Viscosity reducer for improving recovery efficiency of heavy oil reservoir and synthesis method of viscosity reducer

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to a viscosity reducer for improving the recovery efficiency of a heavy oil reservoir and a synthesis method of the viscosity reducer. The synthesis method comprises the following steps: in the presence of a first solvent, carrying out heating reflux on 2-(trimethylsilyl methyl) allyl chloride and sodium hydrogen sulfite, and carrying out an addition reaction to obtain sulfonate; secondly, in the presence of a second solvent, sulfonate and 1-(2-ethoxyl)-2-imidazolinone are subjected to heating reflux for a substitution reaction; on the basis of 1 mole part of 2-(trimethylsilyl methyl) allyl chloride, the dosage of the sodium hydrogen sulfite is 0.9 to 1.5 mole parts, and the dosage of the 1-(2-ethoxyl)-2-imidazolinone is 0.6 to 1 mole part, and the dosage of the sodium hydrogen sulfite is 0.9 to 1.5 mole parts, and the dosage of the 1-(2-ethoxyl)-2-imidazolinone is 0.6 to 1 mole part. The thick oil viscosity reducer has the characteristics of wide raw material source, simple synthesis process and good viscosity reduction effect.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and in particular relates to a viscosity reducer for improving the recovery rate of heavy oil reservoirs and a synthesis method thereof. Background Art

[0002] Heavy oil resources account for a considerable 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 reduction of light and easy-to-recover crude oil, heavy oil production has increasingly attracted the attention of various countries.

[0003] Most heavy oil reservoirs have active edge and bottom water. After years of steam huff-and-puff development, the edge water has been seriously advanced, and the overall water content is high, averaging more than 90%. After the nitrogen injection water cone was adopted, the initial effect was obvious, but the effective period was short, and the overall effect was not ideal. There was no significant improvement in the daily oil and water content of the cycle. The application of viscosity reducers to enhance oil recovery in edge water reservoirs has a significant effect. According to the characteristics of such reservoirs, viscosity reducers are injected from the front of water invasion, mixed with the formation water invaded by the edge to form an active aqueous solution, and this active aqueous solution is used as a displacement medium. The heavy oil viscosity reducer used in this method can effectively reduce the viscosity of high-viscosity crude oil, reduce the oil-water interfacial tension, increase the reservoir energy, and use the energy of the formation itself to form a stable water-in-oil emulsion, which greatly reduces the viscosity of high-viscosity crude oil and significantly reduces the difficulty of mining.

[0004] CN 104194761 A provides a composite viscosity reducer for steam injection development, which is composed of a catalyst and an emulsifier. The composite viscosity reducer can react with heavy oil at 200°C to reduce the viscosity of the heavy oil by more than 98.5%. Compared with conventional viscosity reducers, the viscosity reducer can react chemically with the heavy oil to crack the long carbon chain of the heavy oil, while the main function of the emulsifier is to emulsify the catalyst so that it can be dissolved in the water phase for easy injection. Since it is a chemical reaction, the time and efficiency of the reaction with the heavy oil are far less than those of the physical reaction, and 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 oil fields, wherein the formula contains 15-20% lignin, 5-15% caustic soda, 2-8% soap powder or 1-6% soap, 10-15% synthetic detergent, and the rest is water by weight. The raw materials used for the surfactant are cheap and easy to obtain, and the preparation method is simple. The viscosity reduction rate can reach more than 95%, especially under high temperature conditions of more than 300 degrees Celsius, and the performance is not reduced. When used, it is necessary to compound alkaline substances to have a good viscosity reduction effect on heavy oil, and the addition of alkaline substances will react with calcium and magnesium ions in the formation to produce a large amount of precipitation, blocking the formation, and alkaline substances will make it difficult to demulsify crude oil in the later stage, which also brings certain difficulties to the deep processing of crude oil. Summary of the invention

[0006] The present invention aims at the problems encountered by the existing viscosity reducers and provides a viscosity reducer for improving the recovery rate of heavy oil reservoirs and a synthesis method thereof. The heavy oil viscosity reducer has the characteristics of wide raw material sources, simple synthesis process and good viscosity reduction effect.

[0007] Therefore, in order to achieve the above-mentioned purpose, on the one hand, the present invention discloses a viscosity reducer for improving the recovery rate of heavy oil reservoirs, and the molecular structure of the viscosity reducer 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 synthesis method comprising: 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 secondly, in the presence of a second solvent, the sulfonate and 1-(2-hydroxyethyl)-2-imidazolidinone are heated under reflux to undergo a substitution reaction.

[0010] The viscosity reducer for improving the recovery rate of heavy oil reservoirs of the present invention belongs to a surfactant, is a mixed type of anions and non-ions, has a hydrophilic group of sulfonic acid group and imidazoline, and a lipophilic group of silane, and the entire molecule has a linear structure, which is relatively easy to be inserted into the colloid and asphaltene layers, and weakens the interaction between the aromatic rings in the heavy oil; the silane group belongs to a special lipophilic group, so that the aqueous solution of the present invention has lower surface tension and interfacial tension, and the critical micelle concentration is smaller, so the dosage when used is lower. Under the action of functional groups such as silane group, sulfonic acid group and imidazoline, after the aqueous solution of the present invention is emulsified with the heavy oil, the external phase forms a continuous water film, which can reduce the flow resistance and greatly reduce the viscosity of the 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 characteristics of wide raw material sources and simple synthesis process;

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

[0014] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

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

[0016]

[0017] In a second aspect, the present invention provides a method for synthesizing the above-mentioned viscosity reducer for improving the recovery rate of heavy oil reservoirs, the synthesis method comprising: 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; secondly, in the presence of a second solvent, the sulfonate and 1-(2-hydroxyethyl)-2-imidazolidinone are heated under reflux to undergo a substitution reaction.

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

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

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

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

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

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

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

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

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

[0027] (2) adding 1.5-2 times the weight of the first solvent in distilled water, distilling off 1.3-1.7 times the weight of the first solvent in liquid under reduced pressure, stopping distillation, adjusting the pH to 2-3 with hydrochloric acid, cooling to below 10° C., precipitating solids, filtering, and washing with distilled water 1-2 times;

[0028] (3) dissolving the solid with a second solvent, adjusting the pH to 8-9 with sodium hydroxide, adding 1-(2-hydroxyethyl)-2-imidazolidinone and reacting under reflux for 4-6 hours, and maintaining the pH at 8-9 with sodium hydroxide during the reaction;

[0029] (4) distilling under reduced pressure to obtain a viscous solid, recrystallizing from cyclohexane to obtain a light yellow solid, and drying at 80° C. overnight to obtain a viscosity reducer product.

[0030] The reaction equation for synthesizing the viscosity reducing agent for improving the recovery rate of heavy oil reservoirs of the present 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 further describe various possible combinations.

[0033] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

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

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

[0036] In the following examples and comparative examples, unless otherwise specified, all reagents used were 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 into a four-necked flask, stir, heat, and reflux for 2 h;

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

[0040] (3) The solid was dissolved in 279.3 g of isopropanol, the pH was adjusted to 8-9 with 2 mol / L of sodium hydroxide, 0.12 mol of 1-(2-hydroxyethyl)-2-imidazolidinone was added and refluxed for 4 h, and the pH was maintained at 8-9 with 2 mol / L of sodium hydroxide during the reaction;

[0041] (4) distilling under reduced pressure to obtain a viscous solid, recrystallizing from cyclohexane to obtain a light yellow solid, and drying at 80° C. overnight to obtain a viscosity reducer product.

[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 into a four-necked flask, stir, heat, and reflux for 2 h;

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

[0045] (3) The solid was dissolved in 324 g of ethanol, the pH was adjusted to 8-9 with 2 mol / L sodium hydroxide, 0.12 mol of 1-(2-hydroxyethyl)-2-imidazolidinone was added and refluxed for 4 h, and 2 mol / L sodium hydroxide was used to maintain the pH at 8-9 during the reaction;

[0046] (4) distilling under reduced pressure to obtain a viscous solid, recrystallizing from cyclohexane to obtain a light yellow solid, and drying at 80° C. overnight to obtain a viscosity reducer product.

[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 into a four-necked flask, stir, heat, and reflux for 3 h;

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

[0050] (3) The solid was dissolved in 259.2 g of isopropanol, the pH was adjusted to 8-9 with 2 mol / L sodium hydroxide, 0.2 mol of 1-(2-hydroxyethyl)-2-imidazolidinone was added and refluxed for 4.5 h. During the reaction, 2 mol / L sodium hydroxide was used to maintain the pH at 8-9;

[0051] (4) distilling under reduced pressure to obtain a viscous solid, recrystallizing from cyclohexane to obtain a light yellow solid, and drying at 80° C. overnight to obtain a viscosity reducer product.

[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 into a four-necked flask, stir, heat, and reflux for 3.5 hours;

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

[0055] (3) The solid was dissolved in 294.8 g of isopropanol, the pH was adjusted to 8-9 with 2 mol / L of sodium hydroxide, 0.14 mol of 1-(2-hydroxyethyl)-2-imidazolidinone was added and refluxed for 5 h. During the reaction, 2 mol / L of sodium hydroxide was used to maintain the pH at 8-9;

[0056] (4) distilling under reduced pressure to obtain a viscous solid, recrystallizing from cyclohexane to obtain a light yellow solid, and drying at 80° C. overnight to obtain a viscosity reducer product.

[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 into a four-necked flask, stir, heat, and reflux for 3 h;

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

[0060] (3) The solid was dissolved in 319.2 g of isopropanol, the pH was adjusted to 8-9 with 2 mol / L of sodium hydroxide, 0.15 mol of 1-(2-hydroxyethyl)-2-imidazolidinone was added and refluxed for 6 h. During the reaction, 2 mol / L of sodium hydroxide was used to maintain the pH at 8-9;

[0061] (4) distilling under reduced pressure to obtain a viscous solid, recrystallizing from cyclohexane to obtain a light yellow solid, and drying at 80° C. overnight to obtain a viscosity reducer product.

[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 into a four-necked flask, stir, heat, and reflux for 3 h;

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

[0065] (3) The solid was dissolved in 309 g of ethanol, the pH was adjusted to 8-9 with 2 mol / L sodium hydroxide, 0.17 mol of 1-(2-hydroxyethyl)-2-imidazolidinone was added and refluxed for 6 h. During the reaction, 2 mol / L sodium hydroxide was used to maintain the pH at 8-9;

[0066] (4) distilling under reduced pressure to obtain a viscous solid, recrystallizing from cyclohexane to obtain a light yellow solid, and drying at 80° C. overnight to obtain a viscosity reducer product.

[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 into a four-necked flask, stir, heat, and reflux for 4 h;

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

[0070] (3) dissolving the solid in 324 g of isopropanol, adjusting the pH to 8-9 with 2 mol / L sodium hydroxide, adding 0.16 mol of 1-(2-hydroxyethyl)-2-imidazolidinone and reacting under reflux for 6 h, and maintaining the pH at 8-9 with 2 mol / L sodium hydroxide during the reaction;

[0071] (4) distilling under reduced pressure to obtain a viscous solid, recrystallizing from cyclohexane to obtain a light yellow solid, and drying at 80° C. overnight to obtain a viscosity reducer product.

[0072] Test Example 1 Evaluation of heavy oil viscosity reducer

[0073] (1) Heavy oil from block A of Shengli Oilfield was kept in a constant temperature water bath at 50°C for 1 h and stirred to remove free water and bubbles. Its viscosity μ0 at 50°C was measured with a viscometer within 20 s.

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

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

[0076] The viscosity reduction rate of heavy oil is calculated as follows:

[0077]

[0078] Where: f——viscosity reduction rate;

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

[0080] μ——Viscosity of heavy oil emulsion after adding sample solution, mPa·s.

[0081] Use SHF viscosity reducer from Shengli Oilfield Shengli Chemical Co., Ltd.

[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] It can be seen from Table 1 that when the viscosity reducer of the present invention (Examples 1-7) is used at a concentration of 0.3wt%, the viscosity reduction rate of crude oil with a viscosity of 5800mPa.s can reach more than 98%, among which the viscosity reduction rate of the viscosity reducer prepared in Example 7 is as high as 98.88%; while the viscosity reduction rate of the SHF viscosity reducer of Shengli Oilfield Shengli Chemical Co., Ltd. in the comparative example is 97.31%.

[0084] Test Example 2 Evaluation of Viscosity Reducer for Heavy Oil

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

[0086] Table 1 Viscosity reduction test results of viscosity reducer

[0087]

[0088] It can be seen from Table 1 that when the viscosity reducer of the present invention (Examples 1-7) is used at a concentration of 0.3wt%, the viscosity reduction rate of crude oil with a viscosity of 17600mPa.s can reach more than 99%, among which the viscosity reducer prepared in Example 7 has a highest viscosity reduction rate of 99.59%; while the SHF viscosity reducer of Shengli Oilfield Shengli Chemical Co., Ltd. in the comparative example is not emulsified.

[0089] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs, characterized in that: The synthesis method comprises: in the presence of a first solvent, heating 2-(trimethylsilylmethyl)allyl chloride and sodium bisulfite under reflux to produce an addition reaction to obtain a sulfonate; and secondly, in the presence of a second solvent, heating sulfonate and 1-(2-hydroxyethyl)-2-imidazolidinone under reflux to produce a substitution reaction.

2. A method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as claimed 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-imidazolidinone used are 0.9-1.5 mole and 0.6-1 mole, respectively.

3. A method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as claimed 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-imidazolidinone used are 1.1-1.5 mole and 0.7-0.9 mole, respectively.

4. A method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as claimed in claim 1, characterized in that: The first solvent is 90-95wt% ethanol or 90-95wt% methanol, and the mass ratio of the first solvent to 2-(trimethylsilylmethyl)allyl chloride is 6-8:

1.

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

6. A method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as claimed in claim 5, characterized in that: The addition reaction time is 2-3h.

7. A method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as claimed in claim 1, characterized in that: The second solvent is ethanol or isopropanol, and the mass ratio of the second solvent to 2-(trimethylsilylmethyl)allyl chloride is 8-10:

1.

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

9. A method for synthesizing a viscosity reducer for improving the recovery rate of heavy oil reservoirs as claimed in claim 8, characterized in that: The substitution reaction time is 4-5h.

10. A viscosity reducer for improving the recovery of heavy oil reservoirs, characterized in that: The molecular structural formula of the viscosity reducer is as follows:

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