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Petroleum products, such as gasoline, kerosine, home heating oil,
residual fuel oil, and lubricating oils, come from one source crude
oil found below the earth's surface, as well as under large bodies
of water, from a few hundred feet below the surface to as deep as
5 25,000 feet into the earth's interior. Sometimes crude oil is secured
by drilling a hole through the earth, but more dry holes are drilled
than those producing oil. Pressure at the source or pumping forces
crude oil to the surface.
10 Crude oil wells flow at varying rates, from ten to thousands of barrels
per hour. Petroleum products are always measured in 42-gallon barrels.
Petroleum products vary greatly in physical appearance: thin, thick,
transparent or opaque, but regardless, their chemical composition
15 is made up of only two elements: carbon and hydrogen, which form
compounds called hydrocarbons. Other chemical elements found in union
with the hydrocarbons are few and are classified as impurities. Trace
elements are also found, but these are of such minute quantities
that they are disregarded. The combination of carbon and hydrogen
20 forms many thousands of compounds which are possible because of the
various positions and joinings of these two atoms in the hydrocarbon
molecule.
The various petroleum products are refined from the crude oil by heating
25 and condensing the vapors. These products are the so-called light
oils, such as gasoline, kerosine, and distillate oil. The residue
remaining after the light oils are distilled is known as heavy or
residual fuel oil and is used mostly for burning under boilers. Additional
complicated refining processes rearrange the chemical structure of
30 the hydrocarbons to produce other products, some of which are used
to upgrade and increase the octane rating of various styles of gasolines.
1. Which of the following is not true?
2. Many thousands of hydrocarbon compounds are possible because
3. Which of the following is true?
4. How is crude oil brought to the surface?
5. Which of the following is not listed as a light oil?
Xem lại bài Reading-Comprehension-Lesson 106 và bài Reading-Comprehension-Lesson 105
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