Day 4

Passage 4

Tapping of Petroleum【1】

① Petroleum, or crude oil, is composed of various organic chemicals. It is found in large quantities below the surface of the Earth and is used as a fuel and as a raw material in the chemical industry. Petroleum is considered essential to modern development: the physical structure and way of life of the suburban communities that surround the great cities are the result of an ample and inexpensive supply of petroleum.【2】In addition, the goals of developing countries are based on the assumption of petroleum availability.

② In the 14th century, crude oil in some surface deposits was being distilled to obtain lubricants and medicinal products. But the Industrial Revolution in the 11th century brought about a search for new fuels and a need for good, cheap oil for lamps, and finally led to a great demand for crude oil. Before the appearance of oil wells, people had known that wells drilled for water and salt were occasionally infiltrated by petroleum, so the concept of drilling for crude oil itself soon followed. Many oil wells have been dug ever since and various drilling methods were also created to tap the oil from beneath the Earth.

③ Most oil wells in the United States are drilled by the rotary method, in which the drill string, a series of connected pipes, is supported by a derrick. The string is rotated by being coupled to the rotating table on the derrick floor. The drill bit at the end of the string is generally designed with three cone-shaped wheels tipped with hardened teeth. Drill cuttings are lifted continually to the surface by a circulating-fluid system driven by a pump.

④ Trapped crude oil is under pressure. Were it not trapped by impermeable rock it would have continued to migrate upward, because of the pressure differential caused by its buoyancy, until it escaped at the surface of the Earth. When a well bore is drilled into this pressured accumulation of oil, the oil expands into the low-pressure sink created by the well bore in communication with Earth's surface. Besides, most crude oils contain a significant amount of natural gas kept in solution by the high pressure in the reservoir. Once the gas comes out of the solution when the low pressure in the well bore is encountered, it immediately begins to expand. This expansion, together with the dilution of the column of oil by the less dense gas, results in the propulsion of oil up to Earth's surface. Later, when both the pressure within the reservoir and the amount of gas in solution gradually decreases, the fluid may not reach the surface, so a pump (an artificial lift) and other methods may be installed in the well bore to continue producing the crude oil.

⑤ 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 a battery of tanks, and later transported to a refinery by truck, railroad tank car, barge, or pipeline. In the refinery, crude oil is refined into products such as gasoline, asphalt, and waxes by a process called fractional distillation. During the process, the parts, or fractions, of crude oil are divided out successively by their increasing molecular weight. For instance, gasoline has a low molecular weight and vaporizes at a fairly low temperature. This means that at the appropriate temperature, while all of the rest of the oil is still in liquid form, gasoline may be separated out. The remaining oil goes through the same process at a slightly higher temperature, and jet fuel is divided out. Repeating the distillation process several times will separate out several constituents of crude oil, which are then processed and put to a wide range of uses.

——2012年 4月 20日北美机经

According to Paragraph 4, all the following contribute to the rise of crude oil to the earth surface EXCEPT ______ .

A. its being trapped by impermeable rock creates pressure

B. pressure differential caused by its buoyancy

C. the low-pressure in the well bore

D. the natural gas contained in the reservoir

词汇练习：

阅读下列句子，用所给单词（或词组）的正确形式填空：

solution

sink

rotary

refinery

propulsion

distill

deposit

couple

buoyancy

accumulation

1. The river that formed these ______ was actually not far from an ancient ocean known as the Tethys Sea.（OG：The Origins of Cetaceans）

2. We might think of chondrites as samples of ______ Sun, a sort of solar sludge from which only gases have been removed.（TPO-22：The Allende Meteorite）

3. A ______ engine attached to the steam engine enabled shafts to be turned and machines to be driven, resulting in mills using steam power to spin and weave cotton.（TPO-26：Energy and the Industrial Revolution）

4. ______ with these factors is the loss of the complex interactions among the muscles that can change the route of airflow from nose to mouth.（TPO-24：Breathing During Sleep）

5. On land, the supportive ______ of water is missing, the plant is no longer bathed in a nutrient solution, and air tends to dry things out.（TPO-21：The Evolutionary Origin of Plants）

6. Phosphorus-deficient plants are often stunted, with leaves turning a characteristic dark green, often with the ______ of anthocyanin.（TPO-1：Minerals and Plants）

7. The surface of the ground can ______ if hot groundwater is withdrawn without being replaced.（TPO-21：Geothermal Energy）

8. Once humans possessed such a mind, they were able to find an imaginative ______ to a situation of severe economic crisis such as the farming dilemma described earlier.（TPO-21：The Origins of Agriculture）

9. The large hind legs were used for ______ in water.（OG：The Origins of Cetaceans）

10. At a ______, the crude oil from underground is separated into natural gas, gasoline, kerosene, and various oils.（TPO-4：Petroleum Resources）

参考答案：

1. deposits

2. distilled

3. rotary

4. Coupled

5. buoyancy

6. accumulation

7. sink

8. solution

9. propulsion

10. refinery

【1】关于石油的其他内容，大家可参考 TPO-4中的“Petroleum Resources”这篇文章。

【2】与今日百句译（Sentence 4）相同的句型。