A hyperbranched oil-soluble polyester thick oil viscosity reducer and preparation method thereof

Abstract

The present invention discloses a hyperbranched oil-soluble polyester heavy oil viscosity reducer and a preparation method thereof, belonging to the field of oilfield production additives. The invention first generates a hyperbranched polyester through an esterification reaction between trimethylolpropane, glycerol, and succinic anhydride. This polyester is then reacted with methyl erucate and methyl cinnamate through an ester exchange reaction to prepare a hyperbranched oil-soluble heavy oil viscosity reducer. Experimental results demonstrate that the heavy oil viscosity reducer exhibits significant viscosity reduction capabilities for heavy oil, achieving excellent viscosity reduction effects with a relatively low dosage and low raw material costs. Furthermore, the preparation method is simple, safe, environmentally friendly, and reliable.

Description

Technical Field

[0001] The invention belongs to the field of oilfield oil recovery additives and relates to a hyperbranched oil-soluble polyester heavy oil viscosity reducer and a preparation method thereof, in particular to a hyperbranched oil-soluble polyester heavy oil viscosity reducer prepared from trimethylolpropane, glycerol, succinic anhydride, methyl erucate and methyl cinnamate as main raw materials. Background Art

[0002] Crude oil is a vital natural resource. With the continuous depletion of crude oil, heavy and extra-heavy oil, which account for approximately half of the world's total oil reserves, have garnered widespread attention in recent decades. The high viscosity of heavy oil not only severely impacts extraction, transportation, and refining, but can also cause formation damage, adsorption, and precipitation issues within reservoirs. Viscosity reduction typically involves disrupting asphaltene aggregates and the alternating viscoelastic network formed by asphaltene and resin within the heavy oil. A common approach is to add viscosity reducers to the heavy oil to lower its pour point and low-temperature viscosity, thereby improving its fluidity at low temperatures.

[0003] Chinese invention application publication number CN116285929A discloses a water-based heavy oil viscosity reducer and a preparation method thereof. The raw materials include 60 grams of alkyl chitosan amide betaine, 20 grams of alkylphenol polyoxyethylene ether, and 100 grams of water. The 60 grams of chitosan amide betaine, 20 grams of alkylphenol polyoxyethylene ether, and 100 grams of water are mixed uniformly to obtain a water-based heavy oil viscosity reducer.

[0004] Chinese invention application publication number CN115895628A discloses a heavy oil viscosity reducer, its preparation method, and its use. The method comprises the following steps: 1) dissolving ethylenediamine in water to produce an ethylenediamine aqueous solution; 2) adding the ethylenediamine aqueous solution dropwise to sulfonic acid to react and obtain a solution containing an ammonium salt product; 3) adding ferric molybdate and sulfonic acid to the solution containing the ammonium salt product, filtering, washing, and drying the solution after the reaction to obtain the heavy oil viscosity reducer.

[0005] The Chinese invention application with publication number CN116622357A discloses a salt-resistant heavy oil viscosity reducing composition, a viscosity reducer and its application. The viscosity reducing composition includes a nonionic surfactant, a sulfonate anionic surfactant and an ionic stabilizer; the mass ratio of the nonionic surfactant: sulfonate anionic surfactant: ionic stabilizer is 0.5-1.5:0.5-1.5:0.2-1.

[0006] Chinese invention application publication number CN115386052A discloses a heavy oil viscosity reducer and its application. The heavy oil viscosity reducer is obtained by mixing raw materials containing a hyperbranched material monomer, an oil-soluble dispersing monomer, a water-soluble emulsifying dispersing monomer, an initiator, and a solvent to form a mixed system, and then reacting the mixture to obtain the heavy oil viscosity reducer.

[0007] The Chinese invention application with publication number CN116425903A discloses a method for preparing a chitosan derivative-type oil-soluble viscosity reducer for reducing the viscosity of heavy oil. The heavy oil viscosity reducer is prepared by chemically modifying chitosan and conducting ion exchange. The preparation method comprises the following steps: (1) dispersing chitosan (the chitosan is deacetylated chitosan with a deacetylation degree of greater than 80%) in a mixed solution of isopropyl alcohol and deionized water, adding an aqueous solution of epoxypropyltrimethylammonium chloride, reacting at a constant temperature, and purifying and drying to obtain an intermediate 1; (2) dispersing the intermediate 1 in deionized water, adding an aqueous solution of sodium tetraphenylborate, reacting at a constant temperature, and purifying and drying to obtain an intermediate 2; and (3) dispersing the intermediate 2 in dichloromethane, adding a stearoyl chloride solution, reacting at a constant temperature, and purifying and drying to obtain the heavy oil viscosity reducer.

[0008] Due to the varying molecular structures and contents of colloids and asphaltenes in different heavy oils, heavy oil viscosity reducers are highly selective for heavy oils from different oilfields. Currently, no universal viscosity reducer with excellent viscosity reduction efficacy exists. Oil-soluble viscosity reducer molecules can smoothly insert into heavy oil clusters, disrupting the inherent network structure between colloid and asphaltenes molecules and contributing to the formation of a looser spatial network. This significantly reduces the binding forces between colloid and asphaltenes molecules, thereby lowering the viscosity of the heavy oil. Given the ability to incorporate more functional groups into the molecule, such as polar groups, long-chain alkyl hydrophobic groups, and aromatic groups, coupled with the design and development of branched molecules, oil-soluble viscosity reducers can significantly reduce the selectivity of heavy oil viscosity reduction.

[0009] Water-soluble viscosity reducers generally have the following disadvantages: they require stirring or disturbance to form an oil-in-water dispersion, require demulsification after extraction, are expensive to process, and can easily pollute water resources. Oil-soluble viscosity reducers, on the other hand, can be added directly to heavy oil to reduce viscosity, eliminating the need for subsequent dehydration. However, currently used oil-soluble viscosity reducers suffer from low viscosity reduction rates, high prices, and high usage volumes. Summary of the Invention

[0010] The present invention aims to provide a hyperbranched oil-soluble polyester heavy oil viscosity reducer and a preparation method thereof, which can significantly reduce the viscosity of heavy oil at a relatively low cost and with a relatively small amount of viscosity reducer. The present invention achieves this goal through the following technical solutions.

[0011] A hyperbranched oil-soluble polyester heavy oil viscosity reducer is characterized in that the heavy oil viscosity reducer is obtained by esterifying trimethylolpropane, glycerol and succinic anhydride to generate a hyperbranched polyester, and then subjecting the generated hyperbranched polyester to an ester exchange reaction with methyl erucate and methyl cinnamate.

[0012] The docos-13-ene group and 3-phenyl-2-propene group in the viscosity reducer molecule can produce hydrophobic and lipophilic interactions with the aromatic polycyclic rings of the heavy oil molecule. The hyperbranched structure in the molecular morphology enables it to effectively disperse heavy oil aggregates, which macroscopically manifests as a good viscosity reduction effect on heavy oil, overcoming the current defects of large dosages of oil-soluble viscosity reducers and poor viscosity reduction effects.

[0013] Furthermore, the viscosity reduction rate of the heavy oil viscosity reducer on the heavy oil is above 60%.

[0014] The preparation method of the above-mentioned heavy oil viscosity reducer is characterized by comprising the following steps:

[0015] S1 Esterification reaction: Trimethylolpropane and glycerol are added to a reaction vessel, and protective gas is introduced. The temperature is raised to 60-80°C and the protective gas is continued. After the solid is completely melted, stirring is started and the temperature is raised to 120-130°C. Succinic anhydride and catalyst are gradually added in batches. After the addition is complete, the reaction is continued at this temperature. After the reaction is completed, the protective gas is stopped and the reaction is evacuated until no liquid is distilled out. The reaction is then cooled to room temperature to obtain a white gel-like solid.

[0016] S2 transesterification reaction: methyl erucate and methyl cinnamate are added to the reaction vessel of step S1, and a protective gas is introduced. The reaction is heated to 100-120°C, and a catalyst is added. The reaction is stirred and cooled to room temperature after the reaction is completed to obtain a light yellow gel.

[0017] S3: preparing a viscosity reducer solution: adding the light yellow gel obtained in step S2 to kerosene, heating to 60-80° C., stirring until the gel is completely dissolved, and cooling to room temperature to obtain a light yellow transparent liquid, which is the viscosity reducer solution.

[0018] Furthermore, the protective gas in steps S1 and S2 is nitrogen or argon.

[0019] Furthermore, the catalyst in steps S1 and S2 is benzenesulfonic acid.

[0020] Furthermore, the molar ratio of trimethylolpropane, glycerol and succinic anhydride in step S1 and methyl erucate and methyl cinnamate in step S2 is (1.8-2.2):(1.2-1.4):(3.6-4):(0.8-1.2):1; preferably 6:4:11:3:3.

[0021] The present invention has the following beneficial technical effects: the present invention provides a hyperbranched oil-soluble polyester heavy oil viscosity reducer and a preparation method thereof. Experimental results show that the heavy oil viscosity reducer has significant viscosity reducing ability for heavy oil, only requires a small amount to achieve excellent viscosity reducing effect, the raw material cost is low, and the preparation method is simple, safe, environmentally friendly and reliable. Implementation Method

[0022] The following is a clear and complete description of the technical solution of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention. Example 1

[0023] The method for preparing a hyperbranched oil-soluble polyester heavy oil viscosity reducer comprises the following steps.

[0024] (1) Add 40.2 g of trimethylolpropane and 18.5 g of propylene glycol into a 500 ml three-necked reaction flask. After nitrogen is introduced for 10 minutes, the temperature is raised to 70°C and nitrogen is continued to be introduced. After all the solids have melted, stirring is started and the temperature is raised to 125°C. 55.0 g of succinic anhydride and 3.0 g of benzenesulfonic acid are gradually added in batches over a period of 2 hours. After the addition is complete, the temperature is kept at this temperature for 2 hours. The nitrogen is stopped and the evacuation is carried out until no liquid is distilled out over a period of 1 hour. The mixture is cooled to room temperature to obtain a white gel-like solid for later use.

[0025] (2) 53.0 g of methyl erucate and 24.5 g of methyl cinnamate were added to the reaction flask of step (1), nitrogen was introduced, and the mixture was stirred and heated to 110°C. 3.5 g of benzenesulfonic acid was then added, and the mixture was stirred for reaction for 3 hours. The mixture was cooled to room temperature to obtain a light yellow gel.

[0026] (3) Add the light yellow gel obtained in step (2) to 1500 ml of kerosene, heat to 70°C, stir for 30 minutes to dissolve, and cool to room temperature to obtain a light yellow transparent liquid. Example 2

[0027] The light yellow transparent liquid prepared in Example 1 was weighed, and samples of the agent having agent concentrations of 0.5%, 1%, 1.5%, 2.0%, and 2.5% were prepared using No. -10 diesel. Dehydrated crude oils 1# to 5# from the Liaohe Oilfield of PetroChina were sampled, and the original viscosity of the crude oils was measured. 50 g of the dehydrated crude oils were respectively weighed, 5.0 g of the agent at different concentrations was added, and the crude oils were placed in a constant temperature water bath at 60°C for 24 hours. The viscosity of the crude oils after treatment was measured, and the viscosity reduction rate was calculated. The results are shown in Tables 1 to 5.

[0028] Table 1 Viscosity reduction of 1# dehydrated crude oil by different concentrations of reagents (60℃)

[0029]

[0030] Table 2 Viscosity reduction of 2# dehydrated crude oil by different concentrations of reagents (60℃)

[0031]

[0032] Table 3 Viscosity reduction of 3# dehydrated crude oil by different concentrations of reagents (60℃)

[0033]

[0034] Table 4 Viscosity reduction of 4# dehydrated crude oil by different concentrations of reagents (60℃)

[0035]

[0036] Table 5 Viscosity reduction of 5# dehydrated crude oil by different concentrations of reagents (60℃)

[0037]

[0038] As shown in Tables 1-5, the hyperbranched, oil-soluble polyester heavy oil viscosity reducer prepared in Example 1 achieved viscosity reduction rates exceeding 60% for various crude oils, with greater effectiveness observed for higher crude oil viscosities. The viscosity reduction rate increased with increasing agent concentration. These experimental results demonstrate that the hyperbranched, oil-soluble polyester heavy oil viscosity reducer provided by the present invention exhibits excellent viscosity reduction performance and is adaptable to heavy oils of varying viscosities. Example 3

[0039] The light yellow transparent liquid prepared in Example 1 was weighed and a sample of the agent with a concentration of 2.5% was prepared with No. -10 diesel. 50 g of 4# dehydrated crude oil from the Liaohe Oilfield of PetroChina was weighed, and 0.5 g, 2.5 g, 5.0 g, 7.5 g and 10.0 g of the 2.5% sample of the agent were added, respectively. The mixture was placed in a constant temperature water bath at 60°C for 24 hours. The viscosity of the crude oil after treatment was measured and the viscosity reduction rate was calculated. The results are shown in Table 6.

[0040] Table 6 Viscosity reduction of 4# dehydrated crude oil with different additions of 2.5% reagent (60℃)

[0041]

[0042] As can be seen from Table 6, the hyperbranched oil-soluble polyester heavy oil viscosity reducer prepared in Example 1 can achieve a significant viscosity reduction effect with only a relatively small addition amount. Example 4

[0043] The light yellow transparent liquid prepared in Example 1 was weighed and a sample of the agent with a concentration of 2.5% was prepared with No. -10 diesel. 50 g of 4# dehydrated crude oil from the Liaohe Oilfield of PetroChina was weighed, 5.0 g of a sample of the agent with a concentration of 3% was added, and the mixture was placed in a constant temperature water bath at 30°C, 40°C, 50°C, 60°C and 70°C, respectively. The temperature was kept constant for 24 hours, and the viscosity of the crude oil after treatment was measured, and the viscosity reduction rate was calculated. The results are shown in Table 7.

[0044] Table 7 Viscosity reduction rate of 4# dehydrated crude oil by reagents at different temperatures

[0045]

[0046] As can be seen from Table 7, the hyperbranched oil-soluble polyester thick oil viscosity reducer prepared in Example 1 has a viscosity reduction rate within the range of 30-60°C. The viscosity reduction rate increases with increasing temperature, and a significant viscosity reduction effect can be achieved at a relatively low temperature of 30°C.

[0047] Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A hyperbranched oil-soluble polyester thick oil viscosity reducer, characterized in that: The heavy oil viscosity reducer is prepared by esterifying trimethylolpropane, glycerol and succinic anhydride to generate a hyperbranched polyester, and then subjecting the generated hyperbranched polyester to an ester exchange reaction with methyl erucate and methyl cinnamate. The molar ratio of trimethylolpropane, glycerol, succinic anhydride, methyl erucate and methyl cinnamate is (1.8-2.2):(1.2-1.4):(3.6-4):(0.8-1.2):

1.

2. The thick oil viscosity reducer according to claim 1, characterized in that: The viscosity reduction rate of the heavy oil viscosity reducer on heavy oil is above 60%.

3. The method for preparing the heavy oil viscosity reducer according to claim 1 or 2, wherein: The following steps are involved: S1 Esterification reaction: Trimethylolpropane and glycerol are added to a reaction vessel, and protective gas is introduced. The temperature is raised to 60-80°C and the protective gas is continued. After the solid is completely melted, stirring is started and the temperature is raised to 120-130°C. Succinic anhydride and catalyst are gradually added in batches. After the addition is complete, the reaction is continued at this temperature. After the reaction is completed, the protective gas is stopped and the reaction is evacuated until no liquid is distilled out. The reaction is then cooled to room temperature to obtain a white gel-like solid. S2 transesterification reaction: methyl erucate and methyl cinnamate are added to the reaction vessel of step S1, and a protective gas is introduced. The reaction is heated to 100-120°C, and a catalyst is added. The reaction is stirred and cooled to room temperature after the reaction is completed to obtain a light yellow gel. S3: preparing a viscosity reducing agent solution: adding the light yellow gel obtained in step S2 into kerosene, heating to 60-80° C., stirring until the gel is completely dissolved, and cooling to room temperature to obtain a light yellow transparent liquid.

4. The preparation method according to claim 3, characterized in that The protective gas in steps S1 and S2 is nitrogen or argon.

5. The preparation method according to claim 3, characterized in that The catalyst in steps S1 and S2 is benzenesulfonic acid.

6. The preparation method according to claim 3, characterized in that The molar ratio of trimethylolpropane, glycerol and succinic anhydride in step S1 and methyl erucate and methyl cinnamate in step S2 is 6:4:11:3:3.

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