Temperature-resistant and salt-resistant thickened oil viscosity-reducing oil-displacing agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of tertiary oil recovery, and particularly relates to a temperature-resistant and salt-resistant thickened oil viscosity-reducing oil-displacing agent as well as a preparation method and application thereof. The preparation method comprises the following steps: adding nonyl phenol, DMF (Dimethyl Formamide) and epoxy halopropane into a reactor, stirring and dissolving, carrying out a heat preservation reaction, and carrying out reduced pressure distillation to obtain a viscous solid; adding isopropanol into the viscous solid for dissolving, adding 8-aminonaphthalene-1, 3, 6-trisulfonic acid disodium salt, heating and refluxing for reaction, and performing reduced pressure distillation to obtain a viscous solid; and adding distilled water, heating for dissolving, filtering, adjusting the pH value, separating out solid, standing, separating out supernate, centrifuging the lower-layer solid, concentrating, and drying to obtain the product, namely the viscosity-reducing oil-displacing agent for the thickened oil. The viscosity-reducing oil-displacing agent for the heavy oil has the characteristics of low surface and interface tension, low critical micelle concentration and good viscosity-reducing effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of tertiary oil recovery, and in particular relates to a temperature-resistant and salt-resistant heavy oil viscosity-reducing flooding agent, a preparation method and an application thereof. Background Art

[0002] Heavy oil resources account for a considerable proportion of the world's oil and gas resources. With the continuous reduction of light and easily recoverable crude oil, heavy oil extraction has increasingly attracted the attention of various countries.

[0003] Most heavy oil reservoirs have active edge and bottom water. After years of steam stimulation, the edge water has advanced significantly, resulting in high water content, averaging over 90%. Nitrogen injection and water coning showed initial success, but the effectiveness was short-lived and the overall results were unsatisfactory, with no significant improvement in daily oil production or water content. Viscosity reducers have shown remarkable effectiveness in enhancing oil recovery in edge water reservoirs. To address the characteristics of these reservoirs, viscosity reducers are injected at the water invasion front, where they mix with the invading formation water to form an active aqueous solution, which is then used as the displacement medium. Emulsification viscosity reduction involves thoroughly mixing a chemical surfactant solution with the heavy oil under certain conditions. Due to the strong surface activity of the hydrophilic groups, they can replace natural W / O emulsifiers (such as colloids and asphaltenes) at the oil-water interface, forming a targeted adsorption layer. This adsorption layer significantly alters intermolecular interactions and surface transfer processes, dispersing the highly viscous oil as droplets in the active water, forming a low-viscosity O / W emulsion. This significantly reduces the viscosity of the highly viscous oil and significantly eases recovery.

[0004] Using surfactants to reduce the viscosity of heavy oil and flood it is one of the main research directions for improving crude oil recovery.

[0005] CN1221650A discloses a surfactant primarily used for reducing the viscosity of heavy oil in oilfields. The surfactant's formula comprises, by weight, 15-20% lignin, 5-15% caustic soda, 2-8% soap powder or 1-6% soap, 10-15% synthetic detergent, and the remainder water. The surfactant's raw materials are inexpensive and readily available, and its preparation is simple. Its viscosity reduction rate can reach over 95%, particularly at temperatures exceeding 300°C, with no loss of performance. However, the surfactant requires the addition of an alkaline substance to achieve a good viscosity reduction effect on heavy oil. The addition of the alkaline substance reacts with calcium and magnesium ions in the stratum to produce a large amount of precipitate, clogging the stratum. Furthermore, the alkaline substance can make it difficult to demulsify the crude oil in the later stages, thus creating certain difficulties in deep processing of the crude oil.

[0006] CN112011325A discloses an oil-soluble heavy oil viscosity reducer comprising a fatty acid methyl ester, wherein the carbon number of the fatty acid moiety in the fatty acid methyl ester ranges from 12 to 24. The fatty acid methyl ester of the present invention is synthesized under mild conditions, and the raw materials for synthesis are widely available, with high yield, low price, and readily available, thus reducing costs. For example, in Xinjiang, local resources, particularly cottonseed oil, can be fully utilized. Furthermore, the purity requirements for methanol during the production process vary. The fatty acid methyl ester produced by this invention has good fluidity and viscosity reduction effects, uses readily available raw materials, and has a simple synthesis process, eliminating the need for complex or harsh synthesis conditions. The dosage of the heavy oil viscosity reducer of the present invention does not exceed 40% of the total mass of the heavy oil. Even with a small amount of this viscosity reducer, the viscosity of the heavy oil can be reduced by more than 90%. Therefore, the fatty acid methyl ester of this invention is suitable for large-scale oilfield production and gathering and transportation. However, for super-heavy oil, a 90% viscosity reduction does not meet practical needs, and production and transportation remain difficult. Summary of the Invention

[0007] The present invention addresses the deficiencies of the prior art and provides a temperature-resistant and salt-resistant heavy oil viscosity reducing agent and its preparation method and application. The heavy oil viscosity reducing agent of the present invention has the characteristics of low surface and interfacial tension, low critical micelle concentration and good viscosity reducing effect.

[0008] One of the purposes of the present invention is to disclose a temperature-resistant and salt-resistant heavy oil viscosity-reducing and flooding agent, the molecular structure of which is as follows: .

[0009] Another object of the present invention is to disclose a method for preparing the above-mentioned heavy oil viscosity reducing and flooding agent, which specifically comprises the following steps: (1) Add nonylphenol, DMF, and epihalohydrin into the reactor, stir and dissolve, keep warm and react, use sodium hydroxide to maintain pH 8-9, and distill under reduced pressure to obtain a viscous solid; (2) adding isopropanol to dissolve the above viscous solid, adding 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt, heating to reflux reaction, maintaining the pH at 8-9 with sodium hydroxide, and distilling under reduced pressure to obtain a viscous solid; (3) Add distilled water, heat to dissolve, filter, adjust the pH of the filtrate to 2-3 with hydrochloric acid, precipitate solid, let it stand, separate the supernatant, concentrate the lower solid by centrifugation, dry at 105-110℃ for 2-3h, and obtain the product heavy oil viscosity reducer.

[0010] In the present invention, preferably, based on 1 mol part of nonylphenol, the amounts of the epihalohydrin and 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt are 0.8-1.3 mol parts and 0.4-0.7 mol parts, respectively; more preferably, based on 1 mol part of nonylphenol, the amounts of the epihalohydrin and 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt are 0.9-1.2 mol parts and 0.45-0.6 mol parts, respectively.

[0011] In the present invention, preferably, in step (1), the epihalohydrin is one of epichlorohydrin and epibromohydrin, more preferably epibromohydrin.

[0012] In the present invention, preferably, in step (1), the weight ratio of DMF to nonylphenol is 10-20:1.

[0013] In the present invention, preferably, in step (1), the temperature of the insulation reaction is 70-90° C., and the reaction time is 6-24 h.

[0014] In the present invention, preferably, in step (2), the weight ratio of isopropyl alcohol to nonylphenol is 20-30:1.

[0015] In the present invention, preferably, in step (2), the reflux reaction time is 4-8 hours.

[0016] In the present invention, preferably, in step (3), the weight ratio of distilled water to nonylphenol is 20-30:1.

[0017] The reaction equation for synthesizing the heavy oil viscosity reducing flooding agent of the present invention is as follows: The third aspect of the present invention discloses the use of the above-mentioned heavy oil viscosity reducing and oil displacement agent in the development of heavy oil reservoirs.

[0018] The heavy oil viscosity reducing and flooding agent of the present invention belongs to a multi-headed anionic surfactant, the lipophilic group is nonylbenzene, and the hydrophilic group is three sulfonic acid groups. The nonyl group is a flexible lipophilic group, and the interaction with the benzene ring makes the present invention easy to combine with the colloid asphaltene in the heavy oil, and then the whole molecule is interspersed into the colloid and asphaltene, weakening the interaction between the aromatic rings in the heavy oil; the three sulfonic acid groups make it easy for the heavy oil to interact with the aqueous solution of the present invention to form an O / W emulsion, and the external phase forms a continuous water film, which can reduce flow resistance and significantly reduce crude oil viscosity. The present invention has lower surface tension and interfacial tension than conventional single hydrophilic and lipophilic group surfactants, and a lower critical micelle concentration. Therefore, the dosage when used is lower, the viscosity reduction effect is better, and the crude oil recovery rate can be greatly improved.

[0019] Compared with the prior art, the present invention has the following beneficial effects and advantages: (1) The heavy oil viscosity reducing and flooding agent of the present invention has the characteristics of low surface and interfacial tension, with the surface tension reaching a minimum of 27mN / m and the interfacial tension reaching a minimum of 0.0015mN / m; (2) The heavy oil viscosity reducing and flooding agent of the present invention has the characteristic of low critical micelle concentration, which is as low as 35 mg / L.

[0020] (3) The heavy oil viscosity reducing agent of the present invention has the characteristic of good viscosity reducing effect. The viscosity reducing rate of crude oil with a viscosity of 4500 mPa∙s reaches 98.18% or above, and the viscosity reducing rate of crude oil with a viscosity of 10200 mPa∙s reaches 99.10% or above. DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values ​​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 endpoints of each range, the endpoints of each range and 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 to be specifically disclosed herein.

[0022] The present invention will be further described below with reference to specific embodiments: Example 1 (1) Add 50 mmol of nonylphenol, 110 g of DMF, and 40 mmol of epichlorohydrin into a reactor, stir and dissolve, heat to 70°C, and keep warm for 12 hours. During this time, use sodium hydroxide to maintain the pH at 8-9. Distill under reduced pressure to obtain a viscous solid. (2) The above viscous solid was dissolved in 220 g of isopropanol, and 20 mmol of 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt was added. The mixture was heated under reflux for 6 h, during which the pH was maintained at 8-9 with sodium hydroxide. The mixture was distilled under reduced pressure to obtain a viscous solid. (3) Add 220g of distilled water, heat to dissolve, filter, adjust the pH of the filtrate to 2-3 with hydrochloric acid, precipitate solid, let it stand, separate the supernatant, concentrate the lower solid by centrifugation, and dry at 105℃ for 2h to obtain the product heavy oil viscosity reducer.

[0023] Example 2 (1) Add 50 mmol of nonylphenol, 220 g of DMF, and 65 mmol of epichlorohydrin into a reactor, stir and dissolve, heat to 70°C, and keep warm for 24 hours. During this time, use sodium hydroxide to maintain the pH at 8-9. Distill under reduced pressure to obtain a viscous solid. (2) The above viscous solid was dissolved in 330 g of isopropanol, and 35 mmol of 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt was added. The mixture was heated under reflux for 8 h, during which the pH was maintained at 8-9 with sodium hydroxide. The mixture was distilled under reduced pressure to obtain a viscous solid. (3) Add 330 g of distilled water, heat to dissolve, filter, adjust the pH of the filtrate to 2-3 with hydrochloric acid, precipitate solid, let it stand, separate the supernatant, concentrate the lower solid by centrifugation, and dry at 106 ° C for 3 h to obtain the product heavy oil viscosity reducer.

[0024] Example 3 (1) Add 50 mmol of nonylphenol, 130 g of DMF, and 45 mmol of epichlorohydrin into a reactor, stir and dissolve, heat to 90°C, and keep warm for 6 hours. During this time, use sodium hydroxide to maintain the pH at 8-9. Distill under reduced pressure to obtain a viscous solid. (2) The above viscous solid was dissolved in 250 g of isopropanol, and 22 mmol of 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt was added. The mixture was heated under reflux for 4 h, during which the pH was maintained at 8-9 with sodium hydroxide, and the mixture was distilled under reduced pressure to obtain a viscous solid. (3) Add 240 g of distilled water, heat to dissolve, filter, adjust the pH of the filtrate to 2-3 with hydrochloric acid, precipitate solid, let it stand, separate the supernatant, concentrate the lower solid by centrifugation, and dry at 108 ° C for 2 h to obtain the product heavy oil viscosity reducer.

[0025] Example 4 (1) Add 50 mmol of nonylphenol, 210 g of DMF, and 60 mmol of epichlorohydrin into a reactor, stir and dissolve, heat to 80°C, and keep warm for 10 hours. During this time, use sodium hydroxide to maintain the pH at 8-9. Distill under reduced pressure to obtain a viscous solid. (2) Dissolve the above viscous solid in 300 g of isopropanol, add 32 mmol of 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt, heat and reflux for 5 h, maintain the pH at 8-9 with sodium hydroxide, and distill under reduced pressure to obtain a viscous solid; (3) Add 300g of distilled water, heat to dissolve, filter, adjust the pH of the filtrate to 2-3 with hydrochloric acid, precipitate solid, let it stand, separate the supernatant, centrifuge and concentrate the lower solid, dry at 105℃ for 3h to obtain the product heavy oil viscosity reducer.

[0026] Example 5 (1) Add 50 mmol of nonylphenol, 150 g of DMF, and 50 mmol of epibromopropane into a reactor, stir and dissolve, heat to 75°C, and keep the temperature for 12 hours. During this time, use sodium hydroxide to maintain the pH at 8-9. Distill under reduced pressure to obtain a viscous solid. (2) The above viscous solid was dissolved in 265 g of isopropanol, and 25 mmol of 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt was added. The mixture was heated under reflux for 7 h, during which the pH was maintained at 8-9 with sodium hydroxide, and the mixture was distilled under reduced pressure to obtain a viscous solid. (3) Add 280g of distilled water, heat to dissolve, filter, adjust the pH of the filtrate to 2-3 with hydrochloric acid, precipitate solid, let it stand, separate the supernatant, concentrate the lower solid by centrifugation, and dry at 110℃ for 3h to obtain the product heavy oil viscosity reducer.

[0027] Example 6 (1) Add 50 mmol of nonylphenol, 180 g of DMF, and 52 mmol of epibromopropane into a reactor, stir and dissolve, heat to 80°C, and keep the temperature to react for 12 hours. During this period, use sodium hydroxide to maintain the pH at 8-9. Distill under reduced pressure to obtain a viscous solid. (2) The above viscous solid was dissolved in 278 g of isopropanol, and 30 mmol of 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt was added. The mixture was heated under reflux for 6 h, during which the pH was maintained at 8-9 with sodium hydroxide. The mixture was distilled under reduced pressure to obtain a viscous solid. (3) Add 292 g of distilled water, heat to dissolve, filter, adjust the pH of the filtrate to 2-3 with hydrochloric acid, precipitate solid, let it stand, separate the supernatant, concentrate the lower solid by centrifugation, and dry at 107 ° C for 2.5 h to obtain the product heavy oil viscosity reducer.

[0028] Example 7 (1) Add 50 mmol of nonylphenol, 183 g of DMF, and 55 mmol of epibromopropane into a reactor, stir and dissolve, heat to 80°C, and keep the temperature to react for 12 hours. During this time, use sodium hydroxide to maintain the pH at 8-9. Distill under reduced pressure to obtain a viscous solid. (2) The above viscous solid was dissolved in 290 g of isopropanol, and 28 mmol of 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt was added. The mixture was heated under reflux for 6 h, during which the pH was maintained at 8-9 with sodium hydroxide, and the mixture was distilled under reduced pressure to obtain a viscous solid. (3) Add 287g of distilled water, heat to dissolve, filter, adjust the pH of the filtrate to 2-3 with hydrochloric acid, precipitate solid, let it stand, separate the supernatant, centrifuge and concentrate the lower solid, dry at 109℃ for 2.5h to obtain the product heavy oil viscosity reducer.

[0029] Example 8 Testing of surface tension and interfacial tension The heavy oil viscosity reducing and flooding agents of the present invention (Examples 1-7) were prepared into 500 mg / L aqueous solutions, and the pH was adjusted to 8. The surface tension and interfacial tension were measured according to the method in SY / T 5370-2018, "Surface and Interfacial Tension Determination Methods." The interfacial tension test oil phase used was crude oil from an oil production plant in Shengli Oilfield, with a viscosity of 120 mPa∙s. The results are shown in Table 1.

[0030] A comparative experiment was conducted using sulfonate produced by Shengli Petrochemical Co., Ltd. for oil recovery.

[0031] From Table 1 we can see that: The heavy oil viscosity reducing and flooding agent (Examples 1-7) of the present invention has the characteristics of low surface and interfacial tension. At a concentration of 500 mg / L, the surface tension reaches below 28 mN / m, with the lowest reaching 27 mN / m (Example 7), and the interfacial tension reaches 1×10 -2 mN / m or less, and the lowest reaches 0.0015mN / m (Example 7). In the comparative example, the surface tension of the sulfonate used for oil recovery by Shengli Oilfield Shengli Chemical Co., Ltd. is 29.7mN / m, and the interfacial tension reaches 0.82mN / m, which is significantly higher than that of the present invention.

[0032] Example 9 Test of critical micelle concentration The critical micelle concentration was determined according to the method in GB / T 11276-2007 “Determination of critical micelle concentration of surfactants”. The results are shown in Table 1.

[0033] A comparative experiment was conducted using sulfonate produced by Shengli Petrochemical Co., Ltd. for oil recovery.

[0034] Table 1 Test results of surface tension, interfacial tension and critical micelle concentration Surface tension, mN / m Interfacial tension, mN / m Critical micelle concentration, mg / L Example 1 27.1 0.0098 95 Example 2 27.1 0.0048 65 Example 3 27 0.0068 80 Example 4 27 0.0035 35 Example 5 27 0.004 40 Example 6 27 0.0026 40 Example 7 27 0.0015 35 Comparative Example 29.7 0.82 230 From Table 1 we can see that: The heavy oil viscosity reducers of the present invention (Examples 1-7) have a low critical micelle concentration, which is 100 mg / L or less, with a minimum of 35 mg / L (Examples 4 and 7). In contrast, the critical micelle concentration of the sulfonate used for oil recovery by Shengli Oilfield Shengli Chemical Co., Ltd. in the comparative example is 230 mg / L, which is significantly higher than that of the present invention.

[0035] Example 10 Evaluation of viscosity reduction The heavy oil viscosity reducing and flooding agents of the present invention (Examples 1-7) were prepared into 1000 mg / L solutions, and the viscosity reduction rate was tested according to the method in Q / SH10201519-2016 "General Technical Requirements for Heavy Oil Viscosity Reducers". The crude oils used in the tests were oil samples A and B from Shengli Oilfield. The initial viscosities of the crude oils at 50°C were 4500 mPa∙s and 10200 mPa∙s, respectively. The test results are shown in Table 2.

[0036] A comparative experiment was conducted using sulfonate produced by Shengli Petrochemical Co., Ltd. for oil recovery.

[0037] Table 2 Viscosity reduction test results As can be seen from Table 2, the heavy oil viscosity reducer of the present invention (Examples 1-7) has the characteristics of good viscosity reducing effect: (1) For oil sample A, the initial viscosity of the crude oil is 4500 mPa∙s at 50°C. When the concentration is 1000 mg / L, the viscosity reduction rate reaches 98.18% or above, and the highest reaches 98.44% (Example 7). The viscosity reduction rate of the sulfonate used for oil recovery by Shengli Oilfield Shengli Chemical Co., Ltd. in the comparative example is 96.49%, which is significantly lower than that of the present invention. (2) For oil sample B, the initial viscosity of the crude oil is 10200 mPa∙s at 50°C. When the concentration is 1000 mg / L, the viscosity reduction rate reaches 99.10% or above, and the highest reaches 99.27% ​​(Example 7). In contrast, the sulfonate used for oil recovery by Shengli Chemical Co., Ltd. of Shengli Oilfield is not emulsified.

[0038] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within 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 scope of protection of the present invention.

[0039] 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.

[0040] In addition, the 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.

Claims

1. A method for preparing a heat-resistant and salt-resistant heavy oil viscosity-reducing flooding agent, characterized in that: The preparation method specifically comprises the following steps: (1) Add nonylphenol, DMF, and epihalohydrin into the reactor, stir and dissolve, keep warm and react, use sodium hydroxide to maintain pH 8-9, and distill under reduced pressure to obtain a viscous solid; (2) adding isopropanol to dissolve the above viscous solid, adding 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt, heating to reflux for reaction, maintaining the pH at 8-9 with sodium hydroxide, and distilling under reduced pressure to obtain a viscous solid; (3) Add distilled water, heat to dissolve, filter, adjust the pH of the filtrate to 2-3 with hydrochloric acid, precipitate solid, let it stand, separate the supernatant, centrifuge the lower solid to concentrate, dry at 105-110℃ for 2-3h, and obtain the product heavy oil viscosity reducing flooding agent; Based on 1 mol part of nonylphenol, the amounts of the epihalohydrin and 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt are 0.8-1.3 mol parts and 0.4-0.7 mol parts respectively.

2. The preparation method according to claim 1, characterized in that Based on 1 mol part of nonylphenol, the amounts of the epihalohydrin and 8-aminonaphthalene-1,3,6-trisulfonic acid disodium salt are 0.9-1.2 mol parts and 0.45-0.6 mol parts respectively.

3. The preparation method according to claim 1, characterized in that In step (1), the epihalohydrin is one of epichlorohydrin and epibromohydrin.

4. The preparation method according to claim 1, characterized in that In step (1), the weight ratio of DMF to nonylphenol is 10-20:

1.

5. The preparation method according to claim 1, characterized in that In step (1), the temperature of the insulation reaction is 70-90°C, and the reaction time is 6-24h.

6. The preparation method according to claim 1, characterized in that In step (2), the weight ratio of isopropyl alcohol to nonylphenol is 20-30:

1.

7. The preparation method according to claim 1, characterized in that In step (2), the reflux reaction time is 4-8 hours.

8. The preparation method according to claim 1, characterized in that In step (3), the weight ratio of distilled water to nonylphenol is 20-30:

1.

9. The heavy oil viscosity reducing flooding agent prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The molecular structural formula of the heavy oil viscosity reducing flooding agent is as follows: 。 10. Use of the heavy oil viscosity reducing and flooding agent according to claim 9 in heavy oil reservoir development.

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