Base oil for oil-based drilling fluid and preparation method thereof

Abstract

The invention discloses a preparation method of base oil for oil-based drilling fluid, which comprises the following steps: contacting mineral-based raw oil containing sulfur, nitrogen and aromatic hydrocarbon with a first non-noble metal catalyst in a first reaction zone and a second non-noble metal catalyst in a second reaction zone under hydrogenation conditions to obtain a full-fraction product, the base oil for the oil-based drilling fluid with the aromatic hydrocarbon content being less than or equal to 0.01 wt% and the condensation point being less than-20 DEG C is obtained through a gas-liquid separation unit, a steam stripping unit and a fractionation unit. The base oil for the oil-based drilling fluid has the advantages of lower aromatic hydrocarbon content, lower condensation point, higher biodegradability and lower biotoxicity.

Description

Technical Field

[0001] The invention belongs to the field of petroleum refining, and specifically relates to a base oil for oil-based drilling fluid and a preparation method thereof. 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 content of polycyclic aromatic hydrocarbons is required to be

[0005] ≯7wt%, and there is no limit on the content of monocyclic aromatics. However, the total aromatic content of diesel is currently about 15-20wt%, of 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 oils. Therefore, it is necessary to promote the development of low aromatic content oil-based drilling fluid base oils.

[0006] CN114836235A discloses a method for separating aromatics by coupling adsorption distillation of distillate oil, comprising one or more adsorption distillation towers, wherein the filler inside the adsorption distillation tower is an adsorption filler with aromatic separation capability, and continuous or intermittent separation of distillate oil aromatics is performed, the tower top is a non-aromatic product with low aromatic content, the tower bottom is an aromatic product with high aromatic content, and the obtained product is passed through an aromatic refining unit to obtain high-purity aromatic products and non-aromatic products. Although this technology can obtain a lower aromatic content, with 220-350°C middle distillate oil as raw material, the aromatic content of the non-aromatic component measured is about 6.8-7.6wt%, and the aromatic content is still relatively high, and this process requires a new adsorption separation unit.

[0007] CN103102942B discloses a method for treating deep dearomatization of diesel fractions, wherein the raw oil enters a supergravity reactor equipped with a non-precious metal catalyst, and is countercurrently contacted with hydrogen to carry out desulfurization, denitrogenation and partial aromatic saturation reaction, and then is deeply dearomatized in a fixed bed reactor equipped with a precious metal catalyst. The process can eliminate the stripping separation system in the two-stage process, and can greatly reduce the sulfur and aromatic content in the raw material. According to the embodiment, the aromatic content can be reduced from 36.2wt% to 6.2wt% under mild process conditions. Although the technology can effectively reduce polycyclic aromatic hydrocarbons and monocyclic aromatic hydrocarbons, the process introduces a supergravity reactor and a precious metal catalyst system, which is not conducive to large-scale promotion and application, and the aromatic content is still relatively high.

[0008] 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.

[0009] 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 restrictions on the pour point of the raw material and the pour point of the product, and cannot produce ultra-low pour point light white oil, that is, the white oil product with higher viscosity may not meet the light white oil (I) class standard, and it also has certain exclusivity for the raw material; in addition, the raw material base oil in this method needs to be sequentially catalyzed by three catalysts, which is costly and time-consuming.

[0010] 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.

[0011] CN116064144A uses paraffin-based, intermediate-based or cycloalkyl straight-run diesel as raw materials, and firstly conducts hydrofining; the hydrofining effluent is stripped by 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. The method of the present invention can obtain high-quality Class II industrial white oil, while producing a small amount of light white oil as a by-product, and greatly reduces the energy consumption caused by the two-stage method of boosting-depressurization-boosting, heating-cooling-heating. CN116064104A uses paraffin-based, intermediate-based or cycloalkyl straight-run diesel as raw materials, and first performs hydrofining / hydrodecondensation reaction; the effluent of the hydrofining / hydrodecondensation reaction is stripped by 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 reports the use of medium-pressure hydrogen stripping towers to replace the traditional high-fraction / low-fraction process route.

[0012] 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;

[0013] The above invention shows that the dearomatization of the catalyst can be achieved by adopting a cascade process route of hydrorefining-supplementary refining in two steps. The catalyst and reaction temperature need to be adjusted according to product requirements, and multiple catalysts need to be combined to achieve it.

[0014] 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. The present invention 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.

[0015] In summary, the blended diesel oil produced by the current refinery has a high aromatic content (15-20wt%), which does not meet the requirements of low toxicity and environmental performance of future drilling fluid base oils. At the same time, in order to produce ultra-low aromatic, low toxic and easily degradable drilling fluid base oil raw materials, distillate oil is mainly used as raw material for cascade hydrogenation, noble metal catalysts are used or ultra-gravity reactors are used, and the production of diesel oil with low aromatic content is achieved by regulating the reaction partition. However, the above process route has a high production cost and is difficult to achieve in the existing equipment of the refinery, so it is necessary to develop new low-cost low aromatic and low-condensation point drilling fluid base oil products and production processes. Summary of the invention

[0016] The technical problem to be solved by the present invention is to realize the production of a drilling fluid base oil with low aromatic content and low freezing point from a diesel-based oilfield drilling fluid base oil, which can have good biodegradability, reduce its biological toxicity, and reduce costs.

[0017] In order to solve the problem of high aromatic content (15-20wt%) in diesel produced from mineral oil fractions as raw materials, and to minimize its biological toxicity and difficult degradation performance in the application scenario of drilling fluid base oil, based on the characteristics of raw materials and oil-based drilling fluid base oil products and the reaction behavior characteristics in the hydrocarbon reaction conversion process, the present invention provides a low-aromatic diesel-based drilling fluid base oil and a preparation method thereof, which can effectively solve the problem of high aromatic content in traditional low- and medium-pressure production of diesel, and has obvious process route advantages over the reported two-stage method for producing low-aromatic oil-based drilling fluid base oil.

[0018] To achieve the above object, the present invention provides a method for preparing a base oil for oil-based drilling fluid, the preparation method comprising the following steps:

[0019] The mineral-based feedstock oil containing sulfur, nitrogen and aromatics is contacted with a first non-precious metal catalyst in a first reaction zone and a second non-precious metal catalyst in a second reaction zone under hydrogenation conditions to obtain a full-fraction product, and subjected to gas-liquid separation, steam stripping and fractionation units to obtain a base oil for oil-based drilling fluid having an aromatic content of ≤0.01wt% and a freezing point of <-20°C;

[0020] The mineral-based feedstock oil is mainly straight-run diesel with a distillation range of 180-350°C and a freezing point of -10°C to 30°C;

[0021] The active metal components of the second non-precious metal catalyst are one or two of Ni and Mg, the NiO content is 0.5-2.0wt%, the MgO content is 0-3.0wt%, and the carrier is one or two of ZSM-5 and beta and inert alumina or silicon oxide. In the preparation method of the base oil for oil-based drilling fluid of the present invention, preferably, the distillation range of the mineral-based raw oil is 210-320°C.

[0022] The method for preparing base oil for oil-based drilling fluid of the present invention comprises the following steps: the reaction pressure of the first reaction zone is 8-20 MPa, the reaction temperature is 280-370°C, the hydrogen-oil ratio is 300-2000 v / v, and the space velocity is 0.5-1.5 h -1 .

[0023] The method for preparing base oil for oil-based drilling fluid of the present invention comprises the following steps: the reaction pressure of the second reaction zone is 8-20 MPa, the reaction temperature is 320-380°C, the hydrogen-oil ratio is 300-2000 v / v, and the space velocity is 0.5-3 h -1 .

[0024] In the method for preparing base oil for oil-based drilling fluid of the present invention, the first non-precious metal catalyst is a hydrorefining catalyst, wherein the active metal components are Group VIII metals and Group VIB metals.

[0025] The method for preparing base oil for oil-based drilling fluid of the present invention comprises the following steps: the metal of group VIII is Ni and / or Co, the metal of group VIB is Mo and / or W, and the total content of active metal components is 30-80wt% calculated as their oxides.

[0026] In the method for preparing base oil for oil-based drilling fluid of the present invention, the carrier of the first non-precious metal catalyst is at least one of γ-Al2O3 and amorphous silicon aluminum.

[0027] In the method for preparing base oil for oil-based drilling fluid of the present invention, the first non-precious metal catalyst can be a bulk catalyst or a supported catalyst, and the metal type can be Ni-W or Ni-Mo, Co-Mo bimetallic, or Ni-Mo-W or Co-Mo-W, or Ni-W-Co-Mo.

[0028] In the method for preparing base oil for oil-based drilling fluid of the present invention, the first non-precious metal catalyst further contains one or two of Si, P, B and F.

[0029] It should be pointed out that the present invention aims to improve the dearomatization ability of the reaction system. The saturation of polycyclic aromatic hydrocarbons to monocyclic aromatic hydrocarbons and the production of monocyclic alkanes from monocyclic aromatic hydrocarbons can be achieved by regulating the metal active phase, regulating the acidity of the carrier and optimizing the process conditions. The metal active phase is regulated, and the Ni-Mo active phase, the Ni-W active phase and the Ni-Mo-W active phase are optimized. At the same time, the acidity of the catalyst is improved by doping acidic components such as Si, P, B and F to optimize the aromatic saturation ability.

[0030] The present invention also provides a base oil for oil-based drilling fluid, wherein the aromatic content is ≤0.01wt%, EC 50 Biological toxicity> 25000mg / L, 28-day degradability ≮ 60wt%, closed cup flash point ≮ 80℃, kinematic viscosity at 40℃ is 1.7-3.4mm 2 / s, product freezing point -20~-60℃.

[0031] The oil-based drilling fluid base oil of the present invention is fractionated to obtain a light low-aromatic oil-based drilling fluid base oil and a heavy low-aromatic drilling fluid base oil or a medium drilling fluid base oil.

[0032] The base oil for oil-based drilling fluid of the present invention has a kinematic viscosity of 1.7-2 mm at 40°C. 2 / s, the heavy low aromatic drilling fluid base oil has a kinematic viscosity of 2.5-3.0 mm at 40°C 2 / s, the kinematic viscosity of the medium drilling fluid base oil at 40°C is 2.2-2.8 mm 2 / s.

[0033] Compared with the diesel-based oil-based drilling fluid base oil produced by the traditional diesel hydrofining device, the base oil for oil-based drilling fluid obtained by the preparation method of the present invention has a lower aromatic content (0.01wt%), which is significantly better than the diesel (polycyclic aromatic hydrocarbon content ≯7wt%) specified in the current GB 17147-2016 standard, and has higher biodegradability and lower biological toxicity. The present invention fully combines the two aspects of aromatic reaction kinetics and thermodynamics for comprehensive consideration. In the traditional diesel hydrofining device, a low hydrogen-to-oil ratio and low pressure conditions are often used for reaction. With the increase of temperature, the conversion rate of polycyclic aromatic hydrocarbons reaches a certain level, and the conversion rate of monocyclic aromatic hydrocarbons is further increased with the increase of temperature. However, with the continued increase of temperature, the total aromatic hydrocarbon conversion rate decreases, mainly because the high temperature condition exceeds the thermodynamic equilibrium, further inhibiting the saturation of aromatic hydrocarbons, and under the conditions of high pressure and high hydrogen-to-oil ratio, according to the thermodynamic equilibrium, the reaction can be moved in the direction of aromatic hydrocarbon saturation, and the thermodynamic equilibrium point is pushed toward the high temperature direction, and the aromatic hydrocarbon saturation efficiency is further improved under certain temperature and pressure conditions, and the high pressure condition is also conducive to the saturation of monocyclic aromatic hydrocarbons.

[0034] The preparation method of the present invention only needs to react with the first non-precious metal catalyst and the second non-precious metal catalyst to obtain the base oil for oil-based drilling fluid with lower aromatic content and lower pour point, and does not need to be subjected to the third catalysis, thereby reducing the production cost, and can produce the base oil for drilling fluid that can be used in the western region / eastern region in winter. In addition, the catalysts of the preparation method of the present invention all use non-precious metals as active metals, the active metal components of the second non-precious metal catalyst use Ni and Mg, and the acidic isomerization cracking component is used as a pour point reducing carrier, which can effectively reduce the pour point of the raw material and expand the application range of the product. DETAILED DESCRIPTION

[0035] 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.

[0036] Table 1 Properties of straight-run diesel

[0037]

[0038]

[0039] Embodiment 1:

[0040] Straight-run diesel A was used as the raw material, and the raw material properties were shown in Table 1. The raw material was contacted with the first non-precious metal catalyst in the first reaction zone and the second non-precious metal catalyst in the second reaction zone under hydrogenation conditions; the reaction pressure in the first reaction zone was 18 MPa, the reaction temperature was 300°C, the hydrogen-to-oil ratio was (v / v) 1000, and the space velocity was 1.2 h-1 The reaction pressure of the second reaction zone is 18Mpa, the reaction temperature is 320°C, the hydrogen-to-oil ratio is (v / v) 1000, and the space velocity is 1.2h -1 The first non-precious metal catalyst is a supported Ni-Mo-P / Al2O3 catalyst, wherein the Ni content is 5wt% and the Mo content is 25wt%; the second non-precious metal catalyst is a Ni-Mg-ZSM-5 / Al2O3 catalyst, wherein the Ni content is 1.2wt% and the Mg content is 2.0wt%; the reaction obtains a full fraction product, and after gas-liquid separation, stripping and fractionation units, the obtained fraction is a base oil for oil-based drilling fluid, with a flash point of 90°C and a kinematic viscosity of 2.42mm at 40°C. 2 / s, total aromatic content 0.01wt%, product freezing point -25℃, EC value obtained by testing according to Q / SY 111-2007 "Classification and Detection Methods of Biological Toxicity of Oilfield Chemicals and Drilling Fluids" 50 =45000mg / L, 28-day degradability 68wt%.

[0041] Comparative Example 1:

[0042] The difference from Example 1 is that the reaction pressure of the first reaction zone and the second reaction zone is 4 MPa.

[0043] Straight-run diesel A was used as a raw material, and the properties of the raw material were shown in Table 1. The raw material was contacted with the first non-precious metal catalyst in the first reaction zone and the second non-precious metal catalyst in the second reaction zone under hydrogenation conditions; the reaction pressure in the first reaction zone was 4 MPa, the reaction temperature was 300°C, the hydrogen-to-oil ratio was (v / v) 1000, and the space velocity was 1.2 h -1 The reaction pressure of the second reaction zone is 4Mpa, the reaction temperature is 320°C, the hydrogen-to-oil ratio is (v / v) 1000, and the space velocity is 1.2h -1 The first non-precious metal catalyst is a supported Ni-Mo-P / Al2O3 catalyst, wherein the Ni content is 5wt% and the Mo content is 25wt%; the second non-precious metal catalyst is a Ni-Mg-ZSM-5 / Al2O3 catalyst, wherein the Ni content is 1.2wt% and the Mg content is 2.0wt%; the reaction obtains a full fraction product, and after gas-liquid separation, stripping and fractionation units, the obtained fraction is a base oil for oil-based drilling fluid, with a flash point of 90°C and a kinematic viscosity of 2.52mm at 40°C. 2 / s, total aromatic content 15.9wt%, product freezing point -20℃. EC 50 =4000mg / L, 28-day degradability 15wt%.

[0044] Embodiment 2:

[0045] Straight-run diesel B was used as the raw material, and the raw material properties were shown in Table 1. The raw material was contacted with the first non-precious metal catalyst in the first reaction zone and the second non-precious metal catalyst in the second reaction zone under hydrogenation conditions; the reaction pressure in the first reaction zone was 20 MPa, the reaction temperature was 330°C, the hydrogen-to-oil ratio was (v / v) 1300, and the space velocity was 1.5 h -1 The reaction pressure of the second reaction zone is 20 MPa, the reaction temperature is 340°C, the hydrogen-to-oil ratio is (v / v) 1300, and the space velocity is 3.0 h -1 ; The first non-precious metal catalyst is a Ni-Mo-W / P-Al2O3 non-loaded catalyst, wherein the Ni content is 5wt%, the Mo content is 20wt%, and the W content is 5wt%; the second non-precious metal catalyst is a Ni-Mg-beta-ZSM-5 / Al2O3 catalyst, wherein the Ni content is 0.8wt%, and the Mg content is 1.5wt%; the reaction obtains a full fraction product, and after gas-liquid separation, stripping and fractionation units, the obtained fraction is a base oil for oil-based drilling fluid, with a flash point of 93°C and a kinematic viscosity of 3.01mm at 40°C. 2 / s, total aromatic content 0.01wt%. The freezing point is -30℃. EC values ​​obtained by testing according to Q / SY111-2007 "Classification and Detection Methods of Biological Toxicity of Oilfield Chemicals and Drilling Fluids" 50 =48000mg / L, 28-day degradability 70wt%.

[0046] Embodiment 3:

[0047] Straight-run diesel A was used as a raw material, and the raw material properties were shown in Table 1. The raw material was contacted with a first non-precious metal catalyst in the first reaction zone and a second non-precious metal catalyst in the second reaction zone under hydrogenation conditions; the reaction pressure in the first reaction zone was 20 MPa, the reaction temperature was 370°C, the hydrogen-to-oil ratio was (v / v) 600, and the space velocity was 1.2 h -1 The reaction pressure of the second reaction zone is 20 MPa, the reaction temperature is 370°C, the hydrogen-to-oil ratio is (v / v) 600, and the space velocity is 2.0 h -1 ; The first non-precious metal catalyst is a Ni-Mo-W / P-Al2O3 non-supported catalyst, wherein the Ni content is 5wt%, the Mo content is 18wt%, and the W content is 7wt%; the second non-precious metal catalyst is a Ni-Mg-beta-ZSM-5 / Al2O3 catalyst, wherein the Ni content is 1.0wt%, and the Mg content is 1.0wt%; the reaction obtains a full fraction product, and after gas-liquid separation, stripping and fractionation units, the obtained fraction is a base oil for oil-based drilling fluid, with a flash point of 90°C and a kinematic viscosity of 2.38mm at 40°C. 2 / s, total aromatic content 0.01wt%, freezing point -45℃. EC values ​​obtained by testing according to Q / SY 111-2007 "Classification and Detection Methods of Biological Toxicity of Oilfield Chemicals and Drilling Fluids" 50 =44000mg / L, 28-day degradability 66wt%.

[0048] Comparative Example 2:

[0049] The difference from Example 2 is that the reaction pressure of the first reaction zone and the second reaction zone is 5 MPa.

[0050] Straight-run diesel B was used as the raw material, and the properties of the raw material were shown in Table 1. The raw material was contacted with the first non-precious metal catalyst in the first reaction zone and the second non-precious metal catalyst in the second reaction zone under hydrogenation conditions; the reaction pressure in the first reaction zone was 5 MPa, the reaction temperature was 330°C, the hydrogen-to-oil ratio was (v / v) 1300, and the space velocity was 1.5 h -1 The reaction pressure of the second reaction zone is 5 MPa, the reaction temperature is 340°C, the hydrogen-to-oil ratio is (v / v) 1300, and the space velocity is 3.0 h -1 ; The first non-precious metal catalyst is a Ni-Mo-W / P-Al2O3 non-loaded catalyst, wherein the Ni content is 5wt%, the Mo content is 18wt%, and the W content is 7wt%; the second non-precious metal catalyst is a Ni-Mg-beta-ZSM-5 / Al2O3 catalyst, wherein the Ni content is 1.0wt%, and the Mg content is 1.0wt%; the reaction obtains a full fraction product, and after gas-liquid separation, stripping and fractionation units, the obtained fraction is a base oil for oil-based drilling fluid, with a flash point of 93°C and a kinematic viscosity of 3.07mm at 40°C. 2 / s, total aromatic content 23wt%, product freezing point -25℃. EC tested according to Q / SY 111-2007 "Classification and Detection Methods of Biological Toxicity of Oilfield Chemicals and Drilling Fluids" 50 =3500mg / L, 28-day degradability 13wt%.

[0051] Comparative Example 3:

[0052] The difference from Example 3 is that no catalyst is added to the second reaction zone.

[0053] Straight-run diesel A is used as a raw material, and the properties of the raw material are shown in Table 1. It is contacted with the first non-precious metal catalyst in the first reaction zone under hydrogenation conditions; the reaction pressure in the first reaction zone is 20 MPa, the reaction temperature is 370°C, the hydrogen-to-oil ratio is (v / v) 600, and the space velocity is 1.2 h -1 The reaction pressure of the second reaction zone is 20 MPa, the reaction temperature is 370°C, the hydrogen-to-oil ratio is (v / v) 600, and the space velocity is 2.0 h -1The first non-precious metal catalyst is a Ni-Mo-W / P-Al2O3 non-supported catalyst, wherein the Ni content is 5wt%, the Mo content is 18wt%, and the W content is 7wt%; the reaction obtains a full fraction product, and after gas-liquid separation, stripping and fractionation units, the obtained fraction is a base oil for oil-based drilling fluid, with a flash point of 94°C and a kinematic viscosity of 3.10mm at 40°C. 2 / s, total aromatic content 0.01wt%, product freezing point -10°C. EC50 = 40000mg / L tested according to Q / SY 111-2007 "Classification and Detection Methods of Biological Toxicity of Oilfield Chemicals and Drilling Fluids", 28-day degradability 63wt%.

[0054] Comparative Example 4:

[0055] The density of commercially available 0# diesel at 20℃ is 0.82488g / cm 3 , 40℃ kinematic viscosity is 2.56mm 2 / s, the total aromatic content is 15.1wt%, of which the monocyclic aromatic content is 12.8wt%, and the polycyclic aromatic content is 2.3wt%. The EC 50 =3000mg / L, 28-day degradability 20wt%.

[0056] Embodiment 4:

[0057] Straight-run diesel A was used as a raw material, and the properties of the raw material were shown in Table 1. The raw material was contacted with the first non-precious metal catalyst in the first reaction zone and the second non-precious metal catalyst in the second reaction zone under hydrogenation conditions; the reaction pressure in the first reaction zone was 12 MPa, the reaction temperature was 300°C, the hydrogen-to-oil ratio was (v / v) 1000, and the space velocity was 0.5 h -1 The reaction pressure of the second reaction zone is 12Mpa, the reaction temperature is 300°C, the hydrogen-oil ratio is (v / v) 1000, and the space velocity is 0.5h -1; The first non-precious metal catalyst is a combination of a supported Ni-Mo-P / Al2O3 catalyst and a Ni-Mo-W supported catalyst, the catalyst loading ratio is 1:1, the Ni content in the non-supported Ni-Mo-W supported catalyst is 40wt%, the Mo content is 20wt%, and the W content is 10wt%, the Ni content in the Ni-Mo-P / Al2O3 catalyst is 5wt%, the Mo content is 18wt%, and the W content is 7wt%; the second non-precious metal catalyst is a Ni-Mg-ZSM-5 / Al2O3 catalyst, wherein the Ni content is 1.0wt%, and the Mg content is 1.2wt%; the reaction obtains a full-fraction product, and after full-fraction gas-liquid separation, stripping and fractionation units, the obtained fraction is a base oil for oil-based drilling fluid, with a flash point of 90°C and a kinematic viscosity of 2.43mm at 40°C. 2 / s, total aromatic content 0.01wt%. EC tested according to Q / SY 111-2007 "Classification and Detection Methods of Biological Toxicity of Oilfield Chemicals and Drilling Fluids" 50 =44000mg / L, 28-day degradability 73wt%.

[0058] Embodiment 5:

[0059] Straight-run diesel B was used as the raw material, and the raw material properties were shown in Table 1. The raw material was contacted with the first non-precious metal catalyst in the first reaction zone and the second non-precious metal catalyst in the second reaction zone under hydrogenation conditions; the reaction pressure in the first reaction zone was 16 MPa, the reaction temperature was 340°C, the hydrogen-to-oil ratio was (v / v) 600, and the space velocity was 1.5 h -1 The reaction pressure of the second reaction zone is 16Mpa, the reaction temperature is 340°C, the hydrogen-to-oil ratio is (v / v) 600, and the space velocity is 1.5h -1 ; The first non-precious metal catalyst is a combination of Ni-Mo / P-Al2O3 and Ni-Mo-W non-loaded catalyst, the upper part is Ni-Mo / P-Al2O3, the lower part is Ni-Mo-W non-loaded catalyst, the catalyst ratio is 1:3, the Ni content in Ni-Mo / P-Al2O3 is 5wt%, the Mo content is 25wt%, the Ni content in Ni-Mo-W is 40wt%, the Mo content is 20wt%, and the W content is 10wt%; the second non-precious metal catalyst is Ni-Mg-ZSM-5 / SiO2 catalyst, wherein the Ni content is 1.0wt%, and the Mg content is 2.5wt%; the reaction obtains a full-fraction product, and after gas-liquid separation, stripping and fractionation units, the obtained base oil for oil-based drilling fluid has a flash point of 93°C and a kinematic viscosity of 2.98mm at 40°C. 2 / s, total aromatic content 0.01wt%, freezing point -40℃. EC values ​​obtained by testing according to Q / SY 111-2007 "Classification and Detection Methods of Biological Toxicity of Oilfield Chemicals and Drilling Fluids" 50=43800mg / L, 28-day degradability 68wt%.

[0060] Embodiment 6:

[0061] Straight-run diesel A was used as a raw material, and the properties of the raw material were shown in Table 1. The raw material was contacted with a first non-precious metal catalyst in the first reaction zone and a second non-precious metal catalyst in the second reaction zone under hydrogenation conditions; the reaction pressure in the first reaction zone was 17 MPa, the reaction temperature was 350°C, the hydrogen-to-oil ratio was (v / v) 1000, and the space velocity was 1.2 h -1 The reaction pressure of the second reaction zone is 17 MPa, the reaction temperature is 350°C, the hydrogen-to-oil ratio is (v / v) 1000, and the space velocity is 1.2 h -1 ; The first non-precious metal catalyst is Ni-Mo-W / P-Al2O3 catalyst, wherein the Ni content is 5wt%, the Mo content is 18wt%, and the W content is 7wt%; the second non-precious metal catalyst is Ni-Mg-ZSM-5 / Al2O3 catalyst, wherein the Ni content is 0.5wt%, and the Mg content is 0.5wt%; the reaction obtains a full-fraction product, and after gas-liquid separation, stripping and fractionation units, a light low-aromatic oil-based drilling fluid base oil and a heavy low-aromatic drilling fluid base oil are obtained, wherein the light low-aromatic drilling fluid base oil has a kinematic viscosity of 1.7mm at 40°C. 2 / s, flash point is 95℃, total aromatic content is 0.01wt%, product solidification point is -50℃, heavy low aromatic drilling fluid base oil has a kinematic viscosity of 2.5mm at 40℃ 2 / s, flash point is 110℃, total aromatic content is 0.01wt%, product freezing point is -35℃, and 28-day degradability is 65wt%.

[0062] Embodiment 7:

[0063] Straight-run diesel B was used as the raw material, and the raw material properties were shown in Table 1. The raw material was contacted with the first non-precious metal catalyst in the first reaction zone and the second non-precious metal catalyst in the second reaction zone under hydrogenation conditions; the reaction pressure in the first reaction zone was 17 MPa, the reaction temperature was 350°C, the hydrogen-to-oil ratio was (v / v) 1000, and the space velocity was 0.8 h -1 The reaction pressure of the second reaction zone is 17 MPa, the reaction temperature is 350°C, the hydrogen-to-oil ratio is (v / v) 1000, and the space velocity is 0.8 h -1; The first non-precious metal catalyst is Ni-Mo-WP / Al2O3 catalyst, wherein the Ni content is 5wt%, the Mo content is 18wt%, and the W content is 7wt%; the second non-precious metal catalyst is Ni-ZSM-5 / SiO2 catalyst, wherein the Ni content is 0.8wt%; the reaction obtains a full-fraction product, and after gas-liquid separation, stripping and fractionation units, a light low-aromatic oil-based drilling fluid base oil and a heavy low-aromatic drilling fluid base oil are obtained, and three drilling fluid base oils are obtained after fractionation, wherein the light low-aromatic drilling fluid base oil has a kinematic viscosity of 1.9mm at 40°C 2 / s, flash point is 85℃, aromatic content is 0.01wt%, freezing point is -55℃, medium-low aromatic drilling fluid base oil has a kinematic viscosity of 2.4mm at 40℃ 2 / s, aromatic content 0.01%, freezing point -40℃, flash point 95℃, heavy low aromatic drilling fluid base oil 40℃ kinematic viscosity 2.9mm 2 / s, flash point is 110℃, total aromatic content is 0.01wt%, freezing point is -35℃, and 28-day degradability is 67wt%.

[0064] Embodiment 8:

[0065] The drilling fluid was prepared using the base oil for oil-based drilling fluid obtained in Example 1 as a raw material. The drilling fluid formula was: 240 mL base oil + 8 wt% shear emulsifier + 2.5 wt% organic soil + 60 mL 20 wt% CaCl2 aqueous solution + 2 wt% CaO + 4 wt% fluid loss reducer (12 g) + 650 g barite. The obtained drilling fluid was heated to 65 °C. The reading is 107 after aging at 180℃ The reading was 97, and the high temperature and high pressure filtration loss was 1.6 mL.

[0066] Comparative Example 5:

[0067] The drilling fluid was prepared using the base oil obtained in Comparative Example 1 as a raw material. The drilling fluid formula was: 240 mL base oil + 8 wt% shear emulsifier + 2.5 wt% organic soil + 60 mL 20 wt% CaCl2 aqueous solution + 2 wt% CaO + 4 wt% filtrate reducer (12 g) + 650 g barite. The obtained drilling fluid was heated to 65 °C. The reading is 132 after aging at 180℃ The reading is 100, and the high temperature and high pressure filtration loss is 4.4mL.

[0068] It is not difficult to find from the above examples and comparative examples that, compared with the traditional diesel-based oil-based drilling fluid base oil, the oil-based drilling fluid base oil of the present invention has a lower aromatic content and a lower pour point, higher biodegradability and lower biological toxicity.

Claims

1. A method for preparing a base oil for oil-based drilling fluid, characterized in that: The steps include: The mineral-based feedstock oil containing sulfur, nitrogen and aromatics is contacted with a first non-precious metal catalyst in a first reaction zone and a second non-precious metal catalyst in a second reaction zone under hydrogenation conditions to obtain a full-fraction product, and subjected to gas-liquid separation, steam stripping and fractionation units to obtain a base oil for oil-based drilling fluid having an aromatic content of ≤0.01wt% and a freezing point of <-20°C; The mineral-based feedstock oil is mainly straight-run diesel with a distillation range of 180-350°C and a freezing point of -10°C to 30°C; The active metal components of the second non-precious metal catalyst are one or two of Ni and Mg, the NiO content is 0.5-2.0wt%, the MgO content is 0-3.0wt%, and the carrier is one or two of ZSM-5, beta and inert alumina or silicon oxide.

2. The preparation method according to claim 1, characterized in that: The distillation range of the mineral-based feedstock oil is 210-320°C.

3. The preparation method according to claim 1, characterized in that: The reaction pressure of the first reaction zone is 8-20 MPa, the reaction temperature is 280-370°C, the hydrogen-to-oil ratio is 300-2000 v / v, and the space velocity is 0.5-1.5 h -1 .

4. The preparation method according to claim 1, characterized in that: The reaction pressure of the second reaction zone is 8-20 MPa, the reaction temperature is 320-380°C, the hydrogen-to-oil ratio is 300-2000 v / v, and the space velocity is 0.5-3 h -1 .

5. The preparation method according to claim 1, characterized in that: The first non-precious metal catalyst is a hydrotreating catalyst, wherein the active metal components are Group VIII metals and Group VIB metals.

6. The preparation method according to claim 5, characterized in that: The Group VIII metal is Ni and / or Co, the Group VIB metal is Mo and / or W, and the total content of active metal components is 30-80 wt % calculated as oxides thereof.

7. The preparation method according to claim 5, characterized in that: The carrier of the first non-precious metal catalyst is at least one of γ-Al2O3 and amorphous silicon aluminum.

8. The preparation method according to claim 5, characterized in that: The first non-precious metal catalyst also contains one or two of Si, P, B and F.

9. A base oil for oil-based drilling fluid, characterized in that: The aromatic content of the base oil used in the oil-based drilling fluid is ≤0.01wt%, EC 50 Biological toxicity> 25000mg / L, 28-day degradability ≮ 60wt%, closed cup flash point ≮ 80℃, kinematic viscosity at 40℃ is 1.7-3.4mm 2 / s, the pour point of the base oil is between -20 and -60°C.

10. The base oil for oil-based drilling fluid according to claim 9, characterized in that: The oil-based drilling fluid base oil is fractionated to obtain a light low aromatic oil-based drilling fluid base oil and a heavy low aromatic drilling fluid base oil or a medium drilling fluid base oil; The kinematic viscosity of the light low aromatic oil-based drilling fluid base oil at 40° C. is 1.7-2 mm 2 / s, the heavy low aromatic drilling fluid base oil has a kinematic viscosity of 2.5-3.0 mm at 40°C 2 / s, the kinematic viscosity of the medium drilling fluid base oil at 40°C is 2.2-2.8 mm 2 / s.

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