the amounts of ammonium formate and ethylene oxide are 1-3 moles and 4-100 moles, respectively.

3. The preparation method of the temperature-resistant and salt-resistant heavy oil viscosity-reducing and displacement agent as described in claim 2, characterized in that, Based on 1 mole of 4,4'-difluorobenzophenone, the amounts of ammonium formate and ethylene oxide are 2-3 moles and 10-100 moles, respectively.

4. The preparation method of the temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent as described in claim 1, characterized in that, The Leuckart-Wallach reaction time is 2-4 hours.

5. The preparation method of the temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent as described in claim 4, characterized in that, The Leuckart-Wallach reaction time is 2-3 hours.

6. The preparation method of the temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent as described in claim 1, characterized in that, The catalyst is one of solid sodium hydroxide, solid potassium hydroxide, solid calcium hydroxide, or solid sodium ethoxide.

7. The preparation method of the temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent as described in claim 1, characterized in that, The mass ratio of the catalyst to 4,4'-difluorobenzophenone is 0.05-0.2:

1.

8. The preparation method of the temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent as described in claim 1, characterized in that, The high-temperature conditions are 120-150℃, and the high-pressure conditions are 0.05-0.2MPa.

9. The preparation method of the temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent as described in claim 1, characterized in that, The etherification reaction time is 1-8 hours.

10. The preparation method of the temperature-resistant and salt-resistant heavy oil viscosity-reducing and oil displacement agent as described in claim 9, characterized in that, The etherification reaction time is 2-5 hours.

11. The oil displacement agent prepared by the method for preparing a temperature-resistant and salt-resistant heavy oil viscosity-reducing oil displacement agent according to any one of claims 1-10, characterized in that, The molecular structural formula of the oil displacement agent is as follows: Where: m = 2 - 50; n=5-100。 12. The oil displacement agent as described in claim 11, characterized in that, The molecular structural formula of the oil displacement agent is as follows: Where: m = 5-10; n=25-50。 13. The application of the oil displacement agent as described in claim 11 or 12 in the development of heavy oil reservoirs.

14. The application as described in claim 13, characterized in that, The applied heavy oil reservoir has a temperature of less than 90℃ and a salinity of less than 120,000 mg / L.

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