A viscosity reducer for improving the recovery ratio of thickened oil reservoir and a synthetic method thereof

Abstract

The application belongs to the technical field of oil exploitation, and particularly relates to a viscosity reducer for improving the recovery ratio of heavy oil reservoirs and a synthesis method thereof. The synthesis method comprises the following steps: in the presence of a first solvent, 2-(trimethylsilylmethyl) allyl chloride and sodium bisulfite are heated to reflux to generate an addition reaction to obtain a sulfonate; and then in the presence of a second solvent, the sulfonate and 1-(2-hydroxyethyl)-2-imidazolinone are heated to reflux to generate a substitution reaction. Based on 1 mol of 2-(trimethylsilylmethyl) allyl chloride, the amount of sodium bisulfite and 1-(2-hydroxyethyl)-2-imidazolinone is 0.9-1.5 mol and 0.6-1 mol, respectively. The heavy oil viscosity reducer has the characteristics of wide raw material sources, simple synthesis process and good viscosity reduction effect.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a viscosity reducer for improving the recovery rate of heavy oil reservoirs and its synthesis method. Background Technology

[0002] Heavy oil resources account for a significant proportion of the world's oil and gas resources. According to statistics, heavy oil and extra-heavy oil account for more than 20% of the world's proven crude oil reserves. With the continuous depletion of light and easily extracted crude oil, the exploitation of heavy oil is attracting increasing attention from various countries.

[0003] Heavy oil reservoirs often have active edge and bottom water. After years of steam injection development, edge water advancement has become severe, resulting in high overall water cut, averaging over 90%. While nitrogen injection and water coning have shown initial effectiveness, the effect is short-lived, and the overall results are unsatisfactory, with no significant improvement in daily oil production or water cut. Viscosity reducers have proven highly effective in edge water reservoirs. Targeting the characteristics of these reservoirs, a viscosity reducer is injected from the water front, mixing with the invading formation water to form an active aqueous solution. This active aqueous solution is then used as the displacement medium. This method effectively reduces the viscosity of high-viscosity crude oil, lowers the oil-water interfacial tension, and increases reservoir energy. It utilizes the formation's own energy to form a stable oil-in-water emulsion, significantly reducing the viscosity of the high-viscosity crude oil and substantially lowering the extraction difficulty.

[0004] CN 104194761 A discloses a composite viscosity reducer for steam injection development, comprising a catalyst and an emulsifier. It can undergo a catalytic reaction with heavy oil at 200°C, reducing the viscosity of heavy oil by more than 98.5%. Compared to conventional viscosity reducers, this viscosity reducer can chemically react with heavy oil, causing the long carbon chains of the heavy oil to crack, etc., while the emulsifier mainly plays the role of emulsifying the catalyst to be soluble in the aqueous phase, facilitating injection. Because it is a chemical reaction, the reaction time and efficiency with heavy oil are much slower than physical reactions; therefore, it is not suitable for improving the recovery rate of heavy oil reservoirs.

[0005] CN1221650A discloses a surfactant mainly used for reducing the viscosity of heavy oil in oilfields. Its formulation, by weight, includes 15-20% lignin, 5-15% caustic soda, 2-8% soap powder or 1-6% soap, 10-15% synthetic detergent, and the remainder is water. The raw materials used in this surfactant are inexpensive and readily available, and the preparation method is simple. Its viscosity reduction rate can reach over 95%, especially under high-temperature conditions exceeding 300℃, its performance remains undiminished. However, it requires the addition of alkaline substances to achieve a good viscosity-reducing effect on heavy oil. The addition of alkaline substances can react with calcium and magnesium ions in the formation, producing a large amount of precipitation that can clog the formation. Furthermore, alkaline substances can lead to difficulties in subsequent crude oil demulsification, posing challenges to further crude oil processing. Summary of the Invention

[0006] This invention addresses the problems encountered by existing viscosity reducers by providing a viscosity reducer for improving the recovery rate of heavy oil reservoirs and its synthesis method. The heavy oil viscosity reducer has the advantages of wide availability of raw materials, simple synthesis process, and good viscosity reduction effect.

[0007] Therefore, in order to achieve the above objectives, on the one hand, the present invention discloses a viscosity reducer for improving the recovery rate of heavy oil reservoirs, the molecular structural formula of which is as follows:

[0008]

[0009] On the other hand, the present invention provides a method for synthesizing the above-mentioned viscosity reducer for improving the recovery rate of heavy oil reservoirs. The method comprises: in the presence of a first solvent, 2-(trimethylsilylmethyl)allyl chloride and sodium bisulfite are heated under reflux to undergo an addition reaction to obtain a sulfonate; and in the presence of a second solvent, the sulfonate is heated under reflux to undergo a substitution reaction with 1-(2-hydroxyethyl)-2-imidazolinone.

[0010] The viscosity reducer for improving heavy oil reservoir recovery of this invention belongs to the surfactant category. It is a mixture of anionic and nonionic surfactants, with hydrophilic groups of sulfonic acid and imidazoline, and lipophilic groups of silane. The entire molecule has a linear structure, which makes it relatively easy to penetrate into the resinous and asphaltenes layers, weakening the interaction forces between aromatic rings in heavy oil. The silane group is a special lipophilic group, which makes the aqueous solution of this invention have lower surface tension and interfacial tension, and a lower critical micelle concentration, thus requiring a lower dosage. Under the action of functional groups such as silane, sulfonic acid, and imidazoline, after the aqueous solution of this invention emulsifies with heavy oil, a continuous water film is formed on the external phase, which can reduce flow resistance and significantly reduce the viscosity of heavy oil.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] (1) The viscosity reducer of the present invention has the advantages of wide availability of raw materials and simple synthesis process;

[0013] (2) The viscosity reducer of the present invention has the characteristics of low concentration and high activity. When the concentration is 0.3wt%, the viscosity reduction rate of crude oil with a viscosity of 17600mPa.s can reach more than 99%. Detailed Implementation

[0014] 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.

[0015] According to a first aspect of the present invention, a viscosity reducer for improving the recovery rate of heavy oil reservoirs is disclosed, the molecular structure of which is as follows:

[0016]

[0017] Secondly, the present invention provides a method for synthesizing the above-mentioned viscosity reducer for improving the recovery rate of heavy oil reservoirs. The method comprises: in the presence of a first solvent, 2-(trimethylsilylmethyl)allyl chloride reacts with sodium bisulfite under reflux to undergo an addition reaction to obtain a sulfonate; and in the presence of a second solvent, the sulfonate reacts with 1-(2-hydroxyethyl)-2-imidazolinone under reflux to undergo a substitution reaction.

[0018] In this invention, preferably, based on 1 mole of 2-(trimethylsilylmethyl)allyl chloride, the amounts of sodium bisulfite and 1-(2-hydroxyethyl)-2-imidazolinone are 0.9-1.5 moles and 0.6-1 moles, respectively; more preferably, based on 1 mole of 2-(trimethylsilylmethyl)allyl chloride, the amounts of sodium bisulfite and 1-(2-hydroxyethyl)-2-imidazolinone are 1.1-1.5 moles and 0.7-0.9 moles, respectively.

[0019] In this invention, preferably, the first solvent is 90-95 wt% ethanol or 90-95 wt% methanol, and the mass ratio of the solvent to 2-(trimethylsilylmethyl)allyl chloride is 6-8:1.

[0020] In this invention, preferably, the addition reaction time is 2-4 hours.

[0021] More preferably, the addition reaction time is 2-3 hours.

[0022] In this invention, preferably, the second solvent is ethanol or isopropanol, and the mass ratio of the solvent to 2-(trimethylsilylmethyl)allyl chloride is 8-10:1.

[0023] In this invention, preferably, the substitution reaction time is 4-6 hours.

[0024] More preferably, the substitution reaction time is 4-5 hours.

[0025] According to a more specific preferred embodiment, the method for synthesizing the viscosity reducer for improving the recovery rate of heavy oil reservoirs specifically includes the following steps:

[0026] (1) Add 2-(trimethylsilylmethyl)allyl chloride, first solvent, and sodium bisulfite to a four-necked flask, stir and heat, and reflux for 2-4 hours;

[0027] (2) Add 1.5-2 times the weight of the first solvent of distilled water, distill under reduced pressure to obtain 1.3-1.7 times the weight of the first solvent of liquid, stop distillation, adjust the pH to 2-3 with hydrochloric acid, cool down to below 10℃, precipitate solid, filter, and wash with distilled water 1-2 times;

[0028] (3) Dissolve the solid with a second solvent, adjust the pH to 8-9 with sodium hydroxide, add 1-(2-hydroxyethyl)-2-imidazolinone and reflux for 4-6 hours, maintaining the pH at 8-9 with sodium hydroxide during the reaction.

[0029] (4) A viscous solid was obtained by vacuum distillation, and a pale yellow solid was obtained by recrystallization with cyclohexane. The solid was dried at 80°C overnight to obtain the product viscosity reducer.

[0030] The reaction equation for the synthesis of the viscosity reducer for improving the recovery rate of heavy oil reservoirs in this invention is as follows:

[0031]

[0032] 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.

[0033] 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.

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

[0035] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0036] Unless otherwise specified, all reagents used in the following examples and comparative examples are commercially available chemically pure reagents.

[0037] Example 1

[0038] (1) Add 0.2 mol of 2-(trimethylsilylmethyl)allyl chloride, 194.4 g of 95 wt% ethanol and 0.18 mol of sodium bisulfite to a four-necked flask, stir and heat, and reflux for 2 h;

[0039] (2) Add 388.8g of distilled water, distill under reduced pressure to obtain 330.5g of liquid, stop distillation, adjust pH to 2-3 with 2mol / L hydrochloric acid, cool to below 10℃, precipitate solid, filter, and wash once with distilled water;

[0040] (3) Dissolve the solid in 279.3g isopropanol, adjust the pH to 8-9 with 2mol / L sodium hydroxide, add 0.12mol 1-(2-hydroxyethyl)-2-imidazolinone and reflux for 4h. During the reaction, maintain the pH at 8-9 with 2mol / L sodium hydroxide.

[0041] (4) A viscous solid was obtained by vacuum distillation, and a pale yellow solid was obtained by recrystallization with cyclohexane. The solid was dried at 80°C overnight to obtain the product viscosity reducer.

[0042] Example 2

[0043] (1) Add 0.2 mol of 2-(trimethylsilylmethyl)allyl chloride, 259.2 g of 90 wt% methanol and 0.18 mol of sodium bisulfite to a four-necked flask, stir and heat, and reflux for 2 h;

[0044] (2) Add 388.8g of distilled water, distill under reduced pressure to obtain 337.4g of liquid, stop distillation, adjust pH to 2-3 with 2mol / L hydrochloric acid, cool to below 10℃, precipitate solid, filter, and wash twice with distilled water;

[0045] (3) Dissolve the solid in 324g of ethanol, adjust the pH to 8-9 with 2mol / L sodium hydroxide, add 0.12mol of 1-(2-hydroxyethyl)-2-imidazolinone and reflux for 4h. During the reaction, maintain the pH at 8-9 with 2mol / L sodium hydroxide.

[0046] (4) A viscous solid was obtained by vacuum distillation, and a pale yellow solid was obtained by recrystallization with cyclohexane. The solid was dried at 80°C overnight to obtain the product viscosity reducer.

[0047] Example 3

[0048] (1) Add 0.2 mol of 2-(trimethylsilylmethyl)allyl chloride, 210.8 g of 95 wt% ethanol and 0.2 mol of sodium bisulfite to a four-necked flask, stir and heat, and reflux for 3 h;

[0049] (2) Add 421.6g of distilled water, distill under reduced pressure to get 274g of liquid, stop distillation, adjust pH to 2-3 with 2mol / L hydrochloric acid, cool to below 10℃, precipitate solid, filter, and wash once with distilled water;

[0050] (3) Dissolve the solid in 259.2g isopropanol, adjust the pH to 8-9 with 2mol / L sodium hydroxide, add 0.2mol 1-(2-hydroxyethyl)-2-imidazolinone and reflux for 4.5h. During the reaction, maintain the pH at 8-9 with 2mol / L sodium hydroxide.

[0051] (4) A viscous solid was obtained by vacuum distillation, and a pale yellow solid was obtained by recrystallization with cyclohexane. The solid was dried at 80°C overnight to obtain the product viscosity reducer.

[0052] Example 4

[0053] (1) Add 0.2 mol of 2-(trimethylsilylmethyl)allyl chloride, 230.7 g of 95 wt% methanol and 0.22 mol of sodium bisulfite to a four-necked flask, stir and heat, and reflux for 3.5 h;

[0054] (2) Add 346g of distilled water, distill under reduced pressure to obtain 349.6g of liquid, stop distillation, adjust pH to 2-3 with 2mol / L hydrochloric acid, cool to below 10℃, precipitate solid, filter, and wash once with distilled water;

[0055] (3) Dissolve the solid in 294.8g isopropanol, adjust the pH to 8-9 with 2mol / L sodium hydroxide, add 0.14mol 1-(2-hydroxyethyl)-2-imidazolinone and reflux for 5h. During the reaction, maintain the pH at 8-9 with 2mol / L sodium hydroxide.

[0056] (4) A viscous solid was obtained by vacuum distillation, and a pale yellow solid was obtained by recrystallization with cyclohexane. The solid was dried at 80°C overnight to obtain the product viscosity reducer.

[0057] Example 5

[0058] (1) Add 0.2 mol of 2-(trimethylsilylmethyl)allyl chloride, 245.3 g of 90 wt% ethanol and 0.26 mol of sodium bisulfite to a four-necked flask, stir and heat, and reflux for 3 h;

[0059] (2) Add 456.4g of distilled water, distill under reduced pressure to obtain 350.5g of liquid, stop distillation, adjust pH to 2-3 with 2mol / L hydrochloric acid, cool to below 10℃, precipitate solid, filter, and wash twice with distilled water;

[0060] (3) Dissolve the solid in 319.2g isopropanol, adjust the pH to 8-9 with 2mol / L sodium hydroxide, add 0.15mol 1-(2-hydroxyethyl)-2-imidazolinone and reflux for 6h. During the reaction, maintain the pH at 8-9 with 2mol / L sodium hydroxide.

[0061] (4) A viscous solid was obtained by vacuum distillation, and a pale yellow solid was obtained by recrystallization with cyclohexane. The solid was dried at 80°C overnight to obtain the product viscosity reducer.

[0062] Example 6

[0063] (1) Add 0.2 mol of 2-(trimethylsilylmethyl)allyl chloride, 251.4 g of 95 wt% ethanol and 0.28 mol of sodium bisulfite to a four-necked flask, stir and heat, and reflux for 3 h;

[0064] (2) Add 502.8g of distilled water, distill under reduced pressure to obtain 381.2g of liquid, stop distillation, adjust pH to 2-3 with 2mol / L hydrochloric acid, cool to below 10℃, precipitate solid, filter, and wash once with distilled water;

[0065] (3) Dissolve the solid in 309g of ethanol, adjust the pH to 8-9 with 2mol / L sodium hydroxide, add 0.17mol of 1-(2-hydroxyethyl)-2-imidazolinone and reflux for 6h. During the reaction, maintain the pH at 8-9 with 2mol / L sodium hydroxide.

[0066] (4) A viscous solid was obtained by vacuum distillation, and a pale yellow solid was obtained by recrystallization with cyclohexane. The solid was dried at 80°C overnight to obtain the product viscosity reducer.

[0067] Example 7

[0068] (1) Add 0.2 mol of 2-(trimethylsilylmethyl)allyl chloride, 259.2 g of 95 wt% ethanol and 0.3 mol of sodium bisulfite to a four-necked flask, stir and heat, and reflux for 4 h;

[0069] (2) Add 488.4g of distilled water, distill under reduced pressure to obtain 388.3g of liquid, stop distillation, adjust pH to 2-3 with 2mol / L hydrochloric acid, cool to below 10℃, precipitate solid, filter, and wash twice with distilled water;

[0070] (3) Dissolve the solid in 324g isopropanol, adjust the pH to 8-9 with 2mol / L sodium hydroxide, add 0.16mol 1-(2-hydroxyethyl)-2-imidazolinone and reflux for 6h. During the reaction, maintain the pH at 8-9 with 2mol / L sodium hydroxide.

[0071] (4) A viscous solid was obtained by vacuum distillation, and a pale yellow solid was obtained by recrystallization with cyclohexane. The solid was dried at 80°C overnight to obtain the product viscosity reducer.

[0072] Test Example 1: Evaluation of Heavy Oil Viscosity Reducers

[0073] (1) The heavy oil in block A of Shengli Oilfield was kept at a constant temperature of 50℃ for 1 hour, and the free water and air bubbles were removed by stirring. The viscosity μ0 at 50℃ was measured by a viscometer within 20 seconds.

[0074] (2) Prepare a salt solution containing 3wt% NaCl and 0.3wt% CaCl2, and use the salt solution to prepare a solution with a mass fraction of 0.3% for later use.

[0075] (3) Weigh 280g (accurate to 0.01g) of the heavy oil sample prepared in step (1) into a beaker, add 120g (accurate to 0.01g) of the sample solution prepared in step (2), place it in a constant temperature water bath at 50℃, keep it at a constant temperature for 1h, stir with a stirrer at a speed of 250r / min, and stir for 2min under constant temperature conditions. Measure its viscosity μ at 50℃ using a viscometer within 20s.

[0076] The viscosity reduction rate of heavy oil is calculated using the following formula:

[0077]

[0078] Where: f—viscosity reduction rate;

[0079] μ0——The viscosity of the heavy oil sample at 50℃, mPa·s;

[0080] μ — Viscosity of the thick oil emulsion after the sample solution is added, mPa·s.

[0081] SHF viscosity reducer from Shengli Chemical Co., Ltd. of Shengli Oilfield was used.

[0082] The viscosity of heavy oil in Block A of Shengli Oilfield is 5800 mPa·s. The test results are shown in Table 1.

[0083] As can be seen from Table 1, the viscosity reducer of the present invention (Examples 1-7) can reduce the viscosity of crude oil with a viscosity of 5800 mPa·s by more than 98% when the concentration is 0.3 wt%. Among them, the viscosity reducer prepared in Example 7 has the highest viscosity reduction rate of 98.88%; while the viscosity reduction rate of the SHF viscosity reducer of Shengli Chemical Co., Ltd. of Shengli Oilfield, in the comparative example, is 97.31%.

[0084] Test Example 2: Evaluation of Heavy Oil Viscosity Reducers

[0085] The test method is the same as that in Test Example 1, except for the test oil sample. The viscosity of heavy oil in Block B of Shengli Oilfield is 17600 mPa·s. The rest of the test methods are the same as those in Test Example 1. The test results are shown in Table 1.

[0086] Table 1. Viscosity-reducing test results of viscosity reducers

[0087]

[0088] As can be seen from Table 1, the viscosity reducer of the present invention (Examples 1-7) can reduce the viscosity of crude oil with a viscosity of 17600 mPa·s by more than 99% when the concentration is 0.3 wt%. Among them, the viscosity reducer prepared in Example 7 has the highest viscosity reduction rate of 99.59%. In contrast, the SHF viscosity reducer of Shengli Chemical Co., Ltd. of Shengli Oilfield in the comparative example does not emulsify.

[0089] 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 synthesizing a viscosity reducer to improve the recovery rate of heavy oil reservoirs, characterized in that, The synthesis method includes: in the presence of a first solvent, 2-(trimethylsilylmethyl)allyl chloride undergoes an addition reaction with sodium bisulfite under reflux to obtain a sulfonate; and in the presence of a second solvent, the sulfonate undergoes a substitution reaction with 1-(2-hydroxyethyl)-2-imidazolinone under reflux. The first solvent is 90-95 wt% ethanol or 90-95 wt% methanol, and the mass ratio of 2-(trimethylsilylmethyl)allyl chloride is 6-8:1; The second solvent is ethanol or isopropanol, and the mass ratio of ethanol to 2-(trimethylsilylmethyl)allyl chloride is 8-10:

1.

2. The method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as described in claim 1, characterized in that, Based on 1 mole of 2-(trimethylsilylmethyl)allyl chloride, the amounts of sodium bisulfite and 1-(2-hydroxyethyl)-2-imidazolinone are 0.9-1.5 moles and 0.6-1 moles, respectively.

3. The method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as described in claim 2, characterized in that, Based on 1 mole of 2-(trimethylsilylmethyl)allyl chloride, the amounts of sodium bisulfite and 1-(2-hydroxyethyl)-2-imidazolinone are 1.1-1.5 moles and 0.7-0.9 moles, respectively.

4. The method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as described in claim 1, characterized in that, The addition reaction time is 2-4 hours.

5. The method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as described in claim 4, characterized in that, The addition reaction time is 2-3 hours.

6. The method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as described in claim 1, characterized in that, The substitution reaction time is 4-6 hours.

7. The method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as described in claim 6, characterized in that, The substitution reaction time is 4-5 hours.

8. The viscosity reducer prepared by the synthesis method of the viscosity reducer for improving the recovery rate of heavy oil reservoirs as described in any one of claims 1-7, characterized in that, The molecular structure of the viscosity reducer is as follows: 。

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