Production method of base oil for environment-friendly oil-based drilling fluid

Abstract

The invention discloses a production method of environment-friendly drilling fluid base oil, which comprises the following steps: (1) mixing hydrogenated diesel oil of paraffin base, intermediate base and naphthenic base fractions with hydrogen, and feeding into a sulfur trapping unit filled with a sulfur trapping catalyst; (2) further mixing the material flow distilled by the reaction of the sulfur capture catalyst with hydrogen / ammonia gas, and feeding the mixture into a paraffin transfer unit to carry out paraffin isomerization and chain scission; (3) further contacting the material flow distilled from the alkane transfer unit with a post-treatment catalysis unit; and (4) feeding the material flow distilled from the post-treatment catalysis unit into a fractionation unit to obtain the drilling fluid base oil with different viscosities, and circulating the unconverted tail oil at the tower bottom of the fractionation unit to the paraffin transfer unit and the post-treatment catalysis unit. According to the production method of the environment-friendly drilling fluid base oil, the limit range of the sulfur content of the hydrogenated diesel oil is reduced, and the production of the drilling fluid base oil with different aromatic hydrocarbon contents / paraffin contents is realized.

Description

Technical Field

[0001] The invention belongs to the field of petroleum refining and relates to a method for producing base oil for environmentally friendly oil-based drilling fluid. Background Art

[0002] Oil-based drilling fluid has the characteristics of strong inhibition, good lubrication performance, strong anti-pollution ability and good thermal stability. It can effectively inhibit the hydration expansion of shale and reduce the occurrence of complex situations such as well wall collapse. Therefore, it is widely used in the exploration and development of unconventional oil and gas wells such as shale gas wells, deep wells and ultra-deep wells.

[0003] With the increasing number of unconventional oil and gas wells and increasingly complex geological conditions, the application scope of oil-based drilling fluids is becoming wider and wider. Oil-based drilling fluids are mainly composed of base fluids, emulsifiers, fluid loss reducers, organic soils, etc., and base fluids account for about 70% of the cost of oil-based drilling fluids. The average single-well consumption of base fluids in shale gas horizontal wells is nearly 300 cubic meters; the average single-well consumption of deep wells in the Tarim Kuche piedmont / Junggar Basin is 880 cubic meters; the annual consumption of base fluids by the group company is 200,000 cubic meters, with a cost of more than 1.6 billion yuan.

[0004] At present, the domestic oil-based drilling fluid base oil is mainly diesel-based drilling fluid base oil and white oil-based drilling fluid base oil. The reference standards are mainly ("Automobile Diesel" (GB19147-2016), "Crude White Oil" (NB / SH / T 0914-2015), "Industrial White Oil" (NB / SH / T 0006-2017) and "Light White Oil" (NB / SH / T 0913-2015)). At present, diesel-based drilling fluid base oil is still used in areas where it is not mandatory. According to the GB 19147-2016 automotive diesel standard, the polycyclic aromatic hydrocarbon content is required to be ≯7wt%, and there is no restriction on the content of monocyclic aromatic hydrocarbons. However, the total aromatic content of diesel is currently about 15-20wt%, among which the high aromatic content greatly reduces its biodegradability, and its biological toxicity is toxic / slightly toxic; at the same time, the flash point of conventional 0# diesel is ≮60℃, and the flash point of -20# diesel is ≮-57℃, which is not conducive to the promotion of environmentally friendly oil-based drilling fluid base oil. Therefore, it is necessary to promote the development of low aromatic content oil-based drilling fluid base oil.

[0005] CN03147984.7 discloses a method for deep dearomatization of hydrocarbon oil, wherein the raw oil and hydrogen enter the hydrogenation reactor, contact with the hydrogenation dearomatization catalyst, and the logistics after the reaction are separated to obtain gas phase products and liquid phase products, wherein the gas phase products are compressed and recycled, and the liquid phase products are separated to obtain the target product of low aromatics, and the hydrogenation dearomatization catalyst uses VIII group noble metal as the active metal component, and one or more selected from zeolite, heat-resistant inorganic oxide, activated carbon, carbon fiber, and clay as the carrier. The process conditions of the method are moderate, the reaction pressure is medium and low pressure, the reaction temperature is low, the air velocity is high, the target product obtained has low aromatic content, the noble metal catalyst has high aromatic hydrogenation activity, and has good resistance to sulfur and nitrogen poisoning. The reaction system requires the use of noble metal catalysts, and the processed raw materials are sulfur-containing raw materials, and the sulfur content of the sulfur-containing raw materials is limited to ≯100ppm, which does not meet the conventional traditional hydrofining diesel raw materials.

[0006] CN107937024A discloses a method for producing high-quality light white oil from base oil, which comprises the following steps: the raw base oil is heated to a reaction temperature, fully mixed with hydrogen, and then enters a hydrogenation reactor carrying a catalyst I, and a hydrogenation refining reaction is carried out under the action of the hydrogenation refining catalyst I to remove most of the S, N and aromatic impurities in the raw base oil; the product after the reaction enters two reactors in series carrying catalysts II and III respectively, and contacts with catalysts II and III to carry out S removal and dearomatization reaction; the obtained reactants are separated into gas and liquid by high and low pressure separators, and then enter a fractionation system for fine cutting to obtain a variety of high-quality light white oil products of different grades. This technology can produce high-quality light white oil with good quality, high yield, short distillation range, high purity, low sulfur and low aromatics. However, this method has certain limitations on the pour point of the raw material and the pour point of the product, and cannot produce light white oil with ultra-low pour point, that is, white oil products with higher viscosity may not meet the light white oil (I) class standard. At the same time, it also has certain exclusivity for raw materials.

[0007] CN202010331191.5 also discloses a method for preparing a hydrodearomatization catalyst. Although the above process can obtain low aromatic white oil, it requires multiple catalysts to be graded for use.

[0008] CN116064144A uses paraffin-based, intermediate-based or cycloalkyl straight-run diesel as raw materials, and first performs hydrofining; the hydrofining effluent is stripped with medium-pressure hydrogen to remove impurities such as H2S and NH3 that affect the reduction catalyst, and then enters the supplementary refining-isomerization dewaxing-post-refining reaction zone to reduce the pour point and aromatic content of the oil product and improve the color. CN116064104A uses paraffin-based, intermediate-based or cycloalkyl straight-run diesel as raw materials, and first performs hydrofining / hydrodecondensation reaction; the hydrofining / hydrodecondensation effluent is stripped with medium-pressure hydrogen to remove impurities such as H2S and NH3 that affect the precious metal catalyst, and then enters the supplementary refining reaction zone to reduce the pour point and aromatic content of the oil product and improve the color. The above all report the use of medium-pressure hydrogen stripping towers to replace traditional high-fraction / low-fraction process routes.

[0009] CN116064150A discloses a method for producing light white oil and industrial white oil. In the presence of hydrogen, raw oil is contacted with a hydrotreating catalyst for hydrotreating to obtain a hydrotreating product; the raw oil contains a straight-run kerosene fraction and / or a straight-run diesel fraction; in the presence of hydrogen, the hydrotreating product is contacted with a hydrorefining catalyst for hydrorefining to obtain a hydrorefined oil; and the hydrorefined oil is separated. CN116064103A also discloses a method for producing light white oil and industrial white oil, which comprises: in the presence of hydrogen, bringing the raw oil into contact with a hydrotreating catalyst for hydrotreating to obtain a hydrotreating product; S2: bringing the hydrotreating product into contact with a hydrodecondensation catalyst in the presence of hydrogen to obtain a hydrodecondensation product; S3: bringing the hydrodecondensation product into contact with a hydrorefining catalyst in the presence of hydrogen to obtain a hydrorefining oil; S4: separating the hydrorefining oil;

[0010] Sun Guoquan, Sun Peng, Jin Jihai and others also reported methods for producing light white oil / industrial white oil from diesel raw materials or hydrogenated diesel. Both methods used high-pressure hydrogenation equipment for production. However, the sulfur content of diesel in the method reported by Sun Guoquan was 2.0 μg / g, and the sulfur content of the method reported by Jin Jihai was 1 μg / g (Modern Chemical Industry, 2023, 43(08):230-235; Contemporary Chemical Industry, 2022, 51(09):2216-2219; Petroleum Refining and Chemical Engineering, 2018, 49(12):71-75.).

[0011] CN115353906B discloses a method for producing base oil for drilling fluid, wherein paraffin-based crude oil is processed into distillate oil; the distillate oil is hydrorefined to obtain hydrorefined oil; the hydrorefined oil is simply fractionated, and then subjected to deep hydrogenation saturation treatment, and then subjected to precise fractionation after stripping to obtain light white oil for drilling fluid. This method uses atmospheric distillate oil of specific crude oil and light oil of lubricating oil unit as raw materials, and produces environmentally friendly products that meet green environmental protection requirements through further hydrorefining and precise fractionation treatment, but the paraffin-based raw materials may not meet the requirements when producing high-viscosity white oil due to the condensation point.

[0012] CN114410347A discloses a method for preparing low-aromatic transformer oil by medium-pressure hydrogenation of cycloalkyl distillate oil, comprising the following steps: a. After mixing cycloalkyl distillate oil raw material with hydrogen, the raw material enters a first hydrogenation reactor, and after being impurity-removed by a hydrogenation protective agent, the raw material first contacts with a pre-refined catalyst in an upper hydrogenation refining reaction zone to remove sulfur-containing and nitrogen-containing compounds and partially hydrogenate saturate aromatic hydrocarbons; and then contacts with a hydrogenation dearomatization catalyst in a lower deep dearomatization reaction zone to perform deep hydrogenation saturation of aromatic hydrocarbon compounds; b. Step a The effluent of step b directly enters the second hydrogenation reactor, contacts with the upper selective ring-opening catalyst, and performs the selective ring-opening reaction of polycyclic compounds; then passes through the middle isomerization decondensation reaction zone and contacts with the isomerization decondensation catalyst to perform the isomerization reaction of chain hydrocarbons or branched chains, and improves and optimizes the hydrocarbon composition distribution of the oil product; finally passes through the lower supplementary refining reaction zone to saturate a small amount of cracked olefins; c. After the effluent of step b is separated by gas and liquid, the liquid product enters the distillation tower for fraction separation to obtain transformer oil base oil product and light distillate oil by-product. However, the product obtained by this method is transformer base oil, and the aromatic content is about 10%.

[0013] In summary, the base oil for environmentally friendly mineral-based drilling fluid is mainly light white oil, and the sulfur content of hydrogenated diesel is controlled relatively low for the conversion of light white oil or heavy white oil with hydrogenated diesel, but the long-term stable operation of the catalyst and the poisoning of the downstream catalyst are not considered for the conversion of hydrogenated diesel with a relatively high sulfur content (>6μg / g). It is possible that the catalyst cannot be operated for a long period of time under high sulfur conditions.

[0014] At the same time, if the severity of the upstream hydrogenation unit is increased, if the reaction temperature is increased, it may cause the cycloalkanes produced by hydrogenation to reversely produce monocyclic aromatics and polycyclic aromatics under medium pressure conditions, increasing the load of downstream dearomatization; if the reaction space velocity is reduced, according to the restrictions on desulfurization efficiency and desulfurization content, the catalyst loading amount needs to be increased from 3.0 to 7.0 to reduce the sulfur content from 15μg / g to 0.1μg / g; if the sulfur content is reduced from 15μg / g to 0.1μg / g, the catalyst loading amount may increase by 30-40%. Therefore, it is necessary to develop a special process route for converting hydrogenated diesel to white oil in response to this situation. Summary of the invention

[0015] In order to solve the problem of catalyst poisoning in the process of converting high-sulfur hydrogenated diesel into light white oil or heavy white oil, meet the production of ultra-low aromatics and low freezing point white oil, and broaden the application of low freezing point white oil in other fields, the present invention develops a production method of environmentally friendly drilling fluid base oil based on existing process flow units and hydrocarbon reaction characteristics, reduces the restriction range of sulfur content in hydrogenated diesel, realizes the production of drilling fluid base oils with different aromatics content / paraffin content, and realizes the property regulation of the environmentally friendly drilling fluid base oil.

[0016] To achieve the above object, the present invention provides a method for producing an environmentally friendly drilling fluid base oil, comprising the following steps:

[0017] (1) Hydrogenated diesel of paraffinic, intermediate and naphthenic fractions is mixed with hydrogen and then enters a sulfur capture unit equipped with a sulfur capture catalyst;

[0018] (2) the stream distilled from the sulfur capture catalyst reaction is further mixed with hydrogen and enters the paraffin transfer unit for paraffin isomerization and chain scission;

[0019] (3) the stream distilled from the paraffin transfer unit is further contacted with a post-treatment catalytic unit;

[0020] (4) The distilled stream from the post-treatment catalytic unit enters the fractionation unit to obtain drilling fluid base oils of different viscosities. The unconverted tail oil at the bottom of the fractionation unit is circulated to the paraffin transfer unit and the post-treatment catalytic unit.

[0021] In the method of the present invention, the hydrogenated diesel can be hydrogenated modified diesel or hydrogenated refined diesel, the distillation range of the hydrogenated diesel is 180-360° C., and the sulfur content of the hydrogenated diesel is 5-100 μg / g.

[0022] In the method of the present invention, the operating temperature of the sulfur capture unit is room temperature to 300°C, the pressure is 1Mpa to 8Mpa, and the air velocity is 0.5 to 2.0h -1 The feeding method can be bottom feeding or top feeding.

[0023] In the method of the present invention, the sulfur capture unit is mainly used to remove trace sulfides in hydrogenated diesel, so that the distillate of the sulfur capture unit meets the requirement of sulfur content <6 μg / g or lower requirements, and protects the catalyst of the downstream paraffin transfer unit and the post-treatment catalyst unit. The sulfur capture catalyst of the sulfur capture unit mainly reacts by adsorption or hydrogen sacrificial agent to transfer trace sulfur, which is retained in the sulfur capture unit, and the sulfur capture unit is switched or regenerated according to the adsorption capacity or sacrificial capacity of the sulfur capture unit.

[0024] In the method of the present invention, the sulfur capture unit may be a plurality of units / reactors connected in series or in parallel.

[0025] In the method of the present invention, the active metal of the sulfur capture catalyst is at least one of metals of Group VIII, Group VIB, Group IB and Group IIB, and the carrier can be one or both of inert alumina and Y-type molecular sieve.

[0026] In the method of the present invention, the active metal of the sulfur capture catalyst is at least one of Ni, Mo, W, Zn, and Cu; the catalyst of the sulfur capture unit can be a commercial hydrogenation catalyst such as Ni-Mo / Al2O3, Ni-Mo-W / Al2O3, or a Ni / ZnO-Al2O3 catalyst with sulfur hydrogen decomposition-adsorption function, or a Cu+ modified Y-type molecular sieve. A catalyst with reaction adsorption desulfurization can meet the sulfur capture function. The sulfur capture catalyst also contains an additive P.

[0027] In the method of the present invention, the operating temperature of the paraffin transfer unit is 300-380°C, the pressure is 4-8Mpa, and the air velocity is 0.5-2.0h -1 , hydrogen-to-oil ratio 200-1000 v / v. In the paraffin transfer unit, the paraffins are mainly cracked or isomerized to achieve the decondensation of the hydrogenated diesel fraction.

[0028] In the method of the present invention, the paraffin transfer unit is equipped with a catalyst, the active metal of the catalyst is at least one of Pt, Ni, and Pd, and the acidic active component is at least one of ZSM-5, ZSM-22, ZSM-23, SAPO-11, and ZSM-48.

[0029] In the method of the present invention, the reaction pressure of the post-treatment catalytic unit is 4-8 MPa, the reaction temperature is 150-230°C, the hydrogen-oil ratio is 200-1000 v / v, and the space velocity is 0.5-1.5 h -1 The post-processing catalytic unit mainly realizes the hydrogenation saturation of aromatics under low temperature conditions, which is conducive to the forward reaction of aromatics. However, the reaction rate is limited under low temperature conditions. The post-processing catalytic unit should be adjusted in process and stability based on the aromatic content of the raw materials to ensure that the aromatic content of the product is qualified.

[0030] In the method of the present invention, the post-treatment catalytic unit is equipped with a post-treatment catalyst, the active metal of the post-treatment catalyst is at least one of Pt, Ni, and Pd, and the acidic active component is amorphous silicon aluminum and / or inert aluminum oxide.

[0031] In the method of the present invention, the aromatic content of the environmentally friendly drilling fluid base oil is less than 0.02wt%.

[0032] In the method of the present invention, the stream distilled from the post-treatment catalytic unit enters the fractionation unit to obtain drilling fluid base oils with different viscosities and flash points. The fractionation unit can be a rectification tower.

[0033] In order to ensure stable operation of the long-cycle catalyst and qualified products, the bottom product of the distillation unit can be partially recycled to the paraffin transfer unit or the post-treatment catalytic unit according to the freezing point and the aromatic content to further reduce the aromatic content or the product freezing point.

[0034] The method of the present invention solves the problems of sulfur poisoning and long-cycle operation of downstream catalysts in the process of producing light white oil or drilling fluid base oil from traditional high-sulfur hydrogenated diesel. Sulfide in the reaction system is deposited in the sulfur capture unit in the form of H2S under a hydrogen atmosphere or adsorbed in the sulfur capture unit in the form of sulfide, which can protect the downstream paraffin transfer unit and prevent catalyst poisoning. It is different from the H2S system disclosed in the traditional method, which uses a non-precious metal catalyst or a precious metal system under H2S stripping conditions. The unit using stripping to avoid sulfur pollution is omitted, which has obvious advantages over increasing the upstream severity and increasing the catalyst loading. It can realize the production of low aromatics and low-condensation point drilling fluid base oil from high-sulfur hydrogenated diesel under medium-pressure hydrogenation conditions. It has the advantage of low investment compared with the traditional high-pressure hydrogenation route, and at the same time broadens the source of raw materials. The present invention is based on the understanding of the reaction path of trace sulfur capture. The sulfur capture unit adopted in the present invention realizes the capture of trace sulfur, reduces the possibility of poisoning the catalyst in the downstream paraffin transfer unit and the post-treatment catalytic unit, and simultaneously adopts the highly selective paraffin conversion, cracking and isomerization functions of paraffins to realize the production of ultra-low freezing point light white oil / drilling fluid base oil. Through the regulation of the post-treatment high-activity catalyst, the step-by-step saturation of polycyclic aromatic hydrocarbons in the raw material is realized, and finally the production of low freezing point and low aromatic drilling fluid base oil / light white oil is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a production process flow chart of the environmentally friendly base oil for drilling fluid.

[0036] 1-mixture of hydrogenated diesel and hydrogen; 2-1: sulfur capture unit; 2-2: sulfur capture unit; 3: sulfur capture unit distillate stream; 4-paraffin transfer unit; 5: paraffin conversion distillate stream; 6-post-treatment catalytic unit; 7-post-treatment distillate stream; 8: gas-liquid separator; 9: hydrogen-containing mixed gas after gas-liquid separator; 10: compressed hydrogen; 11: liquid stream after gas-liquid separator; 12: light components at the top of fractionation tower: 13: drilling fluid base oil I; 14: drilling fluid base oil II; 15: drilling fluid base oil III; 16: stream from the bottom of the tower returned to the post-treatment tower; 17: stream from the bottom of the tower returned to the paraffin transfer unit; 18: feed stream of hydrogen and raw material mixture; 19: upper outlet stream of sulfur capture unit; 20: distillation tower.

[0037] Figure 2 This is a trend chart of the change in the aromatic content of the W4 product during the long-term operation period of Example 3.

[0038] Figure 3 This is a trend chart of the change in aromatic content of W4 product during the long-term operation period of Comparative Example 2. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with specific embodiments, but the present invention is not limited by the following embodiments. Any modification that does not exceed the concept and scope of the present invention is within the scope of the present invention.

[0040] The properties of the hydrogenated diesel feedstock used in the following examples are shown in Table 1.

[0041] Table 1 Basic properties of hydrogenated diesel

[0042] project Hydrogenated Diesel I Hydrogenated Diesel II Diesel Fuel <![CDATA[Density, kg / m 3 > 817.3 841.2 0.865 Distillation range, ℃ 180-315 180-360 180-360 Sulfur content, μg / g 20 50 8000 Nitrogen content, μg / g 5 10 325 Paraffin content, wt% 40 20 43 Aromatic content, wt% 16 20 42

[0043] Example 1

[0044] The properties of hydrogenated diesel are shown in Table 1. Hydrogenated diesel I is mixed with hydrogen and enters the sulfur capture unit from the top of the sulfur capture unit, and then mixed with hydrogen and contacted with the paraffin transfer unit and the post-treatment catalytic unit again. The basic process conditions are: the reaction temperature of the sulfur capture unit is 220 ° C, the catalyst is Ni-Mo-P / Al2O3, and the reaction space velocity is 1.0h -1 The reaction temperature of the paraffin transfer unit is 320°C, the catalyst is Ni / ZSM-5, and the reaction space velocity is 1.0h -1 The reaction temperature of the post-treatment catalytic unit is 200°C and the reaction space velocity is 1.5h -1, the catalyst is 0.5wt% Pt / Al2O3. The pressure of the sulfur capture unit, paraffin transfer unit, and post-treatment catalytic unit is 6Mpa, and the hydrogen-oil ratio is 200:1v / v. After the above series reaction, it enters the fractionation unit to obtain drilling fluid base oils of different viscosities. The product properties are shown in Table 2.

[0045] Table 2 Corresponding product properties of Example 1

[0046]

[0047]

[0048] Example 2

[0049] The properties of hydrogenated diesel are shown in Table 1: Hydrogenated diesel II and hydrogen are mixed and enter the sulfur capture unit from the top of the sulfur capture unit, and then contact the paraffin transfer unit and the post-treatment catalytic unit again. The basic process conditions are: the reaction temperature of the sulfur capture unit is 220 ° C, the catalyst is Ni-Mo-P / Al2O3, and the reaction space velocity is 0.5h -1 The reaction temperature of the paraffin transfer unit is 350°C, the catalyst is 0.5wt% Pt-0.2wt% Pd / ZSM-48, and the reaction space velocity is 2.0h -1 The reaction temperature of the post-treatment catalytic unit is 220°C and the reaction space velocity is 1.0h -1 , the catalyst is 0.5wt% Pd / SiO2-Al2O3. The pressure of the sulfur capture unit, paraffin transfer unit, and post-treatment catalytic unit is 8Mpa, and the hydrogen-oil ratio is 1000:1v / v. After the above series reaction, it enters the fractionation unit to obtain drilling fluid base oils of different viscosities. The product properties are shown in Table 3.

[0050] Table 3 Corresponding product properties of Example 2

[0051] project W1 W2 W3 W4 W5 <![CDATA[Density at 20 °C, kg / m 3 > 0.798 0.830 0.835 0.840 0.845 <![CDATA[Kinematic viscosity @ 40°C, mm 2 / s]]> 1.832 2.160 3.012 4.450 6.124 Distillation range, ℃ 185-215 215-245 245-280 280-360 330-360 Sulfur content, μg / g ＜1 ＜1 ＜1 ＜1 ＜1 Nitrogen content, μg / g ＜1 ＜1 ＜1 ＜1 ＜1 Aromatics, wt% 0.005 0.008 0.01 0.015 0.02 Pour point, ℃ ＜-55 ＜-55 -45 -40 -35

[0052] Comparative Example 1

[0053] The difference from Example 1 is that no sulfur capture unit treatment is performed.

[0054] The properties of hydrogenated diesel are shown in Table 1. Hydrogenated diesel I and hydrogen are mixed and directly enter the paraffin transfer unit and the post-treatment catalytic unit for contact. The basic process conditions are: the reaction temperature of the paraffin transfer unit is 320 ° C, the catalyst is Ni / ZSM-5, and the reaction space velocity is 1.0 h -1 The reaction temperature of the post-treatment catalytic unit is 200°C and the reaction space velocity is 1.5h -1The pressure of the paraffin transfer unit and the post-treatment catalytic unit is 6 MPa, and the hydrogen-to-oil ratio is 200:1 v / v. After the above series reaction, it enters the fractionation unit to obtain drilling fluid base oils with different viscosities. The product properties are shown in Table 4.

[0055] Table 4 Product properties corresponding to Comparative Example 1

[0056] project W1 W2 W3 W4 <![CDATA[Density at 20 °C, kg / m 3 > 0.789 0.816 0.825 0.830 <![CDATA[Kinematic viscosity @ 40°C, mm 2 / s]]> 1.635 1.957 2.902 4.205 Distillation range, ℃ 185-215 215-245 245-280 280-330 Sulfur content, μg / g ＜1 ＜1 ＜1 ＜1 Nitrogen content, μg / g ＜1 ＜1 ＜1 ＜1 Aromatics, wt% 0.010 0.015 0.020 0.025 Pour point, ℃ -55 -50 -40 -35

[0057] Through Example 1 and Comparative Example 1, it is found that the aromatic content of the product of Comparative Example 1 is higher than that of the product of Example 1. Since the sulfide produced during the hydrogenation of diesel fuel poisons the post-treatment catalytic unit, the hydrogenation activity is reduced, and thus the aromatic content is higher than that of the product of Example 1.

[0058] Example 3

[0059] The process conditions of this example are the same as those of Example 1, except that the catalyst is operated for 1000 h in this system, and the basic properties of the W4 product change with the reaction time as shown in the attached figure. Figure 2 As shown, the aromatic content of W4 product was stable after 1000 h of operation, basically maintained at around 0.015wt%.

[0060] Comparative Example 2

[0061] The process conditions of this comparative example are the same as those of comparative example 1, except that the catalyst is operated for 1000 h in this system, and the aromatic content of W4 product changes with reaction time as shown in the attached figure. Figure 3 As shown in the figure, the aromatic content of W4 product gradually increases after 1000h operation. At this time, the same effect can be achieved by increasing the temperature or reducing the space velocity.

[0062] Example 4

[0063] The properties of hydrogenated diesel are shown in Table 1. Hydrogenated diesel I and hydrogen are mixed and enter the sulfur capture unit from the top of the sulfur capture unit, and then contact the paraffin transfer unit and the post-treatment catalytic unit again. The basic process conditions are: the reaction temperature of the sulfur capture unit is 80 ° C, the catalyst is Cu ion exchange Y molecular sieve, and the reaction space velocity is 0.5h -1 , reaction temperature of paraffin transfer unit: 380℃, catalyst Pt-Pd / ZSM-23, reaction space velocity 2.0h -1 The reaction temperature of the post-treatment catalytic unit is 150°C and the reaction space velocity is 0.5h -1 , the catalyst is Ni / Al2O3. The pressure of the sulfur capture unit, paraffin transfer unit, and post-treatment catalytic unit is 4Mpa, and the hydrogen-oil ratio is 500:1v / v. After the above series reaction, it enters the fractionation unit to obtain drilling fluid base oils of different viscosities. The product properties are shown in Table 5.

[0064] Table 5 Product properties corresponding to Example 4

[0065] project W1 W2 W3 W4 <![CDATA[Density at 20 °C, kg / m 3 > 0.791 0.818 0.827 0.832 <![CDATA[Kinematic viscosity @ 40 °C, mm 2 / s]]> 1.635 1.957 2.897 4.202 Distillation range, ℃ 185-215 215-245 245-280 280-330 Sulfur content, μg / g ＜1 ＜1 ＜1 ＜1 Nitrogen content, μg / g ＜1 ＜1 ＜1 ＜1 Aromatics, wt% 0.01 0.01 0.01 0.015 Pour point, ℃ -55 -50 -40 -35

[0066] Comparative Example 3

[0067] The high sulfur mixed diesel in Table 1 was hydrotreated with a hydrogen pressure of 6 MPa, a reaction temperature of 370 °C, and a space velocity of 1.36 h -1 , hydrogen-to-oil ratio is 300, catalyst is Ni-Mo-P / Al2O3, under this process condition, the sulfur content of the product is 20μg / g, and the total aromatic content is 36wt%. After further increasing the reaction temperature to 390℃, the sulfur content of the product is 6μg / g, and the total aromatic content is 39wt%.

[0068] For the raw material source of this process condition, if the sulfur content is less than 6 μg / g, increasing the temperature can meet the sulfur content requirement, but the aromatic content will increase further, increasing the load of the downstream post-processing unit.

[0069] Example 5

[0070] The high sulfur mixed diesel in Table 1 was hydrotreated with a hydrogen pressure of 6 MPa, a reaction temperature of 370 °C, and a space velocity of 1.36 h -1 , the hydrogen-to-oil ratio is 300, the catalyst is Ni-Mo-P / Al2O3, the sulfur content of the product obtained under this process condition is 20μg / g, and the total aromatic content is 36wt%. The hydrogenated product further enters the sulfur capture unit, the reaction temperature of the sulfur capture unit is 60℃, the catalyst is Cu ion exchange Y type molecular sieve, and the reaction space velocity is 1.0h -1 The sulfur content of the product obtained was 3 μg / g and the total aromatic content was 36 wt%.

[0071] By comparing Example 5 with Comparative Example 3, it can be found that the high-sulfur diesel hydrogenation and sulfur capture unit can achieve a sulfur content that meets the feed requirements while the aromatics content remains substantially unchanged.

[0072] It is not difficult to find from the above examples and comparative examples that the present invention can process high-sulfur hydrogenated diesel to produce low-aromatic and low-freezing-point drilling fluid base oil, and can expand the low-freezing-point light white oil produced from diesel raw materials and can be applied in other fields.

[0073] Although the present invention has been disclosed as above by way of embodiments, they are not intended to limit the present invention. Any person with common knowledge in the technical field may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope defined by the attached claims.

Claims

1. A method for producing an environmentally friendly drilling fluid base oil, characterized in that: The following steps are involved: (1) Hydrogenated diesel of paraffinic, intermediate and cycloalkyl fractions is mixed with hydrogen and then enters a sulfur capture unit equipped with a sulfur capture catalyst; (2) the stream distilled from the sulfur capture catalyst reaction is further mixed with hydrogen and enters the paraffin transfer unit for paraffin isomerization and chain scission; (3) the stream distilled from the paraffin transfer unit is further contacted with a post-treatment catalytic unit; (4) The distilled stream from the post-treatment catalytic unit enters the fractionation unit to obtain drilling fluid base oils of different viscosities. The unconverted tail oil at the bottom of the fractionation unit is circulated to the paraffin transfer unit and the post-treatment catalytic unit.

2. The method according to claim 1, characterized in that The hydrogenated diesel is at least one of hydrogenated modified diesel and hydrogenated refined diesel; the distillation range of the hydrogenated diesel is 180-360° C., and the sulfur content of the hydrogenated diesel is 5-100 μg / g.

3. The method according to claim 1, characterized in that The operating temperature of the sulfur capture unit is room temperature to 300°C, the pressure is 1Mpa to 8Mpa, and the air velocity is 0.5 to 2.0h -1 .

4. The method according to claim 1, characterized in that The sulfur capture unit is a plurality of units / reactors connected in series or in parallel.

5. The method according to claim 1, characterized in that The active metal of the sulfur capture catalyst is at least one of metals of Group VIII, Group VIB, Group IB and Group IIB, and the carrier is one or both of inert alumina and Y-type molecular sieve.

6. The method according to claim 1, characterized in that The active metal of the sulfur capture catalyst is at least one of Ni, Mo, W, Zn and Cu; the sulfur capture catalyst also contains an additive P.

7. The method according to claim 1, characterized in that The operating temperature of the paraffin transfer unit is 300-380°C, the pressure is 4-8Mpa, and the air velocity is 0.5-2.0h -1 , hydrogen-to-oil ratio 200~1000v / v.

8. The method according to claim 1, characterized in that The paraffin transfer unit is equipped with a catalyst, the active metal of the catalyst is at least one of Pt, Ni, and Pd, and the acidic active component is at least one of ZSM-5, ZSM-22, ZSM-23, SAPO-11, and ZSM-48.

9. The method according to claim 1, characterized in that: The reaction pressure of the post-treatment catalytic unit is 4-8 MPa, the reaction temperature is 150-230°C, the hydrogen-oil ratio is 200-1000 v / v, and the space velocity is 0.5-1.5 h -1 .

10. The method according to claim 1, characterized in that The post-treatment catalytic unit is provided with a post-treatment catalyst, the active metal of the post-treatment catalyst is at least one of Pt, Ni and Pd, and the acidic active component is amorphous silicon aluminum and / or inert aluminum oxide.

11. The method according to claim 1, characterized in that: The aromatic content of the environmentally friendly drilling fluid base oil is less than 0.02 wt %.

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