? 發問於 科學及數學化學 · 1 十年前

crude oil

how was it formed?

where do we get it from and how do we extract it?

what type of substance(element, mixture or compound) is it?

what substance make it up?

how do we get these substance from crude oil?

please give some information of each and answer it separately.

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  • 1 十年前
    最愛解答

    1) how was it formed?

    Petroleum, or crude oil, naturally occurring oily, bituminous liquid composed of various organic chemicals. Crude oil, with complex mixture of hydrocarbons derived from the geologic transformation and decomposition of plants and animals that lived hundreds of millions of years ago. The sediments grow thicker and sink into the seafloor under their own weight.

    As additional deposits pile up, the pressure and the temperature rises. The mud and sand harden into shale and sandstone; carbonate precipitates and skeletal shells harden into limestone; and the remains of the dead organisms are transformed into crude oil and natural gas.

    2) where do we get it from and how do we extract it?

    The oil is always accompanied by water and often by natural gas; all are confined in porous rock, usually such sedimentary rocks as sands, sandstones, arkoses, and fissured limestones and dolomites.

    Once oil has been produced from an oil field, it is treated with chemicals and heat to remove water and solids, and the natural gas is separated. The oil is then stored in a tank, or battery of tanks, and later transported to a refinery by truck, railroad tank car, barge, or pipeline. Large oil fields all have direct outlets to major, common-carrier pipelines.

    3) what type of substance(element, mixture or compound) is it?

    Mixture of comparatively volatile liquid hydrocarbons (compounds composed mainly of hydrogen and carbon with some nitrogen, sulfur, and oxygen) that occurs in the Earth's crust and is extracted for use as fuel and various petroleum products.

    Three broad classes of crude petroleum exist: the paraffin types, the asphaltic types, and the mixed-base types. The characteristic molecules in the asphaltic types are naphthenes. In the mixed-base group are both paraffin hydrocarbons and naphthenes.

    4) what substance make it up?

    Petroleum encompasses the liquid (crude oil), gaseous (natural gas), and viscous or solid (bitumen, asphalt) forms of hydrocarbons that occur in the Earth.

    The first material to be distilled from crude oil is the gasoline fraction, followed in turn by naphtha and then by kerosene. Lubricants and distillate fuel oils were obtained from the upper regions and waxes and asphalt from the lower regions of the distillation apparatus.

    5) how do we get these substance from crude oil?

    REFINING PETROLEUM > Separating Crude Oil into Its Parts

    Oil refining begins with two basic processes: vaporization and condensation. Crude oil is composed of many different liquids, called fractions. Each fraction boils into a vapor and condenses back into a liquid at a different temperature. At the refinery the crude oil is pumped into a pipe still or furnace, where it is heated to 750° F (399° C).

    A. Basic Distillation

    Crude oil begins to vaporize at a temperature less than that required to boil water. Hydrocarbons with the lowest molecular weight vaporize at the lowest temperatures, whereas successively higher temperatures are required to distill larger molecules.

    B. Thermal Cracking

    The heavier portions of the crude oil were heated under pressure and at higher temperatures. This resulted in the large hydrocarbon molecules being split into smaller ones, so that the yield of gasoline from a barrel of crude oil was increased.

    C. Alkylation and Catalytic Cracking

    Two additional basic processes, alkylation and catalytic cracking, further increased the gasoline yield from a barrel of crude oil. Produces branched molecules in the gasoline boiling range that have superior properties—for example, higher antiknock ratings.

    參考資料:

    http://www.britannica.com/eb/article-9028047/crude...

    http://encarta.msn.com/encyclopedia_761576221_4/Pe...

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