Crude oil varies widely in appearance and viscosity from field to field. It ranges in color, odor, and in the properties it contains. While crude oil is essentially a hydrocarbon, the differences in properties, especially the variations in molecular structure, mean that a crude is more or less easy to produce, pipeline, and refine. The variations may even influence its suitability for certain products and the quality of those products.
Crudes or crude oil is roughly classified into three groups, according to the nature of the hydrocarbons they contain.
Paraffinic base crude oils: A crude oil containing paraffin wax but very few asphaltic materials. This type of oil is suitable for motor lubricating oil and kerosene. These contain higher molecular weight paraffins which are solid at room temperature, but little or no asphaltic (bituminous) matter. They can produce high-grade lubricating oils.
Asphaltic-Base Crude Oils: Contain large proportions of asphaltic matter, and little or no paraffin. Some are predominantly naphthenes so yield a lubricating oil that is more sensitive to temperature changes than the paraffin-base crudes.
Mixed-Base Crude Oils: The "gray area" between the two types above. Both paraffins and naphthenes are present, as well as aromatic hydrocarbons. Most crudes fit this category.
Crude oil is a complex mixture of many different components. The separation of these components into useable products is known as refining. Refineries must be designed to handle the type of crude oil they are going to process. Crude oil from the Appalachian Basin (Pennsylvania Grade Crude Oil) contains a lot of wax and paraffin. The amounts of gasoline and fuels that are produced or distilled are relatively small, and in some conditions are by-products of the refining process. The lubricating stocks and waxes that are obtained from Pennsylvania Grade Crude oil are the most desired portions. Other crude oil, such as that from Prudhoe Bay in Alaska, contain much less wax and far more fuel. The bottoms or residue left after the distillation are very asphaltic and very good for making road tar and heavy burner fuel.
Pria, please note - which sort of crude source would be used is depend on what products you are intended for. You can not use Pennsylvania grade crude oil for the product intention of diesel, petrol, or methane, ethane, propane, butane requirements.
From the analysis of the crude oil, it can be determined what the basic composition of the crude is and what applications it is best suited for, (API) gravity methodology determines these differences.
The Pennsylvania Grade Crude oil can be broken down into the following basic fractions, or components: Gasoline, Kerosene and Fuel Oil, Gas Oil, Wax Distillate, and Cylinder Stock or Bottoms.
The gasoline fraction is further refined and through a variety of processes is converted into the fuel we power our cars with. Certain portions of the gasoline fraction are removed and others have their chemical structure changed (isomerized). Some impurities are removed (desulfurized), and others have components added to produce the final product (reformulated gasoline).
The kerosene and fuel oil fraction is basically unchanged and used as fuel for the trucking and construction industry. This fraction can also be processed into some of the specialty solvents used in manufacturing.
The gas oil fraction is a heavy, relatively slow burning, non-volatile fuel, or it is frequently used as a light lubricating oil. This fraction can be used either as a fuel or as an oil. If the gas oil fraction is hydroprocesssed, it can be made into white oil (sewing machine oil) or high quality oils for use in cosmetics and pharmaceuticals.
The wax distillate is a valuable source of lubricating stock and paraffin. By removing the wax or paraffin one of the basic components of lubricant is produced (neutral). Neutrals can be further refined through distillation (fractionation) and hydroprocessing (catalyzation) to produce a series of specialized components used in the manufacture of engine oils, gear lubricants, and greases. The addition of additives to control oxidation, thermal degradation, and viscosity produce the high quality lubricants used today. Paraffins are used in many different aspects of our daily life. They are used not only in candles, but in cosmetics, paper coating, inks, fabrics, and even on our foods.
The Cylinder Stock or Bottoms fraction is what is left over after the crude oil has been put through the distillation tower. The wax portion is removed to create a product called Micro Wax. Micro has a much higher melting point than paraffins and is therefore suitable for a variety of products we use daily, such as a component of many plastics, candy, and in building materials. Many types of candy that would be too soft otherwise, have their form because of the inclusion of micro wax. A Canadian company has even developed a process to form micro wax and polymers into a structural material that does not require maintenance, in essence it is a wax brick. The oil portion of the cylinder stock is further processed to remove the resins. These resins are used to create many different products ranging from high temperature insulations to undercoatings or fuels for ocean going barges. The oil portion of cylinder stock is then a heavy lubricant base stock used in heavy duty gear oil applications and many industrial lubricants.
The refining of crude oil is a complex and involved operation that generate many different components that are the building blocks for virtually every product we use in our daily lives. As you can now see, the products of the refining process are not just limited to the automotive industry, as many people would think, but are important components in almost every modern convenience manufactured today.
Types of Crude Oil accoridng to the U. S. Environmental Protection Agency. The petroleum industry often characterizes crude oils according to their geographical source, e.g., Alaska North Slope Crude. Oils from different geographical areas have unique properties; they can vary in consistency from a light volatile fluid to a semi-solid. Classification of crude oil types by geographical source is generally not a useful classification scheme for response personnel because they offer little information about general toxicity, physical state, and changes that occur with time and weathering. These characteristics are primary considerations in oil spill response. The classification scheme provided below is more useful in a response scenario.
Class A: Light, Volatile Oils. These oils are highly fluid, often clear, spread rapidly on solid or water surfaces, have a strong odor, a high evaporation rate, and are usually flammable. They penetrate porous surfaces such as dirt and sand, and may be persistent in such a matrix. They do not tend to adhere to surfaces; flushing with water generally removes them. Class A oils may be highly toxic to humans, fish, and other biota. Most refined products and many of the highest quality light crudes can be included in this class.
Class B: Non-Sticky Oils. These oils have a waxy or oily feel. Class B oils are less toxic and adhere more firmly to surfaces than Class A oils, although they can be removed from surfaces by vigorous flushing. As temperatures rise, their tendency to penetrate porous substrates increases and they can be persistent. Evaporation of volatiles may lead to a Class C or D residue. Medium to heavy paraffin-based oils fall into this class.
Class C: Heavy, Sticky Oils. Class C oils are characteristically viscous, sticky or tarry, and brown or black. Flushing with water will not readily remove this material from surfaces, but the oil does not readily penetrate porous surfaces. The density of Class C oils may be near that of water and they often sink. Weathering or evaporation of volatiles may produce solid or tarry Class D oil. Toxicity is low, but wildlife can be smothered or drowned when contaminated. This class includes residual fuel oils and medium to heavy crudes.
Class D: Nonfluid Oils. Class D oils are relatively non-toxic, do not penetrate porous substrates, and are usually black or dark brown in color. When heated, Class D oils may melt and coat surfaces making cleanup very difficult. Residual oils, heavy crude oils, some high paraffin oils, and some weathered oils fall into this class.
These classifications are dynamic for spilled oils; weather conditions and water temperature greatly influence the behavior of oil and refined petroleum products in the environment. For example, as volatiles evaporate from a Class B oil, it may become a Class C oil. If a significant temperature drop occurs (e.g., at night), a Class C oil may solidify and resemble a Class D oil. Upon warming, the Class D oil may revert back to a Class C oil.
A method with pulsed electric or magnetic field to reduce the viscosity of crude oil is developed. Specifically, for paraffin-base crude oil, a magnetic field pulse can effectively reduce its viscosity for several hours, while, for asphalt-base crude oil or mixed-base crude oil, an electric field pulse can do the same. The method does not change the temperature of the crude oil; instead, it temporary aggregates paraffin particles or asphaltene particles inside the crude oil into large ones. This particle aggregation changes the rheological property of the crude oil and leads to the viscosity reduction. While this viscosity reduction is not permanent, it is suitable for many important applications, such as oil transport via deep-water pipelines, since it lasts for several hours and is repeatable.
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