On the other hand, heavy crude oil or extra heavy crude oil is any type of crude oil which does not flow easily. Extra heavy oil is defined with API gravity below If its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks.
Heavy oil may also require additional processing, usually referred to as upgrading , after being produced in order to be transported and refined. High density and viscosity have traditionally made their recovery energy demanding in comparison to lighter oils.
However, the technological costs to produce a barrel are currently much higher than with conventional resources. Additionally, the increased energy requirements and unconventional practices in production raise various environmental concerns such as land disturbance, tailing ponds, and higher greenhouse gas emissions. Alberta Oil Magazine. Total Energy. Alberta Tech Futures.
Teledyne ISCO. Alberta Centre for Reclamation and Restoration Ecology. Oil Sands Review. The Wall Street Journal. New York Times. Home Energy Education Topic. Share this page. Jump to:. Gulf Coast tends to be sour.
This measurement reflects how light or heavy a crude oil is compared to water. The API gravity of crude oil can vary greatly, from 10 to Most crude oil falls into the range of 20 to Lighter crude is less expensive to produce. It has a higher percentage of light hydrocarbons that can be recovered with simple distillation at a refinery. Heavy crude has density approaching, or even exceeding, that of water.
With simple distillation, heavier crude oil produces more lower-valued products, compared to the simple distillation of light crude.
Heavy crude oil requires extra refining to produce more valuable and in-demand products. Crude oil's value comes from its ability to be refined and turned into products ranging from asphalt and gasoline to lighter fluid and natural gas—along with a variety of essential elements such as sulfur and nitrogen. Petroleum products are also key components in the manufacturing of medicines, chemicals, and plastics.
These products are all produced through processing or refining, and the less processing necessary, the more valuable the crude becomes. When one type of crude oil is cheaper than another crude oil, that's often because it will take more work to create a desirable product out of the cheaper crude.
Simple distillation—or first-level refinement—of different crude oils produces different results. For example, the U. In contrast, the simple distillation of Saudi Arabia's Arabian Light, the historical benchmark crude, yields almost half "residuum. The lighter the oil, the more of the desirable products it produces through distillation at a range of temperatures.
The lowest distillation temperatures produce products such as liquid petroleum gases LPG , naphtha, and so-called "straight run" gasoline. In the middle range of distillation temperatures, the refinery produces jet fuel, home heating oil, and diesel fuel.
At the highest distillation temperatures—over 1, degrees Fahrenheit—the heaviest products are produced, including residuum or residual fuel oil, which can be used for lubricants. To maximize the output of more desirable products, refineries commonly reprocess the heaviest products into lighter products.
Toxicity refers to how harmful an oil might be to humans, other living organisms, and the environment. Generally speaking, the lighter the oil, the easier it will spread around and permeate through surfaces, making it potentially more toxic for the environment.
Because of the constant potential of spills, the Environmental Protection Agency EPA has classified crude oil in four categories that reflect how the oil would behave in spills and its aftermath. Because they are light and highly liquid, these clear and volatile oils can spread quickly on impervious surfaces and in water. Their odor is strong, and they evaporate quickly, emitting volatiles. Usually flammable, these oils also penetrate porous surfaces, such as dirt and sand, and may remain in areas into which they seep.
Humans, fish, and other forms of plant and animal life face the danger of toxicity from Class A oils. Considered less toxic than Class A, these oils are generally non-sticky but feel waxy or oily instead.
The warmer they get, the more likely Class B oils soak into surfaces—making them potentially hard to remove.
0コメント