A thickened oil viscosity reducing oil displacement agent, its preparation method and application

Abstract

The application belongs to the technical field of tertiary oil recovery, and particularly relates to a heavy oil viscosity-reducing oil-displacing agent and a preparation method and application thereof. The preparation method is as follows: a four-necked flask is added with nonyl phenol, 4-piperidine carboxylic acid, formaldehyde and water, and stirred and heated to reflux until the reaction is completed, cooling water is introduced, unreacted raw materials are distilled out under normal pressure, and the temperature is cooled to room temperature, and the pH is adjusted; the liquid is transferred to an autoclave, nitrogen is blown, then stirred and heated, and then ethylene oxide is introduced, nitrogen is introduced to increase the pressure of the reactor, and then heated, and after the reaction, the temperature is cooled to room temperature to obtain a crude product containing water; the crude product containing water is separated by a silica gel chromatographic column to obtain a dark yellow viscous liquid, which is the product, a viscosity-reducing oil-displacing agent. The heavy oil viscosity-reducing oil-displacing agent has the advantages of wide raw material sources, simple synthesis process, clean process without pollution, easy product obtaining, transportation and storage, etc.

Description

Technical Field

[0001] This invention belongs to the field of tertiary oil recovery technology and relates to a chemical agent used in crude oil extraction, specifically a heavy oil viscosity reducing and displacement agent and its preparation method and application. Background Technology

[0002] my country is rich in heavy oil resources, and with the increasing demand for energy driven by economic development, heavy oil will become one of the main battlegrounds for oil extraction in my country in the future. Heavy oil is characterized by high asphaltene content, high viscosity, and high flow resistance, making it difficult to extract. Currently, the main methods for extracting heavy oil in my country are steam injection and steam drive, which are among the most technically and economically successful technologies for developing heavy oil reservoirs.

[0003] However, the main problem currently facing heavy oil steam drive is that reservoir heterogeneity and differences in the working conditions of each production well make it easy for steam breakthrough to occur in production wells located in high-permeability directions, with high production and small injection-production well spacing, so the reservoir heat utilization rate and economic efficiency cannot be effectively guaranteed.

[0004] Heavy oil viscosity reducers can effectively reduce the viscosity of heavy oil, reduce the interfacial tension between oil and water, increase reservoir energy, and reduce residual oil saturation, thereby improving the development effect of heavy oil reservoirs.

[0005] CN201210026686.2 discloses a viscosity reducer for heavy oil cold-production formation crude oil, applied to the treatment of formation crude oil in cold-production heavy oil in oilfields to improve the fluidity of formation crude oil. The weight percentages of each component are as follows: Sodium N,N-oleoyl bis-taurate: 10.2–11.5%; Sodium lauroyl methyl taurate: 18.6–19.0%; Sodium secondary alkyl sulfate: 15.3–15.8%; Emulsifier OPE-12: 3.5–4.5%; Sodium oleate: 0.1–0.15%; Sodium hydroxide: 0.1–0.15%; the remainder is water, and the sum of the weight percentages of all components is 100%. The effect is to reduce the viscosity of heavy oil in the formation, improve its fluidity, and solve the problem of difficulty in the flow of heavy oil from underground formations into the wellbore. However, this viscosity reducer formula uses sodium hydroxide, making demulsification and dehydration of the produced crude oil more difficult, and also introducing additional workload for further processing of the crude oil.

[0006] CN201910795697.9 discloses a water-soluble hyperbranched heavy oil viscosity reducer and its preparation method. This viscosity reducer is a polymer copolymerized from 0.01%–1.0% functionalized backbone monomers, 10%–20% acrylamide, 10%–20% acrylic acid, 40%–50% nonionic functional monomer octylphenol polyoxyethylene ether, and 20%–25% anionic monomer 2-acrylamidotetradecyl sulfonate sodium. This viscosity reducer exhibits strong aqueous viscosity-increasing ability and good shear resistance, enabling it to control the mobility ratio and expand the swept volume. Simultaneously, it demonstrates strong emulsification properties when mixed with heavy oil, achieving a viscosity reduction rate of over 80% with ordinary heavy oil and easy demulsification, thus achieving the multi-purpose effect of viscosity reduction and oil displacement in one agent. The raw materials for preparing this viscosity reducer are widely available, the preparation process is simple, and the cost is low. However, this formula only has a viscosity reduction rate of about 80%, which is difficult to meet the needs of field applications for heavy oils with high viscosity, thus limiting its practical application. Summary of the Invention

[0007] This invention addresses the problems encountered in heavy oil extraction in China by providing a heavy oil viscosity-reducing and displacement agent, its preparation method, and its application. This heavy oil viscosity-reducing and displacement agent features a wide range of raw material sources, a simple synthesis process, a clean and pollution-free process, and easy-to-obtain, transport, and store products. Furthermore, it boasts advantages such as low concentration, high viscosity reduction rate, and high oil displacement efficiency.

[0008] Therefore, in order to achieve the above objectives, on the one hand, the present invention discloses a heavy oil viscosity reducing and displacement agent, the molecular structural formula of which is as follows:

[0009]

[0010] in:

[0011] m = 2 - 20;

[0012] n = 2 - 20;

[0013] l = 2 - 10.

[0014] On the other hand, the present invention provides a method for preparing the above-mentioned heavy oil viscosity reducing and displacement agent, the preparation method comprising: firstly, under reflux conditions and in the presence of a solvent, nonylphenol, 4-piperidinecarboxylic acid, and formaldehyde undergo a Mannich reaction; secondly, under polyetherification reaction conditions, ethylene oxide is added to undergo a polyetherification reaction.

[0015] The third objective of this invention is to disclose the application of the above-mentioned heavy oil viscosity reducer and oil displacement agent in the development of heavy oil reservoirs.

[0016] The viscosity-reducing and oil displacement agent of this invention belongs to an amphiphilic polymer molecule. The hydrophilic groups are mainly three polyoxyethylene ether functional groups. The pyridine N group is positively charged and possesses a certain degree of hydrophilicity, contributing to the overall hydrophilicity of the molecule. The polymer molecule of this invention contains nonpolar groups such as ester, phenyl, and nonyl groups, exhibiting hydrophobic and lipophilic properties. In particular, the nonyl group is a typical lipophilic group, capable of penetrating deep into crude oil. This allows the molecule to rapidly penetrate from the aqueous phase into the oil phase through the oil-water interface, easily interacting with large aromatic ring compounds and long-chain aliphatic hydrocarbons in heavy oil. Since the hydrophilic groups are immiscible with crude oil, they extend to the outer layer of the crude oil and adsorb outer water molecules, forming a water film. This emulsifies the heavy oil into an O / W emulsion, creating a continuous water film and reducing the flow resistance of the heavy oil. The polymer-type viscosity reducer of this invention has a relatively long molecular chain, thus enabling the emulsification and viscosity reduction of heavy oil even at lower concentrations.

[0017] The beneficial effects and advantages of this invention compared with the prior art are as follows:

[0018] (1) The heavy oil viscosity reducer and oil displacement agent of the present invention has the advantages of wide availability of raw materials, simple synthesis process, clean and pollution-free process, and easy-to-obtain, transport and store product;

[0019] (2) The heavy oil viscosity reducing and displacement agent of the present invention has a good viscosity reducing effect. Under the condition of using a concentration of 500 mg / L, it can reduce the viscosity of heavy oil to below 100 mPa.s, and the viscosity reduction rate reaches more than 99%.

[0020] (3) The heavy oil viscosity reducing and oil displacement agent of the present invention has a good oil displacement effect, and the oil displacement efficiency in the physical model experiment reaches more than 25%. 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 heavy oil viscosity reducer and displacement agent is disclosed, wherein the molecular structural formula of the heavy oil viscosity reducer and displacement agent is as follows:

[0023]

[0024] in:

[0025] m = 2-20, more preferably m = 3-10;

[0026] n = 2-20, more preferably n = 6-12;

[0027] l = 2-10, more preferably l = 3-6.

[0028] Secondly, the present invention provides a method for preparing a heavy oil viscosity reducer and oil displacement agent, the method comprising: firstly, under reflux conditions and in the presence of a solvent, nonylphenol, 4-piperidinecarboxylic acid, and formaldehyde undergo a Mannich reaction; secondly, under polyetherification reaction conditions, ethylene oxide is added to undergo a polyetherification reaction.

[0029] In this invention, preferably, based on 1 mole of nonylphenol, the amounts of 4-piperidinecarboxylic acid and formaldehyde are 1.8-2.2 moles and 2-4 moles, respectively; more preferably, based on 1 mole of nonylphenol, the amounts of 4-piperidinecarboxylic acid and formaldehyde are 1.9-2.1 moles and 2.4-4 moles, respectively; even more preferably, based on 1 mole of nonylphenol, the amounts of 4-piperidinecarboxylic acid and formaldehyde are 1.95-2.05 moles and 2.5-3.5 moles, respectively.

[0030] In this invention, the amount of ethylene oxide used is determined by the pressure applied during reactor pressurization.

[0031] Preferably, the pressure boosting pressure of the reactor is 0.1-0.4 MPa; more preferably, the pressure boosting pressure of the reactor is 0.2-0.3 MPa.

[0032] In this invention, the heating reflux time is 6-12 hours; more preferably, the heating reflux time is 8-10 hours.

[0033] In this invention, the solvent is water, and the amount used is 10-20 times the mass of nonylphenol.

[0034] In this invention, the polyetherification reaction temperature is 120-130℃ and the reaction time is 6-12h; more preferably, the polyetherification reaction temperature is 120-125℃ and the reaction time is 7-10h.

[0035] According to a more specific preferred embodiment, the preparation method of the heavy oil viscosity reducer and oil displacement agent specifically includes the following steps:

[0036] (1) Add nonylphenol, 4-piperidinecarboxylic acid, 40wt% formaldehyde and water to a four-necked flask, stir and heat to reflux at a stirring rate of 200-300 rpm, reflux until the reaction is complete, stop heating, remove the reflux tube, replace it with a straight condenser, pass cooling water through, and distill off 10-20% of the total liquid volume at atmospheric pressure to distill off unreacted raw materials. Cool to room temperature and adjust the pH to 6-8 with 1M sodium hydroxide.

[0037] (2) Transfer the above liquid to a high-pressure reactor, purge the pipeline and reactor with nitrogen for 5-10 minutes, then stir and heat to 80-90℃ at a stirring rate of 200-300 rpm for 5-15 minutes, then stop the nitrogen flow and introduce ethylene oxide at a rate of 2-2.5 ml / min to pressurize the reactor. Adjust the stirring rate to 400-500 rpm and heat to 120-130℃. After 6-12 hours of reaction, gradually reduce the pressure in the reactor until it stabilizes. Use circulating cooling water to cool the system to room temperature to obtain a water-containing crude product.

[0038] (3) The water-containing crude product is separated by silica gel chromatography column to obtain a dark yellow viscous liquid, which is the product viscosity reducer and oil displacement agent.

[0039] The synthesis reaction equation for the heavy oil viscosity reducer and displacement agent is as follows:

[0040]

[0041]

[0042] The third objective of this invention is to disclose the application of the aforementioned heavy oil viscosity reducer and displacement agent in heavy oil reservoir development. No specific requirements are specified for the application; conventional applications in the field are acceptable and will not be elaborated upon here.

[0043] 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.

[0044] 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.

[0045] The present invention will be further described below with reference to specific embodiments.

[0046] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0047] Unless otherwise specified, all reagents used in the following examples and comparative examples are commercially available chemically pure reagents.

[0048] Example 1

[0049] (1) Add 0.1 mol nonylphenol, 0.18 mol 4-piperidinecarboxylic acid, 0.2 mol 40 wt% formaldehyde and 440 g water to a four-necked flask, stir and heat to reflux at a stirring speed of 200 rpm for 6 h, stop heating, remove the reflux tube, replace it with a straight condenser, pass cooling water through, and distill off 10% of the total liquid volume at atmospheric pressure to distill off unreacted raw materials. Cool to room temperature and adjust the pH to 6-8 with 1 M sodium hydroxide.

[0050] (2) Transfer the above liquid to a high-pressure reactor, purge the pipeline and reactor with nitrogen for 5 min, then stir and heat to 80°C at a stirring rate of 200 rpm for 15 min, then stop the nitrogen flow and introduce ethylene oxide at a rate of 2 ml / min to pressurize the reactor to 0.1 MPa. Adjust the stirring rate to 460 rpm and heat to 120°C. After 6 h of reaction, the reactor pressure gradually decreases until it stabilizes. Use circulating cooling water to cool the system to room temperature to obtain a water-containing crude product.

[0051] (3) The water-containing crude product was separated by silica gel chromatography column to obtain a dark yellow viscous liquid, which is the product viscosity reducer and oil displacement agent J1.

[0052] Example 2

[0053] (1) Add 0.1 mol nonylphenol, 0.22 mol 4-piperidinecarboxylic acid, 0.22 mol 40 wt% formaldehyde and 363 g water to a four-necked flask, stir and heat to reflux at a stirring speed of 300 rpm for 7 h, stop heating, remove the reflux tube, replace it with a straight condenser, pass cooling water through, and distill off 12% of the total liquid volume at atmospheric pressure to distill off unreacted raw materials. Cool to room temperature and adjust the pH to 6-8 with 1 M sodium hydroxide.

[0054] (2) Transfer the above liquid to a high-pressure reactor, purge the pipeline and reactor with nitrogen for 5 min, then stir and heat to 90°C at a stirring rate of 220 rpm for 10 min, then stop the nitrogen flow and introduce ethylene oxide at a rate of 2 ml / min to pressurize the reactor to 0.15 MPa. Adjust the stirring rate to 420 rpm and heat to 130°C. After 7 h of reaction, the pressure in the reactor gradually decreases until it stabilizes. Use circulating cooling water to cool the system to room temperature to obtain a water-containing crude product.

[0055] (3) The water-containing crude product was separated by silica gel chromatography column to obtain a dark yellow viscous liquid, which is the product viscosity reducer and oil displacement agent J2.

[0056] Example 3

[0057] (1) Add 0.1 mol nonylphenol, 0.19 mol 4-piperidinecarboxylic acid, 0.25 mol 40 wt% formaldehyde and 320 g water to a four-necked flask, stir and heat to reflux at a stirring speed of 250 rpm for 8 h, stop heating, remove the reflux tube, replace it with a straight condenser, pass cooling water through, and distill off 15% of the total liquid volume at atmospheric pressure to distill off unreacted raw materials. Cool to room temperature and adjust the pH to 6-8 with 1 M sodium hydroxide.

[0058] (2) Transfer the above liquid to a high-pressure reactor, purge the pipeline and reactor with nitrogen for 10 min, then stir and heat to 85°C at a stirring rate of 250 rpm for 12 min, then stop the nitrogen flow and introduce ethylene oxide at a rate of 2.5 ml / min to pressurize the reactor to 0.2 MPa. Adjust the stirring rate to 480 rpm and heat to 125°C. After 8 h of reaction, the pressure in the reactor gradually decreases until it stabilizes. Use circulating cooling water to cool the system to room temperature to obtain a water-containing crude product.

[0059] (3) The water-containing crude product was separated by silica gel chromatography column to obtain a dark yellow viscous liquid, which is the product viscosity reducer and oil displacement agent J3.

[0060] Example 4

[0061] (1) Add 0.1 mol nonylphenol, 0.21 mol 4-piperidinecarboxylic acid, 0.28 mol 40 wt% formaldehyde and 300 g water to a four-necked flask, stir and heat to reflux at a stirring speed of 200 rpm for 9 h, stop heating, remove the reflux tube, replace it with a straight condenser, pass cooling water through, and distill off 16% of the total liquid volume at atmospheric pressure to distill off unreacted raw materials. Cool to room temperature and adjust the pH to 6-8 with 1 M sodium hydroxide.

[0062] (2) Transfer the above liquid to a high-pressure reactor, purge the pipeline and reactor with nitrogen for 10 min, then stir and heat to 87°C at a stirring rate of 260 rpm for 8 min, then stop the nitrogen flow and introduce ethylene oxide at a rate of 2.2 ml / min to pressurize the reactor to 0.25 MPa. Adjust the stirring rate to 450 rpm and heat to 122°C. After 9 h of reaction, the pressure in the reactor gradually decreases until it stabilizes. Use circulating cooling water to cool the system to room temperature to obtain a water-containing crude product.

[0063] (3) The water-containing crude product was separated by silica gel chromatography column to obtain a dark yellow viscous liquid, which is the product viscosity reducer and oil displacement agent J4.

[0064] Example 5

[0065] (1) Add 0.1 mol nonylphenol, 0.195 mol 4-piperidinecarboxylic acid, 0.3 mol 40 wt% formaldehyde and 280 g water to a four-necked flask, stir and heat to reflux at a stirring speed of 280 rpm for 10 h, stop heating, remove the reflux tube, replace it with a straight condenser, pass cooling water through, and distill off 18% of the total liquid volume at atmospheric pressure to distill off unreacted raw materials. Cool to room temperature and adjust the pH to 6-8 with 1 M sodium hydroxide.

[0066] (2) Transfer the above liquid to a high-pressure reactor, purge the pipeline and reactor with nitrogen for 8 minutes, then stir and heat to 85°C at a stirring rate of 280 rpm for 10 minutes, then stop the nitrogen flow and introduce ethylene oxide at a rate of 2.3 ml / min to pressurize the reactor to 0.3 MPa. Adjust the stirring rate to 400 rpm and heat to 128°C. After 9 hours of reaction, the pressure in the reactor gradually decreases until it stabilizes. Use circulating cooling water to cool the system to room temperature to obtain a water-containing crude product.

[0067] (3) The water-containing crude product was separated by silica gel chromatography column to obtain a dark yellow viscous liquid, which is the product viscosity reducer and oil displacement agent J5.

[0068] Example 6

[0069] (1) Add 0.1 mol nonylphenol, 0.205 mol 4-piperidinecarboxylic acid, 0.33 mol 40 wt% formaldehyde and 268 g water to a four-necked flask, stir and heat to reflux at a stirring speed of 220 rpm for 10 h, stop heating, remove the reflux tube, replace it with a straight condenser, pass cooling water through, and distill off 20% of the total liquid volume at atmospheric pressure to distill off unreacted raw materials. Cool to room temperature and adjust the pH to 6-8 with 1 M sodium hydroxide.

[0070] (2) Transfer the above liquid to a high-pressure reactor, purge the pipeline and reactor with nitrogen for 6 minutes, then stir and heat to 82°C at a stirring rate of 300 rpm for 5 minutes, then stop the nitrogen flow and introduce ethylene oxide at a rate of 2.5 ml / min to pressurize the reactor to 0.33 MPa. Adjust the stirring rate to 500 rpm and heat to 127°C. After 12 hours of reaction, the pressure in the reactor gradually decreases until it stabilizes. Use circulating cooling water to cool the system to room temperature to obtain a water-containing crude product.

[0071] (3) The water-containing crude product was separated by silica gel chromatography column to obtain a dark yellow viscous liquid, which is the product viscosity reducer and oil displacement agent J6.

[0072] Example 7

[0073] (1) Add 0.1 mol nonylphenol, 0.21 mol 4-piperidinecarboxylic acid, 0.4 mol 40 wt% formaldehyde and 244 g water to a four-necked flask, stir and heat to reflux at a stirring speed of 270 rpm for 12 h, stop heating, remove the reflux tube, replace it with a straight condenser, pass cooling water through, and distill off 16% of the total liquid volume at atmospheric pressure to distill off unreacted raw materials. Cool to room temperature and adjust the pH to 6-8 with 1 M sodium hydroxide.

[0074] (2) Transfer the above liquid to a high-pressure reactor, purge the pipeline and reactor with nitrogen for 7 min, then stir and heat to 87°C at a stirring rate of 250 rpm for 15 min, then stop the nitrogen flow and introduce ethylene oxide at a rate of 2.4 ml / min to pressurize the reactor to 0.36 MPa. Adjust the stirring rate to 400 rpm and heat to 130°C. After 11 h of reaction, the pressure in the reactor gradually decreases until it stabilizes. Use circulating cooling water to cool the system to room temperature to obtain a water-containing crude product.

[0075] (3) The water-containing crude product was separated by silica gel chromatography column to obtain a dark yellow viscous liquid, which is the product viscosity reducer and oil displacement agent J7.

[0076] Example 8

[0077] (1) Add 0.1 mol nonylphenol, 0.2 mol 4-piperidinecarboxylic acid, 0.35 mol 40 wt% formaldehyde and 220 g water to a four-necked flask, stir and heat to reflux at a stirring speed of 260 rpm for 12 h, stop heating, remove the reflux tube, replace it with a straight condenser, pass cooling water through, and distill off 18% of the total liquid volume at atmospheric pressure to distill off unreacted raw materials. Cool to room temperature and adjust the pH to 6-8 with 1 M sodium hydroxide.

[0078] (2) Transfer the above liquid to a high-pressure reactor, purge the pipeline and reactor with nitrogen for 8 minutes, then stir and heat to 90°C at a stirring rate of 300 rpm for 15 minutes, then stop the nitrogen flow and introduce ethylene oxide at a rate of 2.2 ml / min to pressurize the reactor to 0.4 MPa. Adjust the stirring rate to 500 rpm and heat to 128°C. After 12 hours of reaction, the pressure in the reactor gradually decreases until it stabilizes. Use circulating cooling water to cool the system to room temperature to obtain a water-containing crude product.

[0079] (3) The water-containing crude product was separated by silica gel chromatography column to obtain a dark yellow viscous liquid, which is the product viscosity reducer and oil displacement agent J8.

[0080] Example 9: Evaluation of Heavy Oil Viscosity Reduction

[0081] The crude oil used in this experiment was an oil sample from a block of Shengli Oilfield Xianhe Oil Production Plant. The initial viscosity of the crude oil at 50℃ was 18500 mPa·s.

[0082] Heavy oil viscosity reducers J1, J2, J3, J4, J5, J6, J7, J8, nonionic viscosity reducer OP-10 (alkylphenol polyoxyethylene ether), and anionic viscosity reducer sodium dodecyl sulfate were prepared into solutions of 500 mg / L and 3000 mg / L, respectively.

[0083] The evaluation method refers to Q / SH10201519—2016 "General Technical Requirements 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] Table 1. Viscosity Reduction Test Results of Oil Samples from Xianhe Oilfield

[0091]

[0092]

[0093] As shown in Table 1, at a mass concentration of 500 mg / L, the heavy oil viscosity reducers and displacement agents J1-J8 of this invention exhibit better viscosity reduction effects on the heavy oil produced at the Xianhe Oilfield, with a viscosity reduction rate greater than 99.4%, among which J6 has the highest rate of 99.58%. In contrast, the viscosity reduction rates of OP-10 and sodium dodecyl sulfate are 90.21% and 91.36%, respectively, significantly lower than those of this invention. At a mass concentration of 3000 mg / L, the heavy oil viscosity reducers and displacement agents J1-J8 of this invention achieve a viscosity reduction rate greater than 99.5% on heavy oil, with J8 having the highest rate of 99.61%. In contrast, the viscosity reduction rates of OP-10 and sodium dodecyl sulfate are 94.96% and 95.09%, respectively, significantly lower than those of this invention.

[0094] Example 10 Evaluation of Heavy Oil Viscosity Reduction

[0095] The crude oil used in this experiment was an oil sample from a block of the Shengli Oilfield Hekou Oil Production Plant. The initial viscosity of the crude oil at 50℃ was 48400 mPa·s.

[0096] The testing method is the same as in Example 9.

[0097] The test results are shown in Table 2.

[0098] Table 2. Viscosity Reduction Test Results of Oil Samples from Hekou Oilfield

[0099]

[0100]

[0101] As shown in Table 2, at a mass concentration of 500 mg / L, the heavy oil viscosity reducer and displacement agent J1-J8 of this invention exhibits a better viscosity reduction effect on heavy oil from the Hekou Oilfield, with a viscosity reduction rate greater than 99.7%, among which J8 has the highest rate of 99.83%. In contrast, the viscosity reduction rates of OP-10 and sodium dodecyl sulfate are 91.82% and 92.37%, respectively, significantly lower than those of this invention. At a mass concentration of 3000 mg / L, the heavy oil viscosity reducer and displacement agent J1-J8 of this invention achieves a viscosity reduction rate greater than 99.80% on heavy oil, with J8 having the highest rate of 99.85%. In contrast, the viscosity reduction rates of OP-10 and sodium dodecyl sulfate are 95.29% and 95.58%, respectively, significantly lower than those of this invention.

[0102] Example 10: Evaluation of Oil Displacement Efficiency

[0103] The filling permeability is 1000×10 -3 μm 2 The core was filled with sand; the core was vacuumed and saturated with formation water from reservoir G in the Hekou Oil Production Plant of Shengli Oilfield, and the core pore volume PV was calculated; the core was saturated with dehydrated and degassed crude oil from reservoir G until the oil content in the produced fluid at the core outlet was 100%, and the original oil saturation of the core was calculated; the core was aged at 72℃ for 7 days in reservoir G; a first waterflood was performed until the water cut at the outlet was 98%, and the first waterflood recovery rate was calculated; heavy oil viscosity reducing agents J1-J8, OP-10 and sodium dodecyl sulfate were injected respectively, with a mass concentration of 300 mg / L, an injection volume of 0.3 PV and an injection rate of 1.0 ml / min. After the injection was completed, a second waterflood was performed until the water cut at the outlet was 100%, and the oil displacement efficiency of the physical model was calculated. The results are shown in Table 3.

[0104] Table 3 Evaluation results of the oil displacement effect of heavy oil viscosity reducers and oil displacement agents

[0105]

[0106] Table 3 shows that: at a mass concentration of 500 mg / L, an injection volume of 0.3 PV, an injection rate of 1.0 ml / min, and a core permeability of 1000 × 10⁻⁶, the following conditions were met: -3 μm 2Under the given conditions, the oil displacement efficiencies of the heavy oil viscosity reducing and displacement agents J1-J8 of the present invention are all greater than 26%, with J8 having the highest oil displacement efficiency of 29.2%, demonstrating good oil displacement effect; while the oil displacement efficiencies of OP-10 and sodium dodecyl sulfate are 13.7% and 11.6% respectively, which are significantly lower than those of the present invention.

[0107] 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 viscosity-reducing and oil displacement agent for heavy oil, characterized in that, The preparation method specifically includes the following steps: (1) Add nonylphenol, 4-piperidinecarboxylic acid, 40wt% formaldehyde and water to a four-necked flask, stir and heat to reflux at a stirring rate of 200-300 rpm, reflux until the reaction is complete, stop heating, remove the reflux tube, replace it with a straight condenser, pass cooling water through, and distill off 10-20% of the total liquid volume at atmospheric pressure to distill off unreacted raw materials. Cool to room temperature and adjust the pH to 6-8 with 1M sodium hydroxide. (2) Transfer the above liquid to a high-pressure reactor, purge the pipeline and reactor with nitrogen for 5-10 minutes, then stir and heat to 80-90℃ at a stirring rate of 200-300 rpm for 5-15 minutes, then stop the nitrogen flow and introduce ethylene oxide at a rate of 2-2.5 ml / min to pressurize the reactor. Adjust the stirring rate to 400-500 rpm and heat to 120-130℃. After 6-12 hours of reaction, gradually reduce the pressure in the reactor until it stabilizes. Use circulating cooling water to cool the system to room temperature to obtain a water-containing crude product. (3) The aqueous crude product was separated by silica gel chromatography to obtain a dark yellow viscous liquid, which is the product viscosity reducer and oil displacement agent. Based on 1 mole of nonylphenol, the amounts of 4-piperidinecarboxylic acid and formaldehyde are 1.8-2.2 moles and 2-4 moles, respectively; The pressure of the reactor is 0.1-0.4 MPa; the reflux time is 6-12 h.

2. The preparation method of the heavy oil viscosity reducer and oil displacement agent as described in claim 1, characterized in that, Based on 1 mole of nonylphenol, the amounts of 4-piperidinecarboxylic acid and formaldehyde are 1.9-2.1 moles and 2.4-4 moles, respectively.

3. The preparation method of the heavy oil viscosity reducer and oil displacement agent as described in claim 2, characterized in that, Based on 1 mole of nonylphenol, the amounts of 4-piperidinecarboxylic acid and formaldehyde are 1.95-2.05 moles and 2.5-3.5 moles, respectively.

4. The preparation method of the heavy oil viscosity reducer and oil displacement agent as described in claim 1, characterized in that, The pressure of the reactor is 0.2-0.3 MPa.

5. The preparation method of the heavy oil viscosity reducer and oil displacement agent as described in claim 1, characterized in that, The reflux time is 8-10 hours.

6. A viscosity reducer and oil displacement agent for heavy oil, characterized in that, The molecular structural formula of the heavy oil viscosity reducer and oil displacement agent is as follows: in: m＝2-20； n＝2-20； l＝2-10。 7. The heavy oil viscosity reducer and oil displacement agent as described in claim 6, characterized in that, The molecular structural formula of the heavy oil viscosity reducer and oil displacement agent is as follows: in: m＝3-10； n＝6-12； l＝3-6。 8. The application of the heavy oil viscosity reducer and oil displacement agent as described in any one of claims 6-7 in the development of heavy oil reservoirs.

Images