2024年3月30日发(作者：腾达wifi设置)

新托福TPO4阅读原文(三):Petroleum Resources

TPO-4-3：Petroleum Resources

Petroleum, consisting of crude oil and natural gas, seems to originate from

organic matter in marine sediment. Microscopic organisms settle to the seafloor

and accumulate in marine mud. The organic matter may partially decompose,

using up the dissolved oxygen in the sediment. As soon as the oxygen is gone,

decay stops and the remaining organic matter is preserved.

Continued sedimentation—the process of deposits’settling on the sea

bottom—buries the organic matter and subjects it to higher temperatures and

pressures, which convert the organic matter to oil and gas. As muddy sediments

are pressed together, the gas and small droplets of oil may be squeezed out of

the mud and may move into sandy layers nearby. Over long periods of time

(millions of years), accumulations of gas and oil can collect in the sandy layers.

Both oil and gas are less dense than water, so they generally tend to rise upward

through water-saturated rock and sediment.

Oil pools are valuable underground accumulations of oil, and oil fields are

regions underlain by one or more oil pools. When an oil pool or field has been

discovered, wells are drilled into the ground. Permanent towers, called derricks,

used to be built to handle the long sections of drilling pipe. Now portable drilling

machines are set up and are then dismantled and removed. When the well

reaches a pool, oil usually rises up the well because of its density difference with

water beneath it or because of the pressure of expanding gas trapped above it.

Although this rise of oil is almost always carefully controlled today, spouts of oil, or

gushers, were common in the past. Gas pressure gradually dies out, and oil is

pumped from the well. Water or steam may be pumped down adjacent wells to

help push the oil out. At a refinery, the crude oil from underground is separated

into natural gas, gasoline, kerosene, and various oils. Petrochemicals such as

dyes, fertilizer, and plastic are also manufactured from the petroleum.

As oil becomes increasingly difficult to find, the search for it is extended into

more-hostile environments. The development of the oil field on the North Slope of

Alaska and the construction of the Alaska pipeline are examples of the great

expense and difficulty involved in new oil discoveries. Offshore drilling platforms

extend the search for oil to the ocean’s continental shelves—those gently sloping

submarine regions at the edges of the continents. More than one-quarter of the

world’s oil and almost one-fifth of the world’s natural gas come from offshore,

even though offshore drilling is six to seven times more expensive than drilling on

land. A significant part of this oil and gas comes from under the North Sea

between Great Britain and Norway.

Of course, there is far more oil underground than can be recovered. It may be

in a pool too small or too far from a potential market to justify the expense of

drilling. Some oil lies under regions where drilling is forbidden, such as national

parks or other public lands. Even given the best extraction techniques, only about

30 to 40 percent of the oil in a given pool can be brought to the surface. The rest

is far too difficult to extract and has to remain underground.

Moreover, getting petroleum out of the ground and from under the sea and to

the consumer can create environmental problems anywhere along the line.

Pipelines carrying oil can be broken by faults or landslides, causing serious oil

spills. Spillage from huge oil-carrying cargo ships, called tankers, involved in

collisions or accidental groundings (such as the one off Alaska in 1989) can

create oil slicks at sea. Offshore platforms may also lose oil, creating oil slicks

that drift ashore and foul the beaches, harming the environment. Sometimes, the

ground at an oil field may subside as oil is removed. The Wilmington field near

Long Beach, California, has subsided nine meters in 50 years; protective barriers

have had to be built to prevent seawater from flooding the area. Finally, the

refining and burning of petroleum and its products can cause air pollution.

Advancing technology and strict laws, however, are helping control some of these

adverse environmental effects.

译文：TPO-4-3 石油资源

石油是由原油和天然气组成，似乎都源自于海洋的有机物沉淀。微小的有机

物沉积到海底并堆聚在海泥里，有机物会局部分解，消耗沉淀里的溶解氧，当氧

气消耗殆尽分解便停止，留下剩余的有机物。

持续的沉积——堆积物沉积到海底的过程将有机物埋在海底使之受到海底温

度、高压的影响，最终转变成石油和天然气。当泥状沉积物被挤压在一起时，天

然气和石油液滴会被挤出泥层，然后进入附近的沙层。经过很长的一个周期(数

百万年)，积聚的天然气和石油会在沙层中聚集。因为石油和天然气的密度都比

水低，所以他们通常通过饱含水的岩层和沉积物往上升。

油床是宝贵的地下石油积聚处，而油田是被一个或多个油藏覆盖区域。当人

们发现油藏或油田时，就会把井钻到地下。固定的塔称为井架，建造井架是为了

控制长距离的钻杆。现代使用的便携式钻井机安装使用完成后，会被拆除和移走。

因为石油的密度与在下层的水不同，或者因为石油上面的气体扩张形成的压力，