325 results about "Asphaltene" patented technology

The invention discloses an asphaltene molecule nano-scale characteristic analysis method based on quantum chemistry calculation, which comprises the following steps: acquiring composition information of asphaltene components, and constructing a representative asphaltene molecule three-dimensional model containing a fused aromatic ring skeleton and an alkyl side chain; performing geometric configuration optimization on the representative asphaltene molecule three-dimensional model by adopting a quantum chemistry density functional theory method to obtain a stable configuration of the asphaltene molecule; determining key nano parameters of the asphaltene molecules according to the stable configuration of the asphaltene molecules; and associating the key nano-scale parameters of the asphaltene molecules with the macro-performance of the asphalt material, and establishing an asphalt performance association model. According to the method, the key parameters capable of representing the asphaltene microstructure and property are obtained, so that the understanding of the relationship between the asphaltene composition and the performance of the asphalt material is deepened, the performance of the asphalt material is evaluated from the molecular scale, and a new thought is provided for performance prediction and modification of the asphalt material.

The disclosure provides a process for a hydrothermal feedstock treatment including direct steam injection and cooling, which may be performed in the absence of a reactor. The process can be used to reduce inorganic and organic contaminants, such as salts, minerals, metals, asphaltenes, polymers, and coke precursors in both renewable and non-renewable feedstocks. The hydrothermal feedstock treatment may also be used in soap acidulation processes.

The application discloses a thickened oil viscosity reducer for a main viscosity contribution component of colloid and a preparation method thereof. The thickened oil viscosity reducer comprises the following components in percentage by weight: diethylene glycol methyl ether 25-35%, propylene glycol formate 15-25%, dispersant 5-8%, chelating agent 2-4%, anti-coking agent 0.5-1%, anti-swelling agent 1-2% and corrosion inhibitor 1-2%; and the balance is water. The application is a polar + non-aromatic hydrocarbon solvent system; completely avoids high-risk substances such as nonylphenol polyoxyethylene ether, petroleum sulfonate sodium and organic chlorine; is designed in pertinence and can effectively inhibit metal-induced asphaltene bridging; can withstand working conditions from normal temperature to 250 DEG C and up to 300 DEG C; thermal stability is significantly enhanced, and residual carbon after aging is lower than 8%; viscosity reduction efficiency is higher; the system is more stable, flexible in compounding and suitable for field construction.

The invention provides a free radical excited cross-linked composite hard carbon material as well as a preparation method and application thereof, and relates to the technical field of negative electrode materials. The composite hard carbon material is prepared from lignin and asphaltene as raw materials through lignin activation, wet ball milling, drying and calcination. Through the preparation method of free radical pre-excitation-wet ball-milling crosslinking, collaborative optimization of the sodium storage capacity, the first-week coulombic efficiency, the cycling stability and the rate capability of the composite hard carbon material is realized. Moreover, the preparation process of the composite hard carbon material provided by the invention has the advantages of good process stability, strong controllability, low cost, environmental friendliness and the like, is easy for large-scale production, meets the technical index requirements of industrial application of sodium ion batteries, and has a wide market application prospect.

The invention belongs to the technical field of asphalt pavement materials, and particularly relates to a high-permeability asphalt regenerant as well as a preparation method and application thereof, and the high-permeability asphalt regenerant is prepared from the following components in parts by weight: 100 parts of base oil, 20-50 parts of oil slurry, 5-20 parts of plasticizer and 5-15 parts of anti-aging agent. The high-permeability asphalt regenerant provided by the invention can effectively optimize the composition of old asphalt components, improve the interface fusion efficiency of new asphalt and old asphalt, and enable asphaltene to be better dispersed in aromatic components and saturated components by virtue of colloid to form a stable colloid structure; the indexes such as high and low temperature performance and water stability of the recycled asphalt mixture are improved, the temperature sensitivity of asphalt is reduced, the influence of external environment temperature on asphalt properties is reduced, and the recycled asphalt has excellent low temperature performance; the pavement performance of the RAP material is recovered, so that the performance of the aged asphalt is basically recovered to a non-aged level, and the service life of the asphalt material is prolonged.

The present disclosure discloses a molybdenum amine complex catalyst and a preparation method and use thereof, wherein, the method for preparing the molybdenum amine complex catalyst comprises the following steps: in the presence of a dispersion medium hydrocarbon oil, reacting a hexavalent molybdenum compound with at least one aliphatic amine compound having C4 or more carbon atoms to obtain an active metal catalyst precursor, and uniformly dispersing the active metal catalyst precursor in the dispersion medium hydrocarbon oil to obtain the molybdenum amine complex catalyst. When the molybdenum amine complex catalyst of the present disclosure is applied to the direct coal liquefaction reaction, it can significantly improve the conversion rate of coal and the conversion rate of asphaltene and preasphaltene to oil, allowing the required reaction pressure to be significantly reduced while achieving an oil yield comparable to that of the iron-based catalyst.

The embodiment of the invention provides a compound system determination method and device, a storage medium and a shale oil development method, and belongs to the technical field of shale oil. The determination method comprises the following steps: performing corresponding oil-gas interface tension and liquid-solid interface wettability measurement on a plurality of obtained initial composite nano systems, and screening out a first composite nano system; based on the first composite nano system, calculating parameter values influencing the pore structure, pore size and asphaltene content of the shale reservoir rock, and screening out a second composite nano system; and determining the micro-fluidic sweep efficiency and the core throughput recovery rate of the second composite system to determine the optimal composite nano system. According to the principle from microcosmic to macroscopic and from experiments to mine fields, the optimal composite nano system is screened out through three-stage screening, and the shale oil reservoir development problems that due to the fact that an existing CO2 and chemical additive system is single in screening standard, a displacement relation cannot be established between wells, and the mine field implementation effect is poor are solved.

The invention belongs to the technical field of asphalt preparation, and provides a high-modulus composite modified asphalt material based on natural asphalt and a preparation method thereof. The method comprises the following steps: separating natural asphalt into a high-molecular asphaltene section and a medium-low-molecular colloid section, and preparing activated asphaltene and colloid sections through alkali treatment and spray drying; a styrene-butadiene-styrene block copolymer and a polyurethane prepolymer are taken as the basis, and a dynamic cross-linked polymer is synthesized through the steps of hydrazide treatment, boric acid group introduction, glutaraldehyde cross-linking and the like; organic modified clay and phenylated chitosan are prepared, a polyaniline composite material is prepared through in-situ polymerization of aniline, a PANI-clay-biomass compound is obtained, the ultraviolet absorption characteristic of polyaniline and the shielding effect of montmorillonite cooperate, the ultraviolet aging resistance of the material is improved, through multi-stage temperature control dispersion, the anti-aging performance of the material is improved, and the anti-aging performance of the material is improved. The various modified materials are compounded with a natural asphalt substrate to obtain the high-modulus composite modified asphalt material based on the natural asphalt.

The present invention relates to the field of oilfield chemistry, and is a high-permeability environmental protection wax remover and its preparation method. The raw materials include, by weight percentage: 50% to 70% of an organic solvent, 25% to 42% of an organic solvent penetration promoter, 2% of a penetrant, 0.5% to 1% of a co-penetrant, and the rest is a surfactant. The high-permeability environmental protection wax remover of the present invention uses birch oil as the organic solvent, and its specific gravity can be adjusted between 0.86 g / mL and 1.1 g / mL according to on-site requirements, enabling the wax remover to contact wax, gum, and asphaltene at different sections of the oil well pipe wall, quickly penetrate and dissolve to react, and can better remove wax deposits on the oil well string and gathering and transportation pipelines. It has the characteristics of good permeability, fast wax dissolution rate, safety and environmental protection. At the same time, its preparation method is simple and easy to operate, can be prepared on-site, and is convenient for popularization and application.

The invention relates to the field of preparation of a conductive material for a cable shielding material, and discloses a preparation method, a production system and application of a conductive filler for a high-voltage cable shielding material, the preparation method comprises the following steps: S1, mixing a first solution containing raw material oil with a carbon black raw material in a spray form to obtain a mixed material; wherein the oil absorption value of the carbon black raw material is 180-220 (10 <-5 > m < 3 > / kg); wherein the content of aromatic hydrocarbon in the raw oil is 70-85wt%, and the content of asphaltene in the raw oil is lower than 0.1 wt%; s2, in the presence of carrier gas, enabling the mixed material to flow in a heating section, and carrying out indirect heat exchange with high-temperature fluid; the temperature of the high-temperature fluid is not lower than 1800 DEG C, and the heat exchange time is 30-120 s. The conductive filler prepared by the preparation method has relatively high structural degree and graphitization degree, and can meet the performance requirements of cable shielding materials.

The invention belongs to the technical field of sodium ion battery negative electrode materials, and discloses an asphalt-based hard carbon material for a sodium ion battery and a preparation method of the asphalt-based hard carbon material. The 3, 4, 9, 10-perylenetetracarboxylic dianhydride is adopted as the cross-linking agent, the doping amount of the 3, 4, 9, 10-perylenetetracarboxylic dianhydride is only 10-30% of the mass of the asphalt, and the reversible sodium storage capacity of the asphalt can be remarkably improved under the condition limited by the invention. In an oxygen atmosphere, an anhydride group of 3, 4, 9, 10-perylenetetracarboxylic dianhydride and an oxygen-containing functional group in asphalt are subjected to a cross-linking reaction, and a formed cross-linking structure effectively inhibits melting rearrangement in an asphalt carbonization process, so that the electrochemical performance of the sodium-ion battery hard carbon negative electrode material is remarkably improved. According to the prepared asphalt-based hard carbon negative electrode material, 1 mol / L NaPF6-EC / DEC is used as an electrolyte, and under the current density of 20 mA / g, the initial coulombic efficiency reaches 75.64%, and the reversible capacity is 319.76 mAh / g; and under the current density of 200mA / g, the reversible capacity can still reach 189.14 mAh / g.

A process dissolves or disperses asphaltenes from marine fuels by using at least one quaternary ammonium compound. A weight ratio of saturates to asphaltenes in the marine fuel is at least 4.0. A marine fuel is produced that includes saturates, aromatics, and asphaltenes in addition to at least one quaternary ammonium compound. Another process reduces or prevents fouling caused by asphaltenes in a marine fuel.

The invention belongs to the technical field of oily sludge cleaning, and particularly relates to a macromolecular / micromolecular composite surfactant for intensively cleaning oily sludge. A main monomer (such as acrylamide), a hydrophilic monomer (such as 2-acrylamido-2-methylpropanesulfonic acid) and a hydrophobic monomer (such as methacrylic acid long-chain alkyl ester) are mixed, and the macromolecular surfactant is synthesized through free radical polymerization. The specific long-chain structure of the macromolecular surfactant can form larger micelles, colloid and asphaltene can be effectively wrapped, the macromolecular surfactant is compounded with the micromolecular surfactant for use, and mixed micelles with higher solubilizing capacity can be formed, so that the colloid and asphaltene in the high-medium-concentration oily sludge can be efficiently removed, and the high-medium-concentration oily sludge can be effectively removed. Further, the removal rate of total petroleum hydrocarbon is improved. The invention provides a new technology for high-efficiency deep treatment of high-medium-concentration oily sludge.

Disclosed in the present invention are an ionic liquid demulsifier and a preparation method therefor and a use thereof. The ionic liquid demulsifier of the present invention has a structure as shown in formula I, wherein in formula (I), m=1-16, n=3-5, and i=1-16. The ionic liquid demulsifier has excellent interfacial activity and can quickly migrate to an oil-water interface to reduce the tension of the oil-water interface, so as to destroy an interface film composed of asphaltenes, and promote occurrence of a demulsification process. The ionic liquid demulsifier provided by the present invention has the characteristics of simple synthesis steps, small dosage, good acid-base tolerance, low demulsification temperature, high demulsification efficiency and the like, and can be used for demulsifying crude oil emulsions.

The invention discloses a basalt fiber reinforced asphalt mixture based on solid waste synergy and a preparation method of the basalt fiber reinforced asphalt mixture, and belongs to the field of asphalt mixtures. The basalt fiber reinforced asphalt mixture based on solid waste synergy is prepared from the following raw material components in parts by mass: 1000 to 1200 parts of aggregate, 3 to 5 parts of modified basalt fiber, 50 to 73 parts of waste rubber modified asphalt, 2 to 4.38 parts of amphiphilic epoxy resin, 0.7 to 1.5 parts of curing agent and 0.06 to 0.13 part of accelerant, the modified basalt fiber is obtained by modifying triethoxysilyl butyraldehyde, 3-mercaptopropyltrimethoxysilane and allyl-1, 3-sultone, and the modified basalt fiber is prepared by modifying the triethoxysilyl butyraldehyde, the 3-mercaptopropyltrimethoxysilane and the allyl-1, 3-sultone; the amphiphilic epoxy resin is obtained by reacting dodecyl succinic anhydride, polyethylene glycol monomethyl ether 2000 and epoxy resin; m-phenylenediamine and 2-amino-4-cyanopyridine are adopted as the curing agent; n-methylimidazole is adopted as the accelerant; the asphalt mixture prepared by the invention has good rut resistance, crack resistance and water stability.

The application discloses an asphaltene separation device and an asphaltene separation method. The asphaltene separation device comprises a separation cabin, the separation cabin is in a cylindrical structure, electric heating wires are filled between the inner wall and the outer wall of the separation cabin, the electric heating wires are connected with temperature sensors, a stirring shaft is penetrated through the center of the end face of the bottom end of the separation cabin, stirring blades are sleeved with the end part of the stirring shaft, the stirring blades are in the separation cabin, the end part of the stirring shaft is connected with a stirring motor, and the stirring motor is outside the separation cabin. The asphaltene separation device and the separation method solve the problem that a long time is consumed in the asphaltene separation process, and meet the demand of people for rapid asphaltene separation. The asphaltene separation device is provided with a stirring device composed of a stirring shaft and stirring blades, the dissolution and separation time is reduced through the stirring mode, and the temperature sensors and the electric heating wires are provided, so that the temperature in the separation cabin can be accurately controlled, and the dissolution speed of solutes is accelerated.

The invention relates to the technical field of oilfield chemistry, in particular to a nano-composite viscosity reducer, a preparation method, application and a high-viscosity thick oil viscosity reduction method. According to the preparation method, the nano composite viscosity reducer is prepared from a surface-modified nano oxide and an amphiphilic polymer through a solvent exchange method; the nano oxide is nano silicon dioxide nano particles, zinc oxide nano particles or ferric oxide nano particles, and the amphiphilic polymer is a partial esterification product of a styrene-maleic anhydride copolymer or an octadecyl acrylate-methacrylic acid copolymer. According to the preparation method, the viscosity reducer not only can efficiently disassemble a colloid asphaltene network structure, but also has a certain catalytic modification function, does not influence subsequent treatment of crude oil, and has the advantages of high viscosity reduction efficiency, lasting effect, no formation of stable emulsion, shear resistance, good temperature resistance, strong universality and the like.

Breaker fluids for removing polyolefin agglomerations from wellbore equipment and subterranean formations. An example breaker fluid includes an acid, at least one oxidizer, a corrosion inhibitor, a surfactant, an asphaltene remover, a sludging inhibitor, and an aqueous base fluid. The breaker fluid is introduced to wellbore equipment and subterranean formations and breaks down polyolefin agglomerations present therein.

The utility model discloses an asphalt processing quantitative feeding device which comprises a box body and an observation window, the observation window is arranged on the front wall of the box body, a scale groove is formed in the position, close to the observation window, of the front wall of the box body, and the lower surface of the box body is communicated with a base. And the positions, located at the front end and the rear end of the base, of the lower surface of the box body are each fixedly provided with a set of mounting plates, servo motors are fixedly installed on the side walls of the mounting plates, and threaded rods are fixedly installed at the output ends of the servo motors. According to the asphalt raw material proportioning device disclosed by the utility model, the box body, the observation window, the base, the mounting plate, the servo motor, the threaded rod, the baffle plate, the slot and other parts are matched, so that the function of accurately proportioning asphalt raw materials is realized, and the quantity of the added asphalt raw materials can be clearly known through the observation window and the scale slot, so that the quantity accuracy of the added asphalt raw materials is improved; the asphalt raw material proportioning error is prevented, the influence on the quality of the processed asphalt is avoided, and the yield of asphalt production is improved.

This invention discloses a hydrodesulfurization catalyst and its preparation method and application. The steps are as follows: (1) an organic polymer is modified with acid and then mixed with boehmite powder to obtain a first mixture; (2) an aqueous solution of amorphous silica-alumina and a heated organic polymer is mixed and spheroidized to obtain a first precursor; (3) a second precursor is prepared; (4) a second mixture is prepared; (5) a third precursor is prepared; (6) a support is prepared, and after introducing a hydrogenation active metal component, it is dried and calcined to obtain the hydrodesulfurization catalyst. The prepared catalyst has a non-uniform pore distribution structure, which not only gives it high impurity removal capacity, containment capacity and asphaltenes conversion capacity, but also reduces the sediment content in the generated oil. It is particularly suitable for the hydrotreating process of directly producing low-sulfur marine fuel oil from fluidized bed heavy oil.

The utility model provides a waste oil product regeneration treatment system which comprises a hydrocracking assembly used for receiving waste oil products and hydrocracking the waste oil products; the first atmospheric and vacuum fractionation device is communicated with the hydrocracking assembly and is used for atmospheric and vacuum fractionation operation; the storage assembly is communicated with the first atmospheric and vacuum fractionation device; the oil mixing device is communicated with the first atmospheric and vacuum fractionation device; the hydrofining assembly is communicated with the oil mixing device; and the second atmospheric and vacuum fractionation device is communicated with the hydrofining assembly and the storage assembly. By adopting the waste oil product regeneration treatment system provided by the utility model, phosphorus compounds, chlorine compounds, metal additives, colloid, asphaltene and other impurities in waste oil products can be effectively removed, the regeneration rate of the waste oil products can reach more than 99%, and the problems that the regeneration rate of the waste oil products in the prior art is reduced; meanwhile, secondary pollutants such as waste gas, waste liquid or waste residues are also generated.

The application provides an absorption liquid for absorbing asphalt fume and oil mist waste gas, a preparation method and application, and relates to the field of waste gas treatment. The absorption liquid is prepared from the following raw materials in mass percentage: polyethylene glycol dimethyl ether 60-80%; demulsifier 5-15%; dispersion polymerization inhibitor 3-10%; oxidant carrier 1-3%; slow-release particles 2-9%; cosolvent 5-12%; and defoaming agent 0.1-1%. In the application, the anti-adhesion and polymerization resistance performance are improved through the compounding of various solvents, the continuous operation cycle of the equipment is prolonged to more than 90 days, the pressure difference of the filler is increased by less than 5%, and the frequent shutdown problem caused by asphalt fouling in the traditional technology is completely solved; meanwhile, the demulsification is efficient, the removal rate is high, and another possibility is provided for efficient, green and economic deep treatment of waste gas.

The present application relates to a method for determining effective relative density of steel slag and a method for determining bulk volume relative density, comprising the following steps: obtaining the asphalt mass required for completely wrapping the steel slag according to the asphalt film thickness, and then obtaining the oil-rock ratio, which is the mass ratio of asphalt to steel slag; according to the oil-rock ratio, batching the asphalt and the steel slag, mixing after preheating, and obtaining the uniformly coated steel slag; dispersing the prepared coated steel slag to obtain a dispersion, cooling the dispersion to a set temperature, weighing a set mass of the dispersion, placing it into a negative pressure device, adding water in the negative pressure device, and then vacuumizing; obtaining the theoretical maximum relative density according to the mass of the negative pressure device and the dispersion in water and the mass of the negative pressure device in water; obtaining the effective relative density of the steel slag according to the theoretical maximum relative density and the oil-rock ratio; the method principle is clear, the testing process is simple, and the determined result is more accurate than the traditional testing method.

The invention relates to the field of material science, in particular to an asphalt test detector and a control system thereof.The asphalt test detector comprises a disease area infrared positioning module, an asphalt quality test module, a comprehensive evaluation module, a quality grading feedback module and a management database. The method comprises the following steps: respectively carrying out softening point detection, penetration detection and Englan viscosity detection on an asphalt sample to judge whether each quality index is qualified or not, carrying out comprehensive evaluation to obtain an asphalt comprehensive evaluation coefficient of each disease area of the asphalt pavement, determining a corresponding quality grade, and outputting a grading feedback result. Precise recognition and comprehensive quality detection of asphalt pavement diseases are realized, subjectivity and one-sidedness of manual detection are avoided, and a basis is provided for accurate evaluation of asphalt pavement conditions.

The invention relates to a method for producing a needle coke raw material and a low-carbon olefin raw material, which comprises the following steps of: S1, extracting oil slurry from at least one layer of tower trays from the first layer to the fifth layer of tower trays from the tower bottom to the top of a main fractionating tower of a catalytic cracking device to obtain extracted oil slurry; carrying out purification treatment on the extracted oil slurry to obtain purified oil slurry; the total content of colloid and asphaltene in the purified slurry oil is less than 20wt%; s2, mixing the purified oil slurry with light cycle oil, feeding the mixed raw oil and hydrogen-containing gas into a hydrogenation device, and performing hydrodesulfurization reaction under the action of a hydrogenation catalyst to obtain a hydrogenation product; and S3, carrying out solvent extraction on the hydrogenation product to obtain extract oil and raffinate oil. According to the method provided by the invention, the feeding viscosity of a purification device is greatly reduced, the contents of colloid and asphaltene in the purified slurry oil are greatly reduced, and the generation of an aged intermediate phase is reduced; aromatic hydrocarbon and saturated hydrocarbon in hydrogenation products can be separated to the maximum extent through solvent extraction.

Breaker fluids for removing polyolefin agglomerations from wellbore equipment and subterranean formations. An example breaker fluid includes an acid, at least one oxidizer, a corrosion inhibitor, a surfactant, an asphaltene remover, a sludging inhibitor, and an aqueous base fluid. The breaker fluid is introduced to wellbore equipment and subterranean formations and breaks down polyolefin agglomerations present therein.

The invention provides a combined process method for improving the yield of vacuum residue catalytic cracking products, which comprises the following steps: determining the asphaltene dispersion coefficient d of vacuum residue according to a formula (1), where w asphaltene, w colloid and w aromatics respectively represent the mass fractions of asphaltene, colloid and aromatics in vacuum residue; and carrying out modification and catalytic cracking reaction on the vacuum residue. According to the combined process method, the asphaltene dispersion coefficient d is ingeniously designed, and d is smaller than or equal to 0.5 and dgt; the vacuum residue of which the content is 0.5 is modified by adopting different modification methods, and then catalytic cracking reaction is performed under different conditions, so that the density of a catalyst in a reactor is improved, oil-agent contact in the reactor is improved, the contact instantaneous effective agent-oil ratio can be improved, the catalytic cracking reaction ratio can be remarkably improved, thermal cracking and condensation coke generation reactions are reduced, and the catalytic cracking efficiency is improved. Conversion of inferior heavy oil is promoted, meanwhile, the coke yield is remarkably reduced, and the yield of high-value products is increased.

The application provides a pre-leaching auxiliary solvent extraction method for oil sand or oil sludge containing heavy crude oil, and belongs to the technical field of product separation and solid waste treatment in the field of petroleum chemical industry. The bitumen is dispersed by using aromatic hydrocarbon first, and then extracted by using naphthenic hydrocarbon, so that good extraction effect can be achieved, a surfactant does not need to be added, the solid phase residual oil rate after treatment is less than 1wt%, and the national relevant standard is met; the pre-leaching agent and the extractant used in the application have low boiling points, are easy to distill and recover, and the recovery rate is greater than 85%. In addition, the method provided by the application has the operation temperature of room temperature (20-30 DEG C), the operation condition is mild, the method is simple, the energy consumption is low, the organic solvent and the crude oil (containing bitumen and other heavy components) can be recovered by distillation, and the resource utilization is realized.

This application discloses a nanofluid, its preparation method, and its applications. The nanofluid comprises, by mass fraction: 0.01% to 0.7% modified nanoparticles, 1% to 4% surfactant, 0.2% to 0.6% polymer, and 0.01% to 0.2% short-chain alkanes, with the balance being water. The nanofluid provided in this application, through the synergistic effect between specific components, can significantly improve C / W foam stability and enhance oil recovery. Foam displacement agents prepared using this nanofluid can improve permeability and asphaltene content after displacement, exhibiting good overall performance.

Fuel oil compositions, and methods for blending such fuel oil compositions, to enhance initial compatibility and longer term stability when such fuel oil compositions are blended to meet IMO 2020 low sulfur fuel oil requirements (ISO 8217). In one or more embodiments, asphaltenic resid base stocks are blended with high aromatic slurry oil to facilitate initial compatibility such that low sulfur cutter stocks, e.g., vacuum gas oil and / or cycle oil, may be further blended therein to cut sulfur content while maintaining longer term stability. These fuel oil compositions are economically advantageous when used as marine low sulfur fuel oils because greater concentrations of high viscosity resids are present in the final blend.