Process for improving the flowability of heavy oils

Abstract

The present application provides a heavy oil flowability improving process. The heavy oil flowability improving process of the present application comprises the following steps: 1) performing first distillation cutting on heavy oil to obtain a first light oil fraction and a first heavy oil fraction; 2) performing a cracking reaction on the first heavy oil fraction with a supercritical solvent and a hydrogen donor to obtain a cracking product; and 3) mixing the cracking product and the first light oil fraction to obtain modified oil. The process not only has low cost, but also can improve the depth of viscosity-reducing cracking and ensure the stability of the oil product after viscosity-reducing cracking.

Description

Technical Field

[0001] This invention relates to the field of heavy oil processing technology, and in particular to a process for improving the fluidity of heavy oil. Background Technology

[0002] Currently, to improve the fluidity of heavy oil, it is typically subjected to thermal processing to improve its light point and viscosity, thereby enhancing its fluidity. The modified oil obtained after fluidity improvement can be used not only as feedstock for processes such as catalytic cracking or coking, but also for the production of fuel oil.

[0003] In existing heavy oil flowability improvement processes, the cracking products obtained after high-temperature cracking of heavy oil contain a significant amount of olefins. This necessitates not only distillation of the cracking products but also hydrogenation of the resulting fractions to remove olefins. However, hydrogen is expensive, hindering industrial application. Furthermore, existing heavy oil flowability improvement processes generally suffer from the difficulty of simultaneously achieving both viscosity reduction and improved oil stability.

[0004] Therefore, there is an urgent need to provide a heavy oil flow process that is low in cost and can both improve the depth of viscosity reduction cracking and ensure the stability of the oil products after viscosity reduction cracking. Summary of the Invention

[0005] This invention provides a process for improving the fluidity of heavy oil. This process is not only low in cost, but also increases the depth of viscosity reduction cracking and ensures the stability of the oil after viscosity reduction cracking.

[0006] This invention provides a process for improving the fluidity of heavy oil, comprising the following steps:

[0007] 1) The heavy oil is subjected to a first distillation to obtain a first light oil fraction and a first heavy oil fraction;

[0008] 2) The first heavy oil fraction is subjected to a cracking reaction with a supercritical solvent and a hydrogen donor to obtain cracking products;

[0009] 3) The cracking products and the first light oil fraction are mixed to obtain modified oil.

[0010] The heavy oil flowability improvement process described above, wherein step 2) further includes: subjecting the first heavy oil fraction to a cracking reaction with a supercritical solvent and a hydrogen donor to obtain a reaction product, and separating the reaction product to obtain the cracking product and a first regenerated solvent;

[0011] The first regenerated solvent is returned to participate in the cracking reaction.

[0012] The heavy oil flowability improvement process described above, wherein step 2) further includes post-treatment of the cracking products:

[0013] The post-processing includes a second distillation of the cracking products to obtain a second regenerated solvent, a second light oil fraction, and cracked heavy oil.

[0014] The second regenerated solvent is returned to participate in the cracking reaction.

[0015] The heavy oil flowability improvement process described above, wherein step 3) further includes: mixing the second light oil fraction, the cracked heavy oil and the first light oil fraction to obtain modified oil.

[0016] In the heavy oil flow improvement process described above, the hydrogen donor is selected from cycloalkyl aromatics.

[0017] In the heavy oil flowability improvement process described above, the mass ratio of the first heavy oil fraction, the hydrogen donor, and the supercritical solvent is 1:(0.001-0.1):(0.5-5).

[0018] In the heavy oil flowability improvement process described above, the feed temperature of the first heavy oil fraction is 40-150°C; and / or,

[0019] The feed temperature of the supercritical solvent is 10-40℃; and / or,

[0020] The feed temperature of the hydrogen-donating agent is 10-40℃.

[0021] The heavy oil flowability improvement process described above, wherein the supercritical solvent includes a first supercritical solvent and a second supercritical solvent, and the heavy oil flowability improvement process further includes:

[0022] The first heavy oil fraction, the first supercritical solvent, and the hydrogen donor are subjected to a first preheating treatment to obtain a first preheating system.

[0023] The second supercritical solvent is subjected to a second preheating treatment to obtain a second preheating system;

[0024] The first preheating system and the second preheating system are subjected to a cracking reaction;

[0025] Wherein, the temperature of the first preheating treatment is less than or equal to the temperature of the cracking reaction, and the temperature of the second preheating treatment is greater than the temperature of the cracking reaction.

[0026] In the heavy oil flowability improvement process described above, the temperature of the cracking reaction is 320-430°C; and / or,

[0027] The pressure of the cracking reaction is 6-15 MPa; and / or,

[0028] The cracking reaction takes 1-60 minutes.

[0029] In the heavy oil fluidity improvement process described above, the temperature of the first preheating treatment is less than or equal to 350°C; and / or,

[0030] The temperature of the second preheating treatment is 5-40°C higher than the temperature of the cracking reaction.

[0031] This invention provides a process for improving the fluidity of heavy oil by using a hydrogen donor in the cracking reaction. This process not only increases the depth of viscosity-reducing cracking but also yields modified oil with excellent stability. Furthermore, the improved process is simple, easy to operate, and can reduce production costs. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a spot diagram of the stability test of the modified oil in Example 1 of the present invention;

[0034] Figure 2 This is a spot diagram of the stability test of the modified oil in Example 2 of the present invention;

[0035] Figure 3 This is a spot diagram of the stability test of the modified oil in Example 3 of the present invention;

[0036] Figure 4 This is a spot diagram of the stability test of the modified oil in Comparative Example 1 of the present invention;

[0037] Figure 5 This is a spot diagram of the stability test of the modified oil in Comparative Example 2 of the present invention;

[0038] Figure 6 This is a spot diagram of the stability test of the modified oil in Comparative Example 3 of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0040] This invention discloses a process for improving the fluidity of heavy oil, comprising the following steps:

[0041] 1) The heavy oil is subjected to a first distillation to obtain a first light oil fraction and a first heavy oil fraction;

[0042] 2) The first heavy oil fraction is subjected to a cracking reaction with a supercritical solvent and a hydrogen donor to obtain cracking products;

[0043] 3) The cracking products and the first light oil fraction are mixed to obtain the modified oil.

[0044] The heavy oil flowability improvement process of the present invention specifically includes: performing a first distillation and splitting of the heavy oil into a first light oil fraction and a first heavy oil fraction; then, under the action of a hydrogen donor, using a supercritical solvent to cause the first heavy oil fraction to undergo a cracking reaction to obtain cracking products. Since the hydrogen donor can provide sufficient hydrogen atoms for the cracking reaction, it promotes the deep cracking of the first heavy fraction and can reduce the generation of olefins, thereby obtaining cracking products with excellent stability; the cracking products are mixed with the first light oil fraction to obtain the improved oil with improved flowability.

[0045] This invention does not specifically limit the type of heavy oil; the heavy oil can be any heavy crude oil commonly used in the art. In some embodiments, the heavy oil may be selected from at least one of paraffinic crude oil, intermediate-based crude oil, and naphthenic crude oil with a pour point above 30°C.

[0046] This invention does not limit the temperature of the first distillation cutting process, as long as it can cut the heavy oil into a first light oil fraction and a second light oil fraction. In some embodiments, the temperature of the first distillation cutting can be 200-540°C. This invention can also select the temperature of the first distillation cutting according to the type of heavy oil. For example, when the heavy oil is paraffinic crude oil with a pour point above 30°C, the temperature of the first distillation cutting is 350-540°C, and further, it can be 420-520°C; when the heavy oil is intermediate-based crude oil, the temperature of the first distillation cutting can be 280-540°C, and further, it can be 300-500°C; when the heavy oil is naphthenic crude oil, the temperature of the first distillation cutting can be 200-500°C, and further, it can be 200-450°C.

[0047] This invention does not impose particular limitations on the specific method of the first distillation cut; in some embodiments, the first distillation cut can be performed in a distillation column. This invention also does not impose particular limitations on the specific operation of the distillation column; conventional operations in the art can be employed.

[0048] In this invention, the pressure of the supercritical solvent exceeds its critical pressure, and the temperature of the supercritical solvent exceeds its critical temperature. This invention does not impose any particular limitation on the supercritical solvent; it can be any solvent commonly used in the art that is in a supercritical state. In some embodiments, the supercritical solvent can be a supercritical monocyclic cycloalkanes and / or a supercritical monocyclic aromatic hydrocarbon, wherein the monocyclic cycloalkanes can be selected from cyclopentane and / or cyclohexane, and the monocyclic aromatic hydrocarbons can be selected from at least one of benzene, toluene, and xylene.

[0049] The present invention does not impose any particular limitation on the hydrogen donor, and can select compounds commonly used in the art that can provide hydrogen atoms for the cracking reaction.

[0050] The heavy oil flowability improvement process of the present invention uses a hydrogen donor to participate in the cracking reaction. The hydrogen donor can provide sufficient hydrogen atoms for the cracking reaction, promote the cracking reaction, and reduce the generation of olefins. Therefore, it is beneficial to increase the depth of viscosity reduction cracking and to obtain modified oil with excellent stability. At the same time, the process of improving the heavy oil flowability is simple and easy to operate, which helps to reduce production costs.

[0051] In some embodiments of the present invention, step 2) further includes: subjecting the first heavy oil fraction to a cracking reaction with a supercritical solvent and a hydrogen donor to obtain a reaction product, and separating the reaction product to obtain a cracking product and a first regenerated solvent.

[0052] The first recycled solvent is returned to participate in the cracking reaction.

[0053] In this invention, after the first heavy oil fraction, supercritical solvent, and hydrogen donor undergo a cracking reaction, reaction products are obtained. These products can be separated to obtain the solvent, resulting in a first regenerated solvent. This first regenerated solvent can be returned to participate in the cracking reaction, facilitating solvent recycling and further reducing production costs. In some embodiments, the separation process can be flash evaporation, which can be carried out in a flash evaporator. This invention does not impose particular limitations on the operation of the flash evaporator and can be performed according to conventional practices in the art. In this invention, the separation temperature can be determined based on the boiling point of the solvent.

[0054] In some embodiments of the present invention, step 2) further includes post-treatment of the cracking products:

[0055] Post-processing includes a second distillation of the cracking products to obtain a second regenerated solvent, a second light oil fraction, and cracked heavy oil;

[0056] The second regenerated solvent is returned to participate in the cracking reaction.

[0057] In this invention, the cracking products can also be post-processed, specifically including a second distillation of the cracking products to obtain a second regenerated solvent, a second light oil fraction, and cracked heavy oil, respectively; wherein, the second regenerated solvent can be returned to participate in the cracking reaction, which helps to further realize the recycling of solvent and save production costs; and the second light oil fraction and cracked heavy oil can be mixed with the first light oil fraction to obtain modified oil.

[0058] In this invention, the second regenerated solvent may be the same as or different from the first regenerated solvent. The distillation cut-off temperature of the second regenerated solvent can be determined based on the difference between the content of the solvent required for the cracking reaction and the content of the first regenerated solvent. In specific operation, the second regenerated solvent and the first regenerated solvent can be mixed and the mixture can participate in the cracking reaction; alternatively, the first regenerated solvent and the second regenerated solvent can participate in the cracking reaction separately.

[0059] In this invention, the cut-off temperature for the second light oil fraction can be the initial boiling point (IBP) - 280°C. This invention can also subject the second light oil fraction to sedimentation treatment to further remove small amounts of unstable components (e.g., dienes) and further improve the stability of the modified oil. Sedimentation treatment may include: allowing the second light oil fraction to stand at room temperature for 4-10 days, followed by filtration to obtain the upper oil layer. Further, it may be allowed to stand for 5-7 days.

[0060] This invention can mix a first light oil fraction, cracked heavy oil, and a second light oil fraction after sedimentation treatment to obtain modified oil. By further performing a second cutting process on the cracking products, this invention not only separates the solvent from the cracking products to obtain a second regenerated solvent, but also separates the cracking products into a second light oil fraction and cracked heavy oil. These fractions can then be further processed according to their characteristics to ultimately obtain modified oil with excellent stability.

[0061] In this invention, the hydrogen donor can be further selected to improve the degree of reaction in the cracking reaction. In some embodiments of this invention, the hydrogen donor is selected from cycloalkyl aromatics. Further, the cycloalkyl aromatics can be at least one of tetrahydronaphthalene, decahydronaphthalene, and dihydroanthracene.

[0062] In this invention, the mass ratio of the first heavy oil fraction, the hydrogen donor, and the supercritical solvent can be specifically selected to improve the reaction efficiency of the cracking reaction and reduce the by-products of the cracking reaction while saving solvent and hydrogen donor. In some embodiments of this invention, the mass ratio of the first heavy oil fraction, the hydrogen donor, and the supercritical solvent is 1:(0.001-0.1):(0.5-5). Further, the mass ratio of the first heavy oil fraction to the supercritical solvent can be 1:(1-3), and the mass percentage of the hydrogen donor in the first heavy oil fraction can be 0.3-2%.

[0063] The present invention does not limit the feeding method of the first heavy oil fraction, supercritical solvent and hydrogen donor in the cracking reaction. The first heavy oil fraction, supercritical solvent and hydrogen donor can be fed separately; or any two can be mixed and fed, and the remaining one can be fed separately; or all three can be mixed and fed.

[0064] When the first heavy oil fraction, supercritical solvent, and hydrogen donor are fed separately, in order to improve the efficiency of the cracking reaction and reduce the by-products of the cracking reaction while saving energy, in some embodiments of the present invention, the feed temperature of the first heavy oil fraction is 40-150°C; and / or,

[0065] The feed temperature for supercritical solvents is 10-40℃; and / or,

[0066] The feed temperature of the hydrogen supply agent is 10-40℃.

[0067] Furthermore, the feed temperature of the first heavy oil fraction is 40-150℃, the feed temperature of the supercritical solvent can be room temperature, and the feed temperature of the hydrogen donor can be room temperature.

[0068] In this invention, supercritical solvents can also be classified, and the feed temperature of different supercritical solvents can be determined according to the progress of the cracking reaction. This invention does not limit the number of categories into which supercritical solvents can be classified.

[0069] In some embodiments of the present invention, the supercritical solvent may include a first supercritical solvent and a second supercritical solvent, and the heavy oil flowability improvement process further includes:

[0070] The first heavy oil fraction, the first supercritical solvent, and the hydrogen donor are subjected to a first preheating treatment to obtain a first preheating system.

[0071] A second preheating system is obtained by subjecting the second supercritical solvent to a second preheating treatment.

[0072] The first preheating system and the second preheating system are subjected to a cracking reaction;

[0073] The temperature of the first preheating treatment is less than or equal to the temperature of the cracking reaction, and the temperature of the second preheating treatment is greater than the temperature of the cracking reaction.

[0074] In this invention, the supercritical solvent can be divided into a first supercritical solvent and a second supercritical solvent. The invention mixes a first heavy oil fraction, a first supercritical solvent, and a hydrogen donor, and then subjects the mixture to a first preheating treatment to obtain a first preheating system. The temperature of the first preheating treatment can be less than or equal to the cracking reaction temperature. During the first preheating treatment, the first supercritical solvent can dilute the first heavy oil fraction, reducing the difficulty of transporting the first heavy oil fraction, thereby increasing the linear velocity of the first heavy oil fraction and reducing the risk of coking in the cracking reaction. The second supercritical solvent is then subjected to a second preheating treatment alone to obtain a second preheating system, and the temperature of the second preheating treatment is greater than the cracking reaction temperature. When the higher-temperature second preheating system and the lower-temperature first preheating system undergo a cracking reaction, the first heavy oil in the lower-temperature first preheating system is less likely to coke against the furnace wall, pipes, or reactor wall, which helps to extend the operating cycle of the reaction unit. Meanwhile, the higher-temperature second preheating system can promote the cracking reaction of the first heavy oil in the first preheating system, deepening the degree of the cracking reaction.

[0075] This invention allows for specific selection of the feed amounts of the first and second supercritical solvents to improve the degree of cracking reaction while reducing coking. For example, the feed mass of the first supercritical solvent can account for 5-50% of the mass of the first heavy oil fraction, and further, the feed mass of the first supercritical solvent can account for 10-30% of the mass of the first heavy oil fraction. The feed amount of the second supercritical solvent can be obtained by subtracting the feed amount of the first supercritical solvent from the total feed amount of the supercritical solvents.

[0076] The present invention can further select the temperatures of the first preheating treatment and the second preheating treatment in order to further reduce coking, improve the reaction efficiency of the cracking reaction, and reduce by-products. In some embodiments of the present invention, the temperature of the first preheating treatment is less than or equal to 350°C; and / or,

[0077] The temperature of the second preheating treatment is 5-40°C higher than the temperature of the cracking reaction.

[0078] Furthermore, the temperature of the first preheating treatment is 300-330℃.

[0079] It is understood that in this invention, the first regenerated solvent can be used as either a first supercritical solvent or a second supercritical solvent, and the second regenerated solvent can be used as either a first supercritical solvent or a second supercritical solvent.

[0080] This invention can further refine the specific process parameters of the cracking reaction to improve its efficiency and reduce byproducts while conserving energy. In some embodiments of this invention, the cracking reaction temperature is 320-430°C; and / or,

[0081] The pressure of the cracking reaction is 6-15 MPa; and / or,

[0082] The cracking reaction time is 1-60 min.

[0083] Furthermore, the temperature of the cracking reaction can be 380-420℃, the pressure can be 6-15MPa, and the time can be 1-30min.

[0084] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0085] Example 1

[0086] The heavy oil fluidity improvement process in this embodiment includes the following steps:

[0087] 1) Canadian oil sands bitumen (naphthenic oil) is introduced into a distillation column and subjected to first distillation at a temperature of 420°C to obtain a first light oil fraction (boiling point < 420°C) and a first heavy oil fraction (boiling point ≥ 420°C).

[0088] 2) The first heavy oil fraction is heated to 330°C, tetrahydronaphthalene is heated to 330°C, and cyclohexane is heated to 415°C at 10MPa. The heated first heavy oil fraction, cyclohexane, and tetrahydronaphthalene are sequentially introduced into the tubular cracking reactor from the bottom of the reactor for cracking reaction to obtain reaction products. The reaction products are then introduced into a flash tank for separation to obtain the first regenerated solvent (regenerated cyclohexane) and cracking products.

[0089] The mass ratio of the first heavy oil fraction to cyclohexane is 1:2.2, tetrahydronaphthalene accounts for 0.5% of the mass of the first heavy oil fraction, the cracking reaction temperature is 410℃, the pressure is 10MPa, and the time is 15min.

[0090] 3) The cracking products are introduced into a distillation column for a second distillation and splitting. The second regenerated solvent with a boiling point ≤81℃ and the second light oil fraction with a boiling point ≤280℃ are collected from the top of the distillation column, and the cracked heavy oil with a boiling point >280℃ is collected from the bottom of the column.

[0091] 4) The first regenerated solvent in step 2) and the second regenerated solvent in step 3) are returned to participate in the cracking reaction. The second light oil fraction is introduced into the settler for settling treatment. After standing at room temperature for 7 days, it is filtered. The second light oil fraction obtained after filtration is mixed with the cracked heavy oil and the first light oil fraction to obtain the modified oil.

[0092] Example 2

[0093] The heavy oil fluidity improvement process in this embodiment includes the following steps:

[0094] 1) Chad crude oil (paraffin-based crude oil with a pour point higher than 30°C) is introduced into a distillation column and subjected to first distillation at a temperature of 500°C to obtain the first light oil fraction (boiling point < 500°C) and the first heavy oil fraction (boiling point ≥ 500°C).

[0095] 2) The first heavy oil fraction is heated to 330°C, tetrahydronaphthalene is heated to 330°C, and benzene is heated to 433°C at 10MPa. The heated first heavy oil fraction, benzene, and tetrahydronaphthalene are sequentially introduced into the tubular cracking reactor from the bottom of the reactor for cracking reaction to obtain reaction products. The reaction products are then introduced into a flash tank for separation to obtain the first regenerated solvent (regenerated cyclohexane) and cracking products.

[0096] The mass ratio of the first heavy oil fraction to benzene is 1:2, tetrahydronaphthalene accounts for 1% of the mass of the first heavy oil fraction, the cracking reaction temperature is 425℃, the pressure is 10MPa, and the time is 10min.

[0097] 3) The cracking products are mixed with the first light oil fraction to obtain the modified oil.

[0098] Example 3

[0099] The heavy oil fluidity improvement process in this embodiment includes the following steps:

[0100] 1) Russian crude oil (intermediate base crude oil) is introduced into a distillation tower and subjected to first distillation at a temperature of 450°C to obtain the first light oil fraction (boiling point < 450°C) and the first heavy oil fraction (boiling point ≥ 450°C).

[0101] 2) The first heavy oil fraction is heated to 330°C, the decahydronaphthalene is heated to 330°C, and the cyclohexane is heated to 428°C at 10 MPa. The heated first heavy oil fraction, cyclohexane, and decahydronaphthalene are sequentially introduced into the tubular cracking reactor from the bottom of the reactor for cracking reaction to obtain reaction products. The reaction products are then introduced into a flash tank for separation to obtain the first regenerated solvent (regenerated cyclohexane) and cracking products.

[0102] The mass ratio of the first heavy oil fraction to cyclohexane is 1:3, the decahydronaphthalene accounts for 0.5% of the mass of the first heavy oil fraction, the cracking reaction temperature is 415℃, the pressure is 10MPa, and the time is 15min.

[0103] 3) The cracking products are introduced into a distillation column for a second distillation and splitting. The second regenerated solvent with a boiling point ≤81℃ and the second light oil fraction with a boiling point ≤280℃ are collected from the top of the distillation column, and the cracked heavy oil with a boiling point >280℃ is collected from the bottom of the column.

[0104] 4) The first regenerated solvent in step 2) and the second regenerated solvent in step 3) are returned to participate in the cracking reaction. The second light oil fraction is introduced into the settler for settling treatment. After standing at room temperature for 7 days, it is filtered. The second light oil fraction obtained after filtration is mixed with the cracked heavy oil and the first light oil fraction to obtain the modified oil.

[0105] Comparative Example 1

[0106] The process for improving the flowability of heavy oil in this comparative example is basically the same as that in Example 1, except that:

[0107] In step 2), tetrahydronaphthalene is not added.

[0108] Comparative Example 2

[0109] The process for improving the flowability of heavy oil in this comparative example is basically the same as that in Example 1, except that:

[0110] In step 2), cyclohexane is heated to 433°C at 0.6 MPa, and the pressure of the cracking reaction is 0.6 MPa (cyclohexane is not in a supercritical state).

[0111] Comparative Example 3

[0112] The process for improving the flowability of heavy oil in this comparative example is basically the same as that in Comparative Example 1, except that:

[0113] In step 3), the cracking products are introduced into a distillation column for a second distillation and splitting. The second regenerated solvent with a boiling point ≤81℃, the second light oil fraction with a boiling point ≤280℃, and the third light oil fraction with a boiling point ≤350℃ are collected from the top of the distillation column, and the cracked heavy oil with a boiling point >350℃ is collected from the bottom of the column.

[0114] Step 4) The second regenerated solvent from step 3) is returned to participate in the cracking reaction. The second light oil fraction is introduced into the settling tank for settling treatment and left to stand at room temperature for 7 days. After that, it is filtered. The second and third light oil fractions obtained after filtration are hydrogenated and then mixed with cracked heavy oil and the first light oil fraction to obtain the modified oil.

[0115] Performance testing

[0116] 1. Kinematic viscosity test

[0117] The kinematic viscosity of the first heavy oil fraction and cracking products obtained in the examples and comparative examples were tested according to the test method of GB / T 269. The test results are shown in Table 1.

[0118] The kinematic viscosity of the modified oils obtained in the examples and comparative examples was tested according to the test method of GB / T 269. The test results are shown in Table 2.

[0119] Table 1

[0120]

[0121] In Table 1, “——” indicates that the sample could not be measured at the test temperature because the viscosity was too high.

[0122] As can be seen from Table 1, the heavy oil flowability improvement process in the embodiments of the present invention can achieve a viscosity of less than 200 mPa·s at 50°C, which can meet the requirements for heavy oil transportation.

[0123] Table 2

[0124] <![CDATA[Viscosity at 50°C (mm 2 / s)]]> Example 1 70.9 Example 2 14.2 Example 3 87.2 Comparative Example 1 172.6 Comparative Example 2 201.5 Comparative Example 3 170.5

[0125] As can be seen from Table 2, the heavy oil fluidity improvement process in the embodiments of the present invention can obtain modified oil with lower viscosity.

[0126] 2. Stability Test

[0127] The stability of the modified oils obtained in the examples and comparative examples was tested according to the spot test specified in ASTM D4740-04 (2014). The stability rating criteria are as follows:

[0128] Grade 1: The spots are uniform and there are no ring-shaped structures inside;

[0129] Grade 2: The spots contain fine, indistinct ring-like structures;

[0130] Grade 3: The spots have obvious thin rings inside and are slightly darker than the original color;

[0131] Level 4: Contains more concentrated ring-like structures than Level 3, and is also slightly darker than the original color;

[0132] Level 5: The ring-shaped structures inside the spots are almost solid or nearly solid, and the center of the ring is much blacker than the background color.

[0133] Figure 1 This is a spot diagram of the stability test of the modified oil in Example 1 of the present invention; Figure 2 This is a spot diagram of the stability test of the modified oil in Example 2 of the present invention; Figure 3 This is a spot diagram of the stability test of the modified oil in Example 3 of the present invention; Figure 4This is a spot diagram of the stability test of the modified oil in Comparative Example 1 of the present invention; Figure 5 This is a spot diagram of the stability test of the modified oil in Comparative Example 2 of the present invention; Figure 6 This is a spot diagram showing the stability test results of the modified oil in Comparative Example 3 of this invention. From... Figure 1 and Figure 3 It can be seen that the spots in Examples 1 and 3 are uniform and have no internal ring-like structures, proving that the stability is level 1; from Figure 2 It can be seen that the spots in Example 2 are uniform, with fine ring-shaped structures inside, but no solid material precipitates, proving that the stability is between level 1 and level 2; from Figure 4 It can be seen that the spots in Comparative Example 1 have fine and blurry ring-shaped structures, with a darker color in the center, but no solid material precipitates, proving that the stability is level 2; from Figure 5 It can be seen that the spots in Comparative Example 2 have more concentrated rings, with solid substances precipitating out, and the color of the rings is also slightly darker than the original color of the spots, proving that the stability is level 3; from Figure 6 As can be seen, the spots in Comparative Example 3 have fine and blurry rings, with a darker color in the center, but no solid material precipitates out, proving that the stability is level 2.

[0134] It can be seen that the stability level of the modified oil in the embodiments of the present invention can be 1-2, which proves that the heavy oil fluidity improvement process of the present invention can obtain modified oil with excellent stability without hydrotreating.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for improving the fluidity of heavy oil, characterized in that, Includes the following steps: 1) The heavy oil is subjected to a first distillation to obtain a first light oil fraction and a first heavy oil fraction; 2) The first heavy oil fraction is subjected to a cracking reaction with a supercritical solvent and a hydrogen donor to obtain cracking products; 3) The cracking products and the first light oil fraction are mixed to obtain modified oil; The supercritical solvent includes a first supercritical solvent and a second supercritical solvent, and the heavy oil flowability improvement process further includes: The first heavy oil fraction, the first supercritical solvent, and the hydrogen donor are subjected to a first preheating treatment to obtain a first preheating system. The second supercritical solvent is subjected to a second preheating treatment to obtain a second preheating system; The first preheating system and the second preheating system are subjected to a cracking reaction; Wherein, the temperature of the first preheating treatment is less than or equal to the temperature of the cracking reaction, and the temperature of the second preheating treatment is greater than the temperature of the cracking reaction; The temperature of the first preheating treatment is less than or equal to 350°C; the temperature of the second preheating treatment is 5-40°C higher than the temperature of the cracking reaction.

2. The heavy oil fluidity improvement process according to claim 1, characterized in that, Step 2) further includes: subjecting the first heavy oil fraction to a cracking reaction with a supercritical solvent and a hydrogen donor to obtain a reaction product, and separating the reaction product to obtain the cracking product and the first regenerated solvent; The first regenerated solvent is returned to participate in the cracking reaction.

3. The heavy oil flowability improvement process according to claim 1 or 2, characterized in that, Step 2) also includes post-processing the cracking products: The post-processing includes a second distillation of the cracking products to obtain a second regenerated solvent, a second light oil fraction, and cracked heavy oil. The second regenerated solvent is returned to participate in the cracking reaction.

4. The heavy oil fluidity improvement process according to claim 3, characterized in that, Step 3) further includes: mixing the second light oil fraction, the cracked heavy oil, and the first light oil fraction to obtain modified oil.

5. The heavy oil flowability improvement process according to any one of claims 1-4, characterized in that, The hydrogen donor is selected from cycloalkyl aromatic hydrocarbons.

6. The heavy oil flowability improvement process according to any one of claims 1-5, characterized in that, The mass ratio of the first heavy oil fraction, the hydrogen donor, and the supercritical solvent is 1:(0.001-0.1):(0.5-5).

7. The heavy oil flowability improvement process according to any one of claims 1-6, characterized in that, The feed temperature of the first heavy oil fraction is 40-150℃; and / or, The feed temperature of the supercritical solvent is 10-40℃; and / or, The feed temperature of the hydrogen-donating agent is 10-40℃.

8. The heavy oil flowability improvement process according to any one of claims 1-7, characterized in that, The cracking reaction is carried out at a temperature of 320-430°C; and / or, The pressure of the cracking reaction is 6-15 MPa; and / or, The cracking reaction takes 1-60 minutes.

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