Heavy oil cold production oil displacement agent for combination flooding and preparation method of heavy oil cold production oil displacement agent

Abstract

The invention relates to the technical field of petroleum additives, in particular to a heavy oil cold production oil-displacing agent for combination flooding and a preparation method thereof.The heavy oil cold production oil-displacing agent for combination flooding is prepared according to the following steps that firstly, dimethylamine, formaldehyde and deionized water are added into p-nonylphenol to be heated and subjected to a reflux reaction, a viscous solid is obtained, and then the heavy oil cold production oil-displacing agent for combination flooding is obtained. And adding absolute ethyl alcohol and dodecyl bromide into the viscous solid, carrying out a heating reflux reaction to obtain an off-white solid, and finally, adding toluene, potassium hydroxide and ethylene oxide into the off-white solid, and carrying out a reaction to obtain the product. The heavy oil cold production oil-displacing agent for combination flooding is a composite surfactant, has the characteristics of diversified mechanisms, wide material sources, simple synthesis process, small dosage and good viscosity reduction effect, can enable the viscosity reduction rate of high-viscosity heavy oil to be greater than 99% under the condition that the use concentration is 200mg / L, does not need other auxiliary viscosity reduction measures, greatly reduces the application cost, and has wide application prospects. The method is suitable for various heavy oil reservoirs.

Description

Technical Field

[0001] This invention relates to the field of petroleum additives technology, specifically a heavy oil cold recovery oil displacement agent for composite flooding and its preparation method. Background Technology

[0002] Heavy oil, also known as "heavy crude oil," is characterized by high density, high viscosity, and low light oil content. Cold extraction of heavy oil mainly involves using chemical or biological methods to reduce its viscosity without changing the ambient temperature, thereby improving its fluidity and enabling effective extraction. Examples of methods include emulsification viscosity reduction, microbial viscosity reduction, and alkali flooding.

[0003] Emulsification viscosity reduction involves mixing an aqueous solution of a chemical surfactant with heavy oil under certain conditions to form a low-viscosity O / W type emulsion, thereby significantly reducing the viscosity of the heavy oil, improving its fluidity, and significantly reducing the difficulty of extraction. Emulsification viscosity reduction is recognized as an effective and low-cost chemical viscosity reduction method for heavy oil.

[0004] Most of the currently disclosed viscosity reducers are designed for use in wellbore viscosity reduction or multiple rounds of injection and churn in the near-wellbore zone. For example, Chinese patent document CN102604621A discloses a novel high-efficiency composite viscosity reducer for extra-heavy oil, which is mainly for use in wellbore viscosity reduction. On the other hand, Chinese patent document CN114058356A discloses a heavy oil viscosity reducer and a method for cold production of heavy oil with reduced viscosity, which is mainly for use in multiple rounds of injection and churn in the near-wellbore zone. Neither of these is suitable for long-distance displacement to improve oil recovery.

[0005] Currently, existing emulsified viscosity-reducing cold recovery agents used as alternatives for heavy oil cold recovery operate on relatively simple principles and require large quantities. They need to be used in conjunction with other technologies such as carbon dioxide viscosity reduction. For example, Chinese patent document CN107893648A discloses a carbon dioxide energy storage high-pressure viscosity reduction cold recovery method for heavy oil reservoirs, which has high oil recovery costs. Furthermore, many existing heavy oil cold recovery viscosity reducers contain varying levels of sodium hydroxide. For instance, Chinese patent document CN102604618A discloses a heavy oil cold recovery formation crude oil viscosity reducer with a sodium hydroxide content of 0.1% to 0.15%, which may cause secondary reservoir damage, affecting surface heavy oil processing, and is also relatively expensive. Summary of the Invention

[0006] This invention provides a heavy oil cold recovery agent for composite flooding and its preparation method, which overcomes the shortcomings of the prior art and can effectively solve the problems of single mechanism, high cost and formation damage caused by the addition of alkali to the feedstock.

[0007] One of the technical solutions of this invention is achieved through the following measures: a heavy oil cold recovery oil displacement agent for composite flooding, the chemical structural formula of which is:

[0008]

[0009] Where n is between 5 and 50.

[0010] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions:

[0011] The above-mentioned heavy oil cold recovery agent for composite flooding comprises p-nonylphenol, dimethylamine, formaldehyde, dodecyl bromide and ethylene oxide in a molar ratio of 0.05:(0.1 to 0.2):(0.1 to 0.2):(0.08 to 0.12):(0.15 to 2.00).

[0012] The above-mentioned heavy oil cold recovery agent for composite flooding comprises p-nonylphenol, dimethylamine, formaldehyde, dodecyl bromide and ethylene oxide in a molar ratio of 0.05:(0.15 to 0.2):(0.15 to 0.2):(0.09 to 0.11):(0.25 to 2.00).

[0013] The above-mentioned heavy oil cold recovery agent for combined flooding is obtained by the following method:

[0014] The first step involves preparing dimethylamine and formaldehyde into aqueous solutions with a mass concentration of 30% to 40% and a mass concentration of 30% to 40% respectively. Then, the required amount of dimethylamine aqueous solution, formaldehyde aqueous solution, and deionized water are added to the required amount of p-nonylphenol. After stirring, heating, and reflux reaction, a mixed solution a is obtained.

[0015] The second step is to distill the mixed solution a under reduced pressure to obtain a viscous solid a.

[0016] The third step involves adding the required amount of anhydrous ethanol to the viscous solid a, followed by the required amount of dodecyl bromide, stirring, heating, and reflux reaction to obtain a mixed solution b.

[0017] The fourth step involves distilling the mixed solution b under reduced pressure, recrystallizing, and drying it to obtain a white solid b.

[0018] Fifth step: Add off-white solid b, the required amount of toluene and potassium hydroxide to the reactor. After passing nitrogen gas into the reactor and evacuating it, stir. Then, pass the required amount of ethylene oxide into the reactor at once to react and obtain the reaction product. After cooling and vacuum distillation of the reaction product, obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0019] In the first step above, the mass ratio of deionized water to p-nonylphenol is (20 to 30): 1.

[0020] In the third step above, the mass ratio of anhydrous ethanol to p-nonylphenol is (20 to 40): 1.

[0021] In the fourth step above, the solvent used for recrystallization is cyclohexane, and the mass ratio of cyclohexane to p-nonylphenol is (8 to 10): 1.

[0022] In the fifth step above, the mass ratio of toluene, potassium hydroxide and p-nonylphenol is (10 to 15): (0.1 to 0.3): 1.

[0023] In the first step above, the stirring rate is 200 rpm to 300 rpm, and the reflux reaction time is 12 h to 24 h.

[0024] In the third step above, the reflux reaction time is 24 to 48 hours, and in the fourth step, the drying temperature is 80 to 85 degrees Celsius.

[0025] In the fifth step above, the nitrogen gas is introduced for 5 to 10 minutes, the stirring speed is 400 to 500 rpm, the stirring temperature is 80 to 90°C, the reaction time is 6 to 12 hours, the reaction temperature is 130 to 135°C, and the cooling temperature is 50 to 60°C.

[0026] The second technical solution of the present invention is achieved through the following measures: a method for preparing a heavy oil cold recovery oil displacement agent for composite flooding, which is carried out according to the following method:

[0027] The first step involves preparing dimethylamine and formaldehyde into aqueous solutions with a mass concentration of 30% to 40% and a mass concentration of 30% to 40% respectively. Then, the required amount of dimethylamine aqueous solution, formaldehyde aqueous solution, and deionized water are added to the required amount of p-nonylphenol. After stirring, heating, and reflux reaction, a mixed solution a is obtained.

[0028] The second step is to distill the mixed solution a under reduced pressure to obtain a viscous solid a.

[0029] The third step involves adding the required amount of anhydrous ethanol to the viscous solid a, followed by the required amount of dodecyl bromide, stirring, heating, and reflux reaction to obtain a mixed solution b.

[0030] The fourth step involves subjecting the mixed solution b to vacuum distillation, recrystallization, and drying to obtain an off-white solid b.

[0031] Fifth step: Add off-white solid b, the required amount of toluene and potassium hydroxide to the reactor. After passing nitrogen gas into the reactor and evacuating it, stir. Then, pass the required amount of ethylene oxide into the reactor at once to react and obtain the reaction product. After cooling and vacuum distillation of the reaction product, obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0032] The heavy oil cold recovery agent of this invention for composite flooding is a composite surfactant with diverse mechanisms, wide material sources, simple synthesis process, low dosage and good viscosity reduction effect. Under the condition of using a concentration of 200 mg / L, it can reduce the viscosity of heavy oil with a viscosity of 48000 mPa.s (50℃) by more than 99%, without the need for other auxiliary viscosity reduction measures, which greatly reduces the application cost and is suitable for a variety of heavy oil reservoirs. Detailed Implementation

[0033] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemicals mentioned in this invention are well-known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.

[0034] The present invention will be further described below with reference to embodiments:

[0035] Example 1: The chemical structural formula of the heavy oil cold recovery agent used for composite flooding is as follows:

[0036]

[0037] Where n is between 5 and 50.

[0038] Example 2: As an optimization of the above example, the heavy oil cold recovery agent for composite flooding includes p-nonylphenol, dimethylamine, formaldehyde, dodecyl bromide and ethylene oxide in a molar ratio of 0.05:(0.1 to 0.2):(0.1 to 0.2):(0.08 to 0.12):(0.15 to 2.00).

[0039] Example 3: As an optimization of the above examples, a heavy oil cold recovery agent for composite flooding includes p-nonylphenol, dimethylamine, formaldehyde, dodecyl bromide and ethylene oxide in a molar ratio of 0.05:(0.15 to 0.2):(0.15 to 0.2):(0.09 to 0.11):(0.25 to 2.00).

[0040] Example 4: As an optimization of the above examples, a heavy oil cold recovery oil displacement agent for composite flooding is obtained by the following method:

[0041] The first step involves preparing dimethylamine and formaldehyde into aqueous solutions with a mass concentration of 30% to 40% and a mass concentration of 30% to 40% respectively. Then, the required amount of dimethylamine aqueous solution, formaldehyde aqueous solution, and deionized water are added to the required amount of p-nonylphenol. After stirring, heating, and reflux reaction, a mixed solution a is obtained.

[0042] The second step is to distill the mixed solution a under reduced pressure to obtain a viscous solid a.

[0043] The third step involves adding the required amount of anhydrous ethanol to the viscous solid a, followed by the required amount of dodecyl bromide, stirring, heating, and reflux reaction to obtain a mixed solution b.

[0044] The fourth step involves distilling the mixed solution b under reduced pressure, recrystallizing, and drying it to obtain a white solid b.

[0045] Fifth step: Add off-white solid b, the required amount of toluene and potassium hydroxide to the reactor. After passing nitrogen gas into the reactor and evacuating it, stir. Then, pass the required amount of ethylene oxide into the reactor at once to react and obtain the reaction product. After cooling and vacuum distillation of the reaction product, obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0046] Example 5: As an optimization of the above example, in the first step, the mass ratio of deionized water to p-nonylphenol is (20 to 30): 1.

[0047] Example 6: As an optimization of the above example, in the third step, the mass ratio of anhydrous ethanol to p-nonylphenol is (20 to 40): 1.

[0048] Example 7: As an optimization of the above example, in the fourth step, the solvent used for recrystallization is cyclohexane, and the mass ratio of cyclohexane to p-nonylphenol is (8 to 10): 1.

[0049] Example 8: As an optimization of the above example, in the fifth step, the mass ratio of toluene, potassium hydroxide and p-nonylphenol is (10 to 15): (0.1 to 0.3): 1.

[0050] Example 9: As an optimization of the above example, in the first step, the stirring rate is 200 rpm to 300 rpm, and the reflux reaction time is 12 h to 24 h.

[0051] Example 10: As an optimization of the above example, in the third step, the reflux reaction time is 24h to 48h, and in the fourth step, the drying temperature is 80℃ to 85℃.

[0052] Example 11: As an optimization of the above example, in the fifth step, the nitrogen gas is introduced for 5 to 10 minutes, the stirring speed is 400 to 500 rpm, the stirring temperature is 80 to 90°C, the reaction time is 6 to 12 hours, the reaction temperature is 130 to 135°C, and the cooling temperature is 50 to 60°C.

[0053] The specific reaction equation for the preparation of the heavy oil cold recovery agent for composite flooding in this invention is as follows:

[0054]

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] First, the heavy oil cold recovery oil displacement agent of this invention for composite flooding introduces a nonylbenzene ring and two dodecyl groups. The nonylbenzene ring and two dodecyl groups readily combine with the gum and asphaltenes in the heavy oil, and the entire molecule penetrates into the gum and asphaltenes lamellars, weakening the interaction forces between the fused rings in the heavy oil, effectively destroying the gum and asphaltenes structure, and at the same time facilitating the oil displacement agent molecules to enter the interior of the asphaltenes, thus solving the problem of heavy oil viscosity at its root.

[0057] Secondly, the heavy oil cold recovery agent of the present invention for composite flooding introduces polyethoxy and quaternary ammonium salt. Polyethoxy and quaternary ammonium salt have strong hydrophilicity, and the external phase can easily form a continuous water film. Moreover, polyethoxy has good flexibility and is easy to entangle with crude oil, so that the entire oil-water system can form a stable O / W emulsion under low power, which greatly reduces the viscosity of heavy oil.

[0058] Third, the heavy oil cold recovery agent for composite flooding of this invention introduces multiple nonionic hydrophilic and lipophilic groups. Among them, two quaternary ammonium salts are cationic hydrophilic groups, polyethoxy groups are nonionic hydrophilic groups, and nonylbenzene rings and two dodecyl groups are lipophilic groups. It is a composite surfactant. The rich groups make the product mechanism no longer singular, forming a synergistic effect of multiple mechanisms such as viscosity reduction and emulsification. It no longer relies on a single emulsification mechanism to reduce the viscosity of heavy oil. Moreover, the heavy oil cold recovery agent for composite flooding of this invention has the characteristics of high activity and low concentration. Under the condition of using a concentration of 200 mg / L, it can reduce the viscosity of heavy oil with a viscosity of 48000 mPa·s (50℃) by more than 99%, without the need for other auxiliary viscosity reduction measures, which greatly reduces the application cost.

[0059] Example 12:

[0060] The heavy oil cold recovery agent for combined flooding is obtained by the following method:

[0061] First, add 0.05 mol of p-nonylphenol, 0.1 mol of 40% dimethylamine aqueous solution, 0.1 mol of 40% formaldehyde aqueous solution, and 220 g of deionized water to a flask equipped with a stirrer, condenser, and thermometer. Stir and heat to reflux at a stirring rate of 200 rpm for 12 h until the reaction is complete to obtain mixed solution a.

[0062] The second step is to cool the mixed solution a to below 50°C, transfer the mixed solution a to a rotary evaporator for vacuum distillation, and cool it to room temperature to obtain a viscous solid a.

[0063] The third step involves transferring the viscous solid a to a flask using 220g of anhydrous ethanol, then adding 0.08mol of dodecyl bromide and stirring and heating under reflux for 24 hours to obtain a mixed solution b.

[0064] The fourth step is to distill the mixed solution b under reduced pressure, then add 88g of cyclohexane for recrystallization, and then dry it at 80℃ overnight to obtain a viscous solid b.

[0065] Fifth step: Add off-white solid b, 110g toluene, and 0.11g potassium hydroxide to the high-pressure reactor. Purge the reactor with nitrogen for 5 minutes, evacuate, and stir at 400 rpm while heating to 80°C. Stop evacuating and introduce 0.15 mol of ethylene oxide at once. Then raise the temperature to 134°C and react for 6 hours to obtain the reaction product. Cool the reaction product to 56°C and then distill it under reduced pressure to obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0066] Example 13:

[0067] The heavy oil cold recovery agent for combined flooding is obtained by the following method:

[0068] First, add 0.05 mol of p-nonylphenol, 0.12 mol of 30% dimethylamine aqueous solution, 0.2 mol of 40% formaldehyde aqueous solution, and 230 g of deionized water to a flask equipped with a stirrer, condenser, and thermometer. Stir and heat to reflux at a stirring rate of 300 rpm for 14 h until the reaction is complete to obtain mixed solution a.

[0069] The second step is to cool the mixed solution a to below 50°C, transfer the mixed solution a to a rotary evaporator for vacuum distillation, and cool it to room temperature to obtain a viscous solid a.

[0070] The third step involves transferring the viscous solid a to a flask using 257g of anhydrous ethanol, then adding 0.12mol of dodecyl bromide and stirring while heating under reflux for 28 hours to obtain a mixed solution b.

[0071] Fourth step: Distill the mixed solution b under reduced pressure, then add 92g of cyclohexane for recrystallization, and then dry it at 85℃ overnight to obtain an off-white solid b;

[0072] Fifth step: Add off-white solid b, 118g toluene, and 0.14g potassium hydroxide to the high-pressure reactor. Purge the reactor with nitrogen for 10 minutes, evacuate, and stir at 500 rpm while heating to 85°C. Stop evacuating and introduce 0.2 mol of ethylene oxide at once. Then raise the temperature to 133°C and react for 8 hours to obtain the reaction product. Cool the reaction product to 53°C and then distill under reduced pressure to obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0073] Example 14:

[0074] The heavy oil cold recovery agent for combined flooding is obtained by the following method:

[0075] First, add 0.05 mol of p-nonylphenol, 0.14 mol of 40% dimethylamine aqueous solution, 0.13 mol of 30% formaldehyde aqueous solution, and 266 g of deionized water to a flask equipped with a stirrer, condenser, and thermometer. Stir and heat to reflux at a stirring rate of 250 rpm for 15 h until the reaction is complete to obtain mixed solution a.

[0076] The second step is to cool the mixed solution a to below 50°C, transfer the mixed solution a to a rotary evaporator for vacuum distillation, and cool it to room temperature to obtain a viscous solid a.

[0077] The third step involves transferring the viscous solid a to a flask using 288g of anhydrous ethanol, then adding 0.09mol of dodecyl bromide and stirring and heating under reflux for 30 hours to obtain a mixed solution b.

[0078] Fourth step: the mixed solution b was distilled under reduced pressure, then 96g of cyclohexane was added for recrystallization, and then dried at 82℃ overnight to obtain off-white solid b;

[0079] Fifth step: Add off-white solid b, 122g toluene, and 0.18g potassium hydroxide to the high-pressure reactor. Purge the reactor with nitrogen for 6 minutes, evacuate, and stir at a stirring rate of 450 rpm while heating to 83°C. Stop evacuating, introduce 0.3 mol of ethylene oxide at once, and then heat to 130°C. After reacting for 7 hours, the reaction product is obtained. Cool the reaction product to 58°C and then distill under reduced pressure to obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0080] Example 15:

[0081] The heavy oil cold recovery agent for combined flooding is obtained by the following method:

[0082] First, add 0.05 mol of p-nonylphenol, 0.15 mol of 35% dimethylamine aqueous solution, 0.15 mol of 35% formaldehyde aqueous solution, and 287 g of deionized water to a flask equipped with a stirrer, condenser, and thermometer. Stir and heat to reflux at a stirring rate of 200 rpm for 16 h until the reaction is complete to obtain mixed solution a.

[0083] The second step is to cool the mixed solution a to below 50°C, transfer the mixed solution a to a rotary evaporator for vacuum distillation, and cool it to room temperature to obtain a viscous solid a.

[0084] The third step involves transferring the viscous solid a to a flask using 369g of anhydrous ethanol, then adding 0.114mol of dodecyl bromide and stirring and heating under reflux for 36 hours to obtain a mixed solution b.

[0085] Fourth step: the mixed solution b was distilled under reduced pressure, then 104g of cyclohexane was added for recrystallization, and then dried at 83℃ overnight to obtain off-white solid b;

[0086] Fifth step: Add off-white solid b, 133g toluene, and 0.22g potassium hydroxide to the high-pressure reactor. Purge the reactor with nitrogen for 8 minutes, evacuate, and stir at a stirring rate of 420 rpm while heating to 87°C. Stop evacuating, introduce 0.5 mol of ethylene oxide at once, and then heat to 135°C. After reacting for 7 hours, the reaction product is obtained. Cool the reaction product to 57°C and then distill under reduced pressure to obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0087] Example 16:

[0088] The heavy oil cold recovery agent for combined flooding is obtained by the following method:

[0089] First, add 0.05 mol of p-nonylphenol, 0.16 mol of 32% dimethylamine aqueous solution, 0.17 mol of 36% formaldehyde aqueous solution, and 249 g of deionized water to a flask equipped with a stirrer, condenser, and thermometer. Stir and heat to reflux at a stirring rate of 300 rpm for 18 h until the reaction is complete to obtain mixed solution a.

[0090] The second step is to cool the mixed solution a to below 50°C, transfer the mixed solution a to a rotary evaporator for vacuum distillation, and cool it to room temperature to obtain a viscous solid a.

[0091] The third step involves transferring the viscous solid a to a flask using 372g of anhydrous ethanol, then adding 0.095mol of dodecyl bromide and stirring and heating under reflux for 40 hours to obtain a mixed solution b.

[0092] Fourth step: the mixed solution b was distilled under reduced pressure, then 107g of cyclohexane was added for recrystallization, and then dried at 81℃ overnight to obtain off-white solid b;

[0093] Fifth step: Add off-white solid b, 147g toluene, and 0.27g potassium hydroxide to the high-pressure reactor. Purge the reactor with nitrogen for 7 minutes, evacuate, and stir at a stirring rate of 460 rpm while heating to 85°C. Stop evacuating, introduce 0.8 mol of ethylene oxide at once, and then heat to 133°C. After reacting for 9 hours, the reaction product is obtained. Cool the reaction product to 52°C and then distill under reduced pressure to obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0094] Example 17:

[0095] The heavy oil cold recovery agent for combined flooding is obtained by the following method:

[0096] First, add 0.05 mol of p-nonylphenol, 0.18 mol of 37% dimethylamine aqueous solution, 0.19 mol of 33% formaldehyde aqueous solution, and 304 g of deionized water to a flask equipped with a stirrer, condenser, and thermometer. Stir and heat to reflux at a stirring rate of 260 rpm for 20 h until the reaction is complete to obtain mixed solution a.

[0097] The second step is to cool the mixed solution a to below 50°C, transfer the mixed solution a to a rotary evaporator for vacuum distillation, and cool it to room temperature to obtain a viscous solid a.

[0098] The third step involves transferring the viscous solid a to a flask using 388g of anhydrous ethanol, then adding 0.107mol of dodecyl bromide and stirring and heating under reflux for 38 hours to obtain a mixed solution b.

[0099] Fourth step: the mixed solution b is distilled under reduced pressure, then 108g of cyclohexane is added for recrystallization, and then dried at 83℃ overnight to obtain off-white solid b;

[0100] Fifth step: Add off-white solid b, 152g toluene, and 0.25g potassium hydroxide to the high-pressure reactor. Purge the reactor with nitrogen for 8 minutes, evacuate, and stir at a stirring rate of 480 rpm while heating to 82°C. Stop evacuating, introduce 1.2 mol of ethylene oxide at once, and then heat to 132°C. After reacting for 10 hours, the reaction product is obtained. Cool the reaction product to 55°C and then distill under reduced pressure to obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0101] Example 18:

[0102] The heavy oil cold recovery agent for combined flooding is obtained by the following method:

[0103] First, add 0.05 mol of p-nonylphenol, 0.19 mol of 40% dimethylamine aqueous solution, 0.2 mol of 33% formaldehyde aqueous solution, and 313 g of deionized water to a flask equipped with a stirrer, condenser, and thermometer. Stir and heat to reflux at a stirring rate of 230 rpm for 22 h until the reaction is complete to obtain mixed solution a.

[0104] The second step is to cool the mixed solution a to below 50°C, transfer the mixed solution a to a rotary evaporator for vacuum distillation, and cool it to room temperature to obtain a viscous solid a.

[0105] The third step involves transferring the viscous solid a to a flask with 420g of anhydrous ethanol, then adding 0.097mol of dodecyl bromide and stirring and heating under reflux for 44h to obtain a mixed solution b.

[0106] Fourth step: the mixed solution b is distilled under reduced pressure, then 110g of cyclohexane is added for recrystallization, and then dried at 84℃ overnight to obtain off-white solid b;

[0107] Fifth step: Add off-white solid b, 157g toluene, and 0.28g potassium hydroxide to the high-pressure reactor. Purge the reactor with nitrogen for 5 minutes, evacuate, and stir at a stirring rate of 470 rpm while heating to 80°C. Stop evacuating, introduce 1.6 mol of ethylene oxide at once, and then heat to 130°C. After reacting for 11 hours, the reaction product is obtained. Cool the reaction product to 50°C and then distill under reduced pressure to obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0108] Example 19:

[0109] The heavy oil cold recovery agent for combined flooding is obtained by the following method:

[0110] First, add 0.05 mol of p-nonylphenol, 0.2 mol of 33% dimethylamine aqueous solution, 0.16 mol of 36% formaldehyde aqueous solution, and 330 g of deionized water to a flask equipped with a stirrer, condenser, and thermometer. Stir and heat to reflux at a stirring rate of 280 rpm for 24 h until the reaction is complete to obtain mixed solution a.

[0111] The second step is to cool the mixed solution a to below 50°C, transfer the mixed solution a to a rotary evaporator for vacuum distillation, and cool it to room temperature to obtain a viscous solid a.

[0112] The third step involves transferring the viscous solid a to a flask with 440g of anhydrous ethanol, then adding 0.101mol of dodecyl bromide and stirring and heating under reflux for 48 hours to obtain a mixed solution b.

[0113] Fourth step: Distill the mixed solution b under reduced pressure, then add 110g of cyclohexane for recrystallization, and then dry it at 85℃ overnight to obtain an off-white solid b;

[0114] Fifth step: Add off-white solid b, 165g toluene, and 0.33g potassium hydroxide to the high-pressure reactor. Purge the reactor with nitrogen for 6 minutes, evacuate, and stir at a stirring rate of 450 rpm while heating to 90°C. Stop evacuating, introduce 2.0 mol of ethylene oxide at once, and then heat to 135°C. After reacting for 12 hours, the reaction product is obtained. Cool the reaction product to 60°C and then distill under reduced pressure to obtain the heavy oil cold recovery oil displacement agent for composite flooding.

[0115] Example 20: The viscosity-reducing performance of the heavy oil cold recovery agent for composite flooding of the present invention was tested according to the method specified in Q / SH10201519-2016 "General Technical Conditions for Heavy Oil Viscosity Reducers". The crude oil used in this experiment was heavy oil with a viscosity of 48000 mPa·s at 50°C. The test method was as follows: the heavy oil cold recovery agents for composite flooding prepared in Examples 12 to 19 of the present invention were formulated into solutions of 200 mg / L and 1000 mg / L, respectively. Petroleum sulfonate from Shengli Chemical Plant and commercially available heavy oil agent AED-6 were used as comparisons.

[0116] The test results are shown in Table 1. As can be seen from Table 1, when the concentration is 200 mg / L, the viscosity reduction rate of the heavy oil cold recovery oil displacement agents prepared by the present invention 12 to 19 for composite flooding is greater than 99%, and the highest reaches 99.66% (Example 19). In contrast, petroleum sulfonate and commercially available heavy oil agent AED-6 do not emulsify heavy oil, and their viscosity reduction effect is significantly lower than that of the heavy oil cold recovery oil displacement agents prepared by the present invention 12 to 19 for composite flooding.

[0117] When used at a concentration of 1000 mg / L, the viscosity reduction rate of the heavy oil cold recovery displacement agents for combined flooding prepared according to Examples 12 to 19 of this invention is greater than 99%, reaching a maximum of 99.94% (Example 19). In contrast, the viscosity reduction rates of petroleum sulfonate and the commercially available heavy oil agent AED-6 are 99.63% and 99.49%, respectively, and their viscosity reduction effects are inferior to those of the heavy oil cold recovery displacement agents for combined flooding prepared according to Examples 12 to 19. In summary, the heavy oil cold recovery displacement agents for combined flooding of this invention have a better viscosity reduction effect.

[0118] In summary, the heavy oil cold recovery agent of this invention for composite flooding is a composite surfactant with diverse mechanisms, wide availability of materials, simple synthesis process, low dosage, and good viscosity reduction effect. Under the condition of using a concentration of 200 mg / L, it can reduce the viscosity of heavy oil with a viscosity of 48000 mPa·s (50℃) by more than 99%, without the need for other auxiliary viscosity reduction measures, which greatly reduces the application cost and is suitable for a variety of heavy oil reservoirs.

[0119] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0120] Table 1

[0121]

Claims

1. A heavy oil cold recovery oil displacement agent for combined flooding, characterized in that... Its chemical structural formula is: Where n is between 5 and 50.

2. The heavy oil cold recovery oil displacement agent for composite flooding according to claim 1, characterized in that... The raw materials include p-nonylphenol, dimethylamine, formaldehyde, dodecyl bromide and ethylene oxide in a molar ratio of 0.05:0.1 to 0.2:0.1 to 0.2:0.08 to 0.12:0.15 to 2.

00.

3. The heavy oil cold recovery oil displacement agent for composite flooding according to claim 1 or 2, characterized in that... Obtained using the following method: The first step involves preparing dimethylamine and formaldehyde into aqueous solutions with a mass concentration of 30% to 40% and a mass concentration of 30% to 40% respectively. Then, the required amount of dimethylamine aqueous solution, formaldehyde aqueous solution, and deionized water are added to the required amount of p-nonylphenol. After stirring, heating, and reflux reaction, a mixed solution a is obtained. The second step is to distill the mixed solution a under reduced pressure to obtain a viscous solid a. The third step involves adding the required amount of anhydrous ethanol to the viscous solid a, followed by the required amount of dodecyl bromide, stirring, heating, and reflux reaction to obtain a mixed solution b. The fourth step involves distilling the mixed solution b under reduced pressure, recrystallizing, and drying it to obtain a white solid b. Fifth step: Add off-white solid b, the required amount of toluene and potassium hydroxide to the reactor. After passing nitrogen gas into the reactor and evacuating it, stir. Then, pass the required amount of ethylene oxide into the reactor at once to react and obtain the reaction product. After cooling and vacuum distillation of the reaction product, obtain the heavy oil cold recovery oil displacement agent for composite flooding.

4. The heavy oil cold recovery oil displacement agent for composite flooding according to claim 3, characterized in that... In the first step, the mass ratio of deionized water to p-nonylphenol is 20 to 30:

1.

5. The heavy oil cold recovery oil displacement agent for composite flooding according to claim 3 or 4, characterized in that... In the third step, the mass ratio of anhydrous ethanol to p-nonylphenol is 20 to 40:

1.

6. The heavy oil cold recovery oil displacement agent for composite flooding according to claim 3, 4, or 5, characterized in that... In the fourth step, the solvent used for recrystallization is cyclohexane, and the mass ratio of cyclohexane to p-nonylphenol is 8 to 10:

1.

7. The heavy oil cold recovery agent for combined flooding according to any one of claims 3 to 6, characterized in that... In step 5, the mass ratio of toluene, potassium hydroxide and p-nonylphenol is 10 to 15: 0.1 to 0.3:

1.

8. The heavy oil cold recovery agent for combined flooding according to any one of claims 3 to 7, characterized in that... In the first step, the stirring rate is 200 rpm to 300 rpm, and the reflux reaction time is 12 h to 24 h; or / and in the third step, the reflux reaction time is 24 h to 48 h; and in the fourth step, the drying temperature is 80 °C to 85 °C.

9. The heavy oil cold recovery agent for combined flooding according to any one of claims 3 to 8, characterized in that... In the fifth step, nitrogen is introduced for 5 to 10 minutes, the stirring speed is 400 to 500 rpm, the stirring temperature is 80 to 90°C, the reaction time is 6 to 12 hours, the reaction temperature is 130 to 135°C, and the cooling temperature is 50 to 60°C.

10. A method for preparing a heavy oil cold recovery agent for composite flooding according to any one of claims 1 to 2, 4 to 9, characterized in that... Perform the following steps: The first step involves preparing dimethylamine and formaldehyde into aqueous solutions with a mass concentration of 30% to 40% and a mass concentration of 30% to 40% respectively. Then, the required amount of dimethylamine aqueous solution, formaldehyde aqueous solution, and deionized water are added to the required amount of p-nonylphenol. After stirring, heating, and reflux reaction, a mixed solution a is obtained. The second step is to distill the mixed solution a under reduced pressure to obtain a viscous solid a. The third step involves adding the required amount of anhydrous ethanol to the viscous solid a, followed by the required amount of dodecyl bromide, stirring, heating, and reflux reaction to obtain a mixed solution b. The fourth step involves distilling the mixed solution b under reduced pressure, recrystallizing, and drying it to obtain a white solid b. Fifth step: Add off-white solid b, the required amount of toluene and potassium hydroxide to the reactor. After passing nitrogen gas into the reactor and evacuating it, stir. Then, pass the required amount of ethylene oxide into the reactor at once to react and obtain the reaction product. After cooling and vacuum distillation of the reaction product, obtain the heavy oil cold recovery oil displacement agent for composite flooding.

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