Petroleum forms from the remains of prehistoric organisms in geologic environments. "Crude oil" is a term that describes liquefied petroleum as it comes out of the ground.
Although Virginia is a petroleum producer, in-state production accounts for only a small proportion of the petroleum consumed in state, generally less than one-tenth of one percent.
All of Virginia’s petroleum production occurs in far southwestern Virginia’s Lee and Wise Counties. Some Lee County wells are dedicated to oil production. However, Wise County’s oil is produced from deep geologic reservoirs that also contain natural gas deposits. Extraction of gas from wells tapping these reserves sometimes yields small amounts of crude oil as byproduct. Because petroleum volumes produced from individual Virginia wells are quite small, collection tanks are located at each wellhead. Collection trucks visit each wellhead tank periodically, transporting the collected crude to central location for shipping.
In addition to far southwestern Virginia, mineral experts also believe that crude oil reserves are located in the eastern part of the state and off the coast. However, these reserves are not currently being exploited. To meet demand at this time, Virginia also imports a variety of refined crude products from refineries in other states and overseas.
Prior to distribution and use by consumers, raw crude oil must be transformed into marketable products such as gasoline, kerosene, asphalt, and aviation fuel through a process known as "refining." The state of Virginia has one major refinery, at Yorktown, near the mouth of the York River.
The predominant chemical components of crude oil are carbon (C), oxygen (O), and hydrogen (H); these elements occur in crude in a variety of molecular shapes and forms, primarily carbon-chain organic molecules. The process called "refining" separates those chemical components that are best adapted to specific uses into specific crude "fractions" as a means of manufacturing marketable products. Crude oil also contains impurities such as sulfur (S), nitrogen (N), and trace metals. Some of these impurities (especially S) are removed during the refining process, while others are concentrated within specific crude fractions during refining. Burning petroleum products produces energy by combining the crude components with oxygen (O2), releasing CO2 (carbon dioxide), H2O (water vapor), and other gases as combustion products.
A device known as a "distillation tower" is at the heart of the crude-oil refining process. The crude oil is heated and injected at base of the distillation tower. As the vapors rise up into the tower, they encounter progressively cooler temperatures. Various molecular components condense and are collected at specific points within the tower. Heavier components (larger carbon-chain molecules, such as fuel oil) condense at relatively high temperatures, while lower molecular weight compounds (smaller molecules, such as the components of gasoline and aviation fuels) are able to rise higher in the tower before condensing. Those components that do not evaporate are used to manufacture products such as roofing tar and asphalt.
The term "cracking" refers to the use of processes in refining to break the heavier (and less valuable) petroleum components into smaller fractions that can be used to produce higher-value products, such as gasoline.
Because of the variety of petroleum-based fuels and related products that are used throughout the state, a variety of mechanisms are used to transport these products. Ships and barges, railroads, pipelines, and trucks are all essential components of the petroleum-product transportation network.
Ocean-going vessels bring crude oil to the Yorktown refinery, often from overseas, as more than 50% of US petroleum-based fuels originate from non-domestic sources such as the Middle East, central Africa, northern Europe, and South America. In addition to raw crude oil, the US also imports refined petroleum products from non-US refineries.
A petroleum-product pipeline network serves Virginia and the rest of the nation. Pipelines are the primary means for transporting refined petroleum products over long distances. Petroleum products are shipped through these pipelines to product terminals located throughout the state. Trucks are a common means of transporting products from these terminals to individual distribution points, such as gasoline service stations and fuel oil distributors.
Petroleum-based fuels support more than one-third of Virginia's energy consumption, a larger proportion than any other primary fuel. Most of Virginia's petroleum consumption is in the form of transportation fuels, such as gasoline, diesel fuel, and aviation fuel. Many Virginians use fuel oil to heat their homes and businesses. Other products in widespread use include lubricants, asphalt, and fuel oil for industrial boilers. Petroleum-based fuels power only a small proportion of Virginia's electrical energy production (less than 5 percent).
See EIA/DOE's Petroleum Profile: Virginia
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