Thickened oil viscosity reducer as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of tertiary oil recovery and relates to a thick oil viscosity reducer as well as a preparation method and application thereof. The preparation method comprises the following steps: adding p-nonylphenol, 1-(4-fluorophenyl) piperazine, 40wt% formaldehyde and water into a reactor, stirring, heating, refluxing, and carrying out heat preservation reaction; cooling to below 40 DEG C, extracting, placing in a high-pressure reactor, adding sodium hydroxide solid, introducing nitrogen, vacuumizing, heating, stopping vacuumizing, slowly introducing ethylene oxide, heating, preserving heat and reacting; and carrying out reduced pressure distillation to obtain a viscous liquid, placing the viscous liquid in a high-pressure reactor, adjusting the pH value to 3-4, adding sulfamic acid powder, heating while stirring, carrying out a heat preservation reaction, cooling to 40 DEG C or below, adding ethanolamine, and adjusting the pH value to 7-8 to obtain the product, i.e., the thick oil viscosity reducer. The viscosity reducer has the advantages of low surface tension, low interfacial tension, low critical micelle concentration and good viscosity reduction effect.

Description

Technical Field

[0001] This invention belongs to the field of tertiary oil recovery technology, and relates to a heavy oil viscosity reducer, its preparation method and application. Background Technology

[0002] Heavy oil accounts for over 70% of the world's remaining petroleum resources, and my country also possesses abundant heavy oil reserves. With the continuous depletion of light crude oil resources, the importance of heavy oil extraction is increasingly prominent. Heavy oil, due to its high content of gums and asphaltenes, is characterized by high density and viscosity, which poses significant challenges to extraction and transportation. Its poor fluidity makes normal extraction difficult, increasing energy consumption and equipment wear during the extraction process, and raising extraction costs.

[0003] To improve the recovery rate of heavy oil, it is necessary to effectively reduce the viscosity of heavy oil and improve its fluidity so that the heavy oil can be extracted from the formation more smoothly.

[0004] Currently, commonly used viscosity reduction methods in heavy oil extraction both domestically and internationally include heating viscosity reduction, hydrothermal pyrolysis viscosity reduction, light oil dilution, microbial viscosity reduction, and chemical viscosity reduction. Chemical viscosity reduction refers to the addition of viscosity-reducing agents to crude oil to lower its viscosity.

[0005] The main mechanisms of viscosity reducers include emulsification and wetting: under the action of viscosity reducers, the internal friction between oils is transformed into the friction between waters, thereby significantly reducing the viscosity of heavy oil; viscosity reducers can reverse the oleophilicity of the interface to the hydrophilicity, forming a continuous water film and reducing the flow resistance of heavy oil.

[0006] CN112011325A discloses an oil-soluble viscosity reducer for heavy oil, comprising fatty acid methyl esters, wherein the number of carbon atoms in the fatty acid portion of the fatty acid methyl ester ranges from 12 to 24. The fatty acid methyl ester of this invention has mild synthesis conditions and uses widely available, high-yield, inexpensive, and readily available raw materials, resulting in low cost. For example, in Xinjiang, a cottonseed oil producing region, local resources, especially cottonseed oil resources, can be fully utilized. Furthermore, the purity requirements for methanol vary during the production process. The fatty acid methyl ester obtained by this invention has good flowability and viscosity-reducing effects, uses readily available raw materials, and has a simple synthesis process, requiring no complex or demanding synthesis conditions. The amount of the heavy oil viscosity reducer added by this invention does not exceed 40% of the total mass of the heavy oil. This small amount of viscosity reducer can reduce the viscosity of heavy oil by more than 90%. Therefore, the fatty acid methyl ester of this invention is suitable for large-scale oilfield exploitation and transportation. However, for extra-heavy oil, a 90% reduction in viscosity is insufficient to meet practical needs, and extraction and transportation remain challenging.

[0007] CN102604618A discloses a viscosity reducer for heavy oil cold-production formation crude oil, applied to the treatment of formation crude oil in oilfield heavy oil cold production 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 oil reservoir, improve its fluidity, and solve the problem of difficulty in flowing heavy oil from underground oil reservoirs into the wellbore. However, this invention requires the addition of alkaline substances to achieve a good emulsification and viscosity reduction effect on heavy oil. The addition of alkaline substances can cause clay swelling, which poses a potential hazard to the oil extraction process. In addition, it can make demulsification difficult in the later stages, bringing additional workload to crude oil processing. Summary of the Invention

[0008] This invention addresses the shortcomings of the prior art by providing a heavy oil viscosity reducer, its preparation method, and its application. The viscosity reducer of this invention has the advantages of low surface tension, low interfacial tension, low critical micelle concentration, and good viscosity-reducing effect.

[0009] To achieve the above objectives:

[0010] In the first aspect, this invention discloses a method for preparing a heavy oil viscosity reducer, the specific steps of which are as follows:

[0011] (1) Add p-nonylphenol, 1-(4-fluorophenyl)piperazine, 40wt% formaldehyde and water to the reactor, stir and heat to reflux, and keep the reaction at the temperature for 6-8h;

[0012] (2) Cool down to below 40°C, extract twice with toluene, combine the toluene, place in a high-pressure reactor, add sodium hydroxide solid, introduce nitrogen gas, evacuate, heat to 80-85°C, stop evacuating, slowly introduce ethylene oxide, heat to 140-170°C, keep the temperature for reaction, and stop the reaction when the pressure no longer drops.

[0013] (3) A viscous liquid is obtained by vacuum distillation and placed in a high-pressure reactor. The pH is adjusted to 3-4 with sulfuric acid, and aminosulfonic acid powder is added. The mixture is heated while stirring and kept at 130-140℃ for 2-3 hours. After cooling to below 40℃, 10wt% ethanolamine is added, and the pH is adjusted to 7-8 with sodium hydroxide solution to obtain the product, a thick oil viscosity reducer.

[0014] In this invention, preferably, based on 1 mole of nonylphenol, the amounts of 1-(4-fluorophenyl)piperazine, 40wt% formaldehyde, ethylene oxide, and aminosulfonic acid are 1.6-2.4 moles, 3-5 moles, 2-20 moles, and 0.8-1.2 moles, respectively.

[0015] More preferably, based on 1 mole of nonylphenol, the amounts of 1-(4-fluorophenyl)piperazine, 40 wt% formaldehyde, ethylene oxide, and aminosulfonic acid are 1.8-2.2 moles, 4-5 moles, 5-20 moles, and 0.9-1.1 moles, respectively.

[0016] In this invention, preferably, the weight ratio of water to nonylphenol in step (1) is 6-8:1.

[0017] In this invention, preferably, the weight ratio of toluene to nonylphenol in step (2) is 4-6:1.

[0018] In this invention, preferably, the weight ratio of sodium hydroxide to nonylphenol in step (2) is 0.2-0.3:1.

[0019] In this invention, preferably, the weight ratio of 10wt% ethanolamine to nonylphenol in step (3) is 3-5:1.

[0020] The reaction equation for the heavy oil viscosity reducer of the present invention is as follows:

[0021]

[0022] In another aspect, the present invention discloses a heavy oil viscosity reducer, the molecular structural formula of which is as follows:

[0023]

[0024] Thirdly, this invention discloses the application of the above-mentioned heavy oil viscosity reducer in improving the recovery rate of heavy oil.

[0025] The heavy oil viscosity reducer of this invention is a nonionic and anionic composite viscosity reducer. The lipophilic groups include fluorophenyl and nonyl groups, allowing molecules to rapidly penetrate from the aqueous phase into the oil phase through the oil-water interface. This facilitates intermolecular interactions with aromatic ring compounds and long-chain aliphatic hydrocarbons in crude oil, forming a stable O / W emulsion under low-dynamic conditions, significantly reducing crude oil viscosity. The fluorophenyl group, being a special lipophilic group, exhibits superior interfacial activity. The hydrophilic groups are epoxy ether and ammonium sulfonate, making it a nonionic and anionic composite viscosity reducer. This allows the emulsion's outer phase to form a continuous aqueous film, reducing flow resistance and significantly lowering crude oil viscosity.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) The heavy oil viscosity reducer of the present invention has the characteristics of low surface and interfacial tension. At a concentration of 500 mg / L, the surface tension is as low as 25.8 mN / m and the interfacial tension is as low as 0.65 × 10⁻⁶ m / s. -3 mN / m.

[0028] (2) The heavy oil viscosity reducer of the present invention has the characteristic of low critical micelle concentration, which is as low as 70 mg / L.

[0029] (3) The viscosity reducer of the heavy oil of the present invention has the characteristics of good viscosity reduction effect. For different heavy oils, the viscosity reduction rate reaches more than 99%. Detailed Implementation

[0030] 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.

[0031] The present invention will be further described below with reference to specific embodiments:

[0032] Example 1

[0033] (1) Add 0.1 mol p-nonylphenol, 0.24 mol 1-(4-fluorophenyl)piperazine, 0.35 mol 40 wt% formaldehyde and 176 g water to the reactor, stir and heat to reflux, and keep the reaction at the temperature for 6 h;

[0034] (2) Cool down to below 40°C, extract twice with 132g of toluene, combine the toluene, place in a high-pressure reactor, add 4.8g of sodium hydroxide solid, introduce nitrogen gas, evacuate, heat to 80°C, stop evacuating, slowly introduce 0.4mol of ethylene oxide, heat to 140°C, keep the reaction at the temperature until the pressure no longer decreases and stop the reaction.

[0035] (3) A viscous liquid was obtained by vacuum distillation and placed in a high-pressure reactor. The pH was adjusted to 3-4 with sulfuric acid, and 0.12 mol of aminosulfonic acid powder was added. The mixture was heated while stirring and kept at 130°C for 2 hours. After cooling to below 40°C, 70 g of 10 wt% ethanolamine was added, and the pH was adjusted to 7-8 with sodium hydroxide solution to obtain the product, a thick oil viscosity reducer.

[0036] Example 2

[0037] (1) Add 0.1 mol of p-nonylphenol, 0.18 mol of 1-(4-fluorophenyl)piperazine, 0.4 mol of 40 wt% formaldehyde and 148 g of water to the reactor, stir and heat to reflux, and keep the reaction at the temperature for 6 h;

[0038] (2) Cool down to below 40°C, extract twice with 97g toluene, combine the toluene, place in a high-pressure reactor, add 5.2g of sodium hydroxide solid, introduce nitrogen gas, evacuate, heat to 82°C, stop evacuating, slowly introduce 0.5mol of ethylene oxide, heat to 140°C, keep the reaction at the temperature until the pressure no longer decreases and stop the reaction.

[0039] (3) A viscous liquid was obtained by vacuum distillation and placed in a high-pressure reactor. The pH was adjusted to 3-4 with sulfuric acid, and 0.085 mol of aminosulfonic acid powder was added. The mixture was heated while stirring and kept at 132°C for 2 hours. After cooling to below 40°C, 75 g of 10 wt% ethanolamine was added, and the pH was adjusted to 7-8 with sodium hydroxide solution to obtain the product, a thick oil viscosity reducer.

[0040] Example 3

[0041] (1) Add 0.1 mol of p-nonylphenol, 0.18 mol of 1-(4-fluorophenyl)piperazine, 0.4 mol of 40 wt% formaldehyde and 148 g of water to the reactor, stir and heat to reflux, and keep the reaction at the temperature for 7 h;

[0042] (2) Cool down to below 40°C, extract twice with 97g toluene, combine the toluene, place in a high-pressure reactor, add 5.2g of sodium hydroxide solid, introduce nitrogen gas, evacuate, heat to 83°C, stop evacuating, slowly introduce 0.5mol of ethylene oxide, heat to 150°C, keep the reaction at the temperature until the pressure no longer decreases and stop the reaction.

[0043] (3) A viscous liquid was obtained by vacuum distillation and placed in a high-pressure reactor. The pH was adjusted to 3-4 with sulfuric acid, and 0.085 mol of aminosulfonic acid powder was added. The mixture was heated while stirring and kept at 135°C for 2.5 h. After cooling to below 40°C, 75 g of 10 wt% ethanolamine was added, and the pH was adjusted to 7-8 with sodium hydroxide solution to obtain the product, a thick oil viscosity reducer.

[0044] Example 4

[0045] (1) Add 0.1 mol p-nonylphenol, 0.22 mol 1-(4-fluorophenyl)piperazine, 0.5 mol 40 wt% formaldehyde and 150 g water to the reactor, stir and heat to reflux, and keep the reaction at the temperature for 7 h;

[0046] (2) Cool down to below 40°C, extract twice with 108g toluene, combine the toluene, place in a high-pressure reactor, add 5.6g of sodium hydroxide solid, introduce nitrogen gas, evacuate, heat to 85°C, stop evacuating, slowly introduce 0.8mol of ethylene oxide, heat to 150°C, keep the reaction at the temperature until the pressure no longer decreases and stop the reaction.

[0047] (3) A viscous liquid was obtained by vacuum distillation and placed in a high-pressure reactor. The pH was adjusted to 3-4 with sulfuric acid. 0.105 mol of aminosulfonic acid powder was added. The mixture was heated while stirring and kept at 135°C for 2.5 h. After cooling to below 40°C, 80 g of 10 wt% ethanolamine was added. The pH was adjusted to 7-8 with sodium hydroxide solution to obtain the product, a thick oil viscosity reducer.

[0048] Example 5

[0049] (1) Add 0.1 mol of p-nonylphenol, 0.19 mol of 1-(4-fluorophenyl)piperazine, 0.43 mol of 40 wt% formaldehyde and 166 g of water to the reactor, stir and heat to reflux, and keep the reaction at the temperature for 6 h;

[0050] (2) Cool down to below 40°C, extract twice with 128g toluene, combine the toluene, place in a high-pressure reactor, add 6g of sodium hydroxide solid, introduce nitrogen gas, evacuate, heat to 84°C, stop evacuating, slowly introduce 1.2mol of ethylene oxide, heat to 158°C, keep the temperature and react until the pressure no longer decreases and stop the reaction.

[0051] (3) A viscous liquid was obtained by vacuum distillation and placed in a high-pressure reactor. The pH was adjusted to 3-4 with sulfuric acid. 0.09 mol of aminosulfonic acid powder was added. The mixture was heated while stirring and kept at 138°C for 3 hours. After cooling to below 40°C, 90 g of 10 wt% ethanolamine was added. The pH was adjusted to 7-8 with sodium hydroxide solution to obtain the product, a thick oil viscosity reducer.

[0052] Example 6

[0053] (1) Add 0.1 mol p-nonylphenol, 0.21 mol 1-(4-fluorophenyl)piperazine, 0.45 mol 40 wt% formaldehyde and 152 g water to the reactor, stir and heat to reflux, and keep the reaction at the temperature for 8 h;

[0054] (2) Cool down to below 40°C, extract twice with 118g toluene, combine the toluene, place in a high-pressure reactor, add 6.3g of sodium hydroxide solid, introduce nitrogen gas, evacuate, heat to 82°C, stop evacuating, slowly introduce 1.6mol of ethylene oxide, heat to 165°C, keep the reaction at the temperature until the pressure no longer decreases and stop the reaction.

[0055] (3) A viscous liquid was obtained by vacuum distillation and placed in a high-pressure reactor. The pH was adjusted to 3-4 with sulfuric acid. 0.11 mol of aminosulfonic acid powder was added. The mixture was heated while stirring and kept at 140°C for 2.8 h. After cooling to below 40°C, 100 g of 10 wt% ethanolamine was added. The pH was adjusted to 7-8 with sodium hydroxide solution to obtain the product, a thick oil viscosity reducer.

[0056] Example 7

[0057] (1) Add 0.1 mol of p-nonylphenol, 0.2 mol of 1-(4-fluorophenyl)piperazine, 0.4 mol of 40 wt% formaldehyde and 162 g of water to the reactor, stir and heat to reflux, and keep the reaction at the temperature for 8 h;

[0058] (2) Cool down to below 40°C, extract twice with 110g toluene, combine the toluene, place in a high-pressure reactor, add 6.6g of sodium hydroxide solid, introduce nitrogen gas, evacuate, heat to 80°C, stop evacuating, slowly introduce 2mol of ethylene oxide, heat to 170°C, keep the temperature and react until the pressure no longer drops and stop the reaction.

[0059] (3) A viscous liquid was obtained by vacuum distillation and placed in a high-pressure reactor. The pH was adjusted to 3-4 with sulfuric acid, and 0.1 mol of aminosulfonic acid powder was added. The mixture was heated while stirring and kept at 140°C for 3 hours. After cooling to below 40°C, 110 g of 10 wt% ethanolamine was added, and the pH was adjusted to 7-8 with sodium hydroxide solution to obtain the product, a thick oil viscosity reducer.

[0060] Example 8: Testing of Surface Tension and Interfacial Tension

[0061] The heavy oil viscosity reducer of the present invention (Examples 1-7) was prepared into an aqueous solution of 500 mg / L. The surface tension and interfacial tension were measured according to the method in SY / T 5370-2018 "Method for Determination of Surface and Interfacial Tension". The oil phase used for interfacial tension was n-hexadecane. The results are shown in Table 1.

[0062] A comparative test was conducted using SHF viscosity reducer from Shengli Chemical Co., Ltd. of Shengli Oilfield.

[0063] Example 9: Test of Critical Micelle Concentration

[0064] The critical micelle concentration was determined according to the method in GB / T 11276-2007 "Determination of Critical Micelle Concentration of Viscosity Reducers", and the results are shown in Table 1.

[0065] A comparative test was conducted using SHF viscosity reducer from Shengli Chemical Co., Ltd. of Shengli Oilfield.

[0066] Table 1. Test results of surface tension, interfacial tension, and critical micelle concentration.

[0067]

[0068]

[0069] As can be seen from Table 1:

[0070] (1) The heavy oil viscosity reducer of the present invention (Examples 1-7) has the characteristics of low surface and interfacial tension. At a concentration of 500 mg / L, the surface tension reaches 26 mN / m or less, and the interfacial tension reaches 1×10. -3 The surface tension of the sample was below mN / m, while the surface tension of the SHF from Shengli Chemical Co., Ltd. in Shengli Oilfield, a comparative example, was 30.4 mN / m, and the interfacial tension reached 310 × 10⁻⁶ mN / m. -3 mN / m, significantly higher than that of the present invention;

[0071] (2) The heavy oil viscosity reducer of the present invention (Examples 1-7) has the characteristic of low critical micelle concentration, reaching 100 mg / L and below, with a minimum of 70 mg / L; while the critical micelle concentration of SHF of Shengli Chemical Co., Ltd. of Shengli Oilfield, a comparative example, is 580 mg / L, which is significantly higher than that of the present invention.

[0072] Example 10: Evaluation of viscosity reduction rate

[0073] The heavy oil viscosity reducer of the present invention (Examples 1-7) was prepared into a sample with a concentration of 2000 mg / L using tap water. The viscosity reduction rate was tested according to the method in Q / SH1020 1519—2016 "General Technical Conditions for Heavy Oil Viscosity Reducers". The crude oil used for the test was oil sample from Block A and Block B of Shengli Oilfield. The initial viscosity of the crude oil at 50°C was 7600 mPa·s and 25600 mPa·s, respectively. The results are shown in Table 2.

[0074] A comparative test was conducted using SHF viscosity reducer from Shengli Chemical Co., Ltd. of Shengli Oilfield.

[0075] Table 2. Viscosity reduction results of viscosity reducers

[0076]

[0077]

[0078] As can be seen from Table 2, the heavy oil viscosity reducer of the present invention (Examples 1-7) has the characteristic of good viscosity reduction effect:

[0079] (1) For Block A, the viscosity reduction rate of heavy oil with an initial viscosity of 7600 mPa·s at 50℃ reached over 99%, with a maximum of 99.14%. The viscosity reduction rate of SHF viscosity reducer from Shengli Chemical Co., Ltd. of Shengli Oilfield was 93.16%, which was significantly lower than that of this invention.

[0080] (2) For Block B, the viscosity reduction rate of heavy oil with an initial viscosity of 25600 mPa·s at 50℃ reached over 99.6%, with a maximum of 99.74%. In contrast, the SHF viscosity reducer from Shengli Chemical Co., Ltd. of Shengli Oilfield did not emulsify.

[0081] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0082] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0083] 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.

Claims

1. A method for preparing a heavy oil viscosity reducer, characterized in that: The specific steps of the preparation method are as follows: (1) Adding p-nonylphenol, 1-(4-fluorophenyl)piperazine, 40 wt% formaldehyde and water into a reactor, stirring, heating and reflux, and keeping the temperature for reaction for 6-8 hours; (2) cooling to below 40° C., extracting twice with toluene, combining the toluene, placing in a high-pressure reactor, adding solid sodium hydroxide, introducing nitrogen, evacuating, heating to 80-85° C., stopping evacuating, slowly introducing ethylene oxide, heating to 140-170° C., and reacting at this temperature until the pressure stops decreasing and the reaction is stopped; (3) distilling under reduced pressure to obtain a viscous liquid, placing it in a high-pressure reactor, adjusting the pH to 3-4 with sulfuric acid, adding aminosulfonic acid powder, heating with stirring, keeping the temperature at 130-140° C. for 2-3 hours, cooling to below 40° C., adding 10 wt % ethanolamine, and adjusting the pH to 7-8 with sodium hydroxide solution to obtain a product heavy oil viscosity reducer; Based on 1 mol part of nonylphenol, the usage of 1-(4-fluorophenyl)piperazine, 40 wt% formaldehyde, ethylene oxide and aminosulfonic acid are 1.6-2.4 mol parts, 3-5 mol parts, 2-20 mol parts and 0.8-1.2 mol parts respectively.

2. The preparation method according to claim 1, characterized in that: Based on 1 mol part of nonylphenol, the usage of 1-(4-fluorophenyl)piperazine, 40 wt% formaldehyde, ethylene oxide and aminosulfonic acid are 1.8-2.2 mol parts, 4-5 mol parts, 5-20 mol parts and 0.9-1.1 mol parts respectively.

3. The preparation method according to claim 1, characterized in that: The weight ratio of water to nonylphenol in step (1) is 6-8:

1.

4. The preparation method according to claim 1, characterized in that: The weight ratio of toluene to nonylphenol in step (2) is 4-6:

1.

5. The preparation method according to claim 1, characterized in that: The weight ratio of sodium hydroxide to nonylphenol in step (2) is 0.2-0.3:

1.

6. The preparation method according to claim 1, characterized in that: The weight ratio of 10wt% ethanolamine to nonylphenol in step (3) is 3-5:

1.

7. The heavy oil viscosity reducer prepared according to the preparation method according to any one of claims 1 to 6.

8. The heavy oil viscosity reducer according to claim 7, characterized in that: The molecular structural formula of the heavy oil viscosity reducer is as follows:

9. Use of the heavy oil viscosity reducer according to claim 7 or 8 in improving the recovery rate of heavy oil.

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