A viscosity reducer for super heavy oil and its application

Abstract

The application provides a super-viscous oil viscosity reducer and application thereof, and relates to the technical field of heavy oil exploitation and transportation. The super-viscous oil viscosity reducer is coal tar or by-products of coal tar; the coal tar is at least one selected from low-temperature coal tar, medium-temperature coal tar and high-temperature coal tar generated when coal is dry distillation at 450-1000 DEG C. The low-cost super-viscous oil viscosity reducer has wide sources, low cost and strong reservoir adaptability, can reduce the viscosity of super-viscous oil with a viscosity of 520000 mPa.s at 50 DEG C by more than 98% under the condition of small amount of addition, has high viscosity reduction efficiency, small amount of addition and outstanding economic characteristics, and can be widely applied to viscosity reduction in the process of super-viscous oil exploitation and transportation.

Description

Technical Field

[0001] This invention relates to the field of heavy oil extraction and transportation technology, and specifically to an extra-heavy oil viscosity reducer and its application. Background Technology

[0002] As underground reserves of light crude oil gradually decrease and the proportion of heavy oil increases, the efficient extraction of heavy oil is attracting increasing attention. High viscosity and high density are the main characteristics that distinguish heavy oil from ordinary light crude oil. Heavy oil has a lower content of light fractions, is generally rich in asphaltenes and gums, and contains more elements such as oxygen, nitrogen, and sulfur, as well as metal compounds such as iron, nickel, and vanadium.

[0003] Currently, the main methods for heavy oil extraction are thermal recovery and viscosity reduction by dilution. Thermal recovery, including steam injection and steam drive, is a relatively mature technology, but it consumes a lot of electricity, has high costs, and results in significant heat energy consumption in the wellbore. Furthermore, after multiple rounds of injection and drainage, the oil-steam ratio decreases significantly, leading to poor economic efficiency. While viscosity reduction by dilution can improve the flowability of heavy oil in the wellbore, it requires a large amount of thinner. As the scale of extraction increases, thinner resources are gradually becoming scarce. Therefore, it is essential to find a low-cost, oil-soluble viscosity reducer for heavy oil reservoir extraction and gathering.

[0004] Chinese patent CN 115926768A discloses an oil-soluble viscosity reducer composition, its preparation method and application. The viscosity reducer composition contains medium- and low-temperature coal tar fractions in a weight ratio of 70:30 to 95:5 and multi-branched tail-chain sulfonic acid based on alkylene oxides.

[0005] Chinese patent CN 117304465A discloses a hyperbranched oil-soluble polyester viscosity reducer for heavy oils and its preparation method. First, a hyperbranched polyester is generated by esterification of trimethylolpropane, glycerol, and succinic anhydride. Then, this polyester is reacted with methyl erucate and methyl cinnamate via transesterification to prepare a hyperbranched oil-soluble viscosity reducer for heavy oils.

[0006] Chinese patent CN 117924627A discloses a heavy oil viscosity reducer and its preparation method. The method involves mixing p-tert-butylphenol, KOH solution, and formaldehyde solution, heating the mixture, and then adding an alkaline solution to continue the reaction. After centrifugation, a solid is obtained. The solid is then subjected to in-situ nitration to obtain a white powder, which is subsequently reduced to yield compound A. Compound A and ketone compound B are mixed, and an acidic catalyst is added for condensation to obtain the heavy oil viscosity reducer.

[0007] Chinese patent CN 106939157A discloses a double-chain oil-soluble thick oil viscosity reducer, comprising the following components: styrene, vinyl acetate, and a chain with a chain length of C. 12 -C 20The molar ratio of the three components is 30-35:25-30:40-55.

[0008] Chinese Patent CN 114479060A discloses an oil-soluble viscosity reducer for extra-heavy oils and its preparation method. The oil-soluble viscosity reducer comprises: 10-30% of a viscosity reducer main agent, preferably 16%; 5-15% of a viscosity reducer auxiliary agent, preferably 10%; and the remainder being solvent oil. The viscosity reducer main agent is prepared by reacting p-toluene isocyanate and polyethylene glycol. The viscosity reducer auxiliary agent is one of tetrahydrofuran, hydroquinone, and methylcyclohexane. The solvent oil is one of 120# rubber solvent oil, 190# washing solvent oil, and 200# paint solvent oil.

[0009] Chinese Patent CN 117987116A discloses an oil-soluble viscosity reducer composition, its preparation method, and its uses. The oil-soluble viscosity reducer composition comprises 20-35 parts by weight of pentaerythritol difatty acid ester, 10-25 parts by weight of hydrocarbon resorcinol, and 40-70 parts by weight of penetrant.

[0010] When using coal tar directly to reduce the viscosity of extra-heavy oil, on-site injection is difficult, and the viscosity-reducing effect is not ideal. For example, Chinese patent CN 115926768A discloses an oil-soluble viscosity-reducing agent composition, its preparation method, and its application. This viscosity-reducing agent composition contains medium- and low-temperature coal tar fractions in a weight ratio of 70:30 to 95:5 and multi-branched tail-chain sulfonic acid based on alkylene glycol. Adding 3 wt% of this patented viscosity-reducing agent to heavy oil with a viscosity of 10435 mPa·s can reduce the viscosity to 3516-5890 mPa·s, with a viscosity reduction rate of 43.56%-66.31%; adding 5 wt% of this patented viscosity-reducing agent to heavy oil with a viscosity of 52330 mPa·s can reduce the viscosity to 8983-25613 mPa·s, with a viscosity reduction rate of 51.05%-80.11%. Therefore, it can be seen that the application of this invention patent is for heavy oil with a viscosity of less than 60,000 mPa·s. However, for the large amount of ultra-heavy oil with a viscosity of more than 500,000 mPa·s in oil fields, the extraction is very difficult. Therefore, there is an urgent need to develop a low-cost and easy-to-use viscosity reducer for ultra-heavy oil. Summary of the Invention

[0011] To address the aforementioned problems, this invention provides a viscosity reducer for extra-heavy oil. This low-cost viscosity reducer for extra-heavy oil is widely available, inexpensive, and highly adaptable to oil reservoirs. When added at a dosage of 0.05-5 parts by weight of the heavy oil, it can reduce the viscosity of extra-heavy oil with a viscosity as high as 520,000 mPa·s at 50°C by more than 98%.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] On one hand, the present invention provides an extra-heavy oil viscosity reducer, wherein the extra-heavy oil viscosity reducer is coal tar or a by-product of coal tar; wherein the coal tar is selected from at least one of low-temperature coal tar, medium-temperature coal tar and high-temperature coal tar generated during the dry distillation of coal at 450-1000℃.

[0014] Preferably, the low-temperature coal tar is coal tar produced during the dry distillation of coal at 450-650℃;

[0015] Preferably, the medium-temperature coal tar is the coal tar produced during the dry distillation of coal at 650-900℃;

[0016] Preferably, the high-temperature coal tar is coal tar produced during the dry distillation of coal at 900-1000℃;

[0017] Preferably, the byproducts of the coal tar are selected from at least one of light oil, phenolic oil, naphthalene oil, wash oil, and anthracene oil;

[0018] Preferably, the light oil refers to the product of coal tar before the distillation temperature is 170°C;

[0019] Preferably, the phenolic oil refers to the product of coal tar at a distillation temperature of 170-210℃;

[0020] Preferably, the naphthalene oil refers to the product of coal tar at a distillation temperature of 210-230℃;

[0021] Preferably, the wash oil refers to the product of coal tar at a distillation temperature of 230-300℃;

[0022] Preferably, the anthracene oil refers to the product of coal tar at a distillation temperature of 280-360℃.

[0023] Preferably, the extra-heavy oil viscosity reducer comprises, by weight parts, the following components: 20-40 parts 1-methylnaphthalene, 5-20 parts 2-methylnaphthalene, 10-20 parts acenaphthene, 10-20 parts fluorene oxyfluorene, 5-15 parts fluorene and 10-30 parts other compounds.

[0024] More preferably, the extra-heavy oil viscosity reducer comprises, by weight parts, the following components: 20-30 parts 1-methylnaphthalene, 5-15 parts 2-methylnaphthalene, 15-20 parts acenaphthene, 10-15 parts fluorene oxide, 5-10 parts fluorene and 10-25 parts other compounds.

[0025] Preferably, the other compounds are selected from at least one of indene, naphthalene, quinoline, isoquinoline, 6-methylquinoline, biphenyl, 2-ethylnaphthalene, 1,7-dimethylnaphthalene, 1,8-dimethylnaphthalene, 1,5-dimethylnaphthalene, 2,6-dimethylnaphthalene, 2-isopropylnaphthalene, 2-isopropylphenylnaphthalene, 2,3,5-trimethylnaphthalene, 2,3,6-trimethylnaphthalene, 2,4a-dihydrofluorene, 1,4-dihydrofluorene, 2-hydroxyfluorene, 9-fluorene alcohol, 4-isopropylbiphenyl, 1-methylfluorene, phenanthrene, L-ascorbyl palmitate, acenaphthene, 2-vinylnaphthalene, and (2,4-cyclopentadien-1-methylene)benzene.

[0026] Preferably, the mass ratio of the extra-heavy oil viscosity reducer to the heavy oil is 0.01-6:1.

[0027] More preferably, the mass ratio of the extra-heavy oil viscosity reducer to the heavy oil is 0.05-5:1.

[0028] Furthermore, the present invention provides the application of the above-mentioned extra-heavy oil viscosity reducer in the field of heavy oil viscosity reduction.

[0029] Preferably, the viscosity of the heavy oil is 500,000-600,000 mPa·s at 50°C.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) Existing viscosity reducers are complex to prepare and costly, and most are difficult to apply to viscosity reduction of extra-heavy oils and are difficult to use on a large scale. The coal tar by-product viscosity reducer of the present invention is widely available, low in cost, and has high viscosity reduction efficiency. It can be widely used in viscosity reduction during the extraction and transportation of extra-heavy oils.

[0032] (2) At present, most of the diluents are thin oils, which are expensive and require large dosages. The low-cost, high-efficiency thick oil viscosity reducer provided by this invention can reduce the viscosity of super-thick oil by more than 98% with a low dosage, requiring less diluent and having high viscosity reduction efficiency. Attached Figure Description

[0033] Figure 1 This is a full scan total ion chromatogram of the viscosity reducer in Example 2. Detailed Implementation

[0034] To make the technical means, creative features, achieved objectives, and effects of this invention readily understandable, the invention is further illustrated below with specific embodiments. However, these embodiments are merely preferred embodiments and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the scope of protection of this invention. It is worth noting that the raw materials used in this invention are all common commercially available products, and their sources are not specifically limited. The technical and scientific terms used in the embodiments have the meanings commonly understood by those skilled in the art to which this invention pertains.

[0035] Example 1

[0036] A viscosity reducer for extra-heavy oil is high-temperature coal tar, a product generated during the dry distillation of coal at 900-1000℃.

[0037] The viscosity reducer for extra-heavy oil provided in this embodiment accounts for 2-5 parts by mass of heavy oil. High-temperature coal tar is weighed according to the ratio and added to 1 part of heavy oil. After sealing the oil sample, it is kept at 80℃ for 2 hours, then taken out, mixed evenly, and naturally cooled to room temperature for later use. The viscosity reduction effect is shown in Table 1. The results show that after adding 5 parts of viscosity reducer to extra-heavy oil with a viscosity of 520-350 mPa·s at 50℃, the viscosity reduction rate is >99%, indicating that the viscosity reducer of this invention has excellent viscosity reduction effect on heavy oil.

[0038] Table 1. Viscosity-reducing effect of high-temperature coal tar on heavy oil

[0039]

[0040] Example 2

[0041] A viscosity reducer for extra-heavy oil is a byproduct of coal tar distillation at temperatures of 230-300℃. It comprises the following components: 31.82% monomethylnaphthalene, 12.76% dimethylnaphthalene, 16.39% acenaphthene, 12.58% fluorene oxide, 7.42% fluorene, and 19.03% other compounds, the total percentages of which are 100%.

[0042] The physical properties of the low-cost extra-heavy oil viscosity reducer of this invention are shown in Table 2. The viscosity is <10 mPa·s, the fluidity can be guaranteed at room temperature, the flash point is 67-75℃, and the storage and transportation safety is high.

[0043] Table 2. Physical properties of coal tar by-product distillate oils (distillation temperature 230-300℃)

[0044]

[0045]

[0046] The chemical composition of the low-cost coal tar by-product distillate oil of this invention was analyzed by gas chromatography-mass spectrometry (GC-MS), and the results are shown in the figure. Figure 1 See Table 3. A total of 32 components were detected in the coal tar by-product distillate oil. The most abundant components were naphthalene compounds, acenaphthene, and fluorene oxide, which are the main components of the coal tar by-product distillate oil. The main components are naphthalene compounds, with monomethylnaphthalene having the highest content at 31.82%, containing two isomers: 1-methylnaphthalene and 2-methylnaphthalene, with contents of 20.52% and 11.30%, respectively. Acenaphthene was the second most abundant at 16.39%. Dimethylnaphthalene was the third most abundant at 12.76%, containing four isomers: 1,7-dimethylnaphthalene, 1,8-dimethylnaphthalene, 1,5-dimethylnaphthalene, and 2,6-dimethylnaphthalene, with contents of 3.84%, 6.23%, 1.89%, and 0.80%, respectively. Fluorene oxide was the fourth most abundant at 12.58%.

[0047] Table 3. Results of Gas Chromatography-Mass Spectrometry (GC-MS) Analysis

[0048]

[0049]

[0050]

[0051]

[0052] The viscosity reducer for extra-heavy oil coal tar distillate provided in this embodiment accounts for 0.05-0.25 parts by weight of heavy oil. Coal tar distillate oil is weighed according to the proportion and added to 1 part of heavy oil. After sealing the oil sample, it is kept at 80℃ for 2 hours, then removed, mixed evenly, and allowed to cool naturally to room temperature for later use. The viscosity reduction effect is shown in Table 4. The results show that adding 5%-15% viscosity reducer to extra-heavy oil with a viscosity of 520-350 mPa·s at 50℃ results in a viscosity reduction rate >98%, indicating that the viscosity reducer of this invention has excellent viscosity reduction effect on heavy oil.

[0053] Table 4. Viscosity-reducing effect of coal tar by-product distillate oil on heavy oil in Example 2

[0054]

[0055] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A viscosity reducer for extra-heavy oils, characterized in that, The extra-heavy oil viscosity reducer is coal tar or a by-product of coal tar; the coal tar is selected from at least one of low-temperature coal tar, medium-temperature coal tar and high-temperature coal tar generated during the dry distillation of coal at 450-1000℃.

2. The extra-heavy oil viscosity reducer according to claim 1, characterized in that, The low-temperature coal tar is the coal tar produced during the dry distillation of coal at 450-650℃.

3. The extra-heavy oil viscosity reducer according to claim 1, characterized in that, The medium-temperature coal tar mentioned is the coal tar produced during the dry distillation of coal at 650-900℃.

4. The extra-heavy oil viscosity reducer according to claim 1, characterized in that, The high-temperature coal tar is the coal tar produced during the dry distillation of coal at 900-1000℃.

5. The extra-heavy oil viscosity reducer according to claim 1, characterized in that, The coal tar byproducts are selected from at least one of light oil, phenolic oil, naphthalene oil, wash oil, and anthracene oil.

6. The extra-heavy oil viscosity reducer according to claim 5, characterized in that, The light oil refers to the product of coal tar before its distillation temperature reaches 170°C.

7. The extra-heavy oil viscosity reducer according to claim 5, characterized in that, The phenolic oil refers to the product of coal tar at a distillation temperature of 170-210℃.

8. The extra-heavy oil viscosity reducer according to claim 5, characterized in that, The naphthalene oil refers to the product of coal tar at a distillation temperature of 210-230℃.

9. The extra-heavy oil viscosity reducer according to claim 5, characterized in that, The wash oil refers to the product of coal tar at a distillation temperature of 230-300℃.

10. The extra-heavy oil viscosity reducer according to claim 5, characterized in that, The anthracene oil refers to the product of coal tar at a distillation temperature of 280-360℃.

11. The extra-heavy oil viscosity reducer according to claim 1, characterized in that, The extra-heavy oil viscosity reducer comprises, by weight, the following components: 20-40 parts 1-methylnaphthalene, 5-20 parts 2-methylnaphthalene, 10-20 parts acenaphthene, 10-20 parts fluorene oxyfluorene, 5-15 parts fluorene, and 10-30 parts other compounds.

12. The extra-heavy oil viscosity reducer according to claim 11, characterized in that, The extra-heavy oil viscosity reducer comprises, by weight, the following components: 20-30 parts 1-methylnaphthalene, 5-15 parts 2-methylnaphthalene, 15-20 parts acenaphthene, 10-15 parts fluorene oxyfluorene, 5-10 parts fluorene and 10-25 parts other compounds.

13. The extra-heavy oil viscosity reducer according to claim 11, characterized in that, The other compounds are selected from at least one of indene, naphthalene, quinoline, isoquinoline, 6-methylquinoline, biphenyl, 2-ethylnaphthalene, 1,7-dimethylnaphthalene, 1,8-dimethylnaphthalene, 1,5-dimethylnaphthalene, 2,6-dimethylnaphthalene, 2-isopropylnaphthalene, 2-isopropylphenylnaphthalene, 2,3,5-trimethylnaphthalene, 2,3,6-trimethylnaphthalene, 2,4a-dihydrofluorene, 1,4-dihydrofluorene, 2-hydroxyfluorene, 9-fluorene alcohol, 4-isopropylbiphenyl, 1-methylfluorene, phenanthrene, L-ascorbyl palmitate, acenaphthene, 2-vinylnaphthalene, and (2,4-cyclopentadien-1-methylene)benzene.

14. The extra-heavy oil viscosity reducer according to claim 1, characterized in that, The mass ratio of the extra-heavy oil viscosity reducer to the heavy oil is 0.01-6:

1.

15. The extra-heavy oil viscosity reducer according to claim 14, characterized in that, The mass ratio of the extra-heavy oil viscosity reducer to the heavy oil is 0.05-5:

1.

16. The use of the extra-heavy oil viscosity reducer according to any one of claims 1-15 in the reduction of viscosity in heavy oil.

17. The application according to claim 16, characterized in that, The viscosity of the heavy oil is 500,000-600,000 mPa·s at 50°C.

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